Alkaline phosphatase mediated synthesis of carbon nanotube–hydroxyapatite nanocomposite and its application for electrochemical determination of luteolin

A nanocomposite of hydroxyapatite (HAP)–carbon nanotube (CNT) was synthesized by in-situ transformation of CNT-calcium phenyl phosphate (CaPP) with the assist of alkaline phosphatase. The nanocomposite was characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) and transmission electron microscope (TEM). Then the HAP–CNT was cast onto a glassy carbon electrode (GCE) and used as a sensing platform for the electrochemical determination of luteolin. The electrochemical experiments indicated that the HAP–CNT modified GCE (HAP–CNT/GCE) could greatly enhance the electrochemical response of luteolin. A series of experimental parameters including the type and pH value of supporting electrolyte, accumulation time and accumulation potential were optimized. The electrochemical parameters such as electron transfer rate constant and electron transfer coefficient of luteolin at the HAP–CNT/GCE were also investigated. Under the optimal conditions, the reduction peak currents presented a good linear relationship with the concentration of luteolin in the range of 4.0   ×   10 −7 –1.2   ×   10 −5   M. The detection limit was estimated to be 8.0   ×   10 −8   M.