Peptide-driven bio-assisted removal of metal oxide nanoparticles from an aqueous suspension: A novel strategy for water remediation

Abstract

A novel, bioinspired approach to water remediation is presented in which poly-peptide molecules with specific affinity for non-biological inorganic materials are used to immobilize metal oxide nanoparticles suspended in an aqueous batch. Based on the concept of molecular recognition, the proof of concept demonstrated here comprises a two-stage incubation methodology, whereby TiO2 nanoparticles in very low concentrations (0.04 mg/ml and below) can be effectively removed from a water suspension after being recognized and selectively bound to a properly engineered inorganic-binding peptide. Operating all the time under extraordinary soft conditions of temperature and pH (T = 37 °C, pH 7), the specific methodology involves first attaching the innocuous biomolecules to a substrate and then using the entire assembly to immobilize and remove the suspended nanoparticles. The whole procedure is systematically monitored by FESEM, microRaman and UV–vis analytical measurements and reveal that the immobilization mechanism fits widely in Langmuir’s isothermal adsorption model, with the biomolecule acting as a kind of molecular glue that ensures a stable adhesion with the noxious nanoparticles.