Gold Nanoparticle-Based Colorimetric Assay for Selenium Detection via Hydride Generation

Gold nanoparticles (AuNPs)-based colorimetric assays are of particular interest since molecular events can be easily read out with the color changes of AuNPs by the naked eye. However, the molecular recognitions occur almost exclusively in the liquid phase (i.e., the interaction between target analytes and AuNPs is always proceeded in the presence of the sample matrix). Since the aggregation of the unmodified AuNPs is prone to be influenced by the ionic strength of the solution, sample matrix will cause undesirable interference. Here, we proposed a new type of AuNP-based colorimetric assay, in which target analyte selenium was first converted to its hydride chemical vapor (H2Se) and then delivered into the solution of AuNPs to induce color change. Therefore, sample matrix (for example, high salinity) were eliminated, leading to excellent selectivity. With the aid of hydride generation, the proposed method offered a detection limit of 0.05 μM with UV–vis detection and 1 μM with the naked eye. Successful application of this method for selenium detection in biological and environmental samples was demonstrated.