1
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Schmitt S, Nuhn L, Barz M, Butt HJ, Koynov K. Shining Light on Polymeric Drug Nanocarriers with Fluorescence Correlation Spectroscopy. Macromol Rapid Commun 2022; 43:e2100892. [PMID: 35174569 DOI: 10.1002/marc.202100892] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/04/2022] [Indexed: 11/07/2022]
Abstract
The use of nanoparticles as carriers is an extremely promising way for administration of therapeutic agents, such as drug molecules, proteins and nucleic acids. Such nanocarriers (NCs) can increase the solubility of hydrophobic compounds, protect their cargo from the environment, and if properly functionalized, deliver it to specific target cells and tissues. Polymer-based NCs are especially promising, because they offer high degree of versatility and tunability. However, in order to get a full advantage of this therapeutic approach and develop efficient delivery systems, a careful characterization of the NCs is needed. This Feature Article highlights the fluorescence correlation spectroscopy (FCS) technique as a powerful and versatile tool for NCs characterization at all stages of the drug delivery process. In particular, FCS can monitor and quantify the size of the NCs and the drug loading efficiency after preparation, the NCs stability and possible interactions with, e.g., plasma proteins in the blood stream and the kinetic of drug release in the cytoplasm of the target cells. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Sascha Schmitt
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
| | - Lutz Nuhn
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
| | - Matthias Barz
- Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
| | - Kaloian Koynov
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
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2
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Kumar R, Santa Chalarca CF, Bockman MR, Bruggen CV, Grimme CJ, Dalal RJ, Hanson MG, Hexum JK, Reineke TM. Polymeric Delivery of Therapeutic Nucleic Acids. Chem Rev 2021; 121:11527-11652. [PMID: 33939409 DOI: 10.1021/acs.chemrev.0c00997] [Citation(s) in RCA: 128] [Impact Index Per Article: 42.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.
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Affiliation(s)
- Ramya Kumar
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | | | - Matthew R Bockman
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Craig Van Bruggen
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Christian J Grimme
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Rishad J Dalal
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mckenna G Hanson
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Joseph K Hexum
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Theresa M Reineke
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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3
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Levine RM, Dinh CV, Harris MA, Kokkoli E. Targeting HPV-infected cervical cancer cells with PEGylated liposomes encapsulating siRNA and the role of siRNA complexation with polyethylenimine. Bioeng Transl Med 2016; 1:168-180. [PMID: 29313012 PMCID: PMC5675078 DOI: 10.1002/btm2.10022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 07/14/2016] [Accepted: 07/15/2016] [Indexed: 01/02/2023] Open
Abstract
The greatest obstacle to clinical application of cancer gene therapy is lack of effective delivery tools. Gene delivery vehicles must protect against degradation, avoid immunogenic effects and prevent off target delivery which can cause harmful side effects. PEGylated liposomes have greatly improved tumor localization of small molecule drugs and are a promising tool for nucleic acid delivery as the polyethylene glycol (PEG) coating protects against immune recognition and blood clearance. In this study, small interfering RNA (siRNA) was fully encapsulated within PEGylated liposomes by complexing the siRNA with a cationic polymer, polyethyleneimine (PEI), before encapsulation. Formation methods and material compositions were then investigated for their effects on encapsulation. This technology was translated for protective delivery of siRNA designed for human papillomavirus (HPV) viral gene silencing and cervical cancer treatment. PEGylated liposomes encapsulating siRNA were functionalized with the AG86 targeting peptide-amphiphile which binds to the α6β4 integrin, a cervical cancer biomarker. It was found that both targeting and polymer complexation before encapsulation were critical components to effective transfection.
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Affiliation(s)
- Rachel M. Levine
- Dept. of Chemical Engineering and Materials ScienceUniversity of MinnesotaMinneapolisMN55455
| | - Christina V. Dinh
- Dept. of Chemical Engineering and Materials ScienceUniversity of MinnesotaMinneapolisMN55455
| | - Michael A. Harris
- Dept. of Chemical Engineering and Materials ScienceUniversity of MinnesotaMinneapolisMN55455
| | - Efrosini Kokkoli
- Dept. of Chemical Engineering and Materials ScienceUniversity of MinnesotaMinneapolisMN55455
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4
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Zhang D, Song Y, Wang Y, Liu X, Liu X, Ma X. Insight of In Vitro Small-Interfering RNA Release From Chitosan Nanoparticles Under Enzymolysis With Förster Resonance Energy Transfer Analysis. J Pharm Sci 2016; 105:301-7. [PMID: 26554743 DOI: 10.1002/jps.24698] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/11/2015] [Accepted: 09/30/2015] [Indexed: 01/17/2023]
Abstract
Small-interfering RNA (siRNA)-mediated gene silencing with the aid of chitosan (CS)-based carriers has shown efficient and reliable outcome in vitro, but the gene silencing efficiency in vivo is still limited. It is of great importance to balance the protection and release of siRNA from nanoparticles (NPs) so as to achieve high efficiency. However, siRNA release profile from CS/siRNA NPs has been rarely concerned. Here, Förster resonance energy transfer technique was adopted for in vitro investigation of siRNA release from CS NPs in lysozyme-contained buffer. The results clearly showed that siRNA molecules experienced a fast and short release phase under lysozyme competition to both CS and siRNA, and then a slow and long release under lysozyme degradation on CS. Moreover, lysozyme competition played more important role than enzymolysis on trigging siRNA release. This preliminary study of siRNA release is the first step to get insight of in vivo siRNA release mechanism from CS/siRNA NPs, which will be helpful to adjust the design of CS/siRNA NPs for balancing the protection and release of siRNA molecules.
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5
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Moreno PMD, Santos JC, Gomes CP, Varela-Moreira A, Costa A, Leiro V, Mansur H, Pêgo AP. Delivery of Splice Switching Oligonucleotides by Amphiphilic Chitosan-Based Nanoparticles. Mol Pharm 2016; 13:344-56. [PMID: 26702499 DOI: 10.1021/acs.molpharmaceut.5b00538] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Splice switching oligonucleotides (SSOs) are a class of single-stranded antisense oligonucleotides (ssONs) being used as gene therapeutics and demonstrating great therapeutic potential. The availability of biodegradable and biocompatible delivery vectors that could improve delivery efficiencies, reduce dosage, and, in parallel, reduce toxicity concerns could be advantageous for clinical translation. In this work we explored the use of quaternized amphiphilic chitosan-based vectors in nanocomplex formation and delivery of splice switching oligonucleotides (SSO) into cells, while providing insights regarding cellular uptake of such complexes. Results show that the chitosan amphiphilic character is important when dealing with SSOs, greatly improving colloidal stability under serum conditions, as analyzed by dynamic light scattering, and enhancing cellular association. Nanocomplexes were found to follow an endolysosomal route with a long lysosome residence time. Conjugation of a hydrophobic moiety, stearic acid, to quaternized chitosan was a necessary condition to achieve transfection, as an unmodified quaternary chitosan was completely ineffective. We thus demonstrate that amphiphilic quaternized chitosan is a biomaterial that holds promise and warrants further development as a platform for SSO delivery strategies.
