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Alidokht L, Fitzpatrick K, Butler C, Hunsucker KZ, Braga C, Maza WA, Fears KP, Arekhi M, Lanzarini-Lopes M. UV emitting glass: A promising strategy for biofilm inhibition on transparent surfaces. Biofilm 2024; 7:100186. [PMID: 38495771 PMCID: PMC10940134 DOI: 10.1016/j.bioflm.2024.100186] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 02/20/2024] [Accepted: 02/20/2024] [Indexed: 03/19/2024] Open
Abstract
Marine biofouling causes serious environmental problems and has adverse impacts on the maritime industry. Biofouling on windows and optical equipment reduces surface transparency, limiting their application for on-site monitoring or continuous measurement. This work illustrates that UV emitting glasses (UEGs) can prevent the establishment and growth of biofilm on the illuminated surfaces. Specifically, this paper describes how UEGs are enabled by innovatively modifying the surfaces of the glass with light scattering particles. Modification of glass surface with silica nanoparticles at a concentration 26.5 μg/cm2 resulted in over ten-fold increase in UV irradiance, while maintaining satisfactory visible and IR transparency metrics of over 99 %. The UEG reduced visible biological growth by 98 % and resulted in a decrease of 1.79 log in detected colony forming units when compared to the control during a 20 day submersion at Port Canaveral, Florida, United States. These findings serve as strong evidence that UV emitting glass should be explored as a promising approach for biofilm inhibition on transparent surfaces.
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Affiliation(s)
- Leila Alidokht
- Environmental and Water Resource Engineering, Department of Civil and Environmental Engineering, University of Massachusetts Amherst, MA, USA
| | - Katrina Fitzpatrick
- Environmental and Water Resource Engineering, Department of Civil and Environmental Engineering, University of Massachusetts Amherst, MA, USA
| | - Caitlyn Butler
- Environmental and Water Resource Engineering, Department of Civil and Environmental Engineering, University of Massachusetts Amherst, MA, USA
| | - Kelli Z. Hunsucker
- Center for Corrosion and Biofouling Control, Florida Institute of Technology, Melbourne, FL, USA
| | - Cierra Braga
- Center for Corrosion and Biofouling Control, Florida Institute of Technology, Melbourne, FL, USA
| | - William A. Maza
- Chemistry Division, U.S. Naval Research Laboratory, Washington, DC, USA
| | - Kenan P. Fears
- Center for Biomolecular Science and Engineering, U.S. Naval Research Laboratory, Washington, DC, USA
| | - Marieh Arekhi
- Environmental and Water Resource Engineering, Department of Civil and Environmental Engineering, University of Massachusetts Amherst, MA, USA
| | - Mariana Lanzarini-Lopes
- Environmental and Water Resource Engineering, Department of Civil and Environmental Engineering, University of Massachusetts Amherst, MA, USA
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2
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Wilson MC, Beasley MA, Fears KP, Yates EA, So CR. Role of protein aggregate structure on the strength and underwater performance of barnacle-inspired adhesives. Soft Matter 2023. [PMID: 37249466 DOI: 10.1039/d3sm00342f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nature employs protein aggregates when strong materials are needed to adhere surfaces in extreme environments, allowing organisms to survive conditions ranging from harsh intertidal coasts to open oceans. Amyloids and amyloid-like materials are prevalent and amongst the most densely bonded aggregate structures, though how they contribute to wet adhesion is not well understood. In this work, waterborne protein solutions of individual whey proteins are cured in place using varied temperature to produce model adhesives enriched in amyloid or non-amyloid aggregates. Dry adhesive strengths range from 0.2-1.5 MPa, while wet adhesive strengths range from 0-0.5 MPa across the tested proteins and processing conditions, highlighting that both proper protein selection and controlled aggregation extent are necessary for successful underwater performance. For bovine serum albumin, the amyloid-enriched adhesive was able to retain ca. 500 kPa bond strength underwater throughout extended immersion and thermal degradation testing, while the non-amyloid adhesive weakened by up to 80%. As freestanding gels, higher temperature processing improved underwater stability for all the protein materials, with amyloid-rich structures remaining mostly water-insoluble after 30 days submerged in water. Protein-based adhesives with a controlled aggregate structure shed light on the ability of amyloid-containing materials to remain adhered underwater, a necessary trait for the survival of many organisms.
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Affiliation(s)
- Michael C Wilson
- NRC Postdoctoral Associate sited in Chemistry Division, Code 6176, U.S. Naval Research Laboratory, Washington, DC, USA
| | - Maryssa A Beasley
- NRC Postdoctoral Associate sited in Chemistry Division, Code 6176, U.S. Naval Research Laboratory, Washington, DC, USA
| | - Kenan P Fears
- Chemistry Division, Code 6176, U.S. Naval Research Laboratory, Washington, DC, USA.
| | - Elizabeth A Yates
- U.S. Naval Academy Faculty sited in Chemistry Division, Code 6176, U.S. Naval Research Laboratory, Washington, DC, USA
| | - Christopher R So
- Chemistry Division, Code 6176, U.S. Naval Research Laboratory, Washington, DC, USA.
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3
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Lu Q, Regan DP, Barlow DE, Fears KP. Antimicrobial efficacy of cyclic α- and β-peptides incorporated in polyurethane coatings. Biointerphases 2023; 18:031008. [PMID: 37289032 DOI: 10.1116/6.0002515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/12/2023] [Indexed: 06/09/2023] Open
Abstract
Microbial growth on surfaces poses health concerns and can accelerate the biodegradation of engineered materials and coatings. Cyclic peptides are promising agents to combat biofouling because they are more resistant to enzymatic degradation than their linear counterparts. They can also be designed to interact with extracellular targets and intracellular targets and/or self-assemble into transmembrane pores. Here, we determine the antimicrobial efficacy of two pore-forming cyclic peptides, α-K3W3 and β-K3W3, against bacterial and fungal liquid cultures and their capacity to inhibit biofilm formation on coated surfaces. These peptides display identical sequences, but the additional methylene group in the peptide backbone of β-amino acids results in a larger diameter and an enhancement in the dipole moment. In liquid cultures, β-K3W3 exhibited lower minimum inhibitory concentration values and greater microbicidal power in reducing the number of colony forming units (CFUs) when exposed to a gram-positive bacterium, Staphylococcus aureus, and two fungal strains, Naganishia albida and Papiliotrema laurentii. To evaluate the efficacy against the formation of fungal biofilms on painted surfaces, cyclic peptides were incorporated into polyester-based thermoplastic polyurethane. The formation of N. albida and P. laurentii microcolonies (105 per inoculation) for cells extracted from coatings containing either peptide could not be detected after a 7-day exposure. Moreover, very few CFUs (∼5) formed after 35 days of repeated depositions of freshly cultured P. laurentii every 7 days. In contrast, the number of CFUs for cells extracted from the coating without cyclic peptides was >8 log CFU.
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Affiliation(s)
- Qin Lu
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
| | - Daniel P Regan
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
| | - Daniel E Barlow
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
| | - Kenan P Fears
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375
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4
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Vandadi M, Fears KP, Kolel-Veetil MK, Rahbar N. Effect of Water on the Mechanical Properties of Cyclic Peptide Polymers. ACS Biomater Sci Eng 2023; 9:246-256. [PMID: 36542483 DOI: 10.1021/acsbiomaterials.2c01020] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Biomaterials are an important source of inspiration for the development of strong and tough materials. Many improved and optimized synthetic materials have been recently developed utilizing this bioinspiration concept. Using side-chain-to-side-chain polymerization of cyclic β-peptide rings, a novel class of nanomaterials was recently introduced with outstanding mechanical properties such as toughness values greater than natural silks. In this work, molecular dynamics is used to understand the mechanics of side-chain-to-side-chain polymerization of cyclic β-peptide rings. Unbiased steered molecular dynamics simulations are used to show the difference in the strength of polymerized and unpolymerized processing of similar cyclic rings. The simulations are performed both in aqueous and vacuum environments to capture the role of water on the mechanical properties of the cyclic peptides. Our results show that unpolymerized peptides behave like brittle material, whereas polymerized ones can withstand some stress after initial failure with large values of strain-to-failure. Finally, we have shown that the strength of cyclic peptides in water is higher than in a vacuum.
