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. 2022 Dec 18;12(12):1180.
doi: 10.3390/bios12121180.

A Simple Label-Free Aptamer-Based Electrochemical Biosensor for the Sensitive Detection of C-Reactive Proteins

Huilin Gao  1 , Yongchang Bai  1 , Baixun He  1 , Cherie S Tan  1   2
Affiliations

A Simple Label-Free Aptamer-Based Electrochemical Biosensor for the Sensitive Detection of C-Reactive Proteins

Huilin Gao et al. Biosensors (Basel). .

Abstract

The level of C-reactive protein (CRP) in the human body is closely associated with cardiovascular diseases and inflammation. In this study, a label-free functionalized aptamer sensor was attached to an electrode trimmed with in-gold nanoparticles and carboxylated graphene oxide (AuNPs/GO-COOH) to achieve sensitive measurements relative to CRP. Gold nanoparticles were selected for this study due to super stability, remarkably high electrical conductivity, and biocompatibility. In addition, carboxylated graphene oxide was utilized to promote the anchorage of inducer molecules and to increase detection accuracies. The sensing signal was recorded using differential pulse voltammetry (DPV), and it produced a conspicuous peak current obtained at approximately -0.4 V. Furthermore, the adapted sensor manifested a broad linear span from 0.001 ng/mL to 100 ng/mL. The results also demonstrated that this aptamer sensor had superior stability, specificity, and reproducibility. This aptamer-based electrochemical sensor has enormous potential in complex application situations with interfering substances.

Keywords: C-reactive protein; DNA aptamer; carboxylated graphene oxide; gold nanoparticles.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Illustration of the manufacturing process of the label-free C-reactive protein (CRP) aptamer sensor.
Figure 2
Figure 2
Characterization of the SPE/AuNPs/GO-COOH aptamer’s sensing interface. (A) Electrodeposition of AuNPs using the SWV method with five scans. (B) SEM electron micrograph of the bare electrode. (C) SEM characterization of the electrode surface after the electrodeposition of AuNPs. (D) Surface characterization of the GO-COOH physically adsorbed on an electrode containing AuNPs.
Figure 3
Figure 3
(A) Voltage-current diagram of CRP solutions from 0.001 ng/mL to 100 ng/mL using the DPV method. (B) The curve of peak currents for each concentration of CRP fitted to the difference between the 0 ng/mL CRP solution and the logarithm of the CRP concentration (n = 3).
Figure 4
Figure 4
Selectivity, stability, and reproducibility tests based on the SPE/AuNPs/GO-COOH aptamer sensor. (A) Voltage-current plot of CRP vs. interfering solutions using the DPV method. Red: 1 ng/mL CRP; black: PBS solution; blue: 1 ng/mL PPBP; green: 1 ng/mL BNP; orange: 1 ng/mL PSA; purple: 1 ng/mL CA125. (B) The plot of the selectivity error analysis corresponds to (A) (n = 3). (C) Error analysis plots were obtained by selecting the electrodes on day 1, day 3, day 5, day 7, and day 9 for testing against 1 ng/mL CRP solution (n = 3). (D) Reproducibility test plots of five aptamer-sensing electrodes for multiple assays of 0.001 ng/mL CRP (n = 3).
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