Maleic acid assisted facile plasmonic chip for assessment of adulterants in cattle milk

Abstract

Adulteration in cattle milk is a pervasive issue, where melamine is added to milk due to its high nitrogen content, which ultimately falsely elevates the perceived protein levels of milk. However, its consumption possesses a significant threat, because it can cause severe health hazards. Conventional detection methods are often very expensive and also lack selectivity, and sensitivity towards detection of toxic adulterants. This study addresses these limitations by fabricating a highly selective maleic acid-functionalized silver nanoparticles (MA-AgNPs) based plasmonic nanofilm for highly accurate detection of milk adulterant melamine. At first, chemical reduction method was used to synthesize the AgNP swhich was later functionalized with maleic acid. The functionalized NPs were uniformly coated onto a glass slide to create localized surface plasmon resonance (LSPR) chip. The plasmonic activity of the NPs along with its selective interaction towards melamine resulted in significant shift in plasmonic peak position, enabling melamine detection below the permissible limit. To determine the optical and physical properties of the synthesized AgNPs, UV-vis spectrophotometer, X-ray diffractometer (XRD), Field Emission Scanning Electron Microscope (FESEM), Atomic Force Microscope (AFM), and Transmission Electron Microscope (TEM) studies were conducted. Validation of the milk samples spiked with melamine was performed utilizing the High-Performance Liquid Chromatography (HPLC) method. The developed LSPR-based platform offered a sustainable and inexpensive solution for detecting milk adulterant melamine, with high sensitivity, selectivity and lower detection limit.