1
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Alesio J, Bothun GD. Differential scanning fluorimetry to assess PFAS binding to bovine serum albumin protein. Sci Rep 2024; 14:6501. [PMID: 38499613 PMCID: PMC10948889 DOI: 10.1038/s41598-024-57140-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Accepted: 03/14/2024] [Indexed: 03/20/2024] Open
Abstract
The rapid screening of protein binding affinity for poly- and perfluoroalkyl substances (PFAS) benefits risk assessment and fate and transport modelling. PFAS are known to bioaccumulate in livestock through contaminated food and water. One excretion pathway is through milk, which may be facilitated by binding to milk proteins such as bovine serum albumin (BSA). We report a label-free differential scanning fluorimetry approach to determine PFAS-BSA binding over a broad temperature range. This method utilizes the tryptophan residue within the protein binding pocket as an intrinsic fluorophore, eliminating the need for fluorophore labels that may influence binding. BSA association constants were determined by (a) an equilibrium-based model at the melting temperature of BSA and (b) the Hill adsorption model to account for temperature dependent binding and binding cooperativity. Differences in binding between PFAS and fatty acid analogs revealed that a combination of size and hydrophobicity drives PFAS binding.
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Affiliation(s)
- Jessica Alesio
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, 02881, USA
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, 02881, USA.
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2
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Poonia M, Kurtz K, Green-Gavrielidis L, Oyanedel-Craver V, Bothun GD. Electric Potential Induced Prevention and Removal of an Algal Biofoulant from Planar SERS Substrates. Environ Sci Technol 2023; 57:11666-11674. [PMID: 37499098 DOI: 10.1021/acs.est.3c02574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Ulva zoospores are widespread marine macroalgae and a common organism found in biofouling communities due to their strong adhesive properties and quick settlement times. Using Ulva as a model organism, a strategy is presented where direct-current (DC) electric potentials are applied in conjunction with surface-enhanced Raman spectroscopy (SERS) to characterize, remove, and prevent Ulva from forming a biofilm on gold-capped nanopillar SERS substrates. Experiments were conducted within a poly(tetrafluoroethylene) (PTFE) flow channel device where the SERS substrates were used as an electrode. Ulva density, determined in situ by SERS and ex situ by electron and fluorescence microscopy, decreased under successively increasing low negative potentials up to -1.0 V. The presence of damaged Ulva suggests that the applied potential led to spore rupture. At the highest negative applied potential (-1.0 V), microparticles containing copper, which is known for its antimicrobial properties, were associated with Ulva on the SERS substrate and the lowest Ulva density was observed. These findings indicate that (1) SERS can be employed to study biofilm formation on nanostructured metal surfaces and (2) applying low-voltage electric potentials may be used to control Ulva biofouling on SERS marine sensors.
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Affiliation(s)
- Monika Poonia
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Kayla Kurtz
- Department of Civil and Environmental Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Lindsay Green-Gavrielidis
- Department of Biology and Biomedical Sciences, Salve Regina University, Newport, Rhode Island 02840, United States
| | - Vinka Oyanedel-Craver
- Department of Civil and Environmental Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
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3
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Poonia M, Küster T, Bothun GD. Organic Anion Detection with Functionalized SERS Substrates via Coupled Electrokinetic Preconcentration, Analyte Capture, and Charge Transfer. ACS Appl Mater Interfaces 2022; 14:23964-23972. [PMID: 35522999 DOI: 10.1021/acsami.2c02934] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Detecting ultralow concentrations of anionic analytes in solution by surface-enhanced Raman spectroscopy (SERS) remains challenging due to their low affinity for SERS substrates. Two strategies were examined to enable in situ, liquid phase detection using 5(6)-carboxyfluorescein (5(6)-FAM) as a model analyte: functionalization of a gold nanopillar substrate with cationic cysteamine self-assembled monolayer (CA-SAM) and electrokinetic preconcentration (EP-SERS) with potentials ranging from 0 to +500 mV. The CA-SAM did not enable detection without an applied field, likely due to insufficient accumulation of 5(6)-FAM on the substrate surface limited by passive diffusion. 5(6)-FAM could only be reliably detected with an applied electric field with the charged molecules driven by electroconvection to the substrate surface and the SERS intensity following the Langmuir adsorption model. The obtained limits of detection (LODs) with an applied field were 97.5 and 6.4 nM on bare and CA-SAM substrates, respectively. For the CA-SAM substrates, both the ligand and analyte displayed an ∼15-fold signal enhancement with an applied field, revealing an additional enhancement due to charge-transfer resonance taking place between the metal and 5(6)-FAM that improved the LOD by an order of magnitude.
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Affiliation(s)
- Monika Poonia
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Timo Küster
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
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4
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Marques E, Pfohl M, Wei W, Tarantola G, Ford L, Amaeze O, Alesio J, Ryu S, Jia X, Zhu H, Bothun GD, Slitt A. Replacement per- and polyfluoroalkyl substances (PFAS) are potent modulators of lipogenic and drug metabolizing gene expression signatures in primary human hepatocytes. Toxicol Appl Pharmacol 2022; 442:115991. [PMID: 35337807 PMCID: PMC9036616 DOI: 10.1016/j.taap.2022.115991] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/03/2022] [Accepted: 03/18/2022] [Indexed: 01/12/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a class of environmental toxicants, and some, such as perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have been associated with hepatic steatosis in rodents and monkeys. It was hypothesized that perfluorosulfonic acids (C4, 6, 8), perfluorocarboxylic acids (C4-14), perfluoro(2-methyl-3-oxahexanoic) acid (HFPO-DA), 1H, 1H, 2H, 2H-perfluorooctanesulfonic acid (6:2 FTS) along with 3 PFOS precursors could induce expression of lipid metabolism genes and lipid deposition in human hepatocytes. Five-donor pooled cryopreserved human hepatocytes were cultured and treated with 0.1% DMSO vehicle or various PFAS (0.25 to 25 μM) in media. After a 48-h treatment, mRNA transcripts related to lipid transport, metabolism, and synthesis were measured using a Quantigene Plex assay. After 72-h treatments, hepatocytes were stained with Nile Red dye to quantify intracellular lipids. Overall, PFAS were transcriptionally active at 25 μM. In this model, lipid accumulation was not observed with C8-C12 treatments. Shorter chain PFAS (C4-C5), 6:2 FTS, and PFOS precursor, metFOSA, induced significant liver lipid accumulation, and gene activation at lower concentrations than legacy PFAS. In summary short chain PFAS and other alternative PFAS were more potent gene inducers, and potential health effects of replacement PFAS should be critically evaluated in humans.
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Affiliation(s)
- Emily Marques
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA
| | - Marisa Pfohl
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA
| | - Wei Wei
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA
| | - Giuseppe Tarantola
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA
| | - Lucie Ford
- Department of Biology and Biomedical Sciences, Salve Regina University, Newport, RI 02840, USA
| | - Ogochukwu Amaeze
- Department of Clinical Pharmacy & Biopharmacy, Faculty of Pharmacy, University of Lagos, Nigeria
| | - Jessica Alesio
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, USA
| | - Sangwoo Ryu
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, USA
| | - Xuelian Jia
- The Rutgers Center for Computational and Integrative Biology, Camden, NJ, USA
| | - Hao Zhu
- The Rutgers Center for Computational and Integrative Biology, Camden, NJ, USA; Department of Chemistry, Rutgers University, Camden, NJ, USA
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, USA
| | - Angela Slitt
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA.
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5
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Naumann A, Alesio J, Poonia M, Bothun GD. PFAS fluidize synthetic and bacterial lipid monolayers based on hydrophobicity and lipid charge. J Environ Chem Eng 2022; 10:107351. [PMID: 35463622 PMCID: PMC9029377 DOI: 10.1016/j.jece.2022.107351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Poly- and Perfluoroalkyl substances (PFASs) are pollutants of emerging concern that persist in nature and pose environmental health and safety risks. PFAS disrupt biological membranes resulting in cellular inhibition, but the mechanism of disruption and the role of lipid composition remain unclear. We examine the role of phospholipid saturation and headgroup charge on the interactions between PFASs and phospholipid monolayers comprised of synthetic phosphocholine (PC) and phosphoglycerol (PG) lipids and prepared from bacteria membrane extracts rich in PG lipids from an environmentally relevant marine bacterium Alcanivorax borkumensis. When deposited on a buffered subphase containing PFAS, PFAS mixed within and fluidized zwitterionic and net-anionic monolayers leading to increases in monolayer compressibility that were driven by a combination of PFAS hydrophobicity and monolayer charge density. Differences in the monolayer response using saturated or unsaturated lipids are attributed to the ability of the unsaturated lipids to accommodate PFAS within 'void space' arising from the bent lipid tails. Similar fluidization and compressibility behavior were also observed in A. borkumensis lipid monolayers. This work provides new insight into PFAS partitioning into bacterial membranes and the effect PFAS have on the physicomechanical properties of zwitterionic and charged lipid monolayers.
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Affiliation(s)
- Aleksandra Naumann
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881
| | - Jessica Alesio
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881
| | - Monika Poonia
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881
| | - Geoffrey D. Bothun
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881
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6
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Mkam Tsengam IK, Omarova M, Kelley EG, McCormick A, Bothun GD, Raghavan SR, John VT. Transformation of Lipid Vesicles into Micelles by Adding Nonionic Surfactants: Elucidating the Structural Pathway and the Intermediate Structures. J Phys Chem B 2022; 126:2208-2216. [PMID: 35286100 PMCID: PMC8958590 DOI: 10.1021/acs.jpcb.1c09685] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The phospholipid
lecithin (L) and the nonionic surfactant Tween
80 (T) are used together in various contexts, including in drug delivery
and oil spill remediation. There is hence a need to elucidate the
nanostructures in LT mixtures, which is the focus of this paper. We
study these mixtures using cryogenic transmission electron microscopy
(cryo-TEM), coupled with dynamic light scattering and small-angle
neutron scattering. As the concentration of Tween 80 is increased,
the vesicles formed by lecithin are transformed into spherical micelles.
