Investigation of the Effect of Trypsin Enzyme on theDetection of Carbaryl Pesticide

The detection of residual pesticides in fruits is a significant health concern for society, necessitating the development of a highly efficient, fast, sensitive, and precise tool for on-site detection of these pollutants. Optical biosensors have emerged as a viable solution. In this study, laboratory samples were used to detect carbaryl pesticide at ultra-low concentrations (in the parts per billion range). The sensor relied on the surface plasmon resonance (SPR) phenomenon, utilizing gold nanoparticles with an average size between ۵۰ and ۶۰ nm, along with beta-casein as a bioindicator. Mercaptohexan (MCH) was also employed to disperse the particles. Trypsin enzyme was applied as an overlayer to split beta-casein. The materials were immobilized using the layer-by-layer deposition technique, which is based on the electrostatic self-assembly of molecules. Visible-UV spectrophotometry was employed to assess the sensor's performance in measuring carbaryl concentrations ranging from ۱۰ to ۱۰۶ ppb. The experiments were conducted in two series, one with trypsin and one without. The results showed that the presence of trypsin as a protease caused beta-casein to split, resulting in the appearance of two different absorption peaks at wavelengths around ۵۵۰ and ۶۰۰ nm, in addition to a series of spectra in the UV region. This led to higher sensitivity of the biosensor, with a value of ۰.۰۲۱۵ Absorbance unit per ppb, and a lower limit of detection (LOD) of ۱.۱۶۰ ppb. Consequently, the incorporation of trypsin enhances the accuracy and reliability of the biosensor in detecting even trace amounts of carbaryl, making it a key component in the successful identification of this toxin. Importantly, the biosensor exhibits distinct behavior for concentrations below ۱ ppm and those exceeding this threshold.

کلیدواژه ها:

Biosensor ، Carbaryl ، Trypsin ، Beta_casein