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Affiliation(s)
- Pedro M D Moreno
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto (UPorto) , Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde , UPorto, 4200-135 Porto, Portugal
| | - Joyce C Santos
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto (UPorto) , Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde , UPorto, 4200-135 Porto, Portugal.,CeNano2I, Department of Metallurgical and Materials Engineering, UFMG, 31270-901 Belo Horizonte, Brazil
| | - Carla P Gomes
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto (UPorto) , Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde , UPorto, 4200-135 Porto, Portugal.,Faculdade de Engenharia da UPorto (FEUP), 4200-319 Porto, Portugal
| | - Aida Varela-Moreira
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto (UPorto) , Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde , UPorto, 4200-135 Porto, Portugal.,Faculdade de Medicina da UPorto (FMUP), 4200-319 Porto, Portugal
| | - Artur Costa
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto (UPorto) , Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde , UPorto, 4200-135 Porto, Portugal
| | - Victoria Leiro
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto (UPorto) , Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde , UPorto, 4200-135 Porto, Portugal
| | - Herman Mansur
- CeNano2I, Department of Metallurgical and Materials Engineering, UFMG, 31270-901 Belo Horizonte, Brazil
| | - Ana P Pêgo
- INEB-Instituto de Engenharia Biomédica, Universidade do Porto (UPorto) , Rua Alfredo Allen, 208, 4200-135 Porto, Portugal.,i3S-Instituto de Investigação e Inovação em Saúde , UPorto, 4200-135 Porto, Portugal.,Faculdade de Engenharia da UPorto (FEUP), 4200-319 Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar (ICBAS) , UPorto, 4050-313 Porto, Portugal
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6
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Jones SK, Lizzio V, Merkel OM. Folate Receptor Targeted Delivery of siRNA and Paclitaxel to Ovarian Cancer Cells via Folate Conjugated Triblock Copolymer to Overcome TLR4 Driven Chemotherapy Resistance. Biomacromolecules 2015; 17:76-87. [PMID: 26636884 DOI: 10.1021/acs.biomac.5b01189] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This paper focuses on the ability of a folate-decorated triblock copolymer to deliver a targeted dose of siRNA in order to overcome chemotherapy resistance which can commonly cause complications in ovarian cancer patients. The micelleplexes that are formed upon electrostatic interaction with siRNA are used to deliver siRNA in a targeted manner to SKOV-3 ovarian cancer cells that overexpress folate receptor-α (FRα). The triblock copolymer consists of polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol) (PEI-g-PCL-b-PEG-Fol). In this work, polymers of different molecular weights of PEG, as well as different grafting degrees of the (g-PCL-b-PEG-Fol) chains to PEI, were analyzed to optimize targeted siRNA delivery. The polymers, their micelleplexes, and the in vitro performance of the latter were characterized by nuclear magnetic resonance, dynamic light scattering, transmission electron microscopy, flow cytrometry, western blot, confocal microscopy, and in luciferase assays. The different PEI-g-PCL-b-PEG-Fol conjugates showed suitable sizes below 260 nm, especially at N/P 5, which also allowed for full siRNA condensation. Furthermore, flow cytometry and Western blot analysis demonstrated that our best polymer was able to effectively deliver siRNA and that siRNA delivery resulted in efficient protein knockdown of toll-like receptor 4 (TLR4). Consequently, TLR4 knock down within SKOV-3 cells resensitized them toward paclitaxel (PTX) treatment, and apoptotic events increased. This study demonstrates that PEI-g-PCL-b-PEG-Fol conjugates are a reliable delivery system for siRNA and are able to mediate therapeutic protein knockdown within ovarian cancer cells. Additionally, this study provides further evidence to link TLR4 levels to chemotherapy resistance.
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Affiliation(s)
- Steven K Jones
- Department of Oncology, Wayne State University , 4100 John R Street, Detroit, Michigan 48201, United States
| | - Vincent Lizzio
- School of Medicine, Wayne State University , 540 East Canfield Street, Detroit, Michigan 48201, United States.,Department of Pharmaceutical Sciences, Wayne State University , 259 Mack Avenue, Detroit, Michigan 48201, United States
| | - Olivia M Merkel
- Department of Oncology, Wayne State University , 4100 John R Street, Detroit, Michigan 48201, United States.,Department of Pharmaceutical Sciences, Wayne State University , 259 Mack Avenue, Detroit, Michigan 48201, United States
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7
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Dong C, Badea I, Poorghorban M, Verrall R, Foldvari M. Impact of phospholipids on plasmid packaging and toxicity of gemini nanoparticles. J Mater Chem B 2015; 3:8806-8822. [PMID: 26693021 DOI: 10.1039/c5tb01400j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding the relationship of structural modifications on the assembly and disassembly of synthetic or non-viral gene delivery is crucial with regard to their rational development. This study describes the use of fluorescence correlation spectroscopy (FCS), as a new tool, to investigate the effect of systematic chemical modifications to dicationic N,N-bis(dimethylalkyl)-α,ω-alkanediammonium surfactants (gemini surfactants) on the self-assembly and physical properties of a series of gemini nanoparticles (gemini NPs). A systematic screening of 27 gemini-plasmid (GP) complexes and gemini NPs showed that their final morphology is governed by the pre-compaction of plasmid by the gemini surfactants. The assembly process of gemini-plasmid intermediate complex (GP) and the final gemini NP (or gemini-plasmid-lipid complex, GPL) was monitored by the tracking of the Cy5-labeled plasmid. Based on diffusion properties, GP complexes were larger than gemini NPs (300-500 nm for GP and 200-300 nm for GPLs). Stoichiometric analysis of the raw intensity histograms showed that both GPs and GPLs particles were composed of multiple plasmids. The final GPLs contain fewer plasmids (2-20 per particle) compared to the intermediate GP (5-35 per particle). The addition of phospholipids dispersed and stabilized GPs to form GPL, but the type of phospholipid (DOPE or DD 1:3) had little effect on the final size of the particles. The FCS data were both validated and complemented by the results of studies of dynamic light scattering (DLS), atomic force microscopy (AFM), X-ray scattering and dye-exclusion assays. A model for gemini NP assembly involving supramolecular aggregate intermediates is proposed.
