Agarose hydrogel doped with gold nanobipyramids(AuNBPs@AG)as colorful height readout device for sensing hydrogen peroxide in complex sample matrix

The portable and instrument-free sensing device for quantitative detection is of significant applications in resource constrained countries and regions. Here, a colorful height readout device formed by agarose hydrogel doped with gold nanobipyramids (AuNBPs@AG) is developed for the determination of hydrogen peroxide (H 2 O 2 ) content. The responsive mechanism is based on H 2 O 2 guided etching of AuNBPs, which causes the plasmon-mediated color change of the AuNBPs@AG hydrogel filled in plexiglass tube from top to bottom. We demonstrate the height of color-changed hydrogel is quantitatively related to the concentration of H 2 O 2 . The agarose hydrogel, as the carrier material for loading AuNBPs, guarantees the stability of AuNBPs and promotes the separation of complex samples. The method shows a good linear relationship in four ranges of H 2 O 2 concentrations of 20 − 100 μM, 200 − 1000 μM, 1 − 10 mM and 10 − 100 mM. Compared with previous methods, using this inexpensive and easy to operate device for H 2 O 2 detection can effectively reduce the interference of the color background, overcome the problem of the nanoparticles aggregation, and eliminate the need for expensive and sophisticated detection instruments. The practicality of the method is demonstrated via the analysis of commercial products such as contact lens solution and hair dye with satisfactory results. Our work provides a novel path for developing the height-readout quantitative devices with integrating hydrogels and plasmonic nanomaterials.