Design of low molecular weight pectin and its nanoparticles through combination treatment of pectin by microwave and inorganic salts

Abstract

This study examined primarily the molecular weight and degree of esterification profiles of pectin in response to treatment by microwave as a function of irradiation duration in combination with monovalent (sodium chloride) or divalent (calcium acetate) inorganic salt. The possibility of formation and physical attributes of nanoparticles prepared form these pectins were assessed against their suitability for use as nanocarrier in cancer therapy. The pectin was treated by microwave (900 W) with inorganic salts as the promoter of superheating at liquid state. Its molecular weight, degree of esterification, viscosity, particle size, zeta potential and elemental content were determined. The pectin was subjected to nanospray drying with the size, zeta potential and morphology of the formed nanoparticles examined. The use of calcium acetate translated to the formation of pectin with lower molecular weight and degree of esterification, but higher solution viscosity than that of sodium chloride. Fourier transform infrared spectroscopy, particle size and elemental content analysis indicated such pectin had its molecules crosslinked by soluble calcium at COO- moiety in liquid phase. It experienced a higher heat transfer through salt bridges and chain breakdown propensity particularly with prolonged duration of treatment. The formed nanoparticles were characterized by a mean size smaller than 600 nm and were envisaged appropriate for use as nanocarrier of cancer therapeutics with respect to permeation and retention attributes of tumour vasculature. The combination of microwave with multivalent inorganic salt is a viable approach for use to convert the pectin into matrix material of nanoparticles.