Nanoparticles formulated from biodegradable polymers such as poly (lactic acid) and poly (D,L-lactide-co-glycolide) (PLGA) are being extensively investigated as non-viral gene delivery systems due to their sustained release characteristics and biocompatibility. PLGA nanoparticles for DNA delivery are mainly formulated using an emulsion-solvent evaporation technique. However, this formulation procedure results in the formation of particles with heterogeneous size distribution. The objective of the present study was to determine the relative transfectivity of the smaller- and the larger-sized fractions of nanoparticles in cell culture. PLGA nanoparticles containing a plasmid DNA encoding luciferase protein as a marker were formulated by a multiple emulsion-solvent evaporation method (mean particle diameter=97±3 nm) and were fractionated using a membrane (pore size: 100 nm) filtration technique. The particles that passed through the membrane were designated as the smaller-sized nanoparticles (mean diameter=70±2 nm) and the fraction that was retained on the membrane as the larger-sized nanoparticles (mean diameter=202±9 nm). The smaller-sized nanoparticles showed a 27-fold higher transfection than the larger-sized nanoparticles in COS-7 cell line and a 4-fold higher transfection in HEK-293 cell line. The surface charge (zeta potential), cellular uptake, and the DNA release were almost similar for the two fractions of nanoparticles, suggesting that some other yet unknown factor(s) is responsible for the observed differences in the transfection levels. The results suggest that the particle size is an important factor, and that the smaller-sized fraction of the nanoparticle formulation predominantly contributes towards their transfection.
Bibliographical noteFunding Information:
Grant support from the Nebraska Research Initiative, Gene Therapy Program and the National Institutes of Health, the Heart, Lung and Blood Institute (HL-57234) is appreciated. S.P. is supported by a predoctoral fellowship (DAMD-17-02-1-0506) from Department of Army, the US Army Medical Research Association Activity, 820 Chandler Street, Fort Detrick, MD 21702-5014. J.P. is supported by a predoctoral fellowship from the American Heart Association, Heartland Affiliate. We would like to thank Dr. Sanjeeb Sahoo for his assistance with PVA determination. We would also like to thank Mr. Tom Bargar, UNMC core electron microscopy facility for his assistance with TEM and Ms. Elaine Payne for her administrative support.
Copyright 2008 Elsevier B.V., All rights reserved.
- Biodegradable polymers
- Cellular uptake
- Gene therapy
- Non-viral vectors