Highly Selective Arsenite Sensor Based on Gold Nanoparticles and Ionic Liquids

Here, we report a highly selective arsenite (As(III)) sensor based on gold nanoparticles (AuNPs) and ionic liquids (ILs). AuNPs were citrate-capped with negative charges on their surfaces, and could aggregate and precipitate once electrolytes were introduced to neutralize the negative charges. In this study, we discovered that organic ILs, behaving similarly to inorganic electrolytes such as NaCl, could induce the aggregation and precipitation of AuNPs much more efficiently than inorganic electrolytes. Since As(III) inhibited while ILs promoted the aggregation of AuNPs, we examined the interactions between AuNPs, As(III), and ILs and the possibility of using ILs and AuNPs as a sensing probe to detect arsenite and determine its concentration. Six different ILs were evaluated for this purpose in this study. Repeatability, interference, stability, selectivity, and sensitivity were investigated to evaluate the As(III) sensing probe. The limit of detection (LOD) of the sensor sBMP was as low as 0.18 ppb, ranked as the second lowest among the reported arsenite sensors. The sensing of arsenite was also demonstrated with real water samples and was cross-validated with ICP-OES.