Loading efficiency and surface conductance of heparin-modified poly(lactide-co-glycolide) nanoparticles

Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) with surface modification of heparin were fabricated by microemulsion-diffusion method. These novel colloidal particles were stabilized by lecithin and Tween 80. The effects of lecithin on the loading of heparin onto PLGA NPs and on the surface conductance were analyzed. The electronic micrographs revealed that spherical colloids were prepared and the incorporation of heparin caused a slight coalescence of the particles. In addition, the average diameter of heparin-modified PLGA NPs was between 70 and 220 nm. An increase in the weight percentage of lecithin or in the concentration of heparin enlarged the average diameter. Based on constant amount of surfactants, the loading efficiency of heparin on the particle surfaces reached a maximum when the weight percentage of lecithin was 50%. Moreover. the surface conductance of heparin-modified PLGA NPs was improved by an increased weight percentage of lecithin. A high concentration of heparin in microemulsion also promoted the loading efficiency and surface conductance of heparin-modified PLGA NPs. (C) 2009 Elsevier B.V. All rights reserved.