A Point-of-Care Immunosensor Based on a Quartz Crystal Microbalance with Graphene Biointerface for Antibody Assay

Area of Science:

• Biomedical Engineering
• Materials Science
• Analytical Chemistry

Background:

• Primary membranous nephropathy is diagnosed by detecting anti-PLA2R antibodies.
• Current detection methods can be costly and time-consuming.
• There is a need for rapid, sensitive, and affordable diagnostic tools.

Purpose of the Study:

• To develop and validate a novel graphene-based quartz crystal microbalance (G-QCM) immunoassay.
• To quantify anti-phospholipase A2 receptor (anti-PLA2R) antibodies in undiluted patient serum.
• To assess the G-QCM biosensor's performance against commercial systems and ELISA.

Main Methods:

• Constructed a graphene-protein biointerface using reduced graphene oxide (rGO) and denatured bovine serum albumin (dBSA).
• Immobilized anti-PLA2R antibodies on the dBSA-rGO surface for detection.
• Quantified antibodies in patient serum using the G-QCM biosensor and compared results with a commercial QCM system and ELISA.

Main Results:

• The G-QCM immunoassay demonstrated high sensitivity and specificity for anti-PLA2R antibodies.
• Achieved a detection limit of 100 ng/mL, an order of magnitude better than the commercial QCM system.
• Results from patient sera correlated well with ELISA, indicating clinical feasibility.
• The G-QCM system offered significant cost and time savings.

Conclusions:

• The developed G-QCM biosensor is a sensitive, low-cost, and rapid tool for quantifying antibodies in patient serum.
• The dBSA-rGO platform is a versatile biofunctionalization strategy for immunoassays and biosensors.
• This technology holds potential as an effective screening tool for autoimmune diseases like primary membranous nephropathy.