Thermally influenced, optical and fluorescence properties of Zinc Oxide nanoparticles for glutathione sensing

Glutathione, a non-protein thiol molecule is present in abundance in the human body. It plays a major role in maintaining the intracellular redox states, metabolism and detoxification. A novel idea is introduced where zinc oxide nanoparticles are used for the fluorescence sensing of Glutathione. Zinc oxide nanoparticles prepared by the co-precipitation method has been annealed at 400 °C, 700 °C and 900 °C. XRD studies confirmed the evolution of phase and hexagonal wurtzite structure. FESEM images confirm the high degree of crystallinity. Optical absorption measurements exhibit a red shift in absorption for unannealed, 400 °C and 700 °C and a decrease in absorption wavelength for particle annealed at 900 °C. In addition, the bandgap energy decreases with an increase in annealing temperature indicating the increase in particle size. Photoluminescence studies in room temperature at an excitation of 330 nm show emission in the UV and visible regions. Quenching of fluorescence emission intensity due to electron transfer is noticed while increasing the concentration of Glutathione in nanomolar(nM) range. Quenching of PL intensity due to adsorption-induced electron transfer is explained through band bending effect. These results indicate that zinc oxide nanoparticles can be implemented for optoelectronics, solar photocatalysts and glutathione sensing applications.