Nanostructured Sensors for Detection of Heavy Metals: A Review

Heavy metal pollution is one of the most serious environmental problems, which undermines global sustainability. Many efforts have been made to develop portable sensors for monitoring heavy metals in the environment. Incorporation of nanomaterials and nanostructures into sensors leads to significant improvement in the performance of devices in terms of sensitivity, selectivity, multiplexed detection capability and portability. In addition, small molecules, DNA, proteins and bacteria have been integrated with inorganic materials to selectively bind heavy metals as the molecular recognition probes. This review presents a recent advance in optical, electrochemical and field-effect transistor sensors for heavy metal detection. The optical sensors are focused on colorimetric, fluorescent, surface-enhanced Raman scattering and surface plasmon resonance devices. In addition, optofluidic devices which integrate optical components with microfluidic chips are discussed. Furthermore, nanoparticle-modified electrodes, microelectrode (or nanoelectrode) arrays and microfluidic electrochemical sensors are summarized. This paper highlights the strategies for design of nanostructured sensors and the benefits from the use of nanomaterials and nanostructures.