Acid Treatment of a Carbon Nanotube@Ordered Mesoporous Carbon Composite via a Simple Sonication Procedure: Sensitive Determination of Bisoprolol in Biological and Pharmaceutical Samples

Based on the high specific surface area and electrical conductivity of carbon electrodes, in this work we have fabricated a carbon nanotube@ordered mesoporous carbon (CNT@CMK-3) composite by combining acid treatment and sonication. The CNT@CMK-3 composite after acid treatment retains a tubular and entangled framework. The CNT@CMK-3 nanostructure shows that CMK-3 is uniformly covered by CNTs. The acid-treated CNT@CMK-3 composites, due to the presence of -OH and -COOH groups on defects, show greatly increased hydrophilicity, solubility, tuning structure, real electrochemical active surface (of 0.22 cm2), and electron transfer kinetics. Furthermore, after 500 h, no precipitation is found for acid-treated CNT@CMK-3 dispersions, exhibiting excellent stability. Also, a sensitive electrochemical sensor based on CNT@CMK-3 was fabricated for bisoprolol (BIS) determination. Thin film of the acid-treated CNT@CMK-3 composite was cast on a carbon paste electrode (CPE), and selective and sensitive detection of BIS was studied at electro-oxidation potential of 998 mV, with a linear range of 0.1-35 mu mol L-1, limit of detection of 0.05 mu mol L-1, and sensitivity of 10.76 mu A mu mol-1 L. The presence of functional groups due to acid treatment improved the sensitivity, demonstrating effective electron transfer between CNT@CMK-3 and BIS. Finally, the developed sensor was successfully used to detect BIS in human serum and urine samples and tablets.