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Affiliation(s)
- Chilbert Dong
- School of Pharmacy and Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, ON, Canada N2L 3G1
| | - Ildiko Badea
- College of Pharmacy and Nutrition University of Saskatchewan, Saskatoon, SK. Canada S7N 2Z4
| | - Masoomeh Poorghorban
- College of Pharmacy and Nutrition University of Saskatchewan, Saskatoon, SK. Canada S7N 2Z4
| | - Ronald Verrall
- Department of Chemistry, University of Saskatchewan, Saskatoon, SK. Canada S7N 5C9
| | - Marianna Foldvari
- School of Pharmacy and Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, ON, Canada N2L 3G1 ; The Centre for Bioengineering & Biotechnology University of Waterloo, Waterloo, ON, Canada N2L 3G1
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8
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New Techniques to Assess In Vitro Release of siRNA from Nanoscale Polyplexes. Pharm Res 2014; 32:1957-74. [DOI: 10.1007/s11095-014-1589-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 11/24/2014] [Indexed: 12/29/2022]
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9
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10
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Reliable assessment and quantification of the fluorescence-labeled antisense oligonucleotides in vivo. BIOMED RESEARCH INTERNATIONAL 2014; 2014:196837. [PMID: 24967340 PMCID: PMC4055493 DOI: 10.1155/2014/196837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/22/2014] [Accepted: 04/22/2014] [Indexed: 11/29/2022]
Abstract
The availability of fluorescent dyes and the advances in the optical systems for in vivo imaging have stimulated an increasing interest in developing new methodologies to study and quantify the biodistribution of labeled agents. However, despite these great achievements, we are facing significant challenges in determining if the observed fluorescence does correspond to the quantity of the dye in the tissues. In fact, although the far-red and near-infrared lights can propagate through several centimetres of tissue, they diffuse within a few millimetres as consequence of the elastic scattering of photons. In addition, when dye-labeled oligonucleotides form stable complex with cationic carriers, a large change in the fluorescence intensity of the dye is observed. Therefore, the measured fluorescence intensity is altered by the tissue heterogeneity and by the fluctuation of dye intensity. Hence, in this study a quantification strategy for fluorescence-labeled oligonucleotides was developed to solve these disadvantageous effects. Our results proved that upon efficient homogenization and dilution with chaotropic agents, such as guanidinium thiocyanate, it is possible to achieve a complete fluorescence intensity recovery. Furthermore, we demonstrated that this method has the advantage of good sensitivity and reproducibility, as well as easy handling of the tissue samples.
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12
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Zheng M, Pavan GM, Neeb M, Schaper AK, Danani A, Klebe G, Merkel OM, Kissel T. Targeting the blind spot of polycationic nanocarrier-based siRNA delivery. ACS NANO 2012; 6:9447-54. [PMID: 23036046 PMCID: PMC3882193 DOI: 10.1021/nn301966r] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Polycationic nanocarriers attract increasing attention to the field of siRNA delivery. We investigated the self-assembly of siRNA vs pDNA with polycations, which are broadly used for nonviral gene and siRNA delivery. Although polyethyleneimine (PEI) was routinely adopted as siRNA carrier based on its efficacy in delivering pDNA, it has not been investigated yet why PEI efficiently delivers pDNA to cells but is controversially discussed in terms of efficacy for siRNA delivery. We are the first to investigate the self-assembly of PEI/siRNA vs PEI/pDNA and the steps of complexation and aggregation through different levels of hierarchy on the atomic and molecular scale with the novel synergistic use of molecular modeling, molecular dynamics simulation, isothermal titration calorimetry, and other characterization techniques. We are also the fist to elucidate atomic interactions, size, shape, stoichiometry, and association dynamics for polyplexes containing siRNA vs pDNA. Our investigation highlights differences in the hierarchical mechanism of formation of related polycation-siRNA and polycation-pDNA complexes. The results of fluorescence quenching assays indicated a biphasic behavior of siRNA binding with polycations where molecular reorganization of the siRNA within the polycations occurred at lower N/P ratios (nitrogen/phosphorus). Our results, for the first time, emphasize a biphasic behavior in siRNA complexation and the importance of low N/P ratios, which allow for excellent siRNA delivery efficiency. Our investigation highlights the formulation of siRNA complexes from a thermodynamic point of view and opens new perspectives to advance the rational design of new siRNA delivery systems.
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Affiliation(s)
- Mengyao Zheng
- Department of Pharmaceutics and Biopharmacy, Philipps-Universität Marburg, Germany
| | - Giovanni M. Pavan
- Laboratory of Applied Mathematics and Physics (LamFI), University for Applied Sciences of Southern Switzerland (SUPSI), Switzerland
| | - Manuel Neeb
- Department of Pharmaceutical Chemistry, Philipps-Universität Marburg, Germany
| | | | - Andrea Danani
- Laboratory of Applied Mathematics and Physics (LamFI), University for Applied Sciences of Southern Switzerland (SUPSI), Switzerland
| | - Gerhard Klebe
- Department of Pharmaceutical Chemistry, Philipps-Universität Marburg, Germany
| | - Olivia M. Merkel
- Department of Pharmaceutics and Biopharmacy, Philipps-Universität Marburg, Germany
- Address correspondence to ;
| | - Thomas Kissel
- Department of Pharmaceutics and Biopharmacy, Philipps-Universität Marburg, Germany
- Address correspondence to ;
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13
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Perevoshchikova IV, Kotova EA, Antonenko YN. Fluorescence correlation spectroscopy in biology, chemistry, and medicine. BIOCHEMISTRY (MOSCOW) 2011; 76:497-516. [PMID: 21639831 DOI: 10.1134/s0006297911050014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
This review describes the method of fluorescence correlation spectroscopy (FCS) and its applications. FCS is used for investigating processes associated with changes in the mobility of molecules and complexes and allows researchers to study aggregation of particles, binding of fluorescent molecules with supramolecular complexes, lipid vesicles, etc. The size of objects under study varies from a few angstroms for dye molecules to hundreds of nanometers for nanoparticles. The described applications of FCS comprise various fields from simple chemical systems of solution/micelle to sophisticated regulations on the level of living cells. Both the methodical bases and the theoretical principles of FCS are simple and available. The present review is concentrated preferentially on FCS applications for studies on artificial and natural membranes. At present, in contrast to the related approach of dynamic light scattering, FCS is poorly known in Russia, although it is widely employed in laboratories of other countries. The goal of this review is to promote the development of FCS in Russia so that this technique could occupy the position it deserves in modern Russian science.
