for Heavy Metal Detection in Environmental Media: Recent Advances and Future Trends

Heavy metal pollution has long been an environmental and health problem for thousands of years. Although heavy metal contamination has been well studied and regulated nationally and internationally, remediation of heavy metal polluted environmental media remains a complicated challenge, as exposure to heavy metal continues. Novel heavy metal remediation has become a hot topic being vigorously researched in environmental science and engineering. The emergence of nanotechnology over the last two decades offers new solutions to the existing problems of the environment. Fabricated nanosensors are well recognized to be highly selective and sensitive toward certain heavy metal pollutants. Optical properties including light extinction, intensity, and scattering can be substantially altered and enhanced as a result of surface plasmon resonance phenomenon possessed by metallic nanostructures such as gold, platinum, and silver, and/or achieved by inner filter effect. Moreover, novel nanosensors could act as fluorescence quencher to produce strong fluorescence signals, or act as surface catalyzer to generate autonomous motion. These distinct mechanical, chemical, and electrical properties make many nanosensors promising candidates for environmental remediation. A variety of nanosensors, for example, surface-enhanced Raman spectroscopy and nanojets, has been designed and applied for heavy metal detection. In this review, we present a brief overview of the recent advances in the fabrication of novel nanosensors that provide potential solutions to heavy metal remediation. We also intend to provide perspective on strategies that are needed to assess and reduce the potential hazard of manufactured nanomaterials in a sustainable manner.