Ion-Imprinted Chitosan-Based Localized Surface Plasmon Resonance Sensor for Ni Detection.

Heavy metals are important sources of environmental pollution and cause disease in organisms throughout the food chain. A localized surface plasmon resonance sensor was proposed and demonstrated to realize Ni detection by using ion-imprinted chitosan. Au nanoparticles were coated on the multimode fiber to excite the local surface plasmon resonance, and Ni-imprinted chitosan was then functionalized by using the dip coating technique. Ethylene diamine tetra-acetic acid was used to release the Ni ions and hence form countless voids. Ni was refilled into the voids to increase the refractive index of the sensing material, thus realizing the measurement of Ni by monitoring the wavelength shift in the localized surface plasmon resonant peak. The coating thickness of the Ni-chitosan gel was optimized to obtain greater sensitivity. Experimental results show that the proposed Ni sensor has a sensitivity of 185 pm/μM, and the limit of detection is 0.512 μM. The comparison experiments indicated that the ion-imprinted chitosan has better selectivity than pure chitosan.