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Affiliation(s)
- I V Perevoshchikova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Russia
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14
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Tardani F, Masci G, La Mesa C. Block co-polymers undergoing supra-molecular association. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2011.04.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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15
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Ko YT, Bickel U, Huang J. Polyethylenimine/oligonucleotide polyplexes investigated by fluorescence resonance energy transfer and fluorescence anisotropy. Oligonucleotides 2011; 21:109-14. [PMID: 21417932 DOI: 10.1089/oli.2010.0271] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To advance knowledge on polyplex structure and composition, fluorescence resonance energy transfer (FRET) and anisotropy measurements were applied to polyplexes of rhodamine-labeled polyethylenimine (PEI) and fluorescein-labeled double-stranded oligodeoxynucleotide (ODN). About 25 kDa PEI was compared with low-molecular-weight PEI of 2.7 kDa. FRET reached maxima at amine to phosphate (N/P) ratios of 2 and 3 for 2.7 kDa and 25 kDa PEI, respectively, with similar average distances between donor and acceptor dye molecules in polyplexes. Anisotropy measurements allowed estimating the bound fractions of PEI and ODN. At N/P = 6, all ODN was bound, but only 58% of PEI 25 kDa and 45% of PEI 2.7 kDa. In conclusion, the higher molecular weight of PEI may conformationally restrict the availability of amino groups for charge interaction with phosphate groups in ODN. Moreover, significant fractions of both types of PEI remain free in solution at N/P ratios frequently used for transfection. FRET and anisotropy measurements provide effective tools for probing polyplex compositions and designing optimized delivery systems.
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Affiliation(s)
- Young Tag Ko
- Department of Pharmaceutical Engineering, Sangji University , Wonju, South Korea.
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16
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Zustiak SP, Boukari H, Leach JB. Solute diffusion and interactions in cross-linked poly(ethylene glycol) hydrogels studied by Fluorescence Correlation Spectroscopy. SOFT MATTER 2010; 6:10.1039/C0SM00111B. [PMID: 24282439 PMCID: PMC3838862 DOI: 10.1039/c0sm00111b] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Controlled diffusion and release of soluble molecules is one of the key challenges in developing three-dimensional (3D) scaffolds for tissue engineering and drug delivery applications in part because current methods to measure dynamic transport properties are difficult to perform directly, are strongly affected by the experimental setup, and therefore can be a subject to various artifacts. In this work we present a method for direct measurement of translational diffusion of solutes, namely Fluorescence Correlation Spectroscopy (FCS), by characterizing the diffusion of model proteins through a 3D cross-linked poly(ethylene glycol) (PEG) hydrogel scaffold. We examined both the dynamics of hydrogel structure (e.g., cross-linking and swelling) as well as protein size and their effect on protein diffusivity. For example, we demonstrated that protein diffusivity was closely related to protein size as smaller proteins (e.g., lysozyme) diffused faster than larger proteins (e.g., γ-globulin or Ig). We validated the FCS protein diffusivity results by comparison to standard bulk diffusion assays. Additionally, due to the nature of FCS measurements, we were able to probe for hydrogel-protein interactions during cross-linking that may contribute to the obstructed protein diffusion in the 3D scaffold. We determined that such interactions in this system were not covalent (i.e., were independent of the cross-linking chemistry) but may be due to weaker hydrogen bonding or ionic interactions. Also, these interactions were protein specific and contributed up to 25% of the total decrease in protein diffusivity in the hydrogel as compared to diffusivity in water. Though interactions between various proteins and PEG have been reported, this is the first study that has explored these effects in detail in cross-linked PEG hydrogels using FCS; our findings question the assumption that PEG hydrogels are completely inert to protein interactions when applied as drug delivery matrices and tissue engineering scaffolds.
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Affiliation(s)
- Silviya P. Zustiak
- Department of Chemical and Biochemical Engineering, UMBC, Hilltop Circle, Baltimore, MD, 1000, USA
| | - Hacene Boukari
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
- Department of Anatomy & Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Jennie B. Leach
- Department of Chemical and Biochemical Engineering, UMBC, Hilltop Circle, Baltimore, MD, 1000, USA
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17
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Merkel OM, Beyerle A, Librizzi D, Pfestroff A, Behr TM, Sproat B, Barth PJ, Kissel T. Nonviral siRNA delivery to the lung: investigation of PEG-PEI polyplexes and their in vivo performance. Mol Pharm 2009; 6:1246-60. [PMID: 19606864 DOI: 10.1021/mp900107v] [Citation(s) in RCA: 142] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This study describes the physicobiological characterization of PEI- and PEG-PEI polyplexes containing partially 2'-OMe modified 25/27mer dicer substrate siRNAs (DsiRNAs) and their in vivo behavior regarding biodistribution and systemic bioavailability after pulmonary application as well as their ability to knock down gene expression in the lung. Biophysical characterization included circular dichroism of siRNA in polyplexes, condensation efficiency of polymers and in vitro stability. After in vivo application, biodistribution and kinetics of radiolabeled polyplexes were quantified and recorded over time in three-dimensional SPECT images and by end point scintillation counting. The influence on lung tissue and on the humoral and cellular immunosystem was investigated, and finally knockdown of endogenous gene expression in the lung was determined qualitatively. While all of the polymers used in our study were proven to effectively condense siRNA, stability of the complexes depended on the PEG grafting degree. Interestingly, PEI 25 kDa, which showed the least interaction with mucin or surfactant in vitro, performed poorly in vivo. Our nuclear imaging approach enabled us to follow biodistribution of the instilled nanocarriers over time and indicated that PEGylated nanocarriers are more suitable for lung application. While moderate proinflammatory effects were attributed to PEI25k-PEG(2k)(10) nanocarriers, none of the treatments caused histological abnormalities. Our preliminary in vivo knockdown experiment suggests that PEG-PEI/siRNA complexes are promising nanomedicines for pulmonary siRNA delivery. These results encouraged us to further investigate possible adverse effects and to quantify in vivo gene silencing in the lung after intratracheal instillation of PEG-PEI/siRNA complexes.