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Affiliation(s)
- Mobin Vandadi
- Department of Civil and Environmental Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts01609, United States
| | - Kenan P Fears
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC20375, United States
| | - Manoj K Kolel-Veetil
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC20375, United States
| | - Nima Rahbar
- Department of Civil and Environmental Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts01609, United States.,Materials Program, Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts01609, United States
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5
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Thum MD, Lu Q, Stockmaster KT, Haridas D, Fears KP, Balow RB, Lundin JG. 3D‐printable cyclic peptide loaded microporous polymers for antimicrobial wound dressing materials. POLYM ADVAN TECHNOL 2022. [DOI: 10.1002/pat.5948] [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] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Matthew D. Thum
- Chemistry Division U.S. Naval Research Laboratory Washington, DC USA
| | - Qin Lu
- Chemistry Division U.S. Naval Research Laboratory Washington, DC USA
| | | | - Dhanya Haridas
- Chemistry Division U.S. Naval Research Laboratory Washington, DC USA
| | - Kenan P. Fears
- Chemistry Division U.S. Naval Research Laboratory Washington, DC USA
| | - Robert B. Balow
- Chemistry Division U.S. Naval Research Laboratory Washington, DC USA
| | - Jeffrey G. Lundin
- Chemistry Division U.S. Naval Research Laboratory Washington, DC USA
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6
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Beasley MA, Dunkelberger AD, Thum MD, Ryland ES, Fears KP, Grafton AB, Owrutsky JC, Lundin JG, So CR. Extremophilic behavior of catalytic amyloids sustained by backbone structuring. J Mater Chem B 2022; 10:9400-9412. [PMID: 36285764 DOI: 10.1039/d2tb01605b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Enzyme function relies on the placement of chemistry defined by solvent and self-associative hydrogen bonding displayed by the protein backbone. Amyloids, long-range multi-peptide and -protein materials, can mimic enzyme functions while having a high proportion of stable self-associative backbone hydrogen bonds. Though catalytic amyloid structures have exhibited a degree of temperature and solvent stability, defining their full extremophilic properties and the molecular basis for such extreme activity has yet to be realized. Here we demonstrate that, like thermophilic enzymes, catalytic amyloid activity persists across high temperatures with an optimum activity at 81 °C where they are 30-fold more active than at room temperature. Unlike thermophilic enzymes, catalytic amyloids retain both activity and structure well above 100 °C as well as in the presence of co-solvents. Changes in backbone vibrational states are resolved in situ using non-linear 2D infrared spectroscopy (2DIR) to reveal that activity is sustained by reorganized backbone hydrogen bonds in extreme environments, evidenced by an emergent vibrational mode centered at 1612 cm-1. Restructuring also occurs in organic solvents, and facilitates complete retention of hydrolysis activity in co-solvents of lesser polarity. We support these findings with molecular modeling, where the displacement of water by co-solvents leads to shorter, less competitive, bonding lifetimes that further stabilize self-associative backbone interactions. Our work defines amyloid properties that counter classical proteins, where extreme environments induce mechanisms of restructuring to support enzyme-like functions necessary for synthetic applications.
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Affiliation(s)
- Maryssa A Beasley
- NRC Postdoctoral Associate Sited in Chemistry Division, Code 6176, U.S. Naval Research Laboratory, Washington, DC 20375-5342, USA
| | - Adam D Dunkelberger
- Chemistry Division, Code 6121, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC 20375-5342, USA
| | - Matthew D Thum
- ASEE Postdoctoral Associate Sited in Chemistry Division, Code 6124, U.S. Naval Research Laboratory, Washington, DC 20375-5342, USA
| | - Elizabeth S Ryland
- NRC Postdoctoral Associate Sited in Chemistry Division, Code 6121, U.S. Naval Research Laboratory, Washington, DC 20375-5342, USA
| | - Kenan P Fears
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC 20375-5342, USA.
| | - Andrea B Grafton
- NRC Postdoctoral Associate Sited in Chemistry Division, Code 6121, U.S. Naval Research Laboratory, Washington, DC 20375-5342, USA
| | - Jeffrey C Owrutsky
- Chemistry Division, Code 6121, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC 20375-5342, USA
| | - Jeffrey G Lundin
- Chemistry Division, Code 6124, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC 20375-5342, USA
| | - Christopher R So
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC 20375-5342, USA.
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7
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Estrella LA, Yates EA, Fears KP, Schultzhaus JN, Ryou H, Leary DH, So CR. Engineered Escherichia coli Biofilms Produce Adhesive Nanomaterials Shaped by a Patterned 43 kDa Barnacle Cement Protein. Biomacromolecules 2020; 22:365-373. [PMID: 33135878 DOI: 10.1021/acs.biomac.0c01212] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Barnacles integrate multiple protein components into distinct amyloid-like nanofibers arranged as a bulk material network for their permanent underwater attachment. The design principle for how chemistry is displayed using adhesive nanomaterials, and fragments of proteins that are responsible for their formation, remains a challenge to assess and is yet to be established. Here, we use engineered bacterial biofilms to display a library of amyloid materials outside of the cell using full-length and subdomain sequences from a major component of the barnacle adhesive. A staggered charged pattern is found throughout the full-length sequence of a 43 kDa cement protein (AACP43), establishing a conserved sequence design evolved by barnacles to make adhesive nanomaterials. AACP43 domain deletions vary in their propensity to aggregate and form fibers, as exported extracellular materials are characterized through staining, immunoblotting, scanning electron microscopy, and atomic force microscopy. Full-length AACP43 and its domains have a propensity to aggregate into nanofibers independent of all other barnacle glue components, shedding light on its function in the barnacle adhesive. Curliated Escherichia coli biofilms are a compatible system for heterologous expression and the study of foreign functional amyloid adhesive materials, used here to identify the c-terminal portion of AACP43 as critical in material formation. This approach allows us to establish a common sequence pattern between two otherwise dissimilar families of cement proteins, laying the foundation to elucidate adhesive chemistries by one of the most tenacious marine fouling organisms in the ocean.
