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. 2022 Nov 21;12(11):1059.
doi: 10.3390/bios12111059.

Electrochemical Immunosensor for Early Detection of β-Amyloid Alzheimer's Disease Biomarker Based on Aligned Carbon Nanotubes Gold Nanocomposites

Pushpesh Ranjan  1   2 , Raju Khan  1   2
Affiliations

Electrochemical Immunosensor for Early Detection of β-Amyloid Alzheimer's Disease Biomarker Based on Aligned Carbon Nanotubes Gold Nanocomposites

Pushpesh Ranjan et al. Biosensors (Basel). .

Abstract

Beta-amyloid (βA) peptides accompanying the physiological change in brain induce Alzheimer's disease. In this work, a highly sensitive electrochemical (EC) immunosensor platform has been developed for the quantitative detection of βA peptides, using the gold nanoparticle functionalized chitosan-aligned carbon nanotube (CS-aCNT-Au) nanocomposites on glassy carbon electrodes (GCE). The immunosensor has been fabricated by immobilization of the anti-βA antibody upon CS-aCNT-Au/GCE. In the CS-aCNT nanocomposite, CS has high biocompatibility. Hydroxy and amine functionalities favor the antibody immobilization and prevent the leaching of nanocomposites of the modified electrode due to the adhesive environment. Moreover, aCNT offers high conductivity, stability, and a large surface area (the calculated effective surface area of the CS-aCNT/GCE is 8.594 × 10-2 cm2). However, the incorporation of AuNPs further enhances the conductivity of the CS-aCNT-Au nanocomposite based on differential pulse voltammetry (DPV) results, and also improves the effective surface area (9.735 × 10-2 cm2). The surface morphology and electrochemical studies of the nanocomposite, as well as its modifications by the anti-βA antibody and BSA, were carried out through field emission scanning electron microscope (FESEM), cyclic voltammetry (CV), and DPV. The quantitative immunosensing of the βA in phosphate-buffered saline (PBS) solution is accomplished via DPV, which reveals that the immunosensor has a high sensitivity of 157.60 µA pg-1 mL cm-2 and a broad detection range of 10.0 pg mL-1-100.0 µg mL-1, with a limit of detection (LOD) of 0.87 pg mL-1. Subsequently, we detected the spiked βA in diluted serum with a linear detection range of 10.0 pg mL-1-1.0 ng mL-1 and LOD of 0.95 pg mL-1. Moreover, a selectivity study exhibited a high affinity of immunosensors towards βA. Thus, we propose that this highly efficient immunosensor can potentially be applied for the point-of-care (POC) sensing of βA in clinical samples.

Keywords: Alzheimer’s disease; aligned carbon nanotube; chitosan; electrochemical immunosensor; gold nanoparticles; β-amyloid peptide.

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Conflict of interest statement

There are no conflict to declare by the authors.

Figures

Figure 1
Figure 1
FESEM images of (A) AuNPs, (B) CS, (C,D) CS-aCNT nanocomposite, (E,F) CS-aCNT-Au nanocomposite, (G) antibody/CS-aCNT-Au nanocomposite, and (H) BSA/antibody/CS-aCNT-Au nanocomposite.
Scheme 1
Scheme 1
Schematic of the fabrication of the BSA/antibody/CS-aCNT-Au immunosensor.
Figure 2
Figure 2
(A) CV and (B) DPV measurements of (i) GCE, (ii) CS-aCNT/GCE, (iii) CS-aCNT-Au/GCE, (iv) antibody/CS-aCNT-Au/GCE, and (v) BSA/antibody/CS-aCNT-Au/GCE.
Figure 3
Figure 3
Studies of the scan rate effect of (A) CS-aCNT-Au/GCE, (B) BSA/antibody/CS-aCNT-Au/GCE. The respective straight-line calibration curve of (C) the peak current, (i) Ipa and (ii) Ipc of CS-aCNT-Au/GCE, (iii) Ipa and (iv) Ipc of BSA/antibody/CS-aCNT-Au/GCE, and (D) the peak potential, (i) Epa and (ii) Epc of CS-aCNT-Au/GCE, (iii) Epa and (iv) Epc of BSA/antibody/CS-aCNT-Au/GCE.
Figure 4
Figure 4
Immunosensor performance for βA in PBS. (A) The voltammetric response of the BSA/antibody/CS-aCNT-Au/GCE for the βA from 10.0 pg mL−1 to 100.0 µg mL−1. (B) The related calibration curve of the immunosensor.
Figure 5
Figure 5
Immunosensor performance for βA in biological fluids. (A) The voltammetric response of the BSA/antibody/CS-aCNT-Au/GCE for the βA from 10.0 pg mL−1 to 1.0 ng mL−1. (B) The related calibration curve of the immunosensor.
Figure 6
Figure 6
Selectivity of the immunosensor against various bioanalytes.
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