We identify bicelles (i.e., disc-like micelles) as well as cylindrical
micelles as the key stable nanostructures formed at intermediate L/T
ratios. The bicelles have diameters ∼13–26 nm, and the
bicelle size decreases as the Tween 80 content increases. We propose
that the lecithin lipids form the body of the discs, while the Tween
80 surfactants occupy the rims. This hypothesis is consistent with
geometric arguments because lecithin is double-tailed and favors minimal
curvature, whereas the single-tailed Tween 80 molecules prefer curved
interfaces. In the case of cylindrical micelles, cryo-TEM reveals
that the micelles are short (length < 22 nm) and flexible. We are
able to directly visualize the microstructure of the aggregates formed
by lecithin–Tween 80 mixtures, thereby enhancing the understanding
of morphological changes in the lecithin–Tween 80 system.
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Affiliation(s)
- Igor Kevin Mkam Tsengam
- Department of Chemical and Biomolecular Engineering, Tulane University, 300 Lindy Boggs Building, New Orleans, Louisiana 70118, United States
| | - Marzhana Omarova
- Department of Chemical and Biomolecular Engineering, Tulane University, 300 Lindy Boggs Building, New Orleans, Louisiana 70118, United States
| | - Elizabeth G Kelley
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Alon McCormick
- Department of Chemical Engineering and Material Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 51 Lower College Road; Kingston, Rhode Island 02881, United States
| | - Srinivasa R Raghavan
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Vijay T John
- Department of Chemical and Biomolecular Engineering, Tulane University, 300 Lindy Boggs Building, New Orleans, Louisiana 70118, United States
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7
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Alesio JL, Slitt A, Bothun GD. Critical new insights into the binding of poly- and perfluoroalkyl substances (PFAS) to albumin protein. Chemosphere 2022; 287:131979. [PMID: 34450368 PMCID: PMC8612954 DOI: 10.1016/j.chemosphere.2021.131979] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 07/29/2021] [Accepted: 08/20/2021] [Indexed: 05/06/2023]
Abstract
With an increasing number of health-related impacts of per- and polyfluoroalkyl substances (PFAS) being reported, there is a pressing need to understand PFAS transport within both the human body and the environment. As proteins can serve as a primary transport mechanism for PFAS, understanding PFAS binding to proteins is essential for predictive physiological models where accurate values of protein binding constants are vital. In this work we present a critical analysis of three common models for analyzing PFAS binding to bovine serum albumin (BSA) based on fluorescence quenching: the Stern-Volmer model, the modified Stern-Volmer model, and the Hill equation. The PFAS examined include perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorobutanesulfonic acid (PFBS), perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), and the replacement compound 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate (HFPO-DA or GenX). While all three models capture the general effects of hydrophobicity and steric limitations to PFAS binding, the Hill equation highlighted a unique relationship between binding cooperativity and the number of fluorinated carbons, with PFOA exhibiting the greatest binding cooperativity. The significance of steric limitations was confirmed by comparing results obtained by fluorescence quenching, which is an indirect method based on specific binding, to those obtained by equilibrium dialysis where PFAS binding directly correlated with traditional measures of hydrophobicity. Finally, the binding constants were correlated with PFAS physicochemical properties where van der Waals volume best described the steric limitations observed by fluorescence quenching.
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Affiliation(s)
- Jessica L Alesio
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881, United States
| | - Angela Slitt
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, 7 Greenhouse Rd, Kingston, RI, 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881, United States.
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8
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Corcoran LG, Saldana Almaraz BA, Amen KY, Bothun GD, Raghavan SR, John VT, McCormick AV, Penn RL. Using Microemulsion Phase Behavior as a Predictive Model for Lecithin-Tween 80 Marine Oil Dispersant Effectiveness. Langmuir 2021; 37:8115-8128. [PMID: 34191521 DOI: 10.1021/acs.langmuir.1c00651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Marine oil dispersants typically contain blends of surfactants dissolved in solvents. When introduced to the crude oil-seawater interface, dispersants facilitate the breakup of crude oil into droplets that can disperse in the water column. Recently, questions about the environmental persistence and toxicity of commercial dispersants have led to the development of "greener" dispersants consisting solely of food-grade surfactants such as l-α-phosphatidylcholine (lecithin, L) and polyoxyethylenated sorbitan monooleate (Tween 80, T). Individually, neither L nor T is effective at dispersing crude oil, but mixtures of the two (LT blends) work synergistically to ensure effective dispersion. The reasons for this synergy remain unexplained. More broadly, an unresolved challenge is to be able to predict whether a given surfactant (or a blend) can serve as an effective dispersant. Herein, we investigate whether the LT dispersant effectiveness can be correlated with thermodynamic phase behavior in model systems. Specifically, we study ternary "DOW" systems comprising LT dispersant (D) + a model oil (hexadecane, O) + synthetic seawater (W), with the D formulation being systematically varied (across 0:100, 20:80, 40:60, 60:40, 80:20, and 100:0 L:T weight ratios). We find that the most effective LT dispersants (60:40 and 80:20 L:T) induce broad Winsor III microemulsion regions in the DOW phase diagrams (Winsor III implies that the microemulsion coexists with aqueous and oil phases). This correlation is generally consistent with expectations from hydrophilic-lipophilic deviation (HLD) calculations, but specific exceptions are seen. This study then outlines a protocol that allows the phase behavior to be observed on short time scales (ca. hours) and provides a set of guidelines to interpret the results. The complementary use of HLD calculations and the outlined fast protocol are expected to be used as a predictive model for effective dispersant blends, providing a tool to guide the efficient formulation of future marine oil dispersants.
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Affiliation(s)
- Louis G Corcoran
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Brian A Saldana Almaraz
- Washington Technology Magnet School, 1495 Rice Street, Saint Paul, Minnesota 55117, United States
| | - Kamilah Y Amen
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 51 Lower College Road, Kingston, Rhode Island 02881, United States
| | - Srinivasa R Raghavan
- Department of Chemical and Biomolecular Engineering, University of Maryland, 4418 Stadium Drive, College Park, Maryland 20742, United States
| | - Vijay T John
- Department of Chemical and Biomolecular Engineering, Tulane University, 300 Lindy Boggs Building, New Orleans, Louisiana 70112, United States
| | - Alon V McCormick
- Department of Chemical Engineering and Material Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
| | - R Lee Penn
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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9
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Küster T, Bothun GD. In situ SERS detection of dissolved nitrate on hydrated gold substrates. Nanoscale Adv 2021; 3:4098-4105. [PMID: 36132825 PMCID: PMC9418535 DOI: 10.1039/d1na00156f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/07/2021] [Indexed: 06/14/2023]
Abstract
The accurate and fast measurement of nitrate in seawater is important for monitoring and controlling water quality to prevent ecologic and economic disasters. In this work we show that the in situ detection of nitrate in aqueous solution is feasible at nanomolar concentrations through surface enhanced Raman spectroscopy (SERS) using native nanostructured gold substrates without surface functionalization. Spectra were analyzed as collected or after standard normal variate (SNV) normalization, which was shown through Principal Component Analysis (PCA) to reduce spectral variations between sample sets and improve Langmuir adsorption model fits. An additional normalization approach based on the substrate silicon template showed that silicon provided an internal standard that accounted for the spectral variance without the need for SNV normalization. Nitrate adsorption was well-described by the Langmuir adsorption model, consistent with an adsorbed monolayer, and a limit of detection of 64 nM nitrate was obtained in ultrapure water, representing environmentally relevant concentrations. Free energy calculations based on the Langmuir adsorption constants, approximating equilibrium adsorption constants, and calculated self-energy arising from image charge, accounting for electrostatic interactions with a polarizable nanostructured substrate, suggest that nitrate adsorption was partially driven by an entropy gain presumably due to dehydration of the gold substrate and/or nitrate ion. This work is being extended to determine if similar statistical and normalization methods can be applied to nitrate detection in complex natural waters where non-target ions and molecules are expected to interfere.
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Affiliation(s)
- Timo Küster
- Department of Chemical Engineering, University of Rhode Island 2 East Alumni Ave, Kingston RI 02881 USA +1-401-874-9518
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island 2 East Alumni Ave, Kingston RI 02881 USA +1-401-874-9518
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10
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Fedorenko M, Alesio J, Fedorenko A, Slitt A, Bothun GD. Dominant entropic binding of perfluoroalkyl substances (PFASs) to albumin protein revealed by 19F NMR. Chemosphere 2021; 263:128083. [PMID: 33297081 PMCID: PMC8479757 DOI: 10.1016/j.chemosphere.2020.128083] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 05/05/2023]
Abstract
Mechanistic insight into protein binding by poly- and perfluoroalkyl substances (PFASs) is critical to understanding how PFASs distribute and accumulate within the body and to developing predictive models within and across classes of PFASs. Fluorine nuclear magnetic resonance spectroscopy (19F NMR) has proven to be a powerful, yet underutilized tool to study PFAS binding; chemical shifts of each fluorine group reflect the local environment along the length of the PFAS molecule. Using bovine serum albumin (BSA), we report dissociation constants, Kd, for four common PFASs well below reported critical micelle concentrations (CMCs) - perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), and perfluorooctanesulfonic acid (PFOS) - as a function of temperature in phosphate buffered saline. Kd values were determined based on the difluoroethyl group adjacent to the anionic headgroups and the terminal trifluoromethyl groups. Our results indicate that the hydrophobic tails exhibit greater binding affinity relative to the headgroup, and that the binding affinities are generally consistent with previous results showing that greater PFAS hydrophobicity leads to greater protein binding. However, the binding mechanism was dominated by entropic hydrophobic interactions attributed to desolvation of the PFAS tails within the hydrophobic cavities of the protein and on the surface of the protein. In addition, PFNA appears to form hemimicelles on the protein surfaces below reported CMC values. This work provides a renewed approach to utilizing 19F NMR for PFAS-protein binding studies and a new perspective on the role of solvent entropy.
