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siRNA containing nanoparticles: stability of encapsulation and particle size

Kevin Buyens UGent, Kevin Braeckmans UGent, Jo Demeester UGent, Stefaan De Smedt UGent and Niek Sanders UGent (2010) DRUG DISCOVERY TODAY. 15(23-24). p.1081-1081
abstract
A large effort is currently put into the development of nano-scaled carrier systems that can guide siRNA molecules to their target cells after intravenous injection. One of the main issues in this research is the integrity of the siRNA containing nanoparticles in the blood stream. The integrity of the nanoparticles comprises both the particle size and the stable encapsulation of siRNA. Techniques currently available for studying the disassembly and size distribution of siRNA containing nanoparticles are time-consuming and incompatible with biological fluids. We initially developed a fluorescence fluctuation spectroscopy (FFS) based method which allows us to monitor the integrity of siRNA-carrier complexes in less than one minute in complex biological media and at very low siRNA concentrations. Second, while the size distribution of the complexes can be easily measured in a clear dispersion by dynamic light scattering or electron microscopy, it cannot be measured in more complex biological media such as plasma or whole blood, which contain several different interfering components. To address this issue, we have developed a novel technique, based on single particle tracking (SPT) microscopy, for studying the size distribution (and aggregation) of nanoscopic drug complexes in biological fluids. For stabilization of the particle size of cationic lipid based nanoparticles, inclusion of lipids conjugated with PEG is widely used to sterically hinder aggregate formation. We have demonstrated that in order to obtain remaining siRNA complexation to the cationic liposomes, effective encapsulation inside the liposome, or in between lipid multilayers is required, since siRNA electrostatically bound to the outer side of the liposomes is quickly pushed away by the ubiquitous albumin molecules in blood which leads to siRNA degradation and loss of effectiveness. Formation of siRNA protecting multilayers is hindered by inclusion of PEG-lipids, a hurdle that needs to be overcome either by post-insertion of the PEG-lipid into multilayer containing siRNA-liposome complexes, or by efficient encapsulation of the siRNA inside the aqueous core of the PEGylated liposome. Size stabilization in buffer can be easily achieved by inclusion of minor percentages (not, vert, similar1%) of PEG-lipids. In whole blood however, we demonstrate that much higher percentages of PEG–lipids (5–10%) are required to achieve size stabilization. This requirement has not been previously considered because of the lack of a suitable technique to study the aggregation phenomena in whole blood. In our work we demonstrate that assaying the physicochemical properties of siRNA encapsulating nanoparticles should always be carried out in the biological media they are designed to be employed in. Two novel microscopy based methods were developed that enable such characterization in biological fluids such as serum, plasma or even whole blood.
Please use this url to cite or link to this publication:
author
organization
year
type
conference
publication status
published
subject
in
DRUG DISCOVERY TODAY
Drug Discov. Today
volume
15
issue
23-24
article_number
abstract A4
pages
1081 - 1081
conference name
3rd International Cellular Delivery of Therapeutic Macromolecules (CDTM) symposium
conference location
Cardiff, Wales, UK
conference start
2010-06-26
conference end
2010-06-29
Web of Science type
Meeting Abstract
Web of Science id
000285235700017
JCR category
PHARMACOLOGY & PHARMACY
JCR impact factor
6.422 (2010)
JCR rank
13/249 (2010)
JCR quartile
1 (2010)
ISSN
1359-6446
DOI
10.1016/j.drudis.2010.09.357
language
English
UGent publication?
