No abstract

The present research aims to improve the compatibility between relatively hydrophobic poly(lactic acid) (PLA) and hydrophilic thermoplastic starch (TPS) and the properties of the PLA/TPS blends by replacing TPS from native cassava starch (TPSN) with TPS from acetylated starch (TPSA). The effects of the degree of acetylation (DA) of acetylated starch, that is, 0.021, 0.031, and 0.074, on the morphological characteristics and properties of PLA/TPS blend are investigated. The melt blends of PLA and TPS with a weight proportion of PLA:TPS of 50:50 are fabricated and then blown into films. Scanning electron microscopy confirms the dispersion of TPS phase in the PLA matrix. Better dispersion and smaller size of the TPS phase are observed for the PLA/TPSA blend films with low DA of acetylated starch, resulting in improved tensile and barrier properties and increased storage modulus, thermal stability, and Tg, Tcc, and Tm of PLA. Elongation at break of the PLA/TPSA blend increases up to 57%, whereas its water vapor permeability and oxygen permeability decrease about 15%. The obtained PLA/TPSA blend films have the potential to be applied as biodegradable flexible packaging.

Vitexin is a natural bioactive compound with many functional properties. However, its poor water solubility and dispersion stability and short half-life limit its practical applications for targeting specific sites. The current work demonstrates that encapsulation of vitexin in chitosan nanoparticles via an oil-in-water emulsion followed by ionic gelation using pentasodium triphosphate overcomes these limitations. The successful loading of vitexin into chitosan nanoparticles was confirmed using ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. The vitexin-loaded chitosan nanoparticles were spherical, 50–250 nm in diameter, and had a negatively charged surface (zeta potential of -6.2 mV to -13.8 mV), 2.8–21.0% loading capacity (LC), and 16.6–58.2% encapsulation efficiency. Vitexin LC increased with increasing initial concentration. The vitexin-loaded chitosan nanoparticles showed antioxidant and lipid oxidation retardation activities that increased as a function of LC. Encapsulation of vitexin into chitosan nanoparticles could improve its dispersion stability in water. Vitexin release from chitosan nanoparticles into the buffer media was faster at pH 11 (completed within 10 days) than at pH 7 (80 days) and 3 (> 4 months). These results suggest that vitexin-loaded chitosan nanoparticles are stable in acidic and neutral pH media, and the loaded vitexin can potentially withstand the harsh gastrointestinal environment.