An Electrochemical Immunosensor Based on a Self-Assembled Monolayer Modified Electrode for Label-Free Detection of α-Synuclein.

Chuang-Ye Ge,Lei Jin,Guang-Ri Xu,Md Mahbubur Rahman,Sujin Yoon,Wei Zhang,Nasrin Siraj Lopa,Hohyoun Jang,Whangi Kim

doi:10.3390/s20030617

Abstract

This research demonstrated the development of a simple, cost-effective, and label-free immunosensor for the detection of α-synuclein (α-Syn) based on a cystamine (CYS) self-assembled monolayer (SAM) decorated fluorine-doped tin oxide (FTO) electrode. CYS-SAM was formed onto the FTO electrode by the adsorption of CYS molecules through the head sulfur groups. The free amine (–NH2) groups at the tail of the CYS-SAM enabled the immobilization of anti-α-Syn-antibody, which concurrently allowed the formation of immunocomplex by covalent bonding with α-Syn-antigen. The variation of the concentrations of the attached α-Syn at the immunosensor probe induced the alternation of the current and the charge transfer resistance (Rct) for the redox response of [Fe(CN)6]3−/4−, which displayed a linear dynamic range from 10 to 1000 ng/mL with a low detection limit (S/N = 3) of ca. 3.62 and 1.13 ng/mL in differential pulse voltammetry (DPV) and electrochemical impedance spectra (EIS) measurements, respectively. The immunosensor displayed good reproducibility, anti-interference ability, and good recoveries of α-Syn detection in diluted human serum samples. The proposed immunosensor is a promising platform to detect α-Syn for the early diagnose of Parkinson’s disease, which can be extended for the determination of other biologically important biomarkers.

Highlights

According to a projection of the World Health Organization, neurological disorders and diseases are one of the principal causes of disability and death worldwide, including Parkinson’s, Alzheimer’s, Creutzfeldt-Jakob, Huntington’s, and Wilson’s diseases [1,2]
This can be attributed to the existence of hydrophobic fluorine dopants in the fluorine-doped tin oxide (FTO)
We have successfully fabricated a simple, low-cost, sensitive, and selective electrochemical immunosensor to detect α-Syn, which is a potential biomarker of Parkinson’s disease (PD)

Summary

Introduction

According to a projection of the World Health Organization, neurological disorders and diseases are one of the principal causes of disability and death worldwide, including Parkinson’s, Alzheimer’s, Creutzfeldt-Jakob, Huntington’s, and Wilson’s diseases [1,2]. Is the second leading cause of the neurodegenerative disorder, which affects about 1 and 4% of the people above the ages of 60 and 80 years old, respectively [3]. 50 years old are affected with PD [4]. PD is a chronic and incurable neurodegenerative disorder with the progressive loss of neuronal cells in the substantia nigra [5,6]. The population with PD is anticipated to rise between 8.7 to 9.3 million by 2030 [7].

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Conclusion