Development of Membrane Transport-Inspired Biomimetic System to Degrade Plasticizers.

Abstract

Plasticizers added to plastics are toxic, endocrine-disrupting chemicals that may leach into the environment. Chemical and microbial degradation were reported to degrade the plasticizers. Most chemical methods operate at high temperature and pressure (energy-intensive conditions), whereas microbial hydrolases suffer from issues such as enzyme denaturation and low substrate loading. Therefore, the development of artificial biomimetic hydrolase is crucial. Microbial hydrolases utilize the proximity and proper orientation of the reactants (binding pocket) to catalyze hydrolysis in aqueous media. Inspired by nature, a novel membrane transport-inspired biomimetic approach (nanozyme) was developed to hydrolyze stable esters of aromatic acids (plasticizers) at physiological pH. This approach utilized choline- and thiocholine-based cationic micellar nanostructures to achieve high plasticizer loading in water. The nanozymes were activated by electrochemical stimulation via water splitting near the cathode, and the proximity of the reactants (plasticiser, nucleophilic catalyst, and transiently high pH) was established. Mechanistic investigations suggest that the perturbation of the pKas of hydroxy/thiol groups of nucleophilic choline or thio-choline moieties assisted the nucleophilic attack by the catalyst amphiphiles (NLC, NLTC) to hydrolyze the stable plasticiser esters in the green aqueous medium.