Electrochemical Detection of Acetaminophen with Silicon Nanowires

Abstract

Acetaminophen (APAP) is an antipyretic, analgesic agent, the overdose of which during medical treatment poses a risk for liver failure. Hence, it is important to develop methods to monitor physiological APAP levels to avoid APAP. Here, we report an efficient, selective electrochemical APAP sensor made from depositing silicon nanowires (SiNWs) onto glassy carbon electrodes (GCEs). Electrocatalytic activity of the SiNW/GCE sensors was monitored under varying pH and concentrations of APAP using cyclic voltammetry (CV) and chronoamperometry (CA). CV of the SiNWs at 0.5 to 13 mmol dm^-3 APAP concentrations was used to determine the oxidation and reduction potential of APAP. The selective detection of APAP was then demonstrated using CA at +0.568 V vs Ag/AgCl, where APAP is fully oxidized, in the 0.01 to 3 mmol dm^-3 concentration range with potentially-interfering species. The SiNW sensor has the ability to detect APAP well within the detection limits for APAP toxicity, showing promise as a practical biosensor.

Keywords: acetaminophen; biosensor; silicon nanowires; toxicity monitoring.

Figure 1.

CV of bare and modified GCE in pH = 7.4 phosphate buffer at a scan rate of 50 mV s⁻¹: (a) SiNW/GCE, (b) bare GCE in 10 mmol dm⁻³ APAP, and (c) SiNW/GCE in PBS only.

Figure 2.

Peak current of 10 mmol dm⁻³ APAP of Nafion/SiNW/GCE as a function of pH in different phosphate buffer solutions with a sweep rate of 50 mV s⁻¹ at (A) reduction and (B) oxidation potentials.

Figure 3.

(A) CV for the effect of concentration of APAP in 70 mmol dm⁻³ PBS at pH = 7.4 with a 50 mV s⁻¹ scan rate. (B) Calibration curve of modified GCE current vs concentration under reduction (red, left y-axis) and oxidation (black, right y-axis) potentials.

Figure 4.

(A) CA response of Nafion/SiNW/GCE in PBS, pH = 7.4, after increasing the APAP concentration from 0.01 to 3 mmol dm⁻³ (denoted with arrows in the plot) at +0.568 V with the calibration curve of current vs concentration in the inset. (B) CA response of Nafion/SiNW/GCE in PBS, pH = 7.4 from 0.06 to 0.16 mmol dm⁻³ (indicated by arrows in the plot at +0.568 V with the inset of calibration curve of current vs concentration.

Figure 5.

CA response of Nafion/SiNW/GCE at +0.568 V vs Ag/AgCl to the sequential addition of 1 mmol dm⁻³ APAP, Glu, AA, H₂O₂, FA, UA, and APAP in pH 7.4 PBS.

Figure 6.

(A) CV of 10 mmol dm⁻³ APAP at pH = 7.4 on Nafion/SiNW/GCE at the scan rates indicated in the figure; (B) plot of I_pc vs v^1/2 at reduction (B); and oxidation (C) potentials.

Scheme 1.

Forms of APAP and NAPQI.