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Affiliation(s)
- Olivia M Merkel
- Department of Pharmaceutics and Biopharmacy, Philipps Universitat Marburg, Ketzerbach 63, 35032 Marburg, Germany
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18
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Merkel OM, Librizzi D, Pfestroff A, Schurrat T, Buyens K, Sanders NN, De Smedt SC, Béhé M, Kissel T. Stability of siRNA polyplexes from poly(ethylenimine) and poly(ethylenimine)-g-poly(ethylene glycol) under in vivo conditions: effects on pharmacokinetics and biodistribution measured by Fluorescence Fluctuation Spectroscopy and Single Photon Emission Computed Tomography (SPECT) imaging. J Control Release 2009; 138:148-59. [PMID: 19463870 DOI: 10.1016/j.jconrel.2009.05.016] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 04/15/2009] [Accepted: 05/08/2009] [Indexed: 01/22/2023]
Abstract
In search of optimizing siRNA delivery systems for systemic application, one critical parameter remains their stability in blood circulation. In this study, we have traced pharmacokinetics and biodistribution of each component of siRNA polyplexes formed with polyethylenimine 25 kDa (PEI) or PEGylated PEIs by in vivo real-time gamma camera recording, SPECT imaging, and scintillation counting of blood samples and dissected organs. In vivo behavior of siRNA and polymers were compared and interpreted in the context of in vivo stability of the polyplexes which had been measured by fluorescence fluctuation spectroscopy (FFS). Both pharmacokinetics and biodistribution of polymer-complexed siRNA were dominated by the polymer. PEGylated polymers and their siRNA polyplexes showed significantly less uptake into liver (13.6-19.7% ID of PEGylated polymer and 9.5-10.2% ID of siRNA) and spleen compared to PEI 25 kDa (liver deposition: 36.2% ID of polymer and 14.6% ID of siRNA). With non-invasive imaging methods we were able to predict both kinetics and deposition in living animals allowing the investigation of organ distribution in real time and at different time points. FFS measurements proved stability of the applied polyplexes under in vivo conditions which explained the different behavior of complexed from free siRNA. Despite their stability in circulation, we observed that polyplexes dissociated upon liver passage. Therefore, siRNA/(PEG-)PEI delivery systems are not suitable for systemic administration, but instead may be useful when the first-pass effect is circumvented, which is the case in local application.
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Affiliation(s)
- Olivia M Merkel
- Department of Pharmaceutics and Biopharmacy, Philipps-Universität Marburg, Ketzerbach 63, 35037 Marburg, Germany
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19
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20
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Culbertson MJ, Williams JTB, Cheng WWL, Stults DA, Wiebracht ER, Kasianowicz JJ, Burden DL. Numerical fluorescence correlation spectroscopy for the analysis of molecular dynamics under nonstandard conditions. Anal Chem 2007; 79:4031-9. [PMID: 17447726 DOI: 10.1021/ac062013m] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The suitability of mathematical models used to extract kinetic information from correlated data constitutes a significant issue in fluorescence correlation spectroscopy (FCS). Standard FCS equations are derived from a simple Gaussian approximation of the optical detection volume, but some investigations have suggested this traditional practice can lead to inaccurate and misleading conclusions under many experimental circumstances, particularly those encountered in one-photon confocal measurements. Furthermore, analytical models cannot be derived for all measurement scenarios. We describe a novel numerical approach to FCS that circumvents conventional analytical models, enabling meaningful analyses even under extraordinarily unusual measurement conditions. Numerical fluorescence correlation spectroscopy (NFCS) involves quantitatively matching experimental correlation curves with synthetic curves generated via diffusion simulation or direct calculation based on an experimentally determined 3D map of the detection volume. Model parameters are adjusted iteratively to minimize the residual differences between synthetic and experimental correlation curves. In order to reduce analysis time, we distribute calculations across a network of processors. As an example of this new approach, we demonstrate that synthetic autocorrelation curves correspond well with experimental data and that NFCS diffusion measurements of Rhodamine B remain constant, regardless of the distortion present in a confocal detection volume.
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21
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Remaut K, Lucas B, Raemdonck K, Braeckmans K, Demeester J, De Smedt SC. Can we better understand the intracellular behavior of DNA nanoparticles by fluorescence correlation spectroscopy? J Control Release 2007; 121:49-63. [PMID: 17509716 DOI: 10.1016/j.jconrel.2007.04.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Revised: 04/02/2007] [Accepted: 04/09/2007] [Indexed: 11/21/2022]
Abstract
The use of non-viral gene carriers to deliver small nucleic acids like antisense oligonucleotides (ODNs) and small interfering RNA (siRNA) remains an attractive but challenging goal in antisense therapy. Indeed, different barriers need to be overcome in the delivery process before a therapeutic effect can be obtained. One promising technique which we have been evaluating to improve our understanding of the intracellular behavior of nucleic acids/carrier complexes is Fluorescence Correlation Spectroscopy (FCS). In particular, we have used FCS for studying the protection of the nucleic acids against enzymatic degradation, and the association and dissociation of the nucleic acids with their carrier, both in buffer and in living cells. In this report, we will review our experience and findings on the use of FCS for that purpose and discuss the strengths and weaknesses of this interesting technique.
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MESH Headings
- Animals
- Buffers
- Carbocyanines/metabolism
- Cell Line, Tumor
- Cell Nucleus/metabolism
- Chlorocebus aethiops
- Cytoplasm/metabolism
- DNA/chemistry
- Dextran Sulfate/chemistry
- Fluorescein-5-isothiocyanate/metabolism
- Fluorescence Resonance Energy Transfer
- Fluorescent Dyes/metabolism
- Humans
- Liposomes/chemistry
- Models, Chemical
- Nanoparticles/chemistry
- Oligonucleotides, Antisense/administration & dosage
- Oligonucleotides, Antisense/chemistry
- Oligonucleotides, Antisense/metabolism
- RNA, Small Interfering/administration & dosage
- RNA, Small Interfering/chemistry
- Ribonuclease, Pancreatic/pharmacology
- Spectrometry, Fluorescence/instrumentation
- Spectrometry, Fluorescence/methods
- Vero Cells
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Affiliation(s)
- K Remaut
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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22
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Adjimatera N, Kral T, Hof M, Blagbrough IS. Lipopolyamine-mediated single nanoparticle formation of calf thymus DNA analyzed by fluorescence correlation spectroscopy. Pharm Res 2006; 23:1564-73. [PMID: 16783476 DOI: 10.1007/s11095-006-0278-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 02/27/2006] [Indexed: 11/29/2022]
Abstract
PURPOSE The aim of this study is to analyze linear calf thymus DNA (ct DNA) nanoparticle formation with N4,N9-dioleoylspermine and N1-cholesteryl spermine carbamate. METHODS Fluorescence correlation spectroscopy (FCS) was used to determine the quality of ct DNA condensed by lipopolyamines. ct DNA was prelabeled with PicoGreen (PG) to allow fluorescence intensity fluctuation measurement and analysis. RESULTS N4,N9-dioleoylspermine efficiently condensed ct DNA into point-like molecules with diffusion coefficient (D) = 1.8 x 10(-12) m2/s and particle number (PN) = 0.7 [at ammonium/phosphate (N/P) charge ratio = 1.0-1.5]. The determined PN values are close to the theoretical value of 0.6, providing evidence that the DNA conformation has been fully transformed, and thus a single nanoparticle has been detected. N1-cholesteryl spermine carbamate showed (slightly) poorer DNA condensation efficiency, even at higher N/P ratios (N/P = 1.5-2.5) with D = 1.3 x 10(-12) m2/s and PN value of 5.2. N4,N9-dioleoylspermine is a more efficient DNA-condensing agent than N1-cholesteryl spermine carbamate. CONCLUSIONS FCS measurement using PG as the probe is a novel analytical method to detect single nanoparticles of condensed DNA in nonviral gene therapy formulation studies.