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Affiliation(s)
- Michael Fedorenko
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881, USA
| | - Jessica Alesio
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881, USA
| | - Anatoliy Fedorenko
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881, USA
| | - Angela Slitt
- Department of Biomedical & Pharmaceutical Sciences, University of Rhode Island, 7 Greenhouse Rd, Kingston, RI, 02881, USA
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 2 East Alumni Ave, Kingston, RI, 02881, USA.
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11
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Fernandes JC, Agrawal NR, Aljirafi FO, Bothun GD, McCormick AV, John VT, Raghavan SR. Does the Solvent in a Dispersant Impact the Efficiency of Crude-Oil Dispersion? Langmuir 2019; 35:16630-16639. [PMID: 31804836 DOI: 10.1021/acs.langmuir.9b02184] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Dispersants, used in the mitigation of oil spills, are mixtures of amphiphilic molecules (surfactants) dissolved in a solvent. The recent large-scale use of dispersants has raised environmental concerns regarding the safety of these materials. In response to these concerns, our lab has developed a class of eco-friendly dispersants based on blends of the food-grade surfactants, soy lecithin (L) and Tween 80 (T), in a solvent. We have shown that these "L/T dispersants" are very efficient at dispersing crude oil into seawater. The solvent for dispersants is usually selected based on factors like toxicity, volatility, or viscosity of the overall mixture. However, with regard to the dispersion efficiency of crude oil, the solvent is considered to play a negligible role. In this paper, we re-examine the role of solvent in the L/T system and show that it can actually have a significant impact on the dispersion efficiency. That is, the dispersion efficiency can be altered from poor to excellent simply by varying the solvent while keeping the same blend of surfactants. We devise a systematic procedure for selecting the optimal solvents by utilizing Hansen solubility parameters. The optimal solvents are shown to have a high affinity for crude oil and limited hydrophilicity. Our analysis further enables us to identify solvents that combine high dispersion efficiency, good solubility of the L/T surfactants, a low toxicity profile, and a high flash point.
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Affiliation(s)
- Jay C Fernandes
- Department of Chemical & Biomolecular Engineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Niti R Agrawal
- Department of Chemical & Biomolecular Engineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Futoon O Aljirafi
- Department of Chemical & Biomolecular Engineering , University of Maryland , College Park , Maryland 20742 , United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
| | - Alon V McCormick
- Department of Chemical Engineering & Materials Science , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Vijay T John
- Department of Chemical & Biomolecular Engineering , Tulane University , New Orleans , Louisiana 70118 , United States
| | - Srinivasa R Raghavan
- Department of Chemical & Biomolecular Engineering , University of Maryland , College Park , Maryland 20742 , United States
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12
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Pan A, Jakaria MG, Meenach SA, Bothun GD. Radiofrequency and Near-Infrared Responsive Core–Shell Nanostructures Using Layersome Templates for Cancer Treatment. ACS Appl Bio Mater 2019; 3:273-281. [DOI: 10.1021/acsabm.9b00797] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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13
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Hossain T, Bothun GD, Ilias S. Transport of liquid and supercritical CO 2 and selected organic solvents through surface modified mesoporous γ-alumina and titania membranes. SEP SCI TECHNOL 2019. [DOI: 10.1080/01496395.2019.1594901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Tashfin Hossain
- Department of Chemical, Biological & Bioengineering, North Carolina A&T State University, Greensboro, NC, USA
| | - Geoffrey D. Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, USA
| | - Shamsuddin Ilias
- Department of Chemical, Biological & Bioengineering, North Carolina A&T State University, Greensboro, NC, USA
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14
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Chakraborty S, Abbasi A, Bothun GD, Nagao M, Kitchens CL. Phospholipid Bilayer Softening Due to Hydrophobic Gold Nanoparticle Inclusions. Langmuir 2018; 34:13416-13425. [PMID: 30350687 DOI: 10.1021/acs.langmuir.8b02553] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Liposome-nanoparticle assemblies (LNAs) are vital in the context of novel targeted drug-delivery systems, in addition to investigating nanoparticle-lipid bilayer interactions. Quantifying membrane structural properties and dynamics in presence of nanoparticle inclusions provides a simple model to elucidate nanoparticle effects on membrane biophysical properties. We present experimental evidences of bilayer softening due to small hydrophobic gold nanoparticle inclusions. LNA structure has been investigated by a combination of cryo-transmission electron microscopy, dynamic light scattering, and small-angle neutron scattering. Neutron spin echo spectroscopy demonstrated a remarkable ∼15% bending modulus decrease for LNAs relative to pure liposomes. Clear dependence of bending modulus on gold nanoparticle diameter and concentration was observed from our observations. Our findings point toward local bilayer fluidization by nanoparticle inclusions leading to an overall bilayer softening. These findings add valuable information to liposomal drug-delivery vehicle design and membrane biophysics research.
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Affiliation(s)
- Saptarshi Chakraborty
- Department of Chemical and Biomolecular Engineering , Clemson University , Clemson , South Carolina 29634 , United States
| | - Akram Abbasi
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
| | - Michihiro Nagao
- NIST Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899 , United States
- Center for Exploration of Energy and Matter, Department of Physics , Indiana University , Bloomington , Indiana 47408 , United States
| | - Christopher L Kitchens
- Department of Chemical and Biomolecular Engineering , Clemson University , Clemson , South Carolina 29634 , United States
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15
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Abstract
Alcanivorax borkumensis (AB) is a marine bacterium that dominates bacterial communities around many oil spills because it enzymatically degrades the oil while using it as a nutrient source. Several dispersants have been used to produce oil-in-water emulsions following a spill. Compared to surface slicks, the additional oil-water surface area produced by emulsification provides greater access to the oil and accelerates its degradation. We deliberately cultured AB cells using hexadecane as the only nutrient source. We then examined the first critical step of the biodegradation process, the attachment of these AB cells to hexadecane-water interfaces, using fluorescence microscopy and cryogenic scanning electron microscopy. The hexadecane-in-artificial sea water (ASW) emulsions were produced by gentle shaking and were stabilized either by AB alone, by Corexit 9500, by Tween 20, or by carbon black particles. When no dispersants were used, AB stabilizes the emulsion, and bacterial cells attach to the hexadecane droplets within the first 3 days. When Corexit 9500 was used as the dispersant, AB did not attach to the hexadecane droplets over 3 days, and many AB cells in the aqueous phase appeared dead. Only limited attachment was observed after 7 days. No AB attachment was observed over 3 days when Tween 20 was used as the dispersant. However, the bacteria used Tween 20 in the ASW as a nutrient. Large amounts of AB attached to carbon black stabilized hexadecane droplets within 3 days. An analysis that accounts for van der Waals and electrostatic interactions is unable to predict all of these observations, indicating that the attachment of AB to the hexadecane is a complex phenomenon that goes beyond simple physiochemical effects. While these experiments do not mimic conditions in the open ocean where the large amount of water dilutes any emulsion stabilizer, they provide important insights on bacteria adhesion to oil, a critical step in the oil degradation process following a marine spill.
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Affiliation(s)
- Akram Abbasi
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
| | - Arijit Bose
- Department of Chemical Engineering , University of Rhode Island , Kingston , Rhode Island 02881 , United States
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16
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Ganji N, Khan IA, Bothun GD. Surface Activity of Poly(ethylene glycol)-Coated Silver Nanoparticles in the Presence of a Lipid Monolayer. Langmuir 2018; 34:2039-2045. [PMID: 29309159 DOI: 10.1021/acs.langmuir.7b03743] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We have investigated the surface activity of poly(ethylene glycol) (PEG)-coated silver nanoparticles (Ag-PEG) in the presence or absence of lipid monolayers comprised of monounsaturated dioleoylphosphocholine and dioleoylphosphoglycerol (DOPC/DOPG; 1:1 mol ratio). Dynamic measurements of surface pressure demonstrated that Ag-PEG were surface-active at the air/water interface. Surface excess concentrations suggested that at high Ag-PEG subphase concentrations, Ag-PEG assembled as densely packed monolayers in the presence and absence of a lipid monolayer. The presence of a lipid monolayer led to only a slight decrease in the excess surface concentration of Ag-PEG. Surface pressure-area isotherms showed that in the absence of lipids Ag-PEG increased the surface pressure up to 45 mN m-1 upon compression before the Ag-PEG surface layer collapsed. Our results suggest that surface activity of Ag-PEG was due to hydrophobic interactions imparted by a combination of the amphiphilic polymer coating and the hydrophobic dodecanethiol ligands bound to the Ag-PEG surface. With lipid present, Ag-PEG + lipid surface pressure-area (π-A) isotherms reflected Ag-PEG incorporation within the lipid monolayers. At high Ag-PEG concentrations, the π-A isotherms of the Ag-PEG + lipid films closely resembled that of Ag-PEG alone with a minimal contribution from the lipids present. Analysis of the subphase silver (Ag) and phosphorus (P) concentrations revealed that most of the adsorbed material remained at the air/lipid/water interface and was not forced into the aqueous subphase upon compression, confirming the presence of a composite Ag-PEG + lipid film. While interactions between "water-soluble" nanoparticles and lipids are often considered to be dominated by electrostatic interactions, these results provide further evidence that the amphiphilic character of a nanoparticle coating can also play a significant role.
