Dimethylenebis-(tetra-decyldimethylammonium Bromide)-Driven Metal Nanoparticles: Hg²⁺ Sensing a Competency

We report an excellent anisotropic Au nanoparticle-based colorimetric probe for the detection of Hg²⁺ ions with higher detection ability and selectivity. The manifestation of different morphologies of Au nanoparticles including round, triangular, rectangular, pentagonal, and hexagonal has been realized by the dimethylenebis-(tetra-decyldimethylammonium bromide) (14-2-14 Gemini surfactant) assisted one-step thermal reduction method where the average size of Au nanoparticles was 54.65 ± 44.3 nm. The growth and frequency of Au nanoparticles were enhanced as a function of Gemini surfactant's concentration. The detection limit as low as 1.8 nM was efficaciously achieved and was considerably lower than the required world standards defined the maximum allowable level of Hg²⁺ ions for health hazards. Notably, the Au nanoparticles showed visible detection for 100 μM Hg²⁺ ion by means of the change in the solution color from red to tarnish blue within 180 s followed by saturation in the absorption ratio (A _LSPR/A _TSPR). These results provide novel insight into the detection of the heavy metal ion using Gemini surfactant-assisted grown anisotropic metal nanoparticles. On the basis of obtained results, it is concluded that the size of metal nanoparticles is no longer critical for preparation of efficient selective chemoprobe; rather, growth of more number of edges provides a large number of sights for incoming moieties and plays an important role in improving the detection capability of the anisotropic metal nanoparticle irrespective of their large sizes. We believe that this work provides valuable insight into researchers working in the area of chemosensor applications.