RESUMO
Nanoparticles of ~10 nm in diameter made with chitosan or lactic acid-graftedchitosan were developed for high drug loading and prolonged drug release. A drug encapsulation efficiency of 94.4% and a release rate of 28% from chitosan nanoparticles after 24 hours were demonstrated with bovine serum protein. A drug encapsulation efficiency of 97% and a release rate of 38% from chitosan nanoparticles after 24 hours were demonstrated with Diclofenac sodium. To further increase drug encapsulation, prolongdrug release, and increase chitosan solubility in solution of neutral pH, chitosan was modifiedwith lactic acid by grafting D,L-lactic acid onto amino groups in chitosan without using a catalyst.The lactic acid-grafted chitosan nanoparticles demonstrated a drug encapsulation efficiency of96% and a protein release rate of 15% after 24 hours. And in case of diclofenac,drug encapsulation efficiency of 98% and a diclofenac release rate of 25% after 24 hours. Unlike chitosan, whichis generally soluble only in acid solution, the chitosan modified with lactic acid can be preparedfrom solutions of neutral pH, offering an additional advantage of allowing proteins or drugs tobe uniformly incorporated in the matrix structure with minimal or no denaturization.