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Rapid and high precision detection of toxic metal ions is one of the chief requirements today to combat environment pollution. Gold nanoparticles play a key role in this by assisting the development of smart sensors and detection agents. Their high surface to volume ratio and unique optical property facilitates the development of high sensitive analytical GNP based bio-sensing tools. Recently, a major research thrust area has been the design and development of smartly fabricated GNPs as probes for selective detection of toxic contaminates and metal pollutants. In this review we focus on the use of GNPs and its functionalization for colorimetric detection of metal ions. Colorimetric detection enables cost effective and simple monitoring of toxic ions accompanied with the advantages of on-site applicability, avoids complex instrumentation, ease of analysis and usage. We also discuss the promising prospects and future potentiality of GNPs to serve as next generation multi-functional sensing tools and “lab-on-chip” detection agents. [ABSTRACT FROM AUTHOR]

The ability of self-functionalized biogenic GNPs towards highly selective colorimetric detection of rare earth element cerium is being reported for the first time. GNPs underwent rapid aggregation on addition of cerium indicated by red shift of SPR peak followed by complete precipitation. Hereby, this concept of co-ordination of cerium ions onto the GNP surface has been utilized for detection of cerium. The remarkable capacity of GNPs to sensitively detect Ce without proves beneficial compared to previous reports of colorimetric sensing. MDL was 15 and 35 ppm by DLS and UV–vis spectroscopy respectively, suggesting DLS to be highly sensitive and a practical alternative in ultrasensitive detection studies. The sensing system showed a good linear fit favouring feasible detection of cerium in range of 2–50 ppm. Similar studies further showed the superior selectivity of biogenic GNPs compared to chemically synthesized counterparts. The sensing system favours on-site analysis as it overcomes need of complex instrumentation, lengthy protocols and surface modification of GNP. [ABSTRACT FROM AUTHOR]