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Affiliation(s)
- Nasim Ganji
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kinston, Rhode Island 02881, United States
| | - Iftheker A Khan
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kinston, Rhode Island 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kinston, Rhode Island 02881, United States
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17
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Preiss MR, Cournoyer E, Paquin KL, Vuono EA, Belanger K, Walsh E, Howlett NG, Bothun GD. Tuning the Multifunctionality of Iron Oxide Nanoparticles Using Self-Assembled Mixed Lipid Layers. Bioconjug Chem 2017; 28:2729-2736. [PMID: 29035511 DOI: 10.1021/acs.bioconjchem.7b00483] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We present an approach to tuning the multifunctionality of iron oxide nanoparticles (IONs) using mixed self-assembled monolayers of cationic lipid and anionic polyethylene glycol (PEG) lipid. By forming stable, monodispersed lipid-coated IONs (L-IONs) through a solvent-exchange technique, we were able to demonstrate the relationship between surface charge, the magnetic transverse relaxivity (r2 from T2-weighted images), and the binding capacity of small interfering ribonucleic acids (siRNAs) as a function of the cationic-to-anionic (PEG) lipid ratio. These properties were controlled by the cationic charge and the PEG conformation; relaxivity and siRNA binding could be varied in the mushroom and brush regimes but not at high brush densities. In vitro results combining cell viability, uptake, and transfection efficiency using HeLa cells suggest that the functional physicochemical and biological properties of L-IONs may be best achieved using catanionic lipid coatings near equimolar ratios of cationic to anionic PEG-lipids.
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Affiliation(s)
- Matthew R Preiss
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kingston, Rhode Island 02881, United States
| | - Eily Cournoyer
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kingston, Rhode Island 02881, United States
| | - Karissa L Paquin
- Department of Cell and Molecular Biology, University of Rhode Island , 379 CBLS, 120 Flagg Road, Kingston, Rhode Island 02881, United States
| | - Elizabeth A Vuono
- Department of Cell and Molecular Biology, University of Rhode Island , 379 CBLS, 120 Flagg Road, Kingston, Rhode Island 02881, United States
| | - Kayla Belanger
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kingston, Rhode Island 02881, United States
| | - Edward Walsh
- Department of Neuroscience, Department of Diagnostic Imaging, Institute for Brain Science, Institute for Molecular and Nanoscale Innovation, Associate Director for MRI Physics, Brown University , Sidney E. Frank Hall, 185 Meeting Street, Providence, Rhode Island 02912, United States
| | - Niall G Howlett
- Department of Cell and Molecular Biology, University of Rhode Island , 379 CBLS, 120 Flagg Road, Kingston, Rhode Island 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kingston, Rhode Island 02881, United States
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18
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Xia Y, Jang HS, Shen Z, Bothun GD, Li Y, Nieh MP. Effects of Membrane Defects and Polymer Hydrophobicity on Networking Kinetics of Vesicles. Langmuir 2017; 33:5745-5751. [PMID: 28510460 DOI: 10.1021/acs.langmuir.7b00373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The kinetics of clustering unilamellar vesicles induced by inverse Pluronics [poly(propylene oxide)m-poly(ethylene oxide)n-poly(propylene oxide)m, POm-EOn-POm] was investigated via experiments and molecular dynamic simulations. Two important factors for controlling the networking kinetics are the membrane defects, presumably located at the interfacial region between two lipid domains induced by acyl chain mismatch, and the polymer hydrophobicity. As expected, the clustering rate increases significantly with increasing bilayer defects on the membrane where the insertion of PPO is likely to take place because of the reduced energy barrier for the insertion of PO. The hydrophobic interaction between the PO blocks and membranes with the defects region dictates the "anchoring" kinetics, which is controlled by the association-dissociation of PO with the lipid membrane. As a result, the dependence of clustering rate on polymer concentration is strongly influenced by the hydrophobicity of the PO blocks. Nevertheless, longer PO blocks show stronger association with the membrane, resulting in faster consumption of the "active" sites made of these defect regions (causing mostly "invalid" insertions) with increasing polymer concentration, hence inhibiting the formation of large networking clusters, while shorter PO blocks undergo more frequent association with/dissociation from the defects, allowing continuous formation of larger clusters with increasing polymer concentration. This study provides important insights into how the organization and dynamics of a biomembrane influence its interaction with foreign amphiphilic molecules.
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Affiliation(s)
| | - Hyun-Sook Jang
- Center for Soft and Living Matter (CSLM), Institute for Basic Science (IBS) , Ulju-gun, Ulsan 689-798, Republic of Korea
| | | | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island , Kingston, Rhode Island 02881, United States
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19
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Abstract
Anionic liposomes coated with cationic polyelectrolyte poly-l-lysine (PLL), or layersomes, were used as soft, self-assembled templates for synthesizing gold nanoshells that absorb near-infrared radiation. The gold nanoshells were formed using two techniques: (a) direct reduction of tetrachloroauric acid on the layersomes and (b) the reduction of a tetrachloroauric acid/potassium carbonate "growth" solution on nanosized gold seeds bound to the surface of layersomes. The resulting structures were characterized by transmission and scanning electron microscopy and visible-near-infrared spectroscopy. Direct reduction produced discrete gold nanoparticles on the layersomes. The slower reduction from the growth solution on the gold seeds resulted in more complete shells. The absorption spectra of these suspensions were sensitive to the synthesis method. The morphology of the gold shells was tuned for absorption at biologically safe and tissue-penetrating NIR wavelengths, and laser irradiation at 810 nm produced significant heat. These gold-layersome nanoshells have the potential to be used for photothermal therapy, photothermally mediated drug delivery, and biomedical imaging.
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Affiliation(s)
- Akram Abbasi
- Department of Chemical Engineering, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Keunhan Park
- Department of Mechanical Engineering, University of Utah , Salt Lake City, Utah 84112, United States
| | - Arijit Bose
- Department of Chemical Engineering, University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island , Kingston, Rhode Island 02881, United States
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20
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Abstract
Understanding the effect of embedded nanoparticles on the characteristics and behavior of lipid bilayers is critical to the development of lipid-nanoparticle assemblies (LNAs) for biomedical applications. In this work we investigate the effect of hydrophobic nanoparticle size and concentration on liposomal thermal release behavior. Decorated LNAs (D-LNAs) were formed by embedding 2 nm (GNP2) and 4 nm (GNP4) dodecanethiol-capped gold nanoparticles into DPPC liposomes at lipid to nanoparticle ratios (L:N) of 25,000:1, 10,000:1, and 5,000:1. D-LNA structure was investigated by cryogenic transmission electron microscopy, and lipid bilayer permeability and phase behavior were investigated based on the leakage of a model drug, carboxyfluorescein, and by differential scanning calorimetry, respectively. The presence of bilayer nanoparticles caused changes in the lipid bilayer release and phase behavior compared to pure lipid controls at very low nanoparticle to bilayer volume fractions (0.3%-4.6%). Arrhenius plots of the thermal leakage show that GNP2 led to greater increases in the leakage energy barrier compared to GNP4, consistent with GNP4 causing greater bilayer disruption due to their size relative to the bilayer thickness. Embedding hydrophobic nanoparticles as permeability modifiers is a unique approach to controlling liposomal leakage based on nanoparticle size and concentration.
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Affiliation(s)
- Matthew Ryan Preiss
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kingston, Rhode Island 02881, United States
| | - Ashley Hart
- Department of Chemical and Biomolecular Engineering, Clemson University , 130 Earle Hall, Clemson, South Carolina 29634, United States
| | - Christopher Kitchens
- Department of Chemical and Biomolecular Engineering, Clemson University , 130 Earle Hall, Clemson, South Carolina 29634, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island , 51 Lower College Road, Kingston, Rhode Island 02881, United States
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21
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Bothun GD, Ganji N, Khan IA, Xi A, Bobba C. Anionic and Cationic Silver Nanoparticle Binding Restructures Net-Anionic PC/PG Monolayers with Saturated or Unsaturated Lipids. Langmuir 2017; 33:353-360. [PMID: 27966970 DOI: 10.1021/acs.langmuir.6b02003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have examined the interactions between polymer-coated anionic (Ag-COOH) and cationic (Ag-NH) silver nanoparticles, and net-anionic lipid monolayers using dynamic surface pressure measurements. Monolayers composed of saturated or monounsaturated mixtures of anionic phosphatidylglycerol (PG) and zwitterionic phosphatidylcholine (PC) lipids (3:1 molar ratio) were used to determine how lipid packing and monolayer phase state influence the extent of nanoparticle binding and the monolayer response. Anionic Ag-COOH inserted into saturated dipalmitoyl-PC/PG (DPPC/DPPG) and dioleoyl-PC/PG (DOPC/DOPG) monolayers at a low initial surface pressure (10 mN m-1) and caused lipid condensation at high initial surface pressures (20 and 30 mN m-1). Hydrophobic interactions were responsible for insertion, while electrostatic and charge-dipole interactions with PCs were responsible for condensation. In contrast, cationic Ag-NH inserted only into saturated DPPC/DPPG monolayers and otherwise led to lipid condensation. For Ag-NH, adsorption was driven primarily by electrostatic interactions with PGs. Analysis of the subphase Ag and phosphorus concentrations confirmed that Ag-NH had a higher degree binding compared to Ag-COOH, and that the monolayer response was not due to lipid extraction.
