Surface plasmon resonance based fiber optic sensor for the detection of triacylglycerides utilizing Ag/ZnO nanorods/lipase enzyme (Conference Presentation)

A surface plasmon resonance based fiber optic sensor for the detection of triacylglycerides (TG) has been fabricated by immobilizing lipase enzyme (Lip11) on Zinc Oxide (ZnO) nanorods grown over a silver (Ag) film. The sensor probe exhibits high sensitivity for 0–500 mg/dl triacylglyceride concentration, which covers both the physiological range and high levels (which indicate coronary heart disease and hyperlipoprotenimia). After coating a silver layer of 40 nm on the fiber surface by the thermal evaporation, the ZnO nanorods are grown over the silver layer by first preparing nanoparticles (NPs) of ZnO using the Pacholski method. The silver coated fiber is then dipped into the ZnO nanoparticles solution and the ZnO NPs work as a seed layer for the growth of ZnO nanorods on the fiber surface. Here, ZnO nanorods play a double role in the sensing operation. They act as a matrix with high isoelectric point (9.5) which makes it possible to directly immobilize lipase enzyme which has low isoelectric point (4.9) by electrostatic adsorption without any requirement of functionalization. Second the ZnO nanorods layer enhances the sensitivity of the sensor as it works as a high index layer over the metal layer. As the concentration of TG change in the vicinity of the sensor, the refractive index and thickness of bio-recognition enzyme layer change and as a consequence the resonance wavelength in the absorbance spectra changes. The sensor has a fast response, high selectivity and sensitivity, low cost, label free detection and ease of fabrication.