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Affiliation(s)
- Luis A Estrella
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, D.C. 20375-5342, United States
| | - Elizabeth A Yates
- US Naval Academy Faculty sited in Code 6176, US Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Kenan P Fears
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, D.C. 20375-5342, United States
| | - Janna N Schultzhaus
- National Research Council Research Associateship Programs Fellow sited in Code 6920, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, D.C. 20375-5342, United States
| | - Heonjune Ryou
- Materials Science and Technology Division, Code 6351, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, D.C. 20375-5342, United States
| | - Dagmar H Leary
- Center for Bio/Molecular Science and Engineering, Code 6920, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, D.C. 20375-5342, United States
| | - Christopher R So
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Avenue, SW, Washington, D.C. 20375-5342, United States
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8
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Long JW, Chervin CN, Balow RB, Jeon S, Miller JB, Helms ME, Owrutsky JC, Rolison DR, Fears KP. Zirconia-Based Aerogels for Sorption and Degradation of Dimethyl Methylphosphonate. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c02983] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jeffrey W. Long
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Christopher N. Chervin
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Robert B. Balow
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Seokmin Jeon
- National Research Council Research Associateship Program, U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, District of Columbia 20375, United States
| | - Joel B. Miller
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Maya E. Helms
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Jeffrey C. Owrutsky
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Debra R. Rolison
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
| | - Kenan P. Fears
- Chemistry Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375, United States
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Fears KP, Barnikel A, Wassick A, Ryou H, Schultzhaus JN, Orihuela B, Scancella JM, So CR, Hunsucker KZ, Leary DH, Swain G, Rittschof D, Spillmann CM, Wahl KJ. Adhesion of acorn barnacles on surface-active borate glasses. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190203. [PMID: 31495306 PMCID: PMC6745471 DOI: 10.1098/rstb.2019.0203] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [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] [Accepted: 06/06/2019] [Indexed: 12/16/2022] Open
Abstract
Concerns about the bioaccumulation of toxic antifouling compounds have necessitated the search for alternative strategies to combat marine biofouling. Because many biologically essential minerals have deleterious effects on organisms at high concentration, one approach to preventing the settlement of marine foulers is increasing the local concentration of ions that are naturally present in seawater. Here, we used surface-active borate glasses as a platform to directly deliver ions (Na+, Mg2+ and BO43-) to the adhesive interface under acorn barnacles (Amphibalanus (=Balanus) amphitrite). Additionally, surface-active glasses formed reaction layers at the glass-water interface, presenting another challenge to fouling organisms. Proteomics analysis showed that cement deposited on the gelatinous reaction layers is more soluble than cement deposited on insoluble glasses, indicating the reaction layer and/or released ions disrupted adhesion processes. Laboratory experiments showed that the majority (greater than 79%) of adult barnacles re-attached to silica-free borate glasses for 14 days could be released and, more importantly, barnacle larvae did not settle on the glasses. The formation of microbial biofilms in field tests diminished the performance of the materials. While periodic water jetting (120 psi) did not prevent the formation of biofilms, weekly cleaning did dramatically reduce macrofouling on magnesium aluminoborate glass to levels below a commercial foul-release coating. This article is part of the theme issue 'Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'.
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Affiliation(s)
- Kenan P. Fears
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Andrew Barnikel
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Ann Wassick
- Center for Corrosion and Biofouling Control, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA
| | - Heonjune Ryou
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Janna N. Schultzhaus
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Beatriz Orihuela
- Duke University Marine Laboratory, 135 Duke Marine Laboratory Road, Beaufort, NC 28516, USA
| | - Jenifer M. Scancella
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Christopher R. So
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Kelli Z. Hunsucker
- Center for Corrosion and Biofouling Control, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA
| | - Dagmar H. Leary
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Geoffrey Swain
- Center for Corrosion and Biofouling Control, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901, USA
| | - Daniel Rittschof
- Duke University Marine Laboratory, 135 Duke Marine Laboratory Road, Beaufort, NC 28516, USA
| | - Christopher M. Spillmann
- Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
| | - Kathryn J. Wahl
- Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
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10
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Schultzhaus JN, Dean SN, Leary DH, Hervey WJ, Fears KP, Wahl KJ, Spillmann CM. Pressure cycling technology for challenging proteomic sample processing: application to barnacle adhesive. Integr Biol (Camb) 2019; 11:235-247. [DOI: 10.1093/intbio/zyz020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/08/2019] [Accepted: 05/29/2019] [Indexed: 12/23/2022]
Abstract
AbstractSuccessful proteomic characterization of biological material depends on the development of robust sample processing methods. The acorn barnacle Amphibalanus amphitrite is a biofouling model for adhesive processes, but the identification of causative proteins involved has been hindered by their insoluble nature. Although effective, existing sample processing methods are labor and time intensive, slowing progress in this field. Here, a more efficient sample processing method is described which exploits pressure cycling technology (PCT) in combination with protein solvents. PCT aids in protein extraction and digestion for proteomics analysis. Barnacle adhesive proteins can be extracted and digested in the same tube using PCT, minimizing sample loss, increasing throughput to 16 concurrently processed samples, and decreasing sample processing time to under 8 hours. PCT methods produced similar proteomes in comparison to previous methods. Two solvents which were ineffective at extracting proteins from the adhesive at ambient pressure (urea and methanol) produced more protein identifications under pressure than highly polar hexafluoroisopropanol, leading to the identification and description of >40 novel proteins at the interface. Some of these have homology to proteins with elastomeric properties or domains involved with protein-protein interactions, while many have no sequence similarity to proteins in publicly available databases, highlighting the unique adherent processes evolved by barnacles. The methods described here can not only be used to further characterize barnacle adhesive to combat fouling, but may also be applied to other recalcitrant biological samples, including aggregative or fibrillar protein matrices produced during disease, where a lack of efficient sample processing methods has impeded advancement. Data are available via ProteomeXchange with identifier PXD012730.
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Affiliation(s)
- Janna N Schultzhaus
- National Research Council Research Associateship Programs Fellow, Washington, D.C., USA
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Washington, D.C., USA
| | - Scott N Dean
- National Research Council Research Associateship Programs Fellow, Washington, D.C., USA
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Washington, D.C., USA
| | - Dagmar H Leary
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Washington, D.C., USA
| | - W Judson Hervey
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Washington, D.C., USA
| | - Kenan P Fears
- Chemistry Division, Naval Research Laboratory, Washington, D.C., USA
| | - Kathryn J Wahl
- Chemistry Division, Naval Research Laboratory, Washington, D.C., USA
| | - Christopher M Spillmann
- Center for Bio/Molecular Science & Engineering, Naval Research Laboratory, Washington, D.C., USA
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11
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So CR, Yates EA, Estrella LA, Fears KP, Schenck AM, Yip CM, Wahl KJ. Molecular Recognition of Structures Is Key in the Polymerization of Patterned Barnacle Adhesive Sequences. ACS Nano 2019; 13:5172-5183. [PMID: 30986028 DOI: 10.1021/acsnano.8b09194] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [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: 06/09/2023]
Abstract
The permanent adhesive produced by adult barnacles is held together by tightly folded proteins that form amyloid-like materials distinct among marine foulants. In this work, we link stretches of alternating charged and noncharged linear sequences from a family of adhesive proteins to their role in forming fibrillar nanomaterials. Using recombinant proteins and short barnacle cement derived peptides (BCPs), we find a central sequence with charged motifs of the pattern [Gly/Ser/Val/Thr/Ala-X], where X are charged amino acids, to exert specific control over timing, structure, and morphology of fibril formation. While most BCPs remain dormant, the core segment demonstrates rapid polymerization as well as an ability to template other peptides with no propensity for self-assembly. Patterned charge domains assemble dormant peptides through a specific antiparallel β-sheet structure as measured by FTIR. While charged domains favor an antiparallel structure, BCPs without charged domains switch fibril assembly to favor simpler parallel β-sheet aggregates. In addition to activation, charged domains direct nanofibers to grow into discrete microns long fibrils similar to the natural adhesive, while segments without such domains only form short branched aggregates. The assembly of adhesive sequences through recognition of structured templates outlines a strategy used by barnacles to control physical mechanisms of underwater adhesive delivery, activation, and curing based on molecular recognition between proteins.
