An Ultra-sensitive Nanowire-Transistor Biosensor for Detecting Neurotransmitters Release from Living cells under Stimulation
Date Issued
2015
Date
2015
Author(s)
Hsieh, Ying-Jhu
Abstract
Over the past decade, silicon nanowire field-effect transistors (SiNW-FETs) with their tunable conductivity and biocompatibility have become significant biosensors. Moreover, the thin silicon oxide sheathes on SiNW-FETs are easily functionalized with selected receptors prior to bio-detections, providing strong and specific binding affinity for biomolecules. Because of strong interaction between the receptors and biomolecules, modified SiNW-FETs have been employed for the detections of protein, DNA, cancer markers, viruses, and other biochemical species. The first part of this thesis focuses on the detection of dopamine (DA) released from living PC12 cells under hypoxic stimulation using an ultrasensitive SiNW-FET biosensor. DA is an important neurotransmitter which plays crucial roles in neuronal signal transduction and causes several critical illnesses. However, it is difficult to detect the extremely low DA content in patients using existing electrochemical biosensors with detection limits typically around nanomolar levels (∼10−9 M). This thesis describes a DNA-aptamer modified multiple-parallel-connected (MPC) SiNW-FET (referred as MPC DA-specific aptamer/SiNW-FET) device for ultrasensitive and selective DA detection. The MPC DA-specific aptamer/SiNW-FET has been employed to improve the