Recent Advancement on Peptide-Based Fluorescent/Colorimetric Sensors for Metal Ion Detection

Modernization and technology development lead to an increase in the contamination of toxic metal ions into the direct environment. Unlike the other pollutants, metal ions cannot be degraded by chemical or biological ways, and are hard to abolish. To check and regulate metal ion contamination, numerous advancements have been wittnessed to develop the materials that can sense particular metal ion selectively with synchronized variation in their optical behavior. In this realm, peptide serves as a toolbox with exceptional advantages over other chemical-based metal sensors owing to specific properties, such as biocompatibility, low toxicity, high selectivity, and environment friendly nature. In addition, short peptides affixed with fluorophores have been rationally designed to exhibit high specificity for metal ions by providing multiple coordination sites in their side chains with functionalities, including thiols, amines, carboxyls, and imidazoles, exhibiting promising applications in environmental monitoring, medical diagnostics, and biochemical research. Under this realm, fluorescence-based peptide sensors have been studied for rapid and on-site detection of metal ions, including Fe³⁺, Ni²⁺, Ag¹⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Hg²⁺, As³⁺, and Al³⁺ following various photophysical pathways. This review showcases the recent advancements on the development of peptide-fabricated metal sensing agents and their mechanism of metal binding accompanied with photophysical changes.