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Affiliation(s)
- Christopher R So
- Chemistry Division, Code 6176 , US Naval Research Laboratory , 4555 Overlook Avenue, SW , Washington , DC 20375-5342 , United States
| | - Elizabeth A Yates
- US Naval Academy Faculty Sited in Code 6176 , US Naval Research Laboratory , Washington , DC 20375-5342 , United States
| | - Luis A Estrella
- Chemistry Division, Code 6176 , US Naval Research Laboratory , 4555 Overlook Avenue, SW , Washington , DC 20375-5342 , United States
| | - Kenan P Fears
- Chemistry Division, Code 6176 , US Naval Research Laboratory , 4555 Overlook Avenue, SW , Washington , DC 20375-5342 , United States
| | - Ashley M Schenck
- US Naval Academy Midshipmen Sited in Code 6176 , US Naval Research Laboratory , Washington , DC 20375-5342 , United States
| | - Catherine M Yip
- US Naval Academy Midshipmen Sited in Code 6176 , US Naval Research Laboratory , Washington , DC 20375-5342 , United States
| | - Kathryn J Wahl
- Chemistry Division, Code 6176 , US Naval Research Laboratory , 4555 Overlook Avenue, SW , Washington , DC 20375-5342 , United States
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12
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Dunkelberger AD, Fears KP, Davidson II RB, Dressick WJ, Simpkins BS, Owrutsky JC. Vibrational relaxation of small anions in a polymer film. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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13
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Fears KP, Orihuela B, Rittschof D, Wahl KJ. Acorn Barnacles Secrete Phase-Separating Fluid to Clear Surfaces Ahead of Cement Deposition. Adv Sci (Weinh) 2018; 5:1700762. [PMID: 29938165 PMCID: PMC6010908 DOI: 10.1002/advs.201700762] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/05/2018] [Indexed: 05/06/2023]
Abstract
Marine macrofoulers (e.g., barnacles, tubeworms, mussels) create underwater adhesives capable of attaching themselves to almost any material. The difficulty in removing these organisms frustrates maritime and oceanographic communities, and fascinates biomedical and industrial communities seeking synthetic adhesives that cure and hold steadfast in aqueous environments. Protein analysis can reveal the chemical composition of natural adhesives; however, developing synthetic analogs that mimic their performance remains a challenge due to an incomplete understanding of adhesion processes. Here, it is shown that acorn barnacles (Amphibalanus (=Balanus) amphitrite) secrete a phase-separating fluid ahead of growth and cement deposition. This mixture consists of a phenolic laden gelatinous phase that presents a phase rich in lipids and reactive oxygen species at the seawater interface. Nearby biofilms rapidly oxidize and lift off the surface as the secretion advances. While phenolic chemistries are ubiquitous to arthropod adhesives and cuticles, the findings demonstrate that A. amphitrite uses these chemistries in a complex surface-cleaning fluid, at a substantially higher relative abundance than in its adhesive. The discovery of this critical step in underwater adhesion represents a missing link between natural and synthetic adhesives, and provides new directions for the development of environmentally friendly biofouling solutions.
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Affiliation(s)
- Kenan P. Fears
- Chemistry DivisionNaval Research Laboratory4555 Overlook Ave. SWWashingtonDC20375USA
| | - Beatriz Orihuela
- Duke University Marine Laboratory135 Duke Marine Lab RdBeaufortNC28516USA
| | - Daniel Rittschof
- Duke University Marine Laboratory135 Duke Marine Lab RdBeaufortNC28516USA
| | - Kathryn J. Wahl
- Chemistry DivisionNaval Research Laboratory4555 Overlook Ave. SWWashingtonDC20375USA
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14
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Yates EA, Schenck AM, Yip CM, Fears KP, So CR, Wahl KJ. Adhesive Nanomaterials Derived from the Barnacle Amphibalanus Amphitrite Polymerize by Molecular Recognition of Sequences. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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15
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So CR, Scancella JM, Fears KP, Essock-Burns T, Haynes SE, Leary DH, Diana Z, Wang C, North S, Oh CS, Wang Z, Orihuela B, Rittschof D, Spillmann CM, Wahl KJ. Oxidase Activity of the Barnacle Adhesive Interface Involves Peroxide-Dependent Catechol Oxidase and Lysyl Oxidase Enzymes. ACS Appl Mater Interfaces 2017; 9:11493-11505. [PMID: 28273414 DOI: 10.1021/acsami.7b01185] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [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: 06/06/2023]
Abstract
Oxidases are found to play a growing role in providing functional chemistry to marine adhesives for the permanent attachment of macrofouling organisms. Here, we demonstrate active peroxidase and lysyl oxidase enzymes in the adhesive layer of adult Amphibalanus amphitrite barnacles through live staining, proteomic analysis, and competitive enzyme assays on isolated cement. A novel full-length peroxinectin (AaPxt-1) secreted by barnacles is largely responsible for oxidizing phenolic chemistries; AaPxt-1 is driven by native hydrogen peroxide in the adhesive and oxidizes phenolic substrates typically preferred by phenoloxidases (POX) such as laccase and tyrosinase. A major cement protein component AaCP43 is found to contain ketone/aldehyde modifications via 2,4-dinitrophenylhydrazine (DNPH) derivatization, also called Brady's reagent, of cement proteins and immunoblotting with an anti-DNPH antibody. Our work outlines the landscape of molt-related oxidative pathways exposed to barnacle cement proteins, where ketone- and aldehyde-forming oxidases use peroxide intermediates to modify major cement components such as AaCP43.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Beatriz Orihuela
- Nicholas School of the Environment and Earth Sciences, Duke University Marine Laboratory , Beaufort, North Carolina 28516, United States
| | - Dan Rittschof
- Nicholas School of the Environment and Earth Sciences, Duke University Marine Laboratory , Beaufort, North Carolina 28516, United States
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16
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So CR, Fears KP, Leary DH, Scancella JM, Wang Z, Liu JL, Orihuela B, Rittschof D, Spillmann CM, Wahl KJ. Sequence basis of Barnacle Cement Nanostructure is Defined by Proteins with Silk Homology. Sci Rep 2016; 6:36219. [PMID: 27824121 PMCID: PMC5099703 DOI: 10.1038/srep36219] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [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: 07/05/2016] [Accepted: 10/12/2016] [Indexed: 01/22/2023] Open
Abstract
Barnacles adhere by producing a mixture of cement proteins (CPs) that organize into a permanently bonded layer displayed as nanoscale fibers. These cement proteins share no homology with any other marine adhesives, and a common sequence-basis that defines how nanostructures function as adhesives remains undiscovered. Here we demonstrate that a significant unidentified portion of acorn barnacle cement is comprised of low complexity proteins; they are organized into repetitive sequence blocks and found to maintain homology to silk motifs. Proteomic analysis of aggregate bands from PAGE gels reveal an abundance of Gly/Ala/Ser/Thr repeats exemplified by a prominent, previously unidentified, 43 kDa protein in the solubilized adhesive. Low complexity regions found throughout the cement proteome, as well as multiple lysyl oxidases and peroxidases, establish homology with silk-associated materials such as fibroin, silk gum sericin, and pyriform spidroins from spider silk. Distinct primary structures defined by homologous domains shed light on how barnacles use low complexity in nanofibers to enable adhesion, and serves as a starting point for unraveling the molecular architecture of a robust and unique class of adhesive nanostructures.