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Affiliation(s)
- G D Bothun
- Department of Chemical Engineering, University of Rhode Island , 16 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - N Ganji
- Department of Chemical Engineering, University of Rhode Island , 16 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - I A Khan
- Department of Chemical Engineering, University of Rhode Island , 16 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - A Xi
- Department of Chemical Engineering, University of Rhode Island , 16 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - C Bobba
- Department of Chemical Engineering, University of Rhode Island , 16 Greenhouse Road, Kingston, Rhode Island 02881, United States
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22
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Kashcooli Y, Park K, Bose A, Greenfield M, Bothun GD. Patchy Layersomes Formed by Layer-by-Layer Coating of Liposomes with Strong Biopolyelectrolytes. Biomacromolecules 2016; 17:3838-3844. [DOI: 10.1021/acs.biomac.6b01467] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Yaser Kashcooli
- Department
of Chemical Engineering, University of Rhode Island, 16 Greenhouse
Road, Kingston, Rhode Island 02881, United States
| | - Keunhan Park
- Department
of Mechanical Engineering, University of Utah, 1495 E 100 S, Salt Lake City, Utah 84112, United States
| | - Arijit Bose
- Department
of Chemical Engineering, University of Rhode Island, 16 Greenhouse
Road, Kingston, Rhode Island 02881, United States
| | - Michael Greenfield
- Department
of Chemical Engineering, University of Rhode Island, 16 Greenhouse
Road, Kingston, Rhode Island 02881, United States
| | - Geoffrey D. Bothun
- Department
of Chemical Engineering, University of Rhode Island, 16 Greenhouse
Road, Kingston, Rhode Island 02881, United States
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23
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Abstract
A generalized thermomechanical model for adhesion was developed to elucidate the mechanisms of dissipation within the viscoelastic bulk of a hyperelastic hydrogel. Results show that in addition to the expected energy release rate of interface formation, as well as the viscous flow dissipation, the bulk composition exhibits dissipation due to phase inhomogeneity morphological changes. The mixing thermodynamics of the matrix and solvent determines the dynamics of the phase inhomogeneities, which can enhance or disrupt adhesion. The model also accounts for the time-dependent behaviour. A parameter is proposed to discern the dominant dissipation mechanism in hydrogel contact detachment.
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Affiliation(s)
- J R Torres
- Devices, Sensors and Materials R&D Branch, Sensors and SONAR Systems Department, Naval Undersea Warfare Center, Newport, RI, USA; School of Engineering, Brown University, Providence, RI, USA
| | - G D Jay
- School of Engineering , Brown University , Providence, RI, USA
| | - K-S Kim
- School of Engineering , Brown University , Providence, RI, USA
| | - G D Bothun
- College of Engineering , University of Rhode Island , Kingston, RI, USA
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24
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Riehm DA, Neilsen JE, Bothun GD, John VT, Raghavan SR, McCormick AV. Efficient dispersion of crude oil by blends of food-grade surfactants: Toward greener oil-spill treatments. Mar Pollut Bull 2015; 101:92-97. [PMID: 26589641 DOI: 10.1016/j.marpolbul.2015.11.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 05/23/2023]
Abstract
Effectiveness of oil spill dispersants containing lecithin/Tween 80 (L/T) blends in ethanol was measured as a function of L:T ratio, surfactant:solvent ratio, solvent composition, and dispersant:oil ratio (DOR) using baffled flask dispersion effectiveness tests. Optimal L:T ratios are between 60:40 and 80:20 (w/w); at higher L:T ratios, effectiveness is limited by high interfacial tension, while at lower L:T ratios, insufficient lecithin is present to form a well-packed monolayer at an oil-water interface. These optimal L:T ratios retain high effectiveness at low DOR: 80:20 (w/w) L:T dispersant is 89% effective at 1:25 DOR (v/v) and 77% effective at 1:100 DOR (v/v). Increasing surfactant:solvent ratio increases dispersant effectiveness even when DOR is proportionally reduced to keep total surfactant concentration dosed into the oil constant. Replacing some of the ethanol with octane or octanol also increases dispersant effectiveness, suggesting that ethanol's hydrophilicity lowers dispersant-oil miscibility, and that more hydrophobic solvents would increase effectiveness.
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Affiliation(s)
- David A Riehm
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, United States
| | - John E Neilsen
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston, RI 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston, RI 02881, United States
| | - Vijay T John
- Department of Chemical & Biomolecular Engineering, Tulane University, New Orleans, LA 70118, United States
| | - Srinivasa R Raghavan
- Department of Chemical & Biomolecular Engineering, University of Maryland, College Park, MD 20742, United States
| | - Alon V McCormick
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, United States.
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25
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Bothun GD, Boltz L, Kurniawan Y, Scholz C. Cooperative effects of fatty acids and n-butanol on lipid membrane phase behavior. Colloids Surf B Biointerfaces 2015; 139:62-7. [PMID: 26700234 DOI: 10.1016/j.colsurfb.2015.11.054] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 11/24/2015] [Accepted: 11/26/2015] [Indexed: 11/25/2022]
Abstract
Biodiesel-derived crude glycerol can be fermented to produce n-butanol, which is a platform chemical for biorefining and a biofuel. One limitation to crude glycerol fermentation is the presence of long-chain fatty acids (FAs) that can partition into cellular membranes, leading to membrane fluidization and interdigitation, which can inhibit cellular function. In this work, we have examined the phase behavior of dipalmitoylphosphatidylcholine (DPPC, C16:0) membranes and the membrane partitioning of n-butanol as a function of FA degree of unsaturation (steric, oleic, and linoleic acids) using differential scanning calorimetry (DSC) and monolayer surface pressure studies. All three FAs at 15mol% (85mol% DPPC) prevented interdigitation by n-butanol based on the DSC results. n-Butanol partitioning and membrane expansion was greatest for DPPC/oleic acid membranes, where monounsaturated oleic acid (OA, C18:1) was miscible in gel and fluid phase DPPC. Saturated steric acid (SA, C18:0), which ordered the membranes and yielded a SA-rich phase during melting, led to a modest increase in n-butanol partitioning compared to DPPC alone. Di-unsaturated linoleic acid (LA, C18:2), which disordered the membranes and phase separated, had little affect on n-butanol partitioning into the DPPC-rich phases. The effects of OA and LA are attributed to the additional interfacial area provided by these FAs due to acyl tail 'kinks' at the carbon double bonds. These results show that exogenous FAs can partition into membranes, impacting n-butanol partitioning and acting cooperatively with n-butanol to alter membrane structure.
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Affiliation(s)
- Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI, United States.
| | - Lauren Boltz
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI, United States
| | - Yogi Kurniawan
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI, United States
| | - Carmen Scholz
- Department of Chemistry, University of Alabama in Huntsville, 301 Sparkman Dr, Huntsville, AL, United States
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26
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Gupta A, Sender M, Fields S, Bothun GD. Phase and sedimentation behavior of oil (octane) dispersions in the presence of model mineral aggregates. Mar Pollut Bull 2014; 87:164-170. [PMID: 25172613 DOI: 10.1016/j.marpolbul.2014.07.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 07/24/2014] [Accepted: 07/25/2014] [Indexed: 06/03/2023]
Abstract
Adsorption of suspended particles to the interface of surfactant-dispersed oil droplets can alter emulsion phase and sedimentation behavior. This work examines the effects of model mineral aggregates (silica nanoparticle aggregates or SNAs) on the behavior of oil (octane)-water emulsions prepared using sodium bis(2-ethylhexyl) sulfosuccinate (DOSS). Experiments were conducted at different SNA hydrophobicities in deionized and synthetic seawater (SSW), and at 0.5mM and 2.5mM DOSS. SNAs were characterized by thermogravimetric analysis (TGA) and dynamic light scattering (DLS), and the emulsions were examined by optical and cryogenic scanning electron microscopy. In deionized water, oil-in-water emulsions were formed with DOSS and the SNAs did not adhere to the droplets or alter emulsion behavior. In SSW, water-in-oil emulsions were formed with DOSS and SNA-DOSS binding through cation bridging led to phase inversion to oil-in-water emulsions. Droplet oil-mineral aggregates (OMAs) were observed for hydrophilic SNAs, while hydrophobic SNAs yielded quickly sedimenting agglomerated OMAs.
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Affiliation(s)
- Anju Gupta
- Department of Chemistry & Biology, Department of Engineering, Mathematics, and Physics, Texas A&M International University, 5201 University Blvd, Laredo, TX 78041, United States
| | - Maximilian Sender
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI 02881, United States
| | - Sarah Fields
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI 02881, United States.
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27
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Chen Y, Chen Y, Xiao D, Bose A, Deng R, Bothun GD. Low-dose chemotherapy of hepatocellular carcinoma through triggered-release from bilayer-decorated magnetoliposomes. Colloids Surf B Biointerfaces 2014; 116:452-8. [PMID: 24549047 DOI: 10.1016/j.colsurfb.2014.01.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/10/2014] [Accepted: 01/12/2014] [Indexed: 02/05/2023]
Abstract
Low-dose (LD) chemotherapy is a promising treatment strategy that may be improved by controlled delivery. Polyethylene glycol-stabilized bilayer-decorated magnetoliposomes (dMLs) have been designed as a stimuli-responsive LD chemotherapy drug delivery system and tested in vitro using Huh-7 hepatocellular carcinoma cell line. The dMLs contained hydrophobic superparamagnetic iron oxide nanoparticles within the lipid bilayer and doxorubicin hydrochloride (DOX, 2 μM) within the aqueous core. Structural analysis by cryogenic transmission electron microscopy and dynamic light scattering showed that the assemblies were approximately 120 nm in diameter. Furthermore, the samples consisted of a mixture of dMLs and bare liposomes (no nanoparticles), which provided dual burst and spontaneous DOX release profiles, respectively. Cell viability results show that the cytotoxicity of DOX-loaded dMLs was similar to that of bare dMLs (∼10%), which indicates that spontaneous DOX leakage had little cytotoxic effect. However, when subjected to a physiologically acceptable radiofrequency (RF) electromagnetic field, cell viability was reduced up to 40% after 8h and significant cell death (>90%) was observed after 24h. The therapeutic mechanism was intracellular RF-triggered DOX release from the dMLs and not intracellular hyperthermia due to nanoparticle heating via magnetic losses.
