Unaided-eye detection of diverse metal ions by AuNPs-based nanocomposites: A review

Real-time applications for metal ions detection and monitoring have garnered a lot of interest due to their importance in numerous disciplines as well as in human biological processes and metabolism. Sensors derived from AuNPs are expected to alter the realism of sensing and detecting metal ions due to their adaptable surface features. Researchers from all over the world were inspired to develop the preferred functionalities for metal ion detection since surface functionalizing AuNPs is very simple. When compared to other sensing technologies, AuNP-based colorimetric detection is intriguing since the color change may be observed instantly without sophisticated equipment, analysis times are shorter, sample preparation is simple, and the cost is inexpensive. However, certain important issues for the AuNPs-based colorimetric technique need to be resolved. Even though scientists interested in materials, biology, engineering, and medicine have been lured to studies using AuNPs, the real use of AuNPs in the industry has not yet been studied. As a consequence, indeed, most of the available AuNP review articles focus on their synthesis, characteristics, characterizations, and biological applications. However, in this review, we emphasize the importance and applications of AuNPs and their nanocomposite materials in metal ion sensing utilizing a colorimetric approach. We also emphasised the benefits and drawbacks of AuNPsbased sensors, as well as their optical characteristics, synthesis techniques, and future research objectives. Henceforth, we believe that improved cross-disciplinary collaboration will likely lead to the discovery of new fundamental understandings of AuNP-based nanotechnology.