A self-referenced optical colorimetric sensor based on silver and gold nanoparticles for quantitative determination of hydrogen peroxide

- Synthesis of silver and gold nanoparticles by using a chemical reduction method.
- The changes of the absorbance strength maxima of both LSPR absorption bands are measured.
- A remarkable difference in sensitivity of both LSPR absorption bands are clearly observed.
- A self-referenced colorimetric sensor for the quantitative determination of hydrogen peroxide.
- A novel perspective for the chemical detection of other reactive oxygen species.

In this work, a self-referenced colorimetric sensor for the quantitative determination of hydrogen peroxide is presented. This optical sensor is based on the presence of the Localized Surface Plasmon Resonances of silver and gold nanoparticles which are capped with the same encapsulating agent of poly(diallylammonium chloride) (PDDA). These metallic nanoparticles are synthesized by a chemical reduction method of their corresponding inorganic precursors and characterized by UV-vis spectroscopy and transmission electron microscopy, respectively. A remarkable difference in sensitivity related to both LSPR absorption bands is observed as a function of variable molar concentration of the target molecule. The LSPR band of the silver nanoparticles is gradually decreased whereas the LSPR of the gold nanoparticles is practically unaltered when the hydrogen peroxide molar concentration is increased as a result of its better chemical stability. This stable absorbance LSPR band of the AuNPs is used as an optical reference and the molar concentration of the target molecule is obtained by measuring the changes of the absorbance strength maxima of both LSPR absorption bands. As a result, a very good sensitivity with a high robustness and a linear response over a wide concentration range from 1.25 μM to 1250 μM is obtained. This self-referenced method opens up a new perspective for the chemical detection of other reactive oxygen species or well for the determination of other type of analytes in the future.