Application of Nanosized LiFePO4 Modified Electrode to Electrochemical Sensor and Biosensor

Background: The development of nanomaterials modified electrode can provide more opportunities for the enhancement of the analytical performance in constructing electrochemical sensor and biosensor. LiFePO4 (LFP) is a promising candidate to develop new modified electrodes owing to its advantages such as cheap cost, environmental compatibility, high safety, non-toxicity, large theoretical capacity, long cycle life and abundant earth materials. Objective: The aim of this paper was to construct nanosized LFP modified electrodes, which could be applied as working electrode for rutin analysis and as an electrochemical biosensor for direct electrochemistry of Hemoglobin (Hb). Method: Nanosized LFP was characterized by scanning electron microscopy. The LFP modified electrodes with Carbon Ionic Liquid Electrode (CILE) as substrate electrode were fabricated by dropping method with chitosan (CTS) as film. Cyclic voltammetry and electrochemical impedance spectroscopy were carried out to examine the electrochemical performance of the modified electrodes. Differential pulse voltammetry was used to establish determination methods. Results: Two new LFP-based modified electrodes (CTS/LFP/CILE and CTS/Hb-LFP/CILE) were fabricated. The electrochemical behaviors of rutin on CTS/LFP/CILE were achieved with a pair of enhanced redox peaks. The linear range for rutin analysis was from 4.00-8 to 1.00-4 mol L-1 with a detection limit of 8.00-9 mol L-1. The direct electrochemistry of Hb in CTS/Hb-LFP/CILE was realized with a pair of obvious redox peaks. The electrocatalytic activity of CTS/Hb-LFP/CILE toward trichloroacetic acid and H2O2 reduction were investigated, and the detection limits of 0.068 mmol L-1 for TCA and 0.07 μmol L-1 for H2O2 were obtained. Conclusion: Two kinds of LFP modified electrodes were successfully constructed with improved electrochemical performances. Electrochemistry of rutin and Hb were realized on LFP based electrodes with enhanced responses, and the application of LFP nanoparticle in electrochemical sensor and biosensors was extended.