yes
classification
C3
id
1849868
handle
http://hdl.handle.net/1854/LU-1849868
date created
2011-06-30 15:37:37
date last changed
2011-07-04 14:10:26
@inproceedings{1849868,
  abstract     = {A large effort is currently put into the development of nano-scaled carrier systems that can guide siRNA molecules to their target cells after intravenous injection. One of the main issues in this research is the integrity of the siRNA containing nanoparticles in the blood stream. The integrity of the nanoparticles comprises both the particle size and the stable encapsulation of siRNA. Techniques currently available for studying the disassembly and size distribution of siRNA containing nanoparticles are time-consuming and incompatible with biological fluids. We initially developed a fluorescence fluctuation spectroscopy (FFS) based method which allows us to monitor the integrity of siRNA-carrier complexes in less than one minute in complex biological media and at very low siRNA concentrations. Second, while the size distribution of the complexes can be easily measured in a clear dispersion by dynamic light scattering or electron microscopy, it cannot be measured in more complex biological media such as plasma or whole blood, which contain several different interfering components. To address this issue, we have developed a novel technique, based on single particle tracking (SPT) microscopy, for studying the size distribution (and aggregation) of nanoscopic drug complexes in biological fluids. For stabilization of the particle size of cationic lipid based nanoparticles, inclusion of lipids conjugated with PEG is widely used to sterically hinder aggregate formation. We have demonstrated that in order to obtain remaining siRNA complexation to the cationic liposomes, effective encapsulation inside the liposome, or in between lipid multilayers is required, since siRNA electrostatically bound to the outer side of the liposomes is quickly pushed away by the ubiquitous albumin molecules in blood which leads to siRNA degradation and loss of effectiveness. Formation of siRNA protecting multilayers is hindered by inclusion of PEG-lipids, a hurdle that needs to be overcome either by post-insertion of the PEG-lipid into multilayer containing siRNA-liposome complexes, or by efficient encapsulation of the siRNA inside the aqueous core of the PEGylated liposome. Size stabilization in buffer can be easily achieved by inclusion of minor percentages (not, vert, similar1\%) of PEG-lipids. In whole blood however, we demonstrate that much higher percentages of PEG--lipids (5--10\%) are required to achieve size stabilization. This requirement has not been previously considered because of the lack of a suitable technique to study the aggregation phenomena in whole blood. In our work we demonstrate that assaying the physicochemical properties of siRNA encapsulating nanoparticles should always be carried out in the biological media they are designed to be employed in. Two novel microscopy based methods were developed that enable such characterization in biological fluids such as serum, plasma or even whole blood.},
  articleno    = {abstract A4},
  author       = {Buyens, Kevin and Braeckmans, Kevin and Demeester, Jo and De Smedt, Stefaan and Sanders, Niek},
  booktitle    = {DRUG DISCOVERY TODAY},
  issn         = {1359-6446},
  language     = {eng},
  location     = {Cardiff, Wales, UK},
  number       = {23-24},
  pages        = {abstract A4:1081--abstract A4:1081},
  title        = {siRNA containing nanoparticles: stability of encapsulation and particle size},
  url          = {http://dx.doi.org/10.1016/j.drudis.2010.09.357},
  volume       = {15},
  year         = {2010},
}

Chicago
Buyens, Kevin, Kevin Braeckmans, Jo Demeester, Stefaan De Smedt, and Niek Sanders. 2010. “siRNA Containing Nanoparticles: Stability of Encapsulation and Particle Size.” In Drug Discovery Today, 15:1081–1081.
APA
Buyens, K., Braeckmans, K., Demeester, J., De Smedt, S., & Sanders, N. (2010). siRNA containing nanoparticles: stability of encapsulation and particle size. DRUG DISCOVERY TODAY (Vol. 15, pp. 1081–1081). Presented at the 3rd International Cellular Delivery of Therapeutic Macromolecules (CDTM) symposium.
Vancouver
1.
Buyens K, Braeckmans K, Demeester J, De Smedt S, Sanders N. siRNA containing nanoparticles: stability of encapsulation and particle size. DRUG DISCOVERY TODAY. 2010. p. 1081–1081.
MLA
Buyens, Kevin, Kevin Braeckmans, Jo Demeester, et al. “siRNA Containing Nanoparticles: Stability of Encapsulation and Particle Size.” Drug Discovery Today. Vol. 15. 2010. 1081–1081. Print.