The preparation and characterization of a novel amphiphilic oleoyl-carboxymethyl chitosan self-assembled nanoparticles

Oleoyl-carboxymethyl chitosan (OCMCS) was synthesized by reacting carboxymethyl chitosan (CMCS) with oleoyl chloride. The FT-IR spectra suggested the formation of an amide linkage between amino groups of CMCS and oleoyl chloride. The solubility property of OCMCS was similar with CMCS. The CS was insoluble while the OCMCS and CMCS could be soluble at neutral pH. The improvement of solubility made CS have a wide range of uses in the biotechnology and pharmaceutical fields. All the CS, CMCS, and OCMCS had good biocompatibility based on the results of the erythrocyte toxicity assay. Formation of self-aggregation was observed by use of pyrene as a fluorescent probe in the OCMCS aqueous solution. Nanoparticles were prepared using an o/w emulsification method. The OCMCS nanoparticles were more regular and compact than OCS nanoparticles we prepared previously. Mean diameter of the OCMCS nanoparticles was 161.8 nm. Rifampicin, as a model drug, was investigated for the release properties of OCMCS nanoparticles in vitro. The addition of crosslinker sodium tripolyphosphate (STPP) could slower the release of rifampicin. The rifampicin release rate was sensitive to the pH of the release media.