Chitosan based core–shell microgel support for urease: Step up of enzyme activity, stability and storage

Abstract

Fresh approach of urease encapsulation in a core shell type microgel platform has been extensively utilized to increase the stability and recyclability of enzymes for industrial procedures or applications. This study has explored a selective covalent immobilization method for enzymes on microgels, employing sortase-mediated techniques referred to as sortagging. Microgel enzyme bioconjugates (MEBCs) have been prepared via free radical solution emulsion polymerization method. Urease has maintained its activity inside the microgel shell at different conditions such as various pH and temperatures. The MEBCs have been formulated by combination of a specialized monomer as well as crosslinker i.e., N-Hydroxy Methyl Acrylamide (NHMA), naturally occurring & non-toxic chitosan, hydrophobic styrene, and urease, incorporated into the microgel with the aid of hydrophilic Di-Methyl Acrylamide (DMA) and room temperature (25 °C) initiator VA-044. Three grades of MEBCs have been fabricated by altering the amount of urease enzyme and keeping the remaining reaction feeds same. The synthesized MEBCs grades have demonstrated a swelling capacity up to 1388 %. Stability of MEBCs has been checked for 30 days in working medium and observed excellent enzyme activity, without altering their performance, at three different pH. MEBCs have been characterized by TGA, Power XRD, EDX, DLS, SEM, TEM, FTIR and UV-Vis. Spectroscopy analysis. Further, MEBCs have been well designed to provide thermal, pH and longer storage time stability. The performance of urease has been analysed over a period of 30 days at various temperatures and pH levels by observing the Km values.