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Affiliation(s)
- Yanjing Chen
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston, RI 02881, United States
| | - Yuan Chen
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, 7 Greenhouse Road, Kingston, RI 02881, United States
| | - Da Xiao
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, 7 Greenhouse Road, Kingston, RI 02881, United States
| | - Arijit Bose
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston, RI 02881, United States
| | - Ruitang Deng
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, 7 Greenhouse Road, Kingston, RI 02881, United States
| | - Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston, RI 02881, United States.
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Abstract
Nanotoxicity studies have shown that both carbon-based and inorganic engineered nanoparticles can be toxic to microorganisms. Although the pathways for cytotoxicity are diverse and dependent upon the nature of the engineered nanoparticle and the chemical environment, numerous studies have provided evidence that direct contact between nanoparticles and bacterial cell membranes is necessary for cell inactivation or damage, and may in fact be a primary mechanism for cytotoxicity. The propensities for nanoparticles to attach to and disrupt cell membranes are still not well understood due to the heterogeneous and dynamic nature of biological membranes. Model biological membranes can be employed for systematic investigations of nanoparticle-membrane interactions. In this article, current and emerging experimental approaches to identify the key parameters that control the attachment of ENPs on model membranes and the disruption of membranes by ENPs will be discussed. This critical information will help enable the "safe-by-design" production of engineered nanoparticles that are nontoxic or biocompatible, and also allow for the design of antimicrobial nanoparticles for environmental and biomedical applications.
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Affiliation(s)
- Kai Loon Chen
- Department of Geography and Environmental Engineering, Johns Hopkins University , Baltimore, Maryland 21218-2686
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Shirazi AN, Oh D, Tiwari RK, Sullivan B, Gupta A, Bothun GD, Parang K. Peptide amphiphile containing arginine and fatty acyl chains as molecular transporters. Mol Pharm 2013; 10:4717-27. [PMID: 24215132 PMCID: PMC3873380 DOI: 10.1021/mp400539r] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Peptide amphiphiles (PAs) are promising tools for the intracellular delivery of numerous drugs. PAs are known to be biodegradable systems. Here, four PA derivatives containing arginine and lysine conjugated with fatty acyl groups with different chain lengths, namely, PA1: R-K(C14)-R, PA2: R-K(C16)-R, PA3: K(C14)-R-K(C14), and PA4: K(C16)-R-K(C16), where C16 = palmitic acid and C14 = myristic acid, were synthesized through Fmoc chemistry. Flow cytometry studies showed that, among all synthesized PAs, only K(C16)-R-K(C16), PA4 was able to enhance the cellular uptake of a fluorescence-labeled anti-HIV drug 2',3'-dideoxy-3'-thiacythidine (F'-3TC, F' = fluorescein) and a biologically important phosphopeptide (F'-PEpYLGLD) in human leukemia cells (CCRF-CEM) after 2 h incubation. For example, the cellular uptake of F'-3TC and F'-PEpYLGLD was enhanced approximately 7.1- and 12.6-fold in the presence of the PA4 compared to those of the drugs alone. Confocal microscopy of F'-3TC and F'-PEpYLGLD loaded PA4 in live cells showed significantly higher intracellular localization than the drug alone in human ovarian cells (SK-OV-3) after 2 h incubation. The high-performance liquid chromatography (HPLC) results showed that loading of Dox by the peptide amphiphile was 56% after 24 h. The loaded Dox was released (34%) within 48 h intracellularly. The circular dichrosim (CD) results exhibited that the secondary structure of the peptide was changed upon interactions with Dox. Mechanistic studies revealed that endocytosis is the major pathway of the internalization. These studies suggest that PAs containing the appropriate sequence of amino acids, chain length, charge, and hydrophobicity can be used as cellular delivery tools for transporting drugs and biomolecules.
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Affiliation(s)
- Amir Nasrolahi Shirazi
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
- School of Pharmacy, Chapman University, Orange, California 92866, United States
| | - Donghoon Oh
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Rakesh Kumar Tiwari
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
- School of Pharmacy, Chapman University, Orange, California 92866, United States
| | - Brian Sullivan
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Anju Gupta
- Department of Biology and Chemistry, Department of Engineering, College of Arts and Sciences, Texas A&M International University, Laredo, Texas 78041, United States
| | - Geoffrey D. Bothun
- Department of Chemical Engineering, College of Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
| | - Keykavous Parang
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island 02881, United States
- School of Pharmacy, Chapman University, Orange, California 92866, United States
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Abstract
Cellular adaptation to elevated alcohol concentration involves altering membrane lipid composition to counteract fluidization. However, few studies have examined the biophysical response of biologically relevant heterogeneous membranes. Lipid phase behavior, molecular packing, and elasticity have been examined by surface pressure-area (π-A) analysis in mixed monolayers composed of saturated dipalmitoylphosphatidylcholine (DPPC) and unsaturated dioleoylphosphatidylcholine (DOPC) as a function of DOPC and n-butanol concentration. n-Butanol partitioning into DPPC monolayers led to lipid expansion and increased elasticity. Greater lipid expansion occurred with increasing DOPC concentration, and a maximum was observed at equimolar DPPC:DOPC consistent with n-butanol partitioning between coexisting liquid expanded (LE, DOPC) phases and liquid condensed (LC, DPPC) domains. This led to distinct changes in the size and morphology of LC domains. In DOPC-rich monolayers the effect of n-butanol adsorption on π-A behavior was less pronounced due to DOPC tail kinking. These results point to the importance of lipid composition and phase coexistence on n-butanol partitioning and monolayer restructuring.
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Affiliation(s)
- Yogi Kurniawan
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd., Kingston, Rhode Island 02881, United States
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Kurniawan Y, Venkataramanan KP, Piernavieja M, Scholz C, Bothun GD. Role of Ionic Strength on n-Butanol Partitioning into Anionic Dipalmitoyl Phosphatidylcholine/Phosphatidylglycerol Vesicles. J Phys Chem B 2013; 117:8484-9. [DOI: 10.1021/jp403735h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yogi Kurniawan
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston,
Rhode Island, United States
| | - Keerthi P. Venkataramanan
- Biotechnology Science and Engineering
Program, University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama, United States
| | - Mar Piernavieja
- Department of Chemical and Materials
Engineering, University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama, United States
| | - Carmen Scholz
- Department of Chemistry, University of Alabama in Huntsville, 301 Sparkman Drive,
Huntsville, Alabama, United States
| | - Geoffrey D. Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston,
Rhode Island, United States
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Von White G, Chen Y, Roder-Hanna J, Bothun GD, Kitchens CL. Structural and thermal analysis of lipid vesicles encapsulating hydrophobic gold nanoparticles. ACS Nano 2012; 6:4678-85. [PMID: 22632177 DOI: 10.1021/nn2042016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The structure and stability of hybrid lipid vesicles containing bilayer-encapsulated hydrophobic nanoparticles is dependent upon lipid phase behavior. By embedding stearylamine-stabilized gold nanoparticles in dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylglycerol vesicles, we show that encapsulation at lipid to nanoparticle ratios from 10,000:1 to 5000:1 leads to bilayer thickening and hydrophobic mismatch, favoring nanoparticle inclusion in gel phase vesicles. High loadings lead to large increases in the gel to fluid melting temperature upon heating and significant hysteresis on cooling, which cannot be attributed solely to excess free ligand. This behavior is due to a cooperative effect of excess free SA ligand and nanoparticle embedment. Nanoparticle clustering was observed during lipid melting and could be reversed upon lipid freezing owing to lateral capillary forces within the bilayer. The impact of nanoparticle embedment on vesicle structure and properties at such low concentrations is reminiscent of hydrophobic proteins, suggesting that the underlying lipid biophysics between proteins and nanoparticle are similar and may provide a predictive design tool for therapeutic applications.
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Affiliation(s)
- Gregory Von White
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, South Carolina 29634, USA
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Affiliation(s)
- Yogi Kurniawan
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston,
Rhode Island 02881, United States
| | - Keerthi P. Venkataramanan
- Biotechnology Science and Engineering
program, University of Alabama in Huntsville, 301 Sparkman Dr., Huntsville, Alabama 35899, United States
| | - Carmen Scholz
- Department of Chemistry, University of Alabama in Huntsville, 301 Sparkman Dr.,
Huntsville, Alabama 35899, United States
| | - Geoffrey D. Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston,
Rhode Island 02881, United States
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Chen Y, Bothun GD. Cationic gel-phase liposomes with "decorated" anionic SPIO nanoparticles: morphology, colloidal, and bilayer properties. Langmuir 2011; 27:8645-8652. [PMID: 21649441 DOI: 10.1021/la2011138] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The assembly and complexation of oppositely charged colloids are important phenomena in many natural and synthetic processes. Liposome-nanoparticle assemblies (LNAs) represent an interesting hybrid system that combines "soft" and "hard" colloidal materials. This work describes the formation and characterization of gel-phase LNAs formed by the binding of anionic superparamagnetic iron oxide (SPIO) nanoparticles to cationic dipalmitoylphosphatidylcholine (DPPC)/dipalmitoyltrimethylammonium propane (DPTAP) liposomes. Particles were examined with hydrodynamic diameters below (16 nm) and above (30 nm) the cutoff reported for supported lipid bilayer formation. LNA formation with 16 nm particles was entropically driven and particles bound individually to yield "decorated" structures. In this case, increasing nanoparticle concentration yielded colloidal LNA aggregates and eventual charge inversion. In contrast, LNA formation with 30 nm particles was enthalpically driven, and the nanoparticles aggregated at the bilayer interface. These aggregates led to significant LNA aggregation and large bilayer sheets due to liposome rupture despite minimal charge screening of the liposome surface. In this case SLBs were present, but these structures were not dominant. Differences in LNA structure were also revealed through the lipid phase transition behavior. This work infers size-dependent nanoparticle binding and LNA formation mechanisms that can be used to tailor colloidal and bilayer properties. Analogies are made to polyelectrolyte patch charge heterogeneities and DNA complexation with cationic liposomes.
