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DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation
The ability of poly(amido amine) (or PAMAM) dendrimers to condense semiflexible dsDNA and penetrate cell membranes gives them great potential in gene therapy and drug delivery but their high positive surface charge makes them cytotoxic. Here, we describe the effects of partial neutralization by acet...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6271276/ https://www.ncbi.nlm.nih.gov/pubmed/24005965 http://dx.doi.org/10.3390/molecules180910707 |
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author | Yu, Shi Li, Ming-Hsin Choi, Seok Ki Baker, James R. Larson, Ronald G. |
author_facet | Yu, Shi Li, Ming-Hsin Choi, Seok Ki Baker, James R. Larson, Ronald G. |
author_sort | Yu, Shi |
collection | PubMed |
description | The ability of poly(amido amine) (or PAMAM) dendrimers to condense semiflexible dsDNA and penetrate cell membranes gives them great potential in gene therapy and drug delivery but their high positive surface charge makes them cytotoxic. Here, we describe the effects of partial neutralization by acetylation on DNA condensation using light scattering, circular dichroism, and single molecule imaging of dendrimer-DNA complexes combed onto surfaces and tethered to those surfaces under flow. We find that DNA can be condensed by generation-five (G5) dendrimers even when the surface charges are more than 65% neutralized, but that such dendrimers bind negligibly when an end-tethered DNA is stretched in flow. We also find that when fully charged dendrimers are introduced by flow to end-tethered DNA, all DNA molecules become equally highly coated with dendrimers at a rate that becomes very fast at high dendrimer concentration, and that dendrimers remain bound during subsequent flow of dendrimer-free buffer. These results suggest that the presence of dendrimer-free DNA coexisting with dendrimer-bound DNA after bulk mixing of the two in solution may result from diffusion-limited irreversible dendrimer-DNA binding, rather than, or in addition to, the previously proposed cooperative binding mechanism of dendrimers to DNA. |
format | Online Article Text |
id | pubmed-6271276 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-62712762018-12-18 DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation Yu, Shi Li, Ming-Hsin Choi, Seok Ki Baker, James R. Larson, Ronald G. Molecules Article The ability of poly(amido amine) (or PAMAM) dendrimers to condense semiflexible dsDNA and penetrate cell membranes gives them great potential in gene therapy and drug delivery but their high positive surface charge makes them cytotoxic. Here, we describe the effects of partial neutralization by acetylation on DNA condensation using light scattering, circular dichroism, and single molecule imaging of dendrimer-DNA complexes combed onto surfaces and tethered to those surfaces under flow. We find that DNA can be condensed by generation-five (G5) dendrimers even when the surface charges are more than 65% neutralized, but that such dendrimers bind negligibly when an end-tethered DNA is stretched in flow. We also find that when fully charged dendrimers are introduced by flow to end-tethered DNA, all DNA molecules become equally highly coated with dendrimers at a rate that becomes very fast at high dendrimer concentration, and that dendrimers remain bound during subsequent flow of dendrimer-free buffer. These results suggest that the presence of dendrimer-free DNA coexisting with dendrimer-bound DNA after bulk mixing of the two in solution may result from diffusion-limited irreversible dendrimer-DNA binding, rather than, or in addition to, the previously proposed cooperative binding mechanism of dendrimers to DNA. MDPI 2013-09-03 /pmc/articles/PMC6271276/ /pubmed/24005965 http://dx.doi.org/10.3390/molecules180910707 Text en © 2013 by the authors; licensee MDPI, Basel, Switzerland. http://creativecommons.org/licenses/by/3.0/ This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/). |
spellingShingle | Article Yu, Shi Li, Ming-Hsin Choi, Seok Ki Baker, James R. Larson, Ronald G. DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation |
title | DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation |
title_full | DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation |
title_fullStr | DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation |
title_full_unstemmed | DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation |
title_short | DNA Condensation by Partially Acetylated Poly(amido amine) Dendrimers: Effects of Dendrimer Charge Density on Complex Formation |
title_sort | dna condensation by partially acetylated poly(amido amine) dendrimers: effects of dendrimer charge density on complex formation |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6271276/ https://www.ncbi.nlm.nih.gov/pubmed/24005965 http://dx.doi.org/10.3390/molecules180910707 |
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