Non-enzymatic electrochemical detection of sarcosine in serum of prostate cancer patients by CoNiWBO/rGO nanocomposite

Abstract

Selective and sensitive sarcosine detection is crucial due to its recent endorsement as a prostate cancer (PCa) biomarker in clinical diagnosis. The reduced graphene oxide-cobalt nickel tungsten boron oxides (CoNiWBO/rGO) nanocomposite is developed as a non-enzymatic electrochemical sensor for sarcosine detection in PCa patients' serum. CoNiWBO/rGO is synthesized by the chemical reduction method via a one-pot reduction method followed by calcination at 500 °C under a nitrogen environment for 2 h and characterized by UV-Vis, XRD, TGA, and SEM. CoNiWBO/rGO is then deposited on a glassy carbon electrode, and sarcosine sensing parameters are optimized, including concentration and pH. This non-enzymatic sensor is employed to directly determine sarcosine in serum samples. Differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV) are employed to monitor the electrochemical behavior where sarcosine binding leads to oxidation. Chronoamperometric studies show the stability of the developed sensor. The results demonstrate a wide linear range from 0.1 to 50 µM and low limits of detection, i.e., 0.04 µM and 0.07 µM using DPV and LSV respectivel. Moreover, the calculated recovery of sarcosine in human serum of prostate cancer patients is 78-96%. The developed electrochemical sensor for sarcosine detection can have potential applications in clinical diagnosis.

Keywords: Electrochemical sensor; Prostate cancer; Reduced graphene oxide; Sarcosine; Serum.

Fig. 1

(A) XRD, (B) UV, and (C) TGA (D) FTIR graph of CoNiWBO/rGO.

Fig. 2

(A) SEM image, (B) histogram for size distribution, (C) energy dispersive X-ray spectroscopy, and (D) atomic force microscopy of CoNiWBO/rGO particles.

Fig. 3

The electrochemical response of CoNiWBO/rGO in 0.1 M KCl and 40 mM K₄[Fe(CN)₆] solutions, (A) conductivity, (B) stability, (C) conductivity at varying scan rates 30 mVs^-1 to 100 mVs^-1, and (D) calibration plot showing linear relationship between scan rate, and oxidation and reduction currents.

Fig. 4

Cyclic voltammograms of CoNiWBO/rGO in 0.1 M KCl and 40 mM K₄[Fe(CN)₆] solutions, (A) Chronoamperometric response, (B) Electrochemical Surface Area (ECSA), and (C). ECSA line graph.

Fig. 5

Mechanism of sarcosine electrochemical oxidation.

Fig. 6

LSV findings of sarcosine detection in 0.1 M PBS (pH 7.4) by CoNiWBO/rGO with different parameters, (A) concentrations of 0.1, 10, 20, 30, 40, 50 µM, (B) line graph between sarcosine concentration and current, (C) pH of 7.8, 7.6, 7.4, 7.2, 7.0, 6.8, and (D) line graph between pH and current.

Fig. 7

Differential pulse voltammetry (DPV) response of CoNiWBO/rGO for sarcosine sensing in 0.1 M PBS with different parameters, (A) sarcosine concentrations of 0.1, 10, 20, 30, 40, 50 µM, (B) line graph between sarcosine concentration and current, (C) pH of 7.8, 7.6, 7.4, 7.2, 7.0, 6.8, and (D) line graph between pH and current.

Fig. 8

Nyquist plots showing electrochemical impedance studies of CoNiWBO/rGO, (A) in 0.1 M KCl and 40 mM K₄[Fe(CN)₆] solutions, (B) at sarcosine concentrations of 0.1, 10, 20, 30, 40 and 50 µM in 0.1 M PBS of pH 7.4, and (C) pH of 7.8, 7.6, 7.4, 7.2, 7.0, 6.8 in 0.1 M PBS.

Fig. 9

(A) DPV and (B) LSV repeatability and reproducibility results of CoNiWBO/rGO-GCE from successive seven readings of 50 µM sarcosine detection in 0.1 M PBS. The electrochemical response of CoNiWBO/rGO-GCE in the presence of equal concentrations (50 µM) of interfering species like uric acid, glucose, and creatinine in 0.1 M PBS via (C) DPV and (D) LSV.

Fig. 10

(A) LSV and (B) DPV voltammograms of sarcosine detection in blood serum of prostate cancer patients by CoNiWBO/rGO.