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Affiliation(s)
- Christopher R So
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
| | - Kenan P Fears
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
| | - Dagmar H Leary
- Center for Biomolecular Science and Engineering, Code 6900, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
| | - Jenifer M Scancella
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
| | - Zheng Wang
- Center for Biomolecular Science and Engineering, Code 6900, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
| | - Jinny L Liu
- Center for Biomolecular Science and Engineering, Code 6900, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
| | - Beatriz Orihuela
- Nicholas School of the Environment and Earth Sciences, Duke University Marine Laboratory, 135 Duke Marine Lab Rd, Beaufort, NC, USA
| | - Dan Rittschof
- Nicholas School of the Environment and Earth Sciences, Duke University Marine Laboratory, 135 Duke Marine Lab Rd, Beaufort, NC, USA
| | - Christopher M Spillmann
- Center for Biomolecular Science and Engineering, Code 6900, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
| | - Kathryn J Wahl
- Chemistry Division, Code 6176, US Naval Research Laboratory, 4555 Overlook Ave, SW, Washington, DC, USA
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17
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Golden JP, Burden DK, Fears KP, Barlow DE, So CR, Burns J, Miltenberg B, Orihuela B, Rittshof D, Spillmann CM, Wahl KJ, Tender LM. Imaging Active Surface Processes in Barnacle Adhesive Interfaces. Langmuir 2016; 32:541-550. [PMID: 26681301 DOI: 10.1021/acs.langmuir.5b03286] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Surface plasmon resonance imaging (SPRI) and voltammetry were used simultaneously to monitor Amphibalanus (=Balanus) amphitrite barnacles reattached and grown on gold-coated glass slides in artificial seawater. Upon reattachment, SPRI revealed rapid surface adsorption of material with a higher refractive index than seawater at the barnacle/gold interface. Over longer time periods, SPRI also revealed secretory activity around the perimeter of the barnacle along the seawater/gold interface extending many millimeters beyond the barnacle and varying in shape and region with time. Ex situ experiments using attenuated total reflectance infrared (ATR-IR) spectroscopy confirmed that reattachment of barnacles was accompanied by adsorption of protein to surfaces on similar time scales as those in the SPRI experiments. Barnacles were grown through multiple molting cycles. While the initial reattachment region remained largely unchanged, SPRI revealed the formation of sets of paired concentric rings having alternately darker/lighter appearance (corresponding to lower and higher refractive indices, respectively) at the barnacle/gold interface beneath the region of new growth. Ex situ experiments coupling the SPRI imaging with optical and FTIR microscopy revealed that the paired rings coincide with molt cycles, with the brighter rings associated with regions enriched in amide moieties. The brighter rings were located just beyond orifices of cement ducts, consistent with delivery of amide-rich chemistry from the ducts. The darker rings were associated with newly expanded cuticle. In situ voltammetry using the SPRI gold substrate as the working electrode revealed presence of redox active compounds (oxidation potential approx 0.2 V vs Ag/AgCl) after barnacles were reattached on surfaces. Redox activity persisted during the reattachment period. The results reveal surface adsorption processes coupled to the complex secretory and chemical activity under barnacles as they construct their adhesive interfaces.
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Affiliation(s)
| | | | | | | | | | | | - Benjamin Miltenberg
- American Society for Engineering Education, NREIP , Washington, D.C. 20036, United States
| | - Beatriz Orihuela
- Duke University Marine Lab , Beaufort, North Carolina 28516, United States
| | - Daniel Rittshof
- Duke University Marine Lab , Beaufort, North Carolina 28516, United States
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18
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De Gregorio BT, Stroud RM, Burden DK, Fears KP, Everett RK, Wahl KJ. Shell Structure and Growth in the Base Plate of the Barnacle Amphibalanus amphitrite. ACS Biomater Sci Eng 2015; 1:1085-1095. [PMID: 33429550 DOI: 10.1021/acsbiomaterials.5b00191] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The base plate of the acorn barnacle Amphibalanus amphitrite (equivalent to Balanus amphitrite) is composed of hierarchically scaled, mutually aligned calcite grains, adhered to the substratum via layered cuticular tissue and protein. Acorn barnacles grow by expanding and lengthening their side plates, under which the cuticle is stretched, and adhesive proteins are secreted. In barnacles with mineralized base plates, such as A. amphitrite, a mineralization front follows behind, radially expanding the base plate at the periphery. In this study, we show that the new mineralization develops above the adhesion layers in a unique trilayered structure. Calcite crystallites in each of the layers have distinct sizes, varying from coarse-grained (>1 μm across) in the upper layer, to fine-grained (∼1 μm) in the middle layer, to nanoparticulate (∼40 nm) in the basal layer. The fine-grained crystallites dominate the growth front, comprising the bulk of the shell at the periphery, with later coarse grain development on the top of the base plate (toward the barnacle interior) and nanocrystalline calcite templating underneath in contact with the cuticle/protein layer. While the coarse-grained calcite on the upper surface contains a range of crystal orientations, the underlying fine-grained and nanocrystalline calcite are mutually oriented to within a few degrees of each other. Electron diffraction and X-ray absorption spectroscopy confirm that all of the crystallites are calcite, and metastable aragonite or amorphous calcium carbonate (ACC) phases are not observed. The complex morphology of the leading edge of the base plate suggests that crystallization initiates with the emplacement of mutually aligned fine-grained calcite, followed by the accumulation of coarser grains above and nucleation of highly oriented nanocrystalline grains below.
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Affiliation(s)
- Bradley T De Gregorio
- Nova Research Inc., 1900 Elkin Street, Suite 230, Alexandria, Virginia 22308, United States.,Materials Science and Technology Division, Code 6366, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Rhonda M Stroud
- Materials Science and Technology Division, Code 6366, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Daniel K Burden
- Chemistry Division, Code 6176, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Kenan P Fears
- Chemistry Division, Code 6176, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Richard K Everett
- Materials Science and Technology Division, Code 6366, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States.,Department of Mechanical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Engineering 225-D, Baltimore, Maryland 21250, United States
| | - Kathryn J Wahl
- Chemistry Division, Code 6176, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
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19
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Wang Z, Leary DH, Liu J, Settlage RE, Fears KP, North SH, Mostaghim A, Essock-Burns T, Haynes SE, Wahl KJ, Spillmann CM. Molt-dependent transcriptomic analysis of cement proteins in the barnacle Amphibalanus amphitrite. BMC Genomics 2015; 16:859. [PMID: 26496984 PMCID: PMC4619306 DOI: 10.1186/s12864-015-2076-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [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: 08/18/2015] [Accepted: 10/08/2015] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND A complete understanding of barnacle adhesion remains elusive as the process occurs within and beneath the confines of a rigid calcified shell. Barnacle cement is mainly proteinaceous and several individual proteins have been identified in the hardened cement at the barnacle-substrate interface. Little is known about the molt- and tissue-specific expression of cement protein genes but could offer valuable insight into the complex multi-step processes of barnacle growth and adhesion. METHODS The main body and sub-mantle tissue of the barnacle Amphibalanus amphitrite (basionym Balanus amphitrite) were collected in pre- and post-molt stages. RNA-seq technology was used to analyze the transcriptome for differential gene expression at these two stages and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) was used to analyze the protein content of barnacle secretions. RESULTS We report on the transcriptomic analysis of barnacle cement gland tissue in pre- and post-molt growth stages and proteomic investigation of barnacle secretions. While no significant difference was found in the expression of cement proteins genes at pre- and post-molting stages, expression levels were highly elevated in the sub-mantle tissue (where the cement glands are located) compared to the main barnacle body. We report the discovery of a novel 114kD cement protein, which is identified in material secreted onto various surfaces by adult barnacles and with the encoding gene highly expressed in the sub-mantle tissue. Further differential gene expression analysis of the sub-mantle tissue samples reveals a limited number of genes highly expressed in pre-molt samples with a range of functions including cuticular development, biominerialization, and proteolytic activity. CONCLUSIONS The expression of cement protein genes appears to remain constant through the molt cycle and is largely confined to the sub-mantle tissue. Our results reveal a novel and potentially prominent protein to the mix of cement-related components in A. amphitrite. Despite the lack of a complete genome, sample collection allowed for extended transcriptomic analysis of pre- and post-molt barnacle samples and identified a number of highly-expressed genes. Our results highlight the complexities of this sessile marine organism as it grows via molt cycles and increases the area over which it exhibits robust adhesion to its substrate.
