Physicochemical, Thermal, and Morphological Properties of Chitosan Nanoparticles Produced by Ionic Gelation

Chitosan nanoparticles (CSNPs) can be widely used in the food, pharmaceutical, and cosmetic sectors due to their high performance, unique properties, and high surface area. In this research, CSNPs were produced by the ionic gelation method and using sodium tripolyphosphate (STPP) as an appropriate technique compared to the conventional methods. To evaluate the effects of various factors on the size, zeta potential (ZP), and optimal synthesis conditions, different concentrations of CS (1, 3, and 5 mg/mL), STPP (0.5, 0.75, and 1 mg/mL), and CS to STPP ratio (1:1, 3:1, and 5:1) were applied and optimized using the response surface methodology. The size of CSNPs was increased by using higher concentrations of CS, STPP, and CS/STPP ratios. The value of ZP was determined positive and it increased with increasing CS concentrations and CS/STPP ratios. ATR-FTIR spectra revealed interactions between CS and STPP. The DSC thermogram of CSNPs showed a double sharp endothermic peak at about 74.5 °C (ΔH = 122.00 J/g); further, the TGA thermograms indicated the total weight loss of STPP, CS, and CSNPs as nearly 3.30%, 63.60%, and 52.00%, respectively. The XRD data also revealed a greater chain alignment in the CSNPs. Optimized, the CSNPs can be used as promising carriers for bioactive compounds where they also act as efficient stabilizers in Pickering emulsions.