Sensitive Electrochemical and Acoustic Detection of Myelin Basic Protein Using Antifouling Self-Assembled Monolayers and DNA Aptamer-Based Recognition

Introduction. Myelin basic protein (MBP), which constitutes about 30% of central nervous system myelin, is an important biomarker of demyelination. Concentration of MBP increases in multiple sclerosis (MS). The concentration of MBP in cerebrospinal fluid (CSF) of healthy individuals is typically below 6.2 ng/mL. The therapy of MS required early-stage diagnostics. Biosensors can be effective for this purpose. Methods. We used quartz crystal microbalance with dissipation monitoring (QCM-D) and differential pulse voltammetry (DPV) for MBP detection using DNA aptamers specific to MBP. Recombinant MBP was prepared by heterologous expression in competent Escherichia coli plasmids. The biosensor was based on the gold electrodes with chemisorbed mixed SH MEG COOH/DTT or SH-MEG-COOH/SH-MEG-OH self assembled monolayers (SAM) to suppress nonspecific adsorption. DNA aptamers were immobilized at the SAM using carbodiimide chemistry. Results. Addition of MBP resulted in decrease of resonant frequency in QCM-D and decrease of the current in DPV at presence of [Fe(CN)6]3−/4− probe. This allowed detection of MBP in a range 0.5 ng/mL to 60 µg/mL. The limit of detection (LOD) was 7.8 ng/mL (QCM-D) and 2.8 ng/mL (DPV) . Similar LODs were determined in artificial CSF. Conclusion. The developed aptasensor allowed detection of MBP with sufficient sensitivity and specificity required for clinical sample analysis.

Acknowledgment. We are grateful for financial support by NextGenertion EU Recovery Plan, project No. 09I03-03-V04-00145 and by Science Grant Agency VEGA, project No. 1/0445/23.