NANOMETER SILICA PARTICLES ENCAPSULATING ACTIVE COMPOUNDS - A NOVEL CERAMIC DRUG CARRIER

Novel, injectable, and sprayable nanometer size hydrated silica partic les encapsulating high molecular weight compounds such as [I-125]tyram inylinulin (mol wt 5 kD), FITC-dextran (mol wt 19.6 kD), and horse rad ish peroxidase (mol wt 40 kD) have been prepared and characterized. Th e size of these particles is always below 100 nm in diameter and the e ntrapment efficiency was found to be as high as 80%. The entrapped com pounds show practically zero leachability for more than 45 days. Enzym es entrapped in these particles show Michaelis-Menten kinetics and the catalytic reaction takes place only after the diffusion of substrate molecules into the particles through the pores of the silica matrix. P eroxidase entrapped into silica nanoparticles shows higher stability t oward temperature and pH changes compared to free enzyme molecules.