OBJECTIVE: To elucidate the mechanism of protein drugs
encapsulated by polyalkylcyanoa crytale(PACA)
nanoparticles,specifically,we
used insulin and took out a series of in vitro investigations on these
nanoparticles.METHODS: Size-exclusive chromatography was used to separate freeand
encapsulated insulin molecules.Insulin concentration was measured by radioimmunoassay (RIA).Insulin associated to nanoparticles was digested by trypsin. 125 I insulin nanoparticles were dissolved by acetonitrile and radioactivity distribution was measured by γ Counter.An “antibody capture”procedure was devised.RESULTS: Most insulin (80%) was associated with nanoparticles. This was not due to adsorption,but through tight conjunction. Although the encapsulated insulin was on the surface of the nanoparticles,it could be measured by RIA and was partially resistant to trypsin degradation.When nanoparticles were dissolved,most of the insulin was not free in the solution,but was associated with the dissolved polymer.Finally,we used anti insulin antibody to react with the encapsulated insulin,and this led to capture of the nanoparticles as well,which could be detected by scanning electron microscope (SEM).CONCLUSION: Our results strongly suggested that the insulin was on the surface Of PACA nanoparticles,possibly through covalent bond to the polymer.