DEGRADATION OF POLY(D,L-LACTIC ACID) NANOPARTICLES COATED WITH ALBUMIN IN MODEL DIGESTIVE FLUIDS (USP-XXII)

Entirely biodegradable poly(D,L-lactic acid) (PLA(50)) nanoparticles c oated with albumin were prepared by the solvent evaporation technique. Their degradative properties were investigated in simulated gastric a nd intestinal fluids (USP XXII). The degradation of the albumin coatin g was monitored by HPLC, whereas PLA(50) degradation was determined by size exclusion chromatography (SEC) as well as by the detection of la ctate in bulk solution by enzymatic assay. As expected, the coating ef fect of albumin, a readily digestible protein, rapidly disappeared in both gastric and intestinal media, thus exposing albumin-free PLA(50) cores to hydrolytic processes. In pepsin-rich simulated gastric fluid, no degradation of the PLA(50) core was observed over 8 h incubation t ime. In contrast, in pancreatin-rich simulated intestinal fluid, the P LA(50) nanoparticles were rapidly converted into lactate. The results showed that the PLA(50) degradation was mainly due to an enzymatic cle avage process. Further experiments showed the involvement of lipases i n the degradation of the PLA(50) core in simulated intestinal fluid.