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Affiliation(s)
- Zheng Wang
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, 20375, USA.
| | - Dagmar H Leary
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, 20375, USA.
| | - Jinny Liu
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, 20375, USA.
| | - Robert E Settlage
- Virginia Bioinformatics Institute, 1015 Life Science Circle, Blacksburg, VA, 24061, USA.
| | - Kenan P Fears
- Chemistry Division, Naval Research Laboratory, Washington, DC, 20375, USA.
| | - Stella H North
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, 20375, USA.
| | - Anahita Mostaghim
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, 20375, USA. .,Present address: Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA, 23507, USA.
| | - Tara Essock-Burns
- Chemistry Division, Naval Research Laboratory, Washington, DC, 20375, USA. .,Present address: Duke University Marine Laboratory, 135 Duke Marine Lab Rd. Beaufort, North Carolina, 28516, USA.
| | - Sarah E Haynes
- Chemistry Division, Naval Research Laboratory, Washington, DC, 20375, USA. .,Present address: Department of Chemistry, University of Michigan, 930 N. University Avenue, Ann Arbor, MI, 48109, USA.
| | - Kathryn J Wahl
- Chemistry Division, Naval Research Laboratory, Washington, DC, 20375, USA.
| | - Christopher M Spillmann
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC, 20375, USA.
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20
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So CR, Liu J, Fears KP, Leary DH, Golden JP, Wahl KJ. Self-Assembly of Protein Nanofibrils Orchestrates Calcite Step Movement through Selective Nonchiral Interactions. ACS Nano 2015; 9:5782-5791. [PMID: 25970003 DOI: 10.1021/acsnano.5b01870] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [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: 06/04/2023]
Abstract
The recognition of atomically distinct surface features by adsorbed biomolecules is central to the formation of surface-templated peptide or protein nanostructures. On mineral surfaces such as calcite, biomolecular recognition of, and self-assembly on, distinct atomic kinks and steps could additionally orchestrate changes to the overall shape and symmetry of a bulk crystal. In this work, we show through in situ atomic force microscopy (AFM) experiments that an acidic 20 kDa cement protein from the barnacle Megabalanus rosa (MRCP20) binds specifically to step edge atoms on {101̅4} calcite surfaces, remains bound and further assembles over time to form one-dimensional nanofibrils. Protein nanofibrils are continuous and organized at the nanoscale, exhibiting striations with a period of ca. 45 nm. These fibrils, templated by surface steps of a preferred geometry, in turn selectively dissolve underlying calcite features displaying the same atomic arrangement. To demonstrate this, we expose the protein solution to bare and fibril-associated rhombohedral etch pits to reveal that nanofibrils accelerate only the movement of fibril-forming steps when compared to undecorated steps exposed to the same solution conditions. Calcite mineralized in the presence of MRCP20 results in asymmetric crystals defined by frustrated faces with shared mirror symmetry, suggesting a similar step-selective behavior by MRCP20 in crystal growth. As shown here, selective surface interactions with step edge atoms lead to a cooperative regime of calcite modification, where templated long-range protein nanostructures shape crystals.
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Affiliation(s)
- Christopher R So
- †Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Jinny Liu
- ‡Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Kenan P Fears
- †Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Dagmar H Leary
- ‡Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Joel P Golden
- ‡Center for Bio/Molecular Science and Engineering, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
| | - Kathryn J Wahl
- †Chemistry Division, US Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, United States
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21
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Fears KP, Gonzalez-Begne M, Love CT, Day DE, Koo H. Surface-induced changes in the conformation and glucan production of glucosyltransferase adsorbed on saliva-coated hydroxyapatite. Langmuir 2015; 31:4654-4662. [PMID: 25867796 DOI: 10.1021/la504461h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Glucosyltransferases (Gtfs) from S. mutans play critical roles in the development of virulent oral biofilms associated with dental caries disease. Gtfs adsorbed to the tooth surface produce glucans that promote local microbial colonization and provide an insoluble exopolysaccharides (EPS) matrix that facilitates biofilm initiation. Moreover, agents that inhibit the enzymatic activity of Gtfs in solution often have reduced or no effects on surface-adsorbed Gtfs. This study elucidated the mechanisms responsible for the differences in functionality that GtfB exhibits in solution vs surface-adsorbed. Upon adsorption to planar fused-quartz substrates, GtfB displayed a 37% loss of helices and 36% increase of β-sheets, as determined by circular dichroism (CD) spectroscopy, and surface-induced conformational changes were more severe on substrates modified with CH3- and NH2-terminated self-assembled monolayers. GtfB also underwent substantial conformation changes when adsorbing to hydroxyapatite (HA) microspheres, likely due to electrostatic interactions between negatively charged GtfB and positively charged HA crystal faces. Conformational changes were lessened when HA surfaces were coated with saliva (sHA) prior to GtfB adsorption. Furthermore, GtfB remained highly active on sHA, as determined by in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, producing glucans that were structurally different than GtfB in solution and known to increase the accumulation and virulence of biofilms. Our data provide the first insight into the structural underpinnings governing Gtf conformation and enzymatic function that occur on tooth surfaces in vivo, which may lead to designing potent new inhibitors and improved strategies to combat the formation of pathogenic oral biofilms.
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Affiliation(s)
- Kenan P Fears
- †Chemistry Division, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Mireya Gonzalez-Begne
- ‡Department of Dentistry and Center for Oral Biology, University of Rochester Medical Center, Rochester, New York 14642, United States
| | - Corey T Love
- †Chemistry Division, U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Delbert E Day
- §Department of Materials Science and Engineering and Center for Bone and Tissue Repair and Regeneration, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
| | - Hyun Koo
- ∥Biofilm Research Laboratories, Levy Center for Oral Health, Department of Orthodontics and Division of Pediatric Dentistry and Community Oral Health, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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22
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Affiliation(s)
- Kenan P. Fears
- Chemistry
Division, Naval Research Laboratory, Washington, DC 20375, United States
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23
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Fears KP, Photiadis SJ, Kulp JL, Clark TD. Synthesis and characterization of cyclic peptides that are β
-helical in trifluoroethanol. J Pept Sci 2014; 20:366-74. [DOI: 10.1002/psc.2623] [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] [Received: 08/19/2013] [Revised: 02/07/2014] [Accepted: 02/08/2014] [Indexed: 11/05/2022]
Affiliation(s)
- Kenan P. Fears
- Division of Chemistry; Naval Research Laboratory; Washington DC 20375-5342 USA
| | - Sara J. Photiadis
- Division of Chemistry; Naval Research Laboratory; Washington DC 20375-5342 USA
| | - John L. Kulp
- Division of Chemistry; Naval Research Laboratory; Washington DC 20375-5342 USA
| | - Thomas D. Clark
- Division of Chemistry; Naval Research Laboratory; Washington DC 20375-5342 USA
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24
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Burden DK, Spillmann CM, Everett RK, Barlow DE, Orihuela B, Deschamps JR, Fears KP, Rittschof D, Wahl KJ. Growth and development of the barnacle Amphibalanus amphitrite: time and spatially resolved structure and chemistry of the base plate. Biofouling 2014; 30:799-812. [PMID: 25115515 PMCID: PMC4159999 DOI: 10.1080/08927014.2014.930736] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [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: 05/18/2014] [Accepted: 05/30/2014] [Indexed: 05/11/2023]
Abstract
The radial growth and advancement of the adhesive interface to the substratum of many species of acorn barnacles occurs underwater and beneath an opaque, calcified shell. Here, the time-dependent growth processes involving various autofluorescent materials within the interface of live barnacles are imaged for the first time using 3D time-lapse confocal microscopy. Key features of the interface development in the striped barnacle, Amphibalanus (= Balanus) amphitrite were resolved in situ and include advancement of the barnacle/substratum interface, epicuticle membrane development, protein secretion, and calcification. Microscopic and spectroscopic techniques provide ex situ material identification of regions imaged by confocal microscopy. In situ and ex situ analysis of the interface support the hypothesis that barnacle interface development is a complex process coupling sequential, timed secretory events and morphological changes. This results in a multi-layered interface that concomitantly fulfills the roles of strongly adhering to a substratum while permitting continuous molting and radial growth at the periphery.
