Development of enzyme-loaded nanoparticles: effect of pH

Abstract

Enzyme superoxide dismutase (SOD) incorporation parameters were evaluated after immobilization in polyisobutylcyanoaclylate (PIBCA) nanoparticles. After initialization of the anionic mechanism of polymerization, pH was increased and its effect on the characteristics of PIBCA nanoparticles analysed. Our goal included optimization of enzyme activity during incorporation into nanoparticles and the influence on size distribution. Unloaded nanoparticles were not significantly affected by the pH increase. At pH 3 the size distribution indicates a bimodal distribution: 58 nm (63%) and 146 nm (37%). When pH was increased to 5 after 1 h of polymerization the size distribution is: 57 nm (70%) and 125 nm (30%). When pH was increased to 5, after 2 h of polymerization, the size distribution is 67 nm (56%) and 160 nm (44%). Meanwhile, the retention of activity of SOD in polymerization medium is 49% at pH 3, and 98% at pH 5. The effect of pH increase from 3 to 5, after 1 h of polymerization, on the characteristics of loaded nanoparticles is an increase of retention of enzyme activity (18 to 30%); and the evidence of a pH-dependent smaller size population of loaded nanoparticles. In fact at pH 3 the size distribution is 83 nm (15%), 195 nm (15%), 440 nm (70%) and when pH is increased from 3 to 5 the size distribution becomes 55 nm (30%); 170 nm (30%); 430 nm (40%).