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Affiliation(s)
- Noppadon Adjimatera
- Department of Pharmacy and Pharmacology, University of Bath, Bath, BA2 7AY, UK
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23
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Glodde M, Sirsi SR, Lutz GJ. Physiochemical properties of low and high molecular weight poly(ethylene glycol)-grafted poly(ethylene imine) copolymers and their complexes with oligonucleotides. Biomacromolecules 2006; 7:347-56. [PMID: 16398535 DOI: 10.1021/bm050726t] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inefficient delivery of antisense oligonucleotides (AOs) to target cell nuclei remains as the foremost limitation to their usefulness. Copolymers of cationic poly(ethylene imine) (PEI) and poly(ethylene glycol) (PEG) have been well-studied for delivery of plasmids. However, the properties of PEG-PEI-AO polyplexes have not been comprehensively investigated. Therefore, we synthesized a series of PEG-PEI copolymers and evaluated their physiochemical properties alone and when complexed with AO. The M(w) of PEG was found to be the main determinant of polyplex size, via its influence on particle aggregation. DLS measurements showed that when PEG5000 was grafted to PEI2K and PEI25K, polyplex diameters were extremely small (range 10-90 nm) with minimal aggregation. In contrast, when PEG550 was grafted to PEI2K and PEI25K, polyplexes appeared as much larger aggregates (approximately 250 nm). As expected, the surface charge (zeta potential) was higher for polyplexes containing PEI25K than those containing PEI2K, but decreased with increased levels of PEG grafting. Surprisingly, within the physiological range (pH 7.5-5), the buffering capacity of all copolymers was nearly equivalent to that of unsubstituted PEI2K or PEI25K, and was barely influenced by PEGylation. The stability of polyplexes was evaluated using a heparin polyanion competition assay. Unexpectedly, polyplexes containing PEI2K showed stability equal to or greater than that of PEI25K polyplexes. The level of PEG grafting also had a dramatic effect on polyplex stability. The relationships established between molecular formulations and polyplex size, aggregation, surface charge, and stability should provide a useful guide for future studies aimed at optimizing polymer-mediated AO delivery in cell and animal studies. A summary of the relationships between polyplex structures and recent studies of their transfection capacity is provided.
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Affiliation(s)
- Martin Glodde
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA
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24
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Liu B, Bazan GC. Optimization of the Molecular Orbital Energies of Conjugated Polymers for Optical Amplification of Fluorescent Sensors. J Am Chem Soc 2006; 128:1188-96. [PMID: 16433535 DOI: 10.1021/ja055382t] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cationic water-soluble poly(fluorene-co-phenylene)s with electron withdrawing or donating substituents on the conjugated backbone were designed and synthesized. Fluorescence resonance energy transfer (FRET) experiments between these conjugated polymers and dye-labeled single-stranded DNA (ssDNA-C*) reveal the importance of matching donor and acceptor orbital energy levels to improve the sensitization of C* emission. Quenching of polymer fluorescence with ssDNA-C* and differences in C* emission suggest involvement of photoinduced charge transfer (PCT) as an energy wasting mechanism. The HOMO and LUMO energy levels of the conjugated polymers and C serve as a preliminary basis to understand the competition between FRET and PCT. Dilution of C in polymer/ssDNA-C complexes by addition of ssDNA yields insight into C*...C self-quenching. Under optimized conditions, where there is no probe self-quenching and minimum PCT, efficient signal amplification is demonstrated despite poor spectral overlap between polymer and C.
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Affiliation(s)
- Bin Liu
- Department of Materials and Chemistry and Biochemistry, Institute for Polymers and Organic Solids, University of California at Santa Barbara, 93106, USA
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25
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Remaut K, Lucas B, Braeckmans K, Sanders NN, Demeester J, De Smedt SC. Protection of oligonucleotides against nucleases by pegylated and non-pegylated liposomes as studied by fluorescence correlation spectroscopy. J Control Release 2005; 110:212-26. [PMID: 16298008 DOI: 10.1016/j.jconrel.2005.09.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Revised: 09/20/2005] [Accepted: 09/26/2005] [Indexed: 11/25/2022]
Abstract
Antisense phosphodiester oligonucleotides (ONs), complexed to carriers such as cationic liposomes, inhibit the production of proteins. The biochemical and biophysical phenomena that govern the extent of this inhibition are still not fully understood. Major biological barriers limiting a pronounced antisense effect are the cellular entry and endosomal escape of the ONs containing liposomes, the release of the ONs from the liposomes and the extra- and intracellular degradation of the ONs. In this paper we focus on the latter barrier and evaluate, by fluorescence correlation spectroscopy (FCS), to what extent phosphodiester ONs complexed to DOTAP/DOPE liposomes, are protected against degradation by nucleases. Liposomes studied were either with or without a polyethyleneglycol (PEG) moiety at the surface. Using non-pegylated liposomes the phosphodiester ONs were initially adequately protected when exposed to DNase I. Indeed, in the mechanism for lipoplex formation as suggested by others, the ONs become trapped between lipid bilayers and are therefore shielded from the environment. However, after a few hours the phosphodiester ONs no longer stayed intact. This was explained by a gradual fusion of the lipoplexes in time thereby spontaneously releasing phosphodiester ONs. Using pegylated liposomes, a substantial fraction of the phosphodiester ONs degraded immediately after exposing the complexes to DNase I. Based on experimental evidence we suggest that the presence of the PEG-chains influences lipoplex formation so that the ONs are not trapped between lipid bilayers and therefore remain accessible by the DNase I enzyme.
