Self-assembled peptide nanosheets functionalized with Fe3O4 nanoparticles with enhanced nanozymatic activity for sensitive colorimetric detection and selective adsorption of Hg2+

The determination and adsorption of Hg2+ in/from a solution system is of great significance in environmental monitoring and remediation. In this study, we present the design and synthesis of peptide nanosheets (PNSs) functionalized with Fe3O4 magnetic nanoparticles (MNPs) and develop a simple, fast, and naked-eye observable colorimetric detection nanoplatform and a sustainable adsorption system for Hg2+. For the aims, a functional peptide molecule with motif-designed sequence, Fmoc-FKKGSHC, is used for the formation of PNSs with uniform size by tailoring the molecular self-assembly process. The created PNSs are further modified with -COOH-functionalized Fe3O4 (c-Fe3O4) MNPs through electrostatic interaction to form two-dimensional (2D) PNSs/c-Fe3O4 nanocomposites. Due to the unique nanozymatic activity of c-Fe3O4 and specific interactions between PNSs and Hg2+, the fabricated PNSs/c-Fe3O4 nanocomposites not only exhibit high anti-interference ability towards Hg2+ detection with high sensitivity and a low detection limit of 2.52 nM but also reveal good adsorption efficiency towards Hg2+ at a concentration of 0-100 ppm as a recyclable and sustainable adsorption material. This study not only presents green strategies to prepare functional peptide nanomaterials via regulating molecular self-assembly and biomimetic synthesis but also inspires potential applications of peptide-inspired nanomaterials in biological analysis and environmental monitoring.