A paper based microfluidic device is fabricated that can rapidly detect very low concentrations of As3+ ions using a gold nanosensor, Au–TA–TG.

Functionalization of gold nanorod (GNR) with dimercaptosuccinic acid is reported as a way to develop a sensor, GNR-PEG-DMSA that can rapidly detect very low concentrations of arsenic contamination in water and using the paper strip. The sensor is developed by stepwise chemical conjugations of gold nanorods (GNR) with poly­(ethylene glycol) methyl ether thiol (mPEG-SH) followed by meso-2,3-dimercaptosuccinic acid (DMSA). GNR-PEG-DMSA shows a visible color change in the presence of both inorganic forms of arsenic: AsIII (arsenite) and AsV (arsenate) ions in solution and on a paper substrate, because of the ion-induced aggregation of nanorods through an arsenic complex formation strategy, which is relative to the arsenic concentrations. Colorimetric and spectroscopic analyses are very much selective for both AsIII and AsV ions with a detection limit of ∼1.0 ppb. In addition, the GNR-PEG-DMSA exhibits excellent potential for quantitative estimation of total arsenic in groundwater samples. The paper-based sensing method demonstrates the usefulness in arsenic level screening under field-test mode.