Ultrasensitive probeless capacitive biosensor for amyloid beta (Aβ_1-42) detection in human plasma using...

Area of Science:

• Biomedical Engineering
• Neurodegenerative Disease Diagnostics
• Biosensor Technology

Background:

• Protein misfolding and aggregation, particularly amyloid beta (Aβ) peptides, are key indicators of Alzheimer's disease (AD).
• Early and accurate detection of Aβ biomarkers is crucial for timely diagnosis and management of AD.
• Existing diagnostic methods may lack the sensitivity, speed, or point-of-care suitability required for widespread screening.

Purpose of the Study:

• To develop and validate a highly sensitive, novel immunoassay platform-based interdigitated capacitive biosensor for detecting amyloid beta (Aβ) biomarkers.
• To explore the use of aptamers as molecular recognition probes for specific and high-affinity binding of Aβ.
• To enable label-free, real-time detection of Aβ peptides in biological samples for potential point-of-care applications.

Main Methods:

• Fabrication of a capacitive biosensor functionalized with oligomeric Aβ (oAβ) aptamer and anti-oAβ antibody on a Pt/Ti-featured SiO₂ substrate.
• Utilized aptamers, identified via SELEX, as 'chemical antibodies' for specific molecular recognition.
• Performed analytical studies to confirm specificity, sensitivity, and selective detection of oAβ using a label-free approach.

Main Results:

• The developed bionic capacitive sensor achieved real-time detection of oAβ peptide in plasma within 5 seconds.
• Demonstrated ultra-high affinity detection in the femto-molar concentration range, surpassing ELISA response times.
• The biosensor exhibited selectivity against plasma-borne antigens, stability for 100 days at 4°C, and suitability for point-of-care diagnostics.

Conclusions:

• The novel capacitive biosensor offers a highly sensitive, rapid, and label-free method for detecting Aβ biomarkers, crucial for Alzheimer's disease diagnosis.
• The aptamer-antibody functionalized biochip demonstrates significant potential for point-of-care diagnostic applications due to its portability and scalability.
• This technology holds promise for advancing biomedical applications in neurodegenerative disease diagnostics.