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Affiliation(s)
- Daniel K. Burden
- Chemistry Division, Naval Research Laboratory, Washington, DC, USA
| | | | - Richard K. Everett
- Materials Science & Technology Division, Naval Research Laboratory, Washington, DC, USA
| | - Daniel E. Barlow
- Chemistry Division, Naval Research Laboratory, Washington, DC, USA
| | | | - Jeffrey R. Deschamps
- Center for Biomolecular Sciences & Engineering, Naval Research Laboratory, Washington, DC, USA
| | - Kenan P. Fears
- Chemistry Division, Naval Research Laboratory, Washington, DC, USA
| | | | - Kathryn J. Wahl
- Chemistry Division, Naval Research Laboratory, Washington, DC, USA
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25
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Affiliation(s)
- Kenan P. Fears
- Division
of Chemistry, Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Thomas D. Clark
- Division
of Chemistry, Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Dmitri Y. Petrovykh
- Division
of Chemistry, Naval Research Laboratory, Washington, D.C. 20375, United States
- Department
of Physics, University of Maryland, College Park, Maryland 20742, United States
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26
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Fears KP, Petrovykh DY, Clark TD. Evaluating protocols and analytical methods for peptide adsorption experiments. Biointerphases 2013; 8:20. [PMID: 24706133 DOI: 10.1186/1559-4106-8-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 07/17/2013] [Indexed: 11/10/2022] Open
Abstract
This paper evaluates analytical techniques that are relevant for performing reliable quantitative analysis of peptide adsorption on surfaces. Two salient problems are addressed: determining the solution concentrations of model GG-X-GG, X5, and X10 oligopeptides (G = glycine, X = a natural amino acid), and quantitative analysis of these peptides following adsorption on surfaces. To establish a uniform methodology for measuring peptide concentrations in water across the entire GG-X-GG and X n series, three methods were assessed: UV spectroscopy of peptides having a C-terminal tyrosine, the bicinchoninic acid (BCA) protein assay, and amino acid (AA) analysis. Due to shortcomings or caveats associated with each of the different methods, none were effective at measuring concentrations across the entire range of representative model peptides. In general, reliable measurements were within 30% of the nominal concentration based on the weight of as-received lyophilized peptide. In quantitative analysis of model peptides adsorbed on surfaces, X-ray photoelectron spectroscopy (XPS) data for a series of lysine-based peptides (GGKGG, K5, and K10) on Au substrates, and for controls incubated in buffer in the absence of peptides, suggested a significant presence of aliphatic carbon species. Detailed analysis indicated that this carbonaceous contamination adsorbed from the atmosphere after the peptide deposition. The inferred adventitious nature of the observed aliphatic carbon was supported by control experiments in which substrates were sputter-cleaned by Ar(+) ions under ultra-high vacuum (UHV) then re-exposed to ambient air. In contrast to carbon contamination, no adventitious nitrogen species were detected on the controls; therefore, the relative surface densities of irreversibly-adsorbed peptides were calculated by normalizing the N/Au ratios by the average number of nitrogen atoms per residue.
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Affiliation(s)
- Kenan P Fears
- Division of Chemistry, Naval Research Laboratory, Washington, DC, 20375-5342, USA,
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Fears KP, Petrovykh DY, Photiadis SJ, Clark TD. Circular dichroism analysis of cyclic β-helical peptides adsorbed on planar fused quartz. Langmuir 2013; 29:10095-10101. [PMID: 23845110 DOI: 10.1021/la401544c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Conformational changes of three cyclic β-helical peptides upon adsorption onto planar fused-quartz substrates were detected and analyzed by far-ultraviolet (UV) circular dichroism (CD) spectroscopy. In trifluoroethanol (TFE), hydrophobic peptides, Leu β and Val β, form left- and right-handed helices, respectively, and water-soluble peptide WS β forms a left-handed helix. Upon adsorption, CD spectra showed a mixture of folded and unfolded conformations for Leu β and Val β and predominantly unfolded conformations for WS β. X-ray photoelectron spectroscopy (XPS) provided insight about the molecular mechanisms governing the conformational changes, revealing that ca. 40% of backbone amides in Leu β and Val β were interacting with the hydrophilic substrate, while only ca. 15% of the amines/amides in WS β showed similar interactions. In their folded β-helical conformations, Leu β and Val β present only hydrophobic groups to their surroundings; hydrophilic surface groups can only interact with backbone amides if the peptides change their conformation. Conversely, as a β helix, WS β presents hydrophilic side chains to its surroundings that could, in principle, interact with hydrophilic surface groups, with the peptide retaining its folded structure. Instead, the observed unfolded surface conformation for WS β and the relatively small percentage of surface-bound amides (15 versus 40% for Leu β and Val β) suggest that hydrophilic surface groups induce unfolding. Upon this surface-induced unfolding, WS β interacts with the surface preferentially via hydrophilic side chains rather than backbone amides. In contrast, the unfolded β-hairpin-like form of WS β does not irreversibly adsorb on fused quartz from water, highlighting that solvation effects can be more important than initial conformation in governing peptide adsorption. Both label-free methods demonstrated in this work are, in general, applicable to structural analysis of a broad range of biomolecules adsorbed on transparent planar substrates, the surface properties of which could be customized.
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Affiliation(s)
- Kenan P Fears
- Division of Chemistry, Naval Research Laboratory, Washington, District of Columbia 20375, United States.
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Kolel-Veetil MK, Dominguez DD, Klug CA, Fears KP, Qadri SB, Fragiadakis D, Keller TM. Hybrid inorganic-organic poly(carborane-siloxane-arylacetylene) structural isomers with in-chain aromatics: Synthesis and properties. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/pola.26653] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Dawn D. Dominguez
- Chemistry Division; Naval Research Laboratory; Washington; DC; 20375
| | | | - Kenan P. Fears
- Chemistry Division; Naval Research Laboratory; Washington; DC; 20375
| | - Syed B. Qadri
- Material Science & Technology Division; Naval Research Laboratory; Washington; DC; 20375
| | | | - Teddy M. Keller
- Chemistry Division; Naval Research Laboratory; Washington; DC; 20375
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Abstract
Systems using immobilized enzymes are attractive for a wide range of industrial and medical applications because they allow for the fabrication of stable, reusable substrates with highly specific functionality. The performance of these systems is greatly dependent upon the orientation and conformation of the adsorbed enzymes. To investigate these relationships, we have developed and applied methods to quantitatively assess the secondary structure of adsorbed enzyme layers on planar surfaces using circular dichroism (CD) spectroscopy and evaluate their bioactivity using colorimetric assays. These combined measurements provide molecular-level insights regarding whether observed changes in adsorbed enzyme bioactivity are due to the adsorbed orientation of an enzyme or adsorption-induced changes in its conformation. Using this approach, we investigated the adsorption behavior of lysozyme (HEWL), xylanase (XYL), and glucose oxidase (GOx) on OH-, CH(3)-, NH(2)-, and COOH-terminated alkanethiol self-assembled monolayer (SAM) surfaces. The bioactivities of small enzymes HEWL and XYL had pronounced variations between the different SAM surfaces despite their structural stability, highlighting the role of adsorbed orientation on bioactivity. In contrast, GOx, which is a much larger enzyme, exhibited wide variations in both its structure and bioactivity after adsorption, with adsorption-induced conformational changes actually enhancing its bioactivity. These results provide new insights into protein-surface interactions at the molecular level and demonstrate that adsorption can either promote or inhibit bioactivity depending on how the surface chemistry influences the orientation and conformational state of the enzyme on the surface.