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Affiliation(s)
- Yanjing Chen
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States
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Abstract
INTRODUCTION Nanoscale assemblies are needed that achieve multiple therapeutic objectives, including cellular targeting, imaging, diagnostics and drug delivery. These must exhibit high stability, bioavailability and biocompatibility, while maintaining or enhancing the inherent activity of the therapeutic cargo. Liposome-nanoparticle assemblies (LNAs) combine the demonstrated potential of liposome-based therapies, with functional nanoparticles. Specifically, LNAs can be used to concentrate and shield the nanoparticles and, in turn, stimuli-responsive nanoparticles that respond to external fields can be used to control liposomal release. The ability to design LNAs via nanoparticle encapsulation, decoration or bilayer-embedment offers a range of configurations with different structures and functions. AREAS COVERED This paper reviews the current state of research and understanding of the design, characterization and performance of LNAs. A brief overview is provided on liposomes and nanoparticles for therapeutic applications, followed by a discussion of the opportunities and challenges associated with combining the two in a single assembly to achieve controlled release via light or radiofrequency stimuli. EXPERT OPINION LNAs offer a unique opportunity to combine the therapeutic properties of liposomes and nanoparticles. Liposomes act to concentrate small nanoparticles and shield nanoparticles from the immune system, while the nanoparticle can be used to initiate and control drug release when exposed to external stimuli. These properties provide a platform to achieve nanoparticle-controlled liposomal release. LNA design and application are still in infancy. Research concentrating on the relationships among LNA structure, function and performance is essential for the future clinical use of LNAs.
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Affiliation(s)
- Matthew R Preiss
- Department of Chemical Engineering, Rhode Island Consortium for Nanoscience and Nanotechnology, University of Rhode Island, 16 Greenhouse Road, Kingston, RI 02881, USA.
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Bothun GD, Lelis A, Chen Y, Scully K, Anderson LE, Stoner MA. Multicomponent folate-targeted magnetoliposomes: design, characterization, and cellular uptake. Nanomedicine 2011; 7:797-805. [PMID: 21419872 DOI: 10.1016/j.nano.2011.02.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 02/11/2011] [Accepted: 02/20/2011] [Indexed: 11/28/2022]
Abstract
UNLABELLED Folate-targeted cationic magnetoliposomes (FTMLs) have been prepared with coencapsulated doxorubicin (DOX) and anionic superparamagnetic iron oxide (SPIO) nanoparticles (NPs) with 5 nm γ-Fe(2)O(3) cores and 16 nm hydrodynamic diameters. NP encapsulation (89%) was confirmed by cryogenic transmission electron microscopy (TEM), and the presence of the oppositely charged NPs did not cause liposome aggregation. The FTMLs had an average diameter of 174 ± 53 nm and existed as unilamellar and cup-shaped liposomes, which was attributed to dissimilar lipid packing parameters and the presence of PEG-lipids. A 3-fold increase in DOX release was achieved over 2 hours when the encapsulated SPIO NPs were heated by an alternating current electromagnetic field operating at radio frequencies (RF). Results with human cervical cancer cells (HeLa), which have been shown to exhibit high folate receptor (FR) expression, confirmed FTML surface binding and cellular uptake. In contrast, no uptake was observed for lower FR-expressing human breast carcinoma cells (ZR-75-1). FROM THE CLINICAL EDITOR This study discusses the design and cellular uptake of multifunctional folate-targeted cationic magnetoliposomes enabling doxorubicin delivery and SPIO labeling.
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Affiliation(s)
- Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, USA.
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Bothun GD, Preiss MR. Bilayer heating in magnetite nanoparticle-liposome dispersions via fluorescence anisotropy. J Colloid Interface Sci 2011; 357:70-4. [PMID: 21353234 DOI: 10.1016/j.jcis.2011.01.089] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 01/27/2011] [Accepted: 01/27/2011] [Indexed: 11/25/2022]
Abstract
Temperature measurements have been made within magnetite (Fe(3)O(4)) nanoparticle-liposome dispersions subjected to electromagnetic field at radiofrequency (RF) heating based on the fluorescence anisotropy of diphenylhexatriene (DPH) embedded within the bilayer. Incorporating cholesterol within dipalmitoylphosphatidylcholine (DPPC) bilayers broadened the anisotropy window associated with lipid melting. Cryogenic transmission electron microscopy showed that the dispersions contained magnetoliposomes with nanoparticle aggregates at both low and high encapsulation densities. RF heating results demonstrated the ability to measure the temperature of the ML bilayer with on/off RF cycles using DPH anisotropy. These measurements reflected the temperature of the bulk aqueous phase, which is consistent with previous work showing rapid heat dissipation from a nanoparticle surface during RF heating and a negligible difference between surface and bulk temperature.
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Affiliation(s)
- Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston, RI 02881, USA.
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Ugaonkar S, Needham TE, Bothun GD. Solubility and partitioning of carbamazepine in a two-phase supercritical carbon dioxide/polyvinylpyrrolidone system. Int J Pharm 2011; 403:96-100. [DOI: 10.1016/j.ijpharm.2010.10.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 10/12/2010] [Accepted: 10/18/2010] [Indexed: 10/18/2022]
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Abstract
Nanoscale assemblies that can be activated and controlled through external stimuli represent a next stage in multifunctional therapeutics. We report the formation, characterization, and release properties of bilayer-decorated magnetoliposomes (dMLs) that were prepared by embedding small hydrophobic SPIO nanoparticles at different lipid molecule to nanoparticle ratios within dipalmitoylphosphatidylcholine (DPPC) bilayers. The dML structure was examined by cryogenic transmission electron microscopy and differential scanning calorimetry, and release was examined by carboxyfluorescein leakage. Nanoparticle heating using alternating current electromagnetic fields (EMFs) operating at radio frequencies provided selective release of the encapsulated molecule at low nanoparticle concentrations and under physiologically acceptable EMF conditions. Without radio frequency heating, spontaneous leakage from the dMLs decreased with increasing nanoparticle loading, consistent with greater bilayer stability and a decrease in the effective dML surface area due to aggregation. With radio frequency heating, the initial rate and extent of leakage increased significantly as a function of nanoparticle loading and electromagnetic field strength. The mechanism of release is attributed to a combination of bilayer permeabilization and partial dML rupture.
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Affiliation(s)
- Yanjing Chen
- Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Road, Kingston, Rhode Island 02881, USA
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Xie W, Bothun GD, Lehmler HJ. Partitioning of perfluorooctanoate into phosphatidylcholine bilayers is chain length-independent. Chem Phys Lipids 2010; 163:300-8. [PMID: 20096277 DOI: 10.1016/j.chemphyslip.2010.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 01/04/2010] [Accepted: 01/08/2010] [Indexed: 11/30/2022]
Abstract
The chain length dependence of the interaction of PFOA, a persistent environmental contaminant, with dimyristoyl- (DMPC), dipalmitoyl- (DPPC) and distearoylphosphatidylcholine (DSPC) was investigated using steady-state fluorescence anisotropy spectroscopy, differential scanning calorimetry (DSC) and dynamic light scattering (DLS). PFOA caused a linear depression of the main phase transition temperature T(m) while increasing the width of the phase transition of all three phosphatidylcholines. Although PFOA's effect on T(m) and the transition width decreased in the order DMPC>DPPC>DSPC, its relative effect on the phase behavior was largely independent of the phosphatidylcholine. PFOA caused swelling of DMPC but not DPPC and DSPC liposomes at 37 degrees C in the DLS experiments, which suggests that PFOA partitions more readily into bilayers in the fluid phase. These findings suggest that PFOA's effect on the phase behavior of phosphatidylcholines depends on the cooperativity and state (i.e., gel versus liquid phase) of the membrane. DLS experiments are also consistent with partial liposome solubilization at PFOA/lipid molar ratios>1, which suggests the formation of mixed PFOA-lipid micelles.
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Affiliation(s)
- Wei Xie
- Department of Occupational and Environmental Health, University of Iowa, College of Public Health, Iowa City, IA 52242-5000, USA
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Abstract
Cationic multifluorescent quantum dot liposomes (QD-Ls) have been prepared with both hydrophobic and hydrophilic CdSe/ZnS quantum dots by reverse phase evaporation. QD incorporation was confirmed by fluorescence and confocal microscopy. Incorporation did not affect QD photoactivity or damage bilayer or liposome structure. Cell uptake was examined in human hepatocellular carcinoma cells (HuH-7) using cationic and zwitterionic QD-Ls. Cationic QD-Ls were stable in vitro and exhibited high uptake, while zwitterionic QD-Ls aggregated and exhibited low uptake. Given that liposomes are established and versatile platforms for creating cell-targeting therapeutic agents, multifluorescent QD-Ls may offer advanced techniques for imaging hydrophobic and hydrophilic domains simultaneously. If coupled with an encapsulated drug, QD-Ls could be multifunctional and provide imaging, detection, and drug delivery in a single assembly.
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Affiliation(s)
- Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, 205 Crawford Hall, Kingston, Rhode Island 02881, USA.
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Abstract
Lipid assemblies provide a biocompatible approach for preparing aqueous nanoparticles. In this work, dipalmitoylphosphatidylcholine (DPPC) was used to assist in the formation and dispersion of C(60) and nano-C(60) aggregates using a modified reverse phase evaporation (REV) method. This method led to the rapid formation of aqueous nano-C(60) at DPPC/C(60) molar ratios from 500:1 to 100:1 (12-38 nm; verified by cryogenic transmission electron microscopy), which were present in the bulk phase and encapsulated within vesicles. In addition to forming nanoparticles, C(60) was trapped within the vesicle bilayer and led to a reduction in the lipid melting temperature. Solvent extraction was used to isolate nano-C(60) from the lipids and bilayer-embedded C(60). Our results suggest that bilayer-embedded C(60) was present as molecular C(60) and as small amorphous nano-C(60) (2.3 +/- 0.4 nm), which clustered in the aqueous phase after the lipids were extracted. In addition to developing a new technique for nano-C(60) formation, our results suggest that the lipid bilayer may be used as a hydrophobic region for dispersing and assembling small nano-C(60).
