In situ grown TiO2 nanorod arrays functionalized by molecularly imprinted polymers for salicylic acid recognition and detection

Abstract

Abstract Salicylic acid (SA) is the active agent in a great many analgesics and anti-inflammatory drugs. Its abuse would result in side effects to the health of human beings. Developing a simple and effective method for real-time tracking and monitoring of SA is necessary. In this work, a novel electrochemical sensor based on the molecularly imprinted polymers functionalized TiO2 nanorod arrays modified fluorine doped tin oxide (FTO) glass electrode (MIPs/TiO2 NRAs@FTO) was fabricated for the detection of salicylic acid (SA). TiO2 NRAs were directly grown on FTO by a simple hydrothermal method. SA was imprinted on TiO2 NRAs@FTO through a facile UV polymerization process. The nanorods structure of TiO2 provided a high specific surface area for SA imprinting, raising the number of imprinted sites, minimizing diffusion limitations, improving the internal mass transport, enhancing accessibility of the active sites and consequently boosting the sensitivity and binding capacity of the sensor. Furthermore, TiO2 could act as a photosensitizer in the presence of AIBN initiator to promote the formation of MIPs via a simple photo-polymerization process. The electrodes were characterized by scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to demonstrate the electrochemical sensor construction process. The differential pulse voltammetry (DPV) signal of the MIPs accumulated SA exhibited the linearity to its concentration ranging from 1.0 × 10−7 to 5.0 × 10−5 M under the optimized conditions. The detection limit was down to 3.9 × 10−8 M based on S/N = 3. This sensor has been applied for the detection of SA in the Aspirin tablet successfully. The results showed that this MIPs/TiO2 NRAs@FTO electrochemical sensor could be applied in medical field simply with low-cost. This work may provide new insights into the design and fabrication of a new platform for sensing applications.