Novel paper-based cholesterol biosensor using graphene/polyvinylpyrrolidone/polyaniline nanocomposite

• A novel nanocomposite based on graphene/polyvinylpyrrolidone/polyaniline has been prepared and used for the modification of a paper-based cholesterol biosensor.
• The high conductivity and large surface area of G/PVP/PANI nanocomposite modified paper-based biosensor significantly improves the electrochemical sensitivity in the detection cholesterol.
• This paper-based biosensor provides simple, inexpensive, disposable and portable for the detection of cholesterol in human serum.
• This approach might be an alternative tool for cholesterol screening in medical diagnosis.

A novel nanocomposite of graphene (G), polyvinylpyrrolidone (PVP) and polyaniline (PANI) has been successfully prepared and used for the modification of paper-based biosensors via electrospraying. The droplet-like nanostructures of G/PVP/PANI-modified electrodes are obtained with an average size of 160±1.02 nm. Interestingly, the presence of small amount of PVP (2 mg mL−1) in the nanocomposites can substantially improve the dispersibility of G and increase the electrochemical conductivity of electrodes, leading to enhanced sensitivity of the biosensor. The well-defined cyclic voltammogram of standard ferri/ferrocyanide is achieved on a G/PVP/PANI-modified electrode with a 3-fold increase in the current signal compared to an unmodified electrode. This modified electrode also exhibits excellent electrocatalytic activity towards the oxidation of hydrogen peroxide (H2O2). Furthermore, cholesterol oxidase (ChOx) is attached to G/PVP/PANI-modified electrode for the amperometric determination of cholesterol. Under optimum conditions, a linear range of 50 μM to 10 mM is achieved and the limit of detection is found to be 1 μM for cholesterol. Finally, the proposed system can be applied for the determination of cholesterol in a complex biological fluid (i.e. human serum).

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