Chitosan in immunosensors for early detection of Alzheimer's disease
As the population ages, the number of Alzheimer's cases could triple by 2050. To enable early diagnosis, sensitive and easy-to-use diagnostic platforms are needed. Therefore, in the presented study, an electrochemical immunosensor was fabricated using chitosan and gold nanoparticles functionalized carbon nanotubes.
ELECTROCHEMICAL IMMUNOSENSOR FOR EARLY DETECTION OF β-AMYLOID BIOMARKER OF ALZHEIMER'S DISEASE BASED ON ALIGNED CARBON NANOTUBE-GOLD NANOCOMPOSITES
Ranjan, P.; Khan, R. Electrochemical Immunosensor for Early Detection of β-Amyloid Alzheimer's Disease Biomarker Based on Aligned Carbon Nanotubes Gold Nanocomposites. Biosensors 2022, 12, 1059. https://doi.org/10.3390/bios12111059
Alzheimer's disease is a widespread neurodegenerative disorder that leads to dementia and premature death. The disease accounts for 70% of dementia cases and affects approximately 35 million people. The number is expected to triple by 2050, representing a major social as well as economic burden in the future. The disease is regulated by the formation of β-amyloid peptide fibrils in the brain. These are hydrophobic and self-aggregating in brain tissue and are considered the primary trigger of Alzheimer's disease. Therefore, β-amyloid peptide is an ideal biomarker and therapeutic target.
Previous detection methods such as capillary electrophoresis, ELISA, MRI, MS or PET are not sensitive enough, time consuming, expensive or laboratory intensive. A promising alternative are immunosensor-based diagnostic platforms such as electrochemical immunosensors. These offer ease of use, high sensitivity and selectivity, low detection limit, sufficient stability, and rapid detection. Due to their large surface area, low weight, and electrical conductivity, carbon nanotubes (CNTs) are a preferred sensor material. In addition, their surface can be functionalized with chitosan (CS). Due to the amine and hydroxyl groups, CS is able to provide an active site to immobilize antibodies. It also forms a uniform coating on the surface, which provides a stable environment, improved conductivity and thus enhanced sensitivity of the target. In addition, the conductivity and surface area can be increased by the addition of gold nanoparticles (AuNPs).
Therefore, in the presented study, an electrochemical immunosensor for the detection of β-amyloid peptides was fabricated from an AuNP-functionalized CS-aCNT nanocomposite on glass fiber carbon electrodes (GCEs). This is to be modified with anti-β-amyloid antibodies and BSA. In addition, the electrochemical properties of the nanocomposites and the immunosensor were investigated using electroanalytical techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Subsequently, the fabricated immunosensor was tested for the detection of β-amyloid peptide in BSA.
- Successful immobilization of anti-β-amyloid antibody and BSA on the surface of the fabricated CS-aCNT-Au nanocomposite
- Fabrication of the working electrode by modifying a glass fiber carbon electrode and assembling the immunosensor by adding the CS-aCNT-Au nanocomposite
- Demonstration of the enhancement of the conductivity of the immunosensor or nanocomposite by the GCE as well as the AuNPs
- Addition of anti-β-amyloid antibody and BSA led to a drop in the CV peak suggesting successful immobilization on the immunosensor surface
- DPV measurements were consistent with findings from CV → conclusion the immunosensor prepared can be efficiently used for electrochemical detection of β-amyloid peptide
- Demonstration of high sensitivity of the BSA/antibody/CS-aCNT-Au/GCE immunosensor between 10.0 pg/ml and 100.0 µg/ml in PBS using DPV
- Consistent results for the detection of β-amyloid peptides in biological fluids with sufficiently high selectivity
Summary: In the presented study, an electrochemical immunosensor for the detection of β-amyloid peptides in BSA and biological fluids was successfully fabricated with sufficiently high sensitivity and selectivity. Functionalization with CS resulted in good immobilization of anti-β-amyloid antibodies and BSA on the surface, while AuNPs and GCE enhanced the conductivity. Overall, the prepared BSA/antibody/CS-aCNT-Au/GCE immunosensor showed great potential for the detection of β-amyloid peptide and thus the early detection of Alzheimer's disease.
Link to article: Biosensors | Free Full-Text | Electrochemical Immunosensor for Early Detection of β-Amyloid Alzheimer’s Disease Biomarker Based on Aligned Carbon Nanotubes Gold Nanocomposites (mdpi.com)
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