Ag nanostructures as the surface plasmon resonance (SPR)-based sensors: A mechanistic study with an emphasis on heavy metallic ions detection

The ever increasing release of wastes and pollutants due to rapid industrialization perilously impacts the environment and human lives. The toxic chemicals are routinely released into the environment resulting in various forms of pollution. One requisite towards controlling and managing the emission of toxic chemicals is the online monitoring and facile detecting the level of toxic chemicals; this can be achieved by the proper design and fabrication of plasmonic based sensors. The plasmonic sensors have specific advantages over conventional analytical methods. Ag nanoparticles (AgNPs) are one of the best plasmonic candidates that have been used in surface plasmon resonance (SPR)-based nanosensors for detection of various analytes including enzymes, chemical species and metallic ions. This review summarized the latest published studies in usage of AgNPs-based plasmonic nanosensors with an emphasis on heavy metallic ions (Hg2+, Pb2+, Co2+, Cd2+ and Cu2+). It was attempted to shed more light on the sensing mechanisms namely aggregation/anti-aggregation, oxidation/reduction and dimensional/morphological change. This mechanistic approach can be promisingly considered as a guide for the researchers.