Quantifying Hydrogen Peroxide in Cattle Milk via a Novel Plasmonic Nanofilm

Hydrogen peroxide is an illegal milk adulterant occasionally utilized as a milk preservative to extend its shelf life. While it is highly effective at reducing spoilage, its use poses significant health risks due to its high toxicity on human health, along with strong oxidative and corrosive properties. Plasmonic sensing principles offer a powerful tool for detecting hydrogen peroxide adulteration, even in trace amounts, below permissible limits. Hydrogen peroxide, being a strong oxidizing agent, binds with the functionalized nanoparticles in the sensor. This binding alters the local refractive index by reducing the number of nanoparticles, along with alteration of their shape and size. These changes can be used to quantify the amount of adulterants in milk. Taking cue from this, our work reports fabrication of a localized surface plasmon resonance (LSPR)-based milk adulterant sensor to detect hydrogen peroxide utilizing glass as the primary substrate. In this approach, silver nanoparticles were synthesized using Ocimum tenuiflorum leaves extract, and then coated with polyvinyl alcohol as a functionalizing element. When exposed to hydrogen peroxide, the immobilized nanoparticles interacted with the adulterant, causing a decrease in absorbance along with a shift in the plasmonic peak. This shift was calibrated to accurately estimate the amount of hydrogen peroxide in milk, allowing sensitive detection of the adulterant, even at trace levels much lower than the permissible limit.