Intensifying the synthesis of starch nanoparticles using ultrasound-assisted acid hydrolysis method

Abstract

In the present study, an intensified approach for the synthesis of starch nanoparticles (SNPs) was demonstrated by using ultrasound-assisted acid hydrolysis method. The conventional acid hydrolysis for the synthesis of SNPs was intensified using ultrasound. The overall time required to convert starch granules to SNPs in the conventional acid hydrolysis method (48 h) was significantly reduced to 45 min by simultaneous acid hydrolysis and ultrasound irradiation. The acid concentration was found to be an important parameter for obtaining the desired size and morphology of the synthesized SNPs. The variation in the surface charges associated with the SNPs was confirmed through measuring their zeta potential. These potential charges on the surface of SNPs induce crystal growth among the synthesized nanoparticles. The irregular crystal morphology at higher acid concentration clearly shows SNPs' attachment with each other by coalescence. The higher crystallinity for SNPs was observed at low acid concentration; however, the lower acid concentration (0.5 M) leads to the smaller particle size of SNPs from 40 to 60 nm, with the overall yield of 23%. The proposed ultrasound method is more efficient and reproducible for the synthesis of SNPs for various applications.