Acetylsalicylic acid (ASA), commonly known as aspirin, is one of the most important nonsteroidal anti-inflammatory, analgesic and antipyretic drugs in the world. It is widely used to relieve minor aches, pains and reduce fever and is also great effective in treating the antithrombotic, coronary heart disease, preventing colon cancer and pregnancy induced pre-eclampsy [1,2]. Such widespread use of aspirin has resulted in problems of overdose especially in persons suffering from chronic inflammatory diseases, who take this drug habitually [3]. Therefore, it remains a great challenge to design a rapid, inexpensive but sensitive and selective method to determine ASA in biological fluids. A new nanocomposite imprinted electrochemical sensor was developed for sensitive and selective determination of acetylsalicylic acid (ASA), which is based on a gold electrode modified with one-step electropolymerization of the molecularly imprinted polymer (MIP) composed from polypyrrole (ppy), sol-gel, Silica@Gold core-Shell nanoparticles (SiO2@AuNPs) and acetylsalicylic acid. SiO2@AuNPs were introduced into the polymer matrix for the enhancement of electrical response of [Fe(CN)6]3−/[Fe(CN)6]4− redox couple which was used as an electrochemical active probe. The SiO2@AuNPs, were synthesized chemically by employing a modified Stober method and they were characterized by UV-Vis spectrophotometry, Fourier transform infrared (FT-IR) spectrometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The fabrication process of the electrochemical sensor was also characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The effect of several parameters influencing the performance of the sensor were investigated and optimized. Under the optimized experimental conditions, two linear concentration ranges from 0.1 to 1.0 nM and 1.0 to 10.0 nM with a limit of detection (LOD) of 0.02 nM was obtained. The effects of interfering species on the determination of ASA were investigated and it was found that the proposed sensor has a high recognition capacity towards the acetylsalicylic acid. Moreover, the reproducibility, repeatability and stability of the imprinted sensor were all found to be satisfactory. Finally, the modified electrode was successfully applied for determination of acetylsalicylic acid in tablet and urine samples.

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