Tin oxide-polyaniline nanocomposite modified nickel foam for highly selective and sensitive detection of cholesterol in simulated blood serum samples.

Cholesterol (CH) is a vital diagnostic marker for a variety of diseases, making its detection crucial in biological applications including clinical practice. In this work, we report the synthesis of tin oxide-polyaniline nanocomposite-modified nickel foam (SnO 2 -PANI/NF) for non-enzymatic detection of CH in simulated human blood serum. SnO 2 was synthesized via the hydrothermal method, followed by the synthesis of SnO 2 -PANI nanocomposite through in situ chemical polymerization of aniline using ammonium persulfate as the oxidizing agent. Morphological studies display agglomerated SnO 2 -PANI, which possess diameters ranging from an average particle size of ∼50 to ∼500 nm, and the XRD analysis revealed the tetragonal structure of the SnO 2 -PANI nanocomposite. Optimization studies demonstrating the effect of pH and weight percentage are performed to improve the electrocatalytic performance of the sensor. The non-enzymatic SnO 2 -PANI/NF sensor exhibits a linear range of 1-100 μ M with a sensitivity of 300 μ A μ M -1 /cm -2 towards CH sensing and a low limit of detection of 0.25 μ M (=3 S m -1 ). SnO 2 -PANI/NF facilitates the electrooxidation of CH to form cholestenone by accepting electrons generated during the reaction and transferring them to the nickel foam electrode via Fe (III)/Fe (IV) conversion, resulting in an increased electrochemical current response. The SnO 2 -PANI/NF sensor demonstrated excellent selectivity against interfering species such as Na + , Cl - , K + , glucose, ascorbic acid, and SO 4 2- . The sensor successfully determined the concentration of CH in simulated blood serum samples, demonstrating SnO 2 -PANI as a potential platform for a variety of electrochemical-based bioanalytical applications.