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Affiliation(s)
- K Remaut
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Belgium.
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26
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Platonova GA, Tennikova TB. Chromatographic investigation of macromolecular affinity interactions. J Chromatogr A 2005; 1065:75-81. [PMID: 15782953 DOI: 10.1016/j.chroma.2004.10.073] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
High-performance monolithic disk affinity chromatography was applied to the investigation of formation of complexes between (1) complementary polyriboadenylic and polyribouridylic acids, e.g. poly(A) and poly(U), respectively, (2) poly(A) and synthetic polycation poly(allylamine), pAA. Polyriboadenylic acid and poly(allylamine) were immobilized on macroporous disks (CIM disks). Quantitative parameters of affinity interactions between macromolecules were established using frontal analysis at different flow rates.
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Affiliation(s)
- Galina A Platonova
- Institute of Macromolecular Compounds, Russian Academy of Sciences, St Petersburg 199004, Russia
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27
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Complexation of well-controlled low-molecular weight polyelectrolytes with antisense oligonucleotides. Colloid Polym Sci 2005. [DOI: 10.1007/s00396-005-1311-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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28
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Lucas B, Remaut K, Sanders NN, Braeckmans K, De Smedt SC, Demeester J. Towards a better understanding of the dissociation behavior of liposome-oligonucleotide complexes in the cytosol of cells. J Control Release 2005; 103:435-50. [PMID: 15763625 DOI: 10.1016/j.jconrel.2004.12.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Revised: 12/10/2004] [Accepted: 12/16/2004] [Indexed: 11/21/2022]
Abstract
To obtain real breakthroughs in antisense therapy, it is necessary to understand the cellular behavior of antisense delivery systems. Fluorescence fluctuation spectroscopy (FFS), which measures in time fluorescence fluctuations in the excitation volume of a microscope and which can thus be applied on a cellular scale, shows potential for this purpose. In this study dual color FFS was explored to characterize the complexation (association and dissociation) between Cy5-labeled oligonucleotides (Cy5-ONs) and FITC-labeled cationic liposomes (FITC-liposomes) in respectively buffer, cell lysate and the cytosol of Vero cells. In Hepes buffer the association of the Cy5-ONs to the FITC-liposomes could be clearly observed from the high peaks of Cy5- and FITC-fluorescence, which appeared simultaneously in the excitation volume. This was explained by the fact that in the complexed state many Cy5-ONs and FITC-liposomes are bound to each other and thus move together through the excitation volume thereby resulting in high fluorescence 'FITC/Cy5-peaks'. FFS measurements on FITC-liposome/Cy5-ONs complexes in cell lysate revealed that a minor part of the Cy5-ONs was released from the complexes. The major part of the Cy5-ONs remained in the complexes, which also seemed to aggregate in cell lysate. In agreement with the measurements in cell lysate, after microinjection of FITC-liposome/Cy5-ONs complexes in the cytosol of Vero cells a part of the Cy5-ONs was released (as Cy-ONs were detected by FFS in the nuclei) while the other part remained bound (as Cy5-peaks were frequently observed in the cytosol). As will be explained, the Cy5-peaks could be due both to Cy5-ONs clustered with cytosol components and Cy5-ONs still complexed to FITC-liposomes with quenched FITC-fluorescence.
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Affiliation(s)
- B Lucas
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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29
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Remaut K, Lucas B, Braeckmans K, Sanders NN, De Smedt SC, Demeester J. FRET-FCS as a tool to evaluate the stability of oligonucleotide drugs after intracellular delivery. J Control Release 2004; 103:259-71. [PMID: 15710516 DOI: 10.1016/j.jconrel.2004.11.019] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 11/03/2004] [Accepted: 11/15/2004] [Indexed: 10/26/2022]
Abstract
The intracellular degradation of single-stranded, double-labeled oligonucleotides (ONs) was studied by following the disappearance of Fluorescence Resonance Energy Transfer (FRET) between the rhodamine green and Cy5 fluorophores attached to respectively the 3' and 5' end of the ONs. The green and red fluorescence intensities upon rhodamine green excitation were monitored using the ultra-sensitive detectors of a dual-color Fluorescence Correlation Spectroscopy (FCS) instrument. The ratio of the red to green fluorescence (R/G ratio) as obtained from such FRET-FCS measurements showed to give accurate information on the integrity of the ONs, without the need for additional auto- or cross-correlation analysis of the registered fluorescence intensity fluctuations. Intracellular measurements revealed that most of the 40mer phosphodiester ONs were degraded before they entered the nucleus. For the 20mer phosphodiester ONs, this degradation occurred more slowly, and both intact and degraded ONs entered the nucleus. For the 20mer phosphorothioate ONs, no intracellular degradation was observed during the measured time period. The sensitive detection of the intracellular fluorescence by the FCS setup will be particularly useful in situations where the expected fluorescence is too low to be detected by FRET-imaging as may occur after intracellular delivery of ONs by cationic carriers.
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Affiliation(s)
- K Remaut
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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30
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Brus C, Kleemann E, Aigner A, Czubayko F, Kissel T. Stabilization of oligonucleotide-polyethylenimine complexes by freeze-drying: physicochemical and biological characterization. J Control Release 2004; 95:119-31. [PMID: 15013239 DOI: 10.1016/j.jconrel.2003.10.021] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2003] [Accepted: 10/18/2003] [Indexed: 10/26/2022]
Abstract
In the present study the lyophilization of oligodeoxynucleotide-polyethylenimine (ODN-PEI) complexes was investigated regarding the maintenance of physicochemical properties and influence on biological activity. To achieve this, we used PEI of different molecular weights, in the range of 800-0.8 kDa, as complexing agents for unmodified ODN and ribozymes. The hydrodynamic diameter was measured by photon correlation spectroscopy (PCS) and the zeta potential was determined using laser Doppler anemometry (LDA) of ODN complexes with PEI derivatives of different molecular weights both before and after lyophilization. Atomic force microscopy (AFM) was used to visualize freshly prepared, stored and lyophilized complexes in solution. The biological activity of the ODN, as well as of plasmid DNA, in lyophilized PEI complexes was examined and compared to freshly prepared complexes using standard transfection assays. All PEI derivatives formed very small complexes with ODN displaying hydrodynamic diameters ranging from 15 to 30 nm. Marginal changes in size after lyophilization were observed for ODN-PEI complexes. In contrast, plasmid complexed with PEI was found to aggregate. In either cases minimal or no influence of the added amount of lyoprotectant was observed. The shape of the very small and highly condensed ODN complexes was not altered by lyophilization as seen in the AFM images. The transfection efficiency of lyophilized ribozyme-PEI complexes relative to freshly prepared complexes was approximately 100%, whereas a decrease was seen for lyophilized plasmid-PEI complexes. An additive of the lyoprotectants trehalose, mannitol or sucrose preserved biological activity. This study demonstrates the particular suitability of ODN-PEI complexes to be formulated as lyophilized systems with no loss in physical stability or biological activity.
