Exploiting the high conjugation capacity of creatinine on 3,3′-dithiodipropionic acid di(N-hydroxysuccinimide ester) functionalized gold nanoparticles towards sensitive determination of mercury (II) ion in water

Mercury (Hg) contamination of the major environmental matrices, arising from human indiscriminate pursuit of industrialization without recourse to environment beneficiation is rife and worrisome. Amongst all the different forms of Hg, huge interest has been devoted to the inorganic Hg2+ determination, especially in water. Herein, a creatinine (CRN) conjugated on 3,3′-dithiodipropionic acid di(N-hydroxysuccinimide ester) (DTSP) functionalized gold nanoparticles (Au@DTSP/CRN)-based colorimetric assay was developed for Hg2+ detection in water samples. The DTSP was used to functionalize gold nanoparticles through the Au–S interaction, so as to impart a significantly high stability on the fabricated Au@DTSP, while also conferring coordination capacity on the nanoparticles. The Au@DTSP can bind to the amino group of CRN through its N-hydroxysuccinimide ester moiety, with the formation of an amide bond. The generated optical probe Au@DTSP/CRN aggregated in the presence of Hg2+, with a distinct change of solution colors from ruby red, through purple and to blue-grey within 10 min. The detection limit of 28.5 nM was achieved with linear calibration curves within 0.10–0.35 and 0.35–4.00 μM, while using the absorbance ratio (A680/A521) as the analytical response. Recoveries of 99.0–103.2% were obtained and the relative standard deviations were less than 5.5%. The Au@DTSP/CRN nanoprobe was applied for quantitative determination of Hg2+ in real water samples without significant interference from other metal ions, which is a positive indication of its utilitarian potentiality for Hg2+ profiling in aqueous environment.