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Affiliation(s)
- Yanjing Chen
- Department of Chemical Engineering, University of Rhode Island, Kingston RI. 02881, USA
| | - Geoffrey D. Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston RI. 02881, USA
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Bothun GD. Hydrophobic silver nanoparticles trapped in lipid bilayers: Size distribution, bilayer phase behavior, and optical properties. J Nanobiotechnology 2008; 6:13. [PMID: 19014492 PMCID: PMC2596172 DOI: 10.1186/1477-3155-6-13] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 11/12/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lipid-based dispersion of nanoparticles provides a biologically inspired route to designing therapeutic agents and a means of reducing nanoparticle toxicity. Little is currently known on how the presence of nanoparticles influences lipid vesicle stability and bilayer phase behavior. In this work, the formation of aqueous lipid/nanoparticle assemblies (LNAs) consisting of hydrophobic silver-decanethiol particles (5.7 +/- 1.8 nm) embedded within 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers is demonstrated as a function of the DPPC/Ag nanoparticle (AgNP) ratio. The effect of nanoparticle loading on the size distribution, bilayer phase behavior, and bilayer fluidity is determined. Concomitantly, the effect of bilayer incorporation on the optical properties of the AgNPs is also examined. RESULTS The dispersions were stable at 50 degrees C where the bilayers existed in a liquid crystalline state, but phase separated at 25 degrees C where the bilayers were in a gel state, consistent with vesicle aggregation below the lipid melting temperature. Formation of bilayer-embedded nanoparticles was confirmed by differential scanning calorimetry and fluorescence anisotropy, where increasing nanoparticle concentration suppressed the lipid pretransition temperature, reduced the melting temperature, and disrupted gel phase bilayers. The characteristic surface plasmon resonance (SPR) wavelength of the embedded nanoparticles was independent of the bilayer phase; however, the SPR absorbance was dependent on vesicle aggregation. CONCLUSION These results suggest that lipid bilayers can distort to accommodate large hydrophobic nanoparticles, relative to the thickness of the bilayer, and may provide insight into nanoparticle/biomembrane interactions and the design of multifunctional liposomal carriers.
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Affiliation(s)
- Geoffrey D Bothun
- Department of Chemical Engineering, University of Rhode Island, Kingston, RI, 02881, USA.
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Liu T, Garner P, DeSimone JM, Roberts GW, Bothun GD. Particle Formation in Precipitation Polymerization: Continuous Precipitation Polymerization of Acrylic Acid in Supercritical Carbon Dioxide. Macromolecules 2006. [DOI: 10.1021/ma061260p] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tao Liu
- Department of Chemical and Biomolecular Engineering, Campus Box 7905, North Carolina State University, Raleigh, North Carolina 27695; Department of Mechanical and Chemical Engineering, 618 McNair Hall, North Carolina A&T State University, Greensboro, North Carolina 27411; and Department of Chemistry, CB #3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290
| | - Pamela Garner
- Department of Chemical and Biomolecular Engineering, Campus Box 7905, North Carolina State University, Raleigh, North Carolina 27695; Department of Mechanical and Chemical Engineering, 618 McNair Hall, North Carolina A&T State University, Greensboro, North Carolina 27411; and Department of Chemistry, CB #3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290
| | - Joseph M. DeSimone
- Department of Chemical and Biomolecular Engineering, Campus Box 7905, North Carolina State University, Raleigh, North Carolina 27695; Department of Mechanical and Chemical Engineering, 618 McNair Hall, North Carolina A&T State University, Greensboro, North Carolina 27411; and Department of Chemistry, CB #3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290
| | - George W. Roberts
- Department of Chemical and Biomolecular Engineering, Campus Box 7905, North Carolina State University, Raleigh, North Carolina 27695; Department of Mechanical and Chemical Engineering, 618 McNair Hall, North Carolina A&T State University, Greensboro, North Carolina 27411; and Department of Chemistry, CB #3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290
| | - Geoffrey D. Bothun
- Department of Chemical and Biomolecular Engineering, Campus Box 7905, North Carolina State University, Raleigh, North Carolina 27695; Department of Mechanical and Chemical Engineering, 618 McNair Hall, North Carolina A&T State University, Greensboro, North Carolina 27411; and Department of Chemistry, CB #3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290
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Lehmler HJ, Xie W, Bothun GD, Bummer PM, Knutson BL. Mixing of perfluorooctanesulfonic acid (PFOS) potassium salt with dipalmitoyl phosphatidylcholine (DPPC). Colloids Surf B Biointerfaces 2006; 51:25-9. [PMID: 16814996 PMCID: PMC2593940 DOI: 10.1016/j.colsurfb.2006.05.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 05/03/2006] [Accepted: 05/19/2006] [Indexed: 11/20/2022]
Abstract
Perfluorooctane-1-sulfonic acid (PFOS) is emerging as an important persistent environmental pollutant. To gain insight into the interaction of PFOS with biological systems, the mixing behavior of dipalmitoylphosphatidylcholine (DPPC) with PFOS was studied using differential scanning calorimetry (DSC) and fluorescence anisotropy measurements. In the DSC experiments the onset temperature of the DPPC pretransition (Tp) decreased with increasing PFOS concentration, disappearing at XDPPC < or = 0.97. The main DPPC phase transition temperature showed a depression and peak broadening with increasing mole fraction of PFOS in both the DSC and the fluorescence anisotropy studies. From the melting point depression in the fluorescence anisotropy studies, which was observed at a concentration as low as 10 mg/L, an apparent partition coefficient of K = 5.7 x 10(4) (mole fraction basis) was calculated. These results suggest that PFOS has a high tendency to partition into lipid bilayers. These direct PFOS-DPPC interactions are one possible mechanism by which PFOS may contribute to adverse effects, for example neonatal mortality, in laboratory studies and possibly in humans.
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Affiliation(s)
- H-J Lehmler
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242, USA.
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Bothun GD, Knutson BL, Strobel HJ, Nokes SE. Liposome fluidization and melting point depression by compressed and liquid n-alkanes. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.12.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bothun GD, Kho YW, Berberich JA, Shofner JP, Robertson T, Tatum KJ, Knutson BL. Surface Activity of Lysozyme and Dipalmitoyl Phosphatidylcholine Vesicles at Compressed and Supercritical Fluid Interfaces. J Phys Chem B 2005; 109:24495-501. [PMID: 16375453 DOI: 10.1021/jp0548772] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The surface activities of lysozyme and dipalmitoyl phosphatidylcholine (DPPC) vesicles at aqueous/compressed fluid interfaces are examined via high-pressure interfacial tension measurements using the pendant drop technique. The density and interfacial tension in compressible fluid systems vary significantly with pressure, providing a versatile medium for elucidating interactions between biomolecules and fluid interfaces and a method to elicit pressure-dependent interfacial morphological responses. The effects of lysozyme concentration (0.0008, 0.01, and 1 mg/mL) and pressure (> or = 7 MPa) on the dynamic surface response in the presence of ethane, propane, N2, and CO2 at 298 K were examined. Interfacial lysozyme adsorption reduced the induction phase and quickly led to interfacial tensions consistent with protein conformational changes and monolayer saturation at the compressed fluid interfaces. Protein adsorption, as indicated by surface pressure, correlated with calculated Hamaker constants for the compressed gases, denoting the importance of dispersion interactions. For DPPC at aqueous/compressed or aqueous/supercritical CO2 interfaces (1.8-20.7 MPa, 308 K), 2-3-fold reductions in interfacial tension were observed relative to the pure binary fluid system. The resulting surface pressures infer pressure-dependent morphological changes within the DPPC monolayer.
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Affiliation(s)
- Geoffrey D Bothun
- NSF-STC Environmentally Responsible Solvents and Processes, Department of Mechanical and Chemical Engineering, North Carolina A&T State University, Greensboro, North Carolina 27411, USA
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Bothun GD, Knutson BL, Strobel HJ, Nokes SE. Liposome fluidization and melting point depression by pressurized CO2 determined by fluorescence anisotropy. Langmuir 2005; 21:530-536. [PMID: 15641820 DOI: 10.1021/la0496542] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The influence of CO2 on the bilayer fluidity of liposomes, which are representative of model cellular membranes, was examined for the first time at the elevated pressures (up to 13.9 MPa) associated with CO2-based processing of liposomes and microbial sterilization. Fluidization and melting point depression of aqueous dipalmitoylphosphatidylcholine (DPPC) liposomes by pressurized CO2 (present as an excess phase) were studied by steady-state fluorescence anisotropy using the membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH). Isothermal experiments revealed reversible, pressure-dependent fluidization of DPPC bilayers at temperatures corresponding to near-gel (295 K) and fluid (333 K) phases at atmospheric pressure, where the gel-to-fluid phase transition (Tm) occurs at approximately 315 K. Isobaric measurements (PCO2 =1.8, 7.0, and 13.9 MPa) of DPH anisotropy demonstrate substantial melting point depression (DeltaTm = -4.8 to -18.5 K) and a large broadening of the gel-fluid phase transition region, which were interpreted using conventional theories of melting point depression. Liposome fluidity is influenced by CO2 accumulation in the hydrocarbon core and polar headgroup region, as well as the formation of carbonic acid and/or the presence of buffering species under elevated CO2 pressure.
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Affiliation(s)
- Geoffrey D Bothun
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky 40506-0046, USA
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