Bioactive collagen/chitosan complexes were prepared by an ion crosslinking method using fish skin collagen and chitosan solution as raw materials. Scanning electron microscopy observation confirmed that the collagen/chitosan complexes were of a uniform spherical shape and uniform particle size. The complexes were stable at different pH values for a certain period of time through swelling experiments. Differential scanning calorimetry (DSC) showed the collagen/ chitosan complexes were more stable than collagen. X-ray diffraction (XRD) showed that the complexes had a strong crystal structure, and Fourier transform infrared spectroscopy (FTIR) data revealed the changes in the secondary structure of the protein due to chitosan and TPP crosslinking. The content of malondialdehyde (MDA) in the complex treatment group was considerably lower, but the content of SOD was significantly higher than that of the collagen group or chitosan group. In addition, the collagen/chitosan complexes could considerably reduce melanin content, inhibit tyrosinase activity, and down-regulate tyrosinase mRNA expression. In conclusion, the collagen/chitosan complexes were potential oral protein preparation for antioxidant enhancement and inhibiting melanin synthesis.
The aim of the study is to design octaarginine (R8)-modified insulin-alginate nanoparticles (INS-SA/R8 NPs) as the oral insulin delivery system, and further investigate its penetrating mechanism. The characterization results indicated that the surface of INS-SA/R8 NPs was smooth and the average diameter was about 300 nm. INS-SA/R8 NPs exhibited a stronger stability in the simulated gastrointestinal fluids and had a better controlled release than unmodified alginate nanoparticles (INS-SA NPs). Moreover, INS-SA/R8 NPs group had the strongest insulin transport capacity and the largest amount of insulin uptake in all experimental groups. Most importantly, the improvement of insulin intestinal uptake was further confirmed in rat intestine in vivo, and its penetrating mechanism might be involved in the production of endogenous nitric oxide (NO) signal molecule. In addition, in vivo hypoglycemic studies showed that orally administrated INS-SA/R8 NPs produced a better hypoglycemic effect as compared with INS-SA NPs in diabetic rats. Meanwhile, from the cytotoxicity analysis, INS-SA/R8 NPs were safe for oral administration. Taken together, INS-SA/R8 NPs was a good oral insulin delivery system, which might also be suitable for other protein drugs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.