A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers

Background: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (A beta O) in blood or cerebrospinal fluid (CSF) are the pathogenic biomarker correlated with AD. Methods: A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs) hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrPC) peptide probe was immobilized on GNPs of the hydrogel electrode to construct an A beta O biosensor. Electrochemical impedance spectroscopy was utilized for A beta O analysis. Results: The specific binding between A beta O and PrPC probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for A beta O detection. It could selectively differentiate A beta O from amyloid-beta (A beta) monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM A beta O in artificial CSF or blood plasma. The linear range for A beta O detection is from 0.1 pM to 10 nM. Conclusion: This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure.