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 = 37oC, 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.