Microencapsulation of gallic acid in biopolymeric pectin-alginate matrices for its application in biodegradable batteries

Abstract

Gallic acid is an important phenolic compound with remarkable activities such as antimicrobial, antiviral and antioxidant. Nevertheless, there is a not so common application that is being explored by this work; its electrochemical properties. Gallic acid is able to conduct electricity in order to function inside a biobattery, however the intrinsic properties of the molecule make it susceptible to degradation in alkaline pHs, aqueous environments and light exposure. There is a wide variety of techniques used to increase the stability and the shelf life of a molecule like gallic acid. One of this techniques is the microencapsulation by the Spray Drying method. For this technique two biopolymers were proposed, alginate and pectin as they are able to form a pH responsive microcapsule needed for the function of the gallic acid molecule inside a battery. The microcapsules produced had a retention and encapsulation efficiency in the ranges of 45-82% and 79-90% respectively. The scanning electron microscopy showed smooth spherical shape capsules with some flat zones in the middle part of the capsule, however they did not present fractures or damage signals. The dynamic light scattering registered average particle sizes from 1327 to 1591 in d.nm. The Fourier-Transform infrared spectroscopy showed signals corresponding to the common peaks of each one of the wall materials. The cyclic voltammetry reported that the microcapsules are stable and have a good electrical performance at a pH value of 7, however they do not function properly in a pH value of 14. The results obtained suggest that the microcapsules have the ability to conduct currents and that gallic acid is fulfilling its role, but not it alkaline pHs as the particles have short dissolution times and gallic acid is susceptible to alkaline pH values