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Affiliation(s)
- Carola Brus
- Department of Pharmaceutics and Biopharmacy, Philipps-University Marburg, Ketzerbach 63, 35037 Marburg, Germany
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31
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Weyermann J, Lochmann D, Georgens C, Rais I, Kreuter J, Karas M, Wolkenhauer M, Zimmer A. Physicochemical characterisation of cationic polybutylcyanoacrylat-nanoparticles by fluorescence correlation spectroscopy. Eur J Pharm Biopharm 2004; 58:25-35. [PMID: 15207534 DOI: 10.1016/j.ejpb.2004.02.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Revised: 02/02/2004] [Accepted: 02/02/2004] [Indexed: 11/22/2022]
Abstract
The aim of this study was to compare different physical and chemical methods with fluorescence correlation spectroscopy (FCS) in order to characterise cationic acrylate nanoparticles (NP), which can deliver oligonucleotides (ON) into mammalian cells. These positively charged nanoparticles were prepared from diethylaminoethyl dextran (DEAE-dextran) and poly(n-butyl-2-cyanoacrylate) (PBCA). NP consists of PBCA oligochains with an average size of PBCA 9 mer and were formed by entrapping DEAE-dextran and dextran 70,000 in high amounts into the particle matrix. The oligochain length of PBCA was investigated by mass-spectroscopy (MALDI TOF). The molecular weight of a particle with d = 108 nm was estimated to be approximately 3.6 x 10(8) Da. The mean size of the nanoparticles were in a range of dh = 130-140 nm, as determined independently by FCS and dynamic light scattering. Atomic force microscopy and scanning electron microscopy images confirm this size range. Furthermore, the particle mass of the PBCA-NP was estimated by FCS measurements. For this approach two new methods for fluorescence labelling of cationic particles were developed. Fluorescent labelled dextran 70,000 was entrapped into the particle matrix; in addition, the derivatisation of hydroxyl groups of the NP was achieved with 5-([4,6-dichlorotriazin-2-yl]amino) fluorescein (DTAF). ON can be localised in a complex with the NP by dual-colour fluorescence cross correlation spectroscopy measurements. The zetapotential of the unloaded NP was positively charged with about +39 mV and decreased down to -40 mV on addition of excess ON. After centrifugation quantification of the ON loading onto the particles by strong anion exchange high performance liquid chromatography (SAX HPLC) and FCS showed that approximately 20 microg ON per 100 g NP was adsorbed. The FCS measurements of the ON adsorption in situ was found to be much higher with approximately 95 microg ON per 100 g NP.
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Affiliation(s)
- Jörg Weyermann
- Institute for Pharmaceutical Technology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany
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32
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Lucas B, Remaut K, Braeckmans K, Haustraete J, De Smedt SC, Demeester J. Studying Pegylated DNA Complexes by Dual Color Fluorescence Fluctuation Spectroscopy. Macromolecules 2004. [DOI: 10.1021/ma035780l] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- B. Lucas
- Laboratory for General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - K. Remaut
- Laboratory for General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - K. Braeckmans
- Laboratory for General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - J. Haustraete
- Laboratory for General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - S. C. De Smedt
- Laboratory for General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - J. Demeester
- Laboratory for General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
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34
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Clamme JP, Azoulay J, Mély Y. Monitoring of the formation and dissociation of polyethylenimine/DNA complexes by two photon fluorescence correlation spectroscopy. Biophys J 2003; 84:1960-8. [PMID: 12609898 PMCID: PMC1302765 DOI: 10.1016/s0006-3495(03)75004-8] [Citation(s) in RCA: 223] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Polyethylenimines (PEI) constitute efficient nonviral vectors for gene transfer. However, because free PEI shows some cytotoxicity and because intracellular dissociation of PEI/DNA complexes seems to be required for efficient transfection, it is important to monitor the concentrations of free and bound partners in the mixtures of DNA and PEI used for transfection. To reach this objective, we used fluorescence correlation spectroscopy with two-photon excitation to characterize the complexes formed with either rhodamine-labeled 25 kDa PEI or DNA plasmid molecules. At the molar ratios of PEI nitrogen atoms to DNA phosphate usually used for transfection, we found that approximately 86% of the PEI molecules were in a free form. The PEI/DNA complexes are composed on the average by 3.5 (+/-1) DNA plasmids and approximately 30 PEI molecules. From this composition and the pK(a) of PEI, it could be inferred that in contrast to DNA condensation by small multivalent cations, only a limited neutralization of the DNA phosphate groups is required for DNA condensation by PEI. Moreover, DNA appears only poorly compacted in the PEI/DNA complexes. As an application, fluorescence correlation spectroscopy was used to monitor the purification of PEI/DNA complexes by ultrafiltration as well as the heparin-induced dissociation of the complexes.
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Affiliation(s)
- Jean Pierre Clamme
- Laboratoire Pharmacologie et Physico-Chimie des Interactions Cellulaires et Moléculaires, UMR 7034 du CNRS, Faculté de Pharmacie, Université Louis Pasteur de Strasbourg, 74, Route du Rhin, 67401 Illkirch Cedex, France
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Lucas B, Van Rompaey E, De Smedt SC, Demeester J, Van Oostveldt P. Dual-Color Fluorescence Fluctuation Spectroscopy To Study the Complexation between Poly-l-lysine and Oligonucleotides. Macromolecules 2002. [DOI: 10.1021/ma0202383] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- B. Lucas
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - E. Van Rompaey
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - S. C. De Smedt
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - J. Demeester
- Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Harelbekestraat 72, 9000 Ghent, Belgium
| | - P. Van Oostveldt
- Laboratory of Biochemistry and Molecular Cytology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
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