Recent adaptations in fluorescent SiO₂ nanomaterial’s for detection of Hg²⁺ ion: a short review

The good “natural” surroundings and health of animals and plants on the earth will be maintained by the early detection and removal of potentially hazardous heavy metal (Hg²⁺) ions. Several conventional and advanced techniques such as GC–MS, ICP–MS, AAS, HPLC, Surface-Enhanced Raman Spectroscopy (SERS), Colorimetric, Electrochemical and fluorescence-based sensors were employed for this ecological remediation. The colorimetric and fluorescent detection methods are quickly responsive, easy to probe synthesis/availability, cost-effective and highly sensitive. The SiO₂-containing hybrid nanomaterials are fluorescent, biocompatible, cost-effective, easily multi-functionalizeable, highly sensitive and selective to the analytes. Considering these advantages and the flexibility of modifications, the hybrid SiO₂ nanomaterial developed. In the present short review, we have revised and evaluated the recent modifications (2017–2023) in the silica nanoparticle relative to their functionality, methods of synthesis, range of detections, and limit of detections. In addition, the general fluorescence sensing mechanisms of this studied hybrid silicon nanoparticles to the Hg²⁺ ions have been discussed. Further, the future perspective of research for modified silica/silicon nanomaterials is discussed. The distance-dependant change in the fluorescence of these modified Si-NPs demonstrate that the doping/mixing of Si-NPs with fluorophore leads to the fluorescence ‘Turn-On’ response with few exceptions while covalently linked fluorophores with Si-NPs show ‘Turn-off’ response.