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Affiliation(s)
- Kenan P. Fears
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | - Robert A. Latour
- Department of Bioengineering, Clemson University, Clemson, SC, USA
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Fears KP, Sivaraman B, Powell GL, Wu Y, Latour RA. Probing the conformation and orientation of adsorbed enzymes using side-chain modification. Langmuir 2009; 25:9319-27. [PMID: 19610641 PMCID: PMC3830457 DOI: 10.1021/la901885d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The bioactivity of enzymes that are adsorbed on surfaces can be substantially influenced by the orientation of the enzyme on the surface and adsorption-induced changes in the enzyme's structure. Circular dichroism (CD) is a powerful method for observing the secondary structure of proteins; however, it provides little information regarding the tertiary structure of a protein or its adsorbed orientation. In this study, we developed methods using side-chain-specific chemical modification of solvent-exposed tryptophan residues to complement CD spectroscopy and bioactivity assays to provide greater detail regarding whether changes in enzyme bioactivity following adsorption are due to adsorbed orientation and/or adsorption-induced changes in the overall structure. These methods were then applied to investigate how adsorption influences the bioactivity of hen egg white lysozyme (HEWL) and glucose oxidase (GOx) on alkanethiol self-assembled monolayers over a range of surface chemistries. The results from these studies indicate that surface chemistry significantly influences the bioactive state of each of these enzymes but in distinctly different ways. Changes in the bioactive state of HEWL are largely governed by its adsorbed orientation, while the bioactive state of adsorbed GOx is influenced by a combination of both adsorbed orientation and adsorption-induced changes in conformation.
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Affiliation(s)
- Kenan P. Fears
- Department of Bioengineering, Clemson University, Clemson, SC, USA
| | | | - Gary L. Powell
- Emeritus Professor of Genetics and Biochemistry, Clemson University, Clemson, SC, USA
| | - Yonnie Wu
- Clemson University Genomics Institute, Clemson University, Clemson, SC, USA
| | - Robert A. Latour
- Department of Bioengineering, Clemson University, Clemson, SC, USA
- Corresponding Author:
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Raynor JE, Petrie TA, Fears KP, Latour RA, García AJ, Collard DM. Saccharide Polymer Brushes To Control Protein and Cell Adhesion to Titanium. Biomacromolecules 2009; 10:748-55. [DOI: 10.1021/bm8011924] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jenny E. Raynor
- School of Chemistry and Biochemistry, and Woodruff School of Mechanical Engineering and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, and Department of Bioengineering, Clemson University, Clemson, South Carolina 29634
| | - Timothy A. Petrie
- School of Chemistry and Biochemistry, and Woodruff School of Mechanical Engineering and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, and Department of Bioengineering, Clemson University, Clemson, South Carolina 29634
| | - Kenan P. Fears
- School of Chemistry and Biochemistry, and Woodruff School of Mechanical Engineering and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, and Department of Bioengineering, Clemson University, Clemson, South Carolina 29634
| | - Robert A. Latour
- School of Chemistry and Biochemistry, and Woodruff School of Mechanical Engineering and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, and Department of Bioengineering, Clemson University, Clemson, South Carolina 29634
| | - Andrés J. García
- School of Chemistry and Biochemistry, and Woodruff School of Mechanical Engineering and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, and Department of Bioengineering, Clemson University, Clemson, South Carolina 29634
| | - David M. Collard
- School of Chemistry and Biochemistry, and Woodruff School of Mechanical Engineering and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, and Department of Bioengineering, Clemson University, Clemson, South Carolina 29634
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Sivaraman B, Fears KP, Latour RA. Investigation of the effects of surface chemistry and solution concentration on the conformation of adsorbed proteins using an improved circular dichroism method. Langmuir 2009; 25:3050-6. [PMID: 19437712 PMCID: PMC2891683 DOI: 10.1021/la8036814] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
In this paper we present the development of methods using circular dichroism spectropolarimetry with a custom-designed cuvette to increase the signal-to-noise ratio for the measurement of the secondary structure of adsorbed proteins, thus providing enhanced sensitivity and reproducibility. These methods were then applied to investigate how surface chemistry and solution concentration influence both the amount of adsorbed proteins and their secondary structure. Human fibrinogen and albumin were adsorbed onto alkanethiol self-assembled monolayers (SAMs) on gold with CH3, OCH2-CF3, NH2, COOH, and OH terminal groups from both dilute (0.1 mg/mL) and moderately concentrated (1.0 mg/mL) solutions. An increase in surface hydrophobicity was found to cause an increase in both the amount of the protein adsorbed and the degree of structural change that was caused by the adsorption process, while an increase in solution concentration caused an increase in the amount of protein adsorbed but a decrease in the degree of conformational change, with these effects being more pronounced on the more hydrophobic surfaces. The combined use of these two parameters (i.e., surface chemistry and solution concentration) thus provides ameans of independently varying the degree of structural change following adsorption from the amount of adsorbed protein. Further studies are underway to examine which of these factors most strongly influences platelet response, with the overall goal of developing a better understanding of the fundamental factors governing the hemocompatibility of biomaterial surfaces.
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Fears KP, Creager SE, Latour RA. Determination of the surface pK of carboxylic- and amine-terminated alkanethiols using surface plasmon resonance spectroscopy. Langmuir 2008; 24:837-43. [PMID: 18181651 PMCID: PMC2777623 DOI: 10.1021/la701760s] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
When using self-assembled monolayers (SAMs) with ionizable functional groups, such as COOH and NH2, the dissociation constant (pKd) of the surface is an important property to know, since it defines the charge density of the surface for a given bulk solution pH. In this study, we developed a method using surface plasmon resonance (SPR) spectroscopy for the direct measurement of the pKd of a SAM surface by combining the ability of SPR to detect the change in mass concentration close to a surface and the shift in ion concentration over the surface as a function of surface charge density. This method was then applied to measure the pKd values of both COOH- and NH2-functionalized SAM surfaces using solutions of CsCl and NaBr salts, respectively, which provided pKd values of 7.4 and 6.5, respectively, based on the bulk solution pH. An analytical study was also performed to theoretically predict the shape of the SPR plots by calculating the excess mass of salt ions over a surface as a function of the difference between the solution pH and surface pKd. The analytical relationships show that the state of surface charge also influences the local hydrogen ion concentration, thus resulting in a substantial local shift in pH at the surface compared to the bulk solution as a function of the difference between the bulk solution pH and the pKd of the surface.
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Affiliation(s)
- Kenan P. Fears
- Department of Bioengineering, Clemson University, Clemson, South Carolina
| | | | - Robert A. Latour
- Department of Chemistry, Clemson University, Clemson, South Carolina
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