Application of polyaniline/zinc oxide nanocomposites for non-enzymatic cholesterol detection: A preliminary investigation on the effect of dopants on the morphology, thermal stability, electrochemical and sensing behavior of the nanocomposites.

Cholesterol is a major cause for cardiovascular diseases; and therefore, timely detection of cholesterol is of paramount importance to prevent such diseases. Herein, a non-enzymatic sensor for the detection of cholesterol has been fabricated using polyaniline (PANI) and its nanocomposites (NCs) with ZnO nanoparticles (NPs). For this purpose, a series of NCs has been synthesized by varying the loading of the ZnO NPs as 2%, 3%, 5% and 8% with respect to the weight percentage of the aniline monomer. In addition, two different doping agents, namely camphor sulfonic acid (CSA) and hydrochloric acid, have been used to prepare PANI and its NCs. Electrochemical studies have revealed that as the amount of ZnO NPs increased, the capacitive behavior of the composite also increased. Similar trend was observed in case of HCl-doped polyaniline NCs. PANI/ZnO 8% NCs for both HCl and CSA dopant indicated good capacitive behavior for sensing cholesterol. The best electrode was further tested for sensitivity, and was found to exhibit a value of 0.38 mA mM−1 cm−2. The limit of detection of the prepared sensor was found to be 0.30 mM concentration in PBS buffer under the linearity range of 0.75 mM to 1.5 mM (adj. R2 = 0.97). Polyaniline/ZnO nanocomposites (2%, 3%, 5%, and 8%) with two different doping agents (CSA and HCl) were synthesized and compared. Physical, optical, and electrochemical properties of the nanocomposites resulted in favor of 8% ZnO loadings. Cholesterol sensor fabricated with PANI-HCl/ZnO 8% nanocomposite showed better response than PANI-CSA/ZnO 8%. LOD of the prepared non-enzymatic cholesterol biosensor was found to be 0.30 mM. The fabricated cholesterol sensor using PANI/ZnO nanocomposite exhibited a sensitivity of 0.38 mA mM−1 cm−2. [ABSTRACT FROM AUTHOR]