Abstract
γ-Aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the central nervous system (CNS), which acts as a major biomarker for neurological disorders such as Parkinson’s disease and Meningitis. To this end, the precise measurement of GABA molecule arisen as an important subject for the effective diagnosis and treatment of neurological disorders. However, yet highly sensitive biosensor systems which can analyze a wide range of GABA molecule in a fast response manner have not been reported. In this study, for the first time, a silicon nanowire field-effect transistor (FET) device based immunosensor was developed to detect GABA molecule. Zig-zag shaped silicon nanowires has been fabricated by electron beam lithography and the electrical property p-type FET device was validated through semiconductor analyzer. The optimal immobilizing condition of antibody against GABA molecule was determined by the fluorescent signal measurement. Various concentrations of GABA ranging from 970 fM to 9.7 μM were sensitively measured by conductance change on silicon nanowire-based through the immunoreactions. Further, owing to the ease of miniaturization and label-free system, we believe that the suggested device system has a potential to be utilized for an implantable biosensor to detect neurotransmitter in the brain and can create new opportunities in the field of diagnosis and treatment of neurological disorders.
Highlights
It is estimated that the tendency of patients suffering from neurological disorder is increasing every year
The structure of fabricated silicon nanowire pattern on silicon on insulator (SOI) wafer was verified by scanning electron microscopy (SEM) images (Fig. 2a, b). 25 silicon nanowires were fabricated in parallel between source and drain electrodes
In case of the p-type silicon nanowire, which is used in this experiment, the conductance will increase as applying negative gate voltage, or decrease as applying positive gate voltage because electron holes work as a carrier in the p-type silicon nanowire [19]
Summary
It is estimated that the tendency of patients suffering from neurological disorder is increasing every year. There are other instruments which are more sensitive than piezoelectric immuno-sensor such as liquid chromatography, but they are inefficient and time-consuming because of sample pretreatments [17] Another alternative detection system must be needed to overcome these problems of the conventional GABA detection systems. Significant advantages such as portability, high sensitivity, fast response, low manufacturing cost, and label-free detection procedure have provided a clear aspect to develop FET-based biosensors for analyzing bio/chemical molecules. To this end, in this study silicon nanowire, FET device was utilized for the first time to develop a highly sensitive biosensor for detecting GABA molecule in a fast response manner (Fig. 1). The structure of fabricated silicon nanowire on SOI wafer was verified with scanning electron microscopy (SEM) (JSM-6700, 15–30 kV)
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