Designing of Modified Cerium Oxide-Based Enzyme Mimic Nanomaterials as Optical Sensors for the Sensitive and Selective Detection of Hydrogen Peroxide

Abstract

Imbalance in the amount of biological substances like hydrogen peroxide is the key reason behind different ailments and cell damage. Different approaches have been developed for the detection of hydrogen peroxide. However, they have many drawbacks, such as high cost of the substrates, expensive instruments which require trained personnel to handle and low sensitivity and selectivity. Therefore, to overcome mentioned limitations we devised a sensor-based system which is facile, easy to handle and less expensive. Nanorods comprising of cerium oxide doped iron and cobalt with variable concentrations were synthesized using hydrothermal method. To study its properties various characterization techniques were used such as FTIR analysis for the confirmation of different functional groups in the composite (Fe3+-Co2+-CeO2), XRD studies to study the crystallite size and growth of iron and cobalt inside the cerium oxide lattice of the prepared composites. SEM analysis was performed to check the surface morphology and the grain size of the synthesized samples. As a proof of the concept studies these prepared nanocomposites were used for the detection of hydrogen peroxide. Before using these nanocomposites for the detection, concentrations of different parameters were optimized, such as buffer amount and pH, incubation time, temperature and TMB (3, 3', 5, 5'-Tetramethyl-benzidine) amount etc. which have lot of impact on the sensor properties and its activity. TMB was used as a chromogenic substrate for colorimetric analysis of the prepared sample. The nanocomposite (Fe3+-Co2+-CeO2) helped in decomposition of hydrogen peroxide in its radicals and these radicals oxidized TMB in the reaction mixture which led to color change as a result. This change in color is the indication of amount of hydrogen peroxide present in the system, the more the color change the more the amount of hydrogen peroxide and vice versa. UV-Vis spectroscopy was used for measuring the absorbance of different percentages. The limit of detection (LOD) estimated using the data obtained under optimal conditions and within a linear range of 0.1 μm-20mM (R2=0.9402) was found to be as low as 0.057 μm. The selectivity of the platform was confirmed by the study of certain interfering species. The results confirmed the sensitivity of this colorimetric sensor for the detection of hydrogen peroxide.