Thermoresponsive metalloprotein-based hybrid hydrogels for the reversible and highly selective removal of lead() from water

It is interesting to develop biomaterials for easily removing ultra-trace toxic metal ions from the environment. Herein, we have synthesized a thermoresponsive hybrid hydrogel PNIPAM- co -PbrRP by incorporating a reconstituted lead-binding peptide (PbrRP) derived from metalloregulatory protein PbrR691 into the network of poly( N -isopropylacrylamide) (PNIPAM). Combining the high sensitivity and selectivity for Pb( ii ) of PbrRP and the thermoresponsive property of PNIPAM, the hybrid hydrogel achieves innovative dual functions. It can turn into a shrunken or swollen state while the temperature is above or below the lower critical solution temperature (LCST) (34.36 °C). This shape change could provide a sufficient driving force to tune the conformation of immobilized PbrRP so that the peptide could adsorb or release lead ions reversibly. The hydrogel showed high selectivity toward Pb( ii ) even in the presence of a series of competing metal ions. By simply changing the environmental temperature across the LCST, we have enriched nanomolar Pb( ii ) from natural water samples with high efficiency, which represents a promising practical material for environmental remediation. A thermoresponsive hybrid hydrogel PNIPAM- co -PbrRP was synthesized by incorporating peptide PbrRP into the PNIPAM network. By simply changing the temperature across LCST, it can enrich nanomolar Pb(II) from natural water samples with high efficiency.