Practical immune-barometer sensor for trivalent chromium ion detection using gold core platinum shell nanoparticle probes

The technology progress of biosensors has markedly improved healthcare, disease diagnosis, environment monitoring, and food safety control over the past few decades. However, development of sensitive, robust, low-cost and portable assays for on-site bioanalysis is still a great challenge. In this study, we described a portable, feasible and miniaturized immune-barometer sensor (IBS), which can be used to sensitively measure the changes in a pressure signal, and we applied this IBS in the detection of Cr(III). In this system, a competitive immunoassay was incorporated as a signaling technique for Cr(III) detection. To generate a signal of pressure changes (ΔP), Au@PtNPs (gold core platinum shell nanoparticles) were prepared for decomposing H2O2 to generate O2 in a sealed chamber. The expansion of gas volume was accurately detected using a sensitive barometer in the sealed reaction chamber. The ΔP correlated well with Cr(III) concentrations ranging from 0.39 to 25 ng mL−1. The limit of detection (LOD) of the IBS was estimated to be as low as 0.35 ng mL−1. Furthermore, the IBS has high specificity and high recovery for Cr(III) detection in tap water samples (97.5%–108.7%) and in the Pearl River water samples (95.6%–110.2%). Compared with the traditional enzyme-linked immunosorbent assay (ELISA), the IBS was observed to be more sensitive, of low-cost and portable for the on-site detection of Cr(III). Therefore, the IBS is a promising potential method for the detection of heavy metals in aqueous solutions and many other fields.