Biomolecule-assisted synthesis and functionality of metal nanoclusters for biological sensing: a review

Abstract

Recent progresses in interdisciplinary sciences have yielded a new class of fluorescent nanomaterials: biomolecule-assisted fluorescent metal nanoclusters (NCs). Typically, a variety of metal NCs have been fabricated, such as those involving Ag, Au, Cu, Pt, and Cd, as well as comprising several to dozens of atoms with diameters <2 nm. The delicate introduction of biomolecules not only promotes the controllable synthesis and stability of such metal clusters, but also induces novel characteristic bioactivity that closely correlates with biological systems and the environment. Due to convenient synthesis, ultrasmall size, tunable fluorescent properties, and excellent biocompatibility, biomolecule-encapsulated metal NCs have gradually become an alternative biosensor among various fluorescent materials. Such innovative biosensors can inherently possess biomolecular shell–metal core structure and fluorescent capability, as well as exhibit desirable properties, such as simplicity, high sensitivity, better selectivity, and low cost, for improving the sensing efficacy. The current work presents a comprehensive overview involving several synthesis strategies for metal NCs using diverse biomolecules (protein, peptide, and DNA) as the stabilizing agents intended for the detection of various biological targets. In addition, based on their fluorescence quenching and enhancement mechanisms, current sensing strategies for biological analytes were also highlighted. Finally, we summarized challenges and opportunities for the potential applications of biological sensing.