Water Pollutants p-Cresol Detection Based on Au-ZnO Nanoparticles Modified Tapered Optical Fiber

In this work, a localized plasmon-based sensor is developed for para-cresol (p-cresol) - a water pollutant detection. A nonadiabatic 40 mu m of tapered optical fiber (TOF) has been experimentally fabricated and computationally analyzed using beam propagation method. For optimization of sensor's performance, two probes are proposed, where probe 1 is immobilized with gold nanoparticles (AuNPs) and probe 2 is immobilized with the AuNPs along with zinc oxide nanoparticles (ZnO-NPs). The synthesized metal nanomaterials were characterized by ultraviolet-visible spectrophotometer (UV-vis spectrophotometer) and transmission electron microscope (HR-TEM). The nanomaterials coating on the surface of the sensing probe were characterized by a scanning electron microscope (SEM). Thereafter, to increase the specificity of the sensor, the probes are functionalized with tyrosinase enzyme. Different solutions of p-cresol in the concentration range of 0 mu M - 1000 mu M are prepared in an artificial urine solution for sensing purposes. Different analytes such as uric acid, beta-cyclodextrin, L-alanine, and glycine are prepared for selectivity measurement. The linearity range, sensitivity, and limit of detection (LOD) of probe 1 are 0 mu M - 700 mu M, 7.2 nm/mM (accuracy 0.977), and 59.90 mu M, respectively; and for probe 2 are 0 mu M - 1000 mu M, 5.6 nm/mM (accuracy 0.981), and 57.43 mu M, respectively. Thus, the overall performance of probe 2 is quite better due to the inclusion of ZnO-NPs that increase the biocompatibility of sensor probe. The proposed sensor structure has potential applications in the food industry and clinical medicine.

Automated summary

A localized plasmon-based sensor was developed for detecting the water pollutant para-cresol, utilizing gold and zinc oxide nanoparticles to optimize performance and increase specificity through functionalized probes. The sensor with zinc oxide nanoparticles showed better overall performance, indicating potential applications in the food industry and clinical medicine.