A Mini-review on the Application of Chemically Modified Sensing Platforms for the Detection of Heavy Metal Ions in Water

High levels of metallic ions, particularly heavy metals, can cause serious damage not only to public health but to the whole ecosystem. Therefore, rapid and precise detection and monitoring of heavy metals have become vital. The detection of heavy metals in water using conventional monitoring approaches based on physicochemical and analytical procedures, e.g., inductively coupled plasma combined with atomic absorption spectroscopy, X-ray fluorescence, instrumental neutron activation analysis, etc., has been immensely utilized. However, the sophisticated sample preparation and evaluation procedures for most of the mentioned methods are time- and labor-intensive, and economically more favorable detection approaches, e.g., sensors and lab-on-a-chip techniques, are being developed. Chemical sensors (electrochemical, optical, and piezogravimetric) with different sensing platforms (nanostructures, biological, polymeric, and macrocyclic) have been considered to be the most promising ones, owing to their strong adsorption of target elements, fast electron transfer kinetics, and biocompatibility, which are very apt for sensing applications. The combination of electrochemical, optical, and piezogravimetric techniques with nanomaterials has enhanced the sensitivity, limit of detection, and robustness of the chemosensors. Following this perspective, this review highlights surface modification platforms of sensors that enhance the detection properties (sensitivity, selectivity, limit of detection, and linear range) of the proposed devices, including nanostructures, biological networks, polymers, and macrocycles with a special emphasis on calixarenes/resorcinarenes oligomers. The capabilities, limitations, and prospect assessments of the covered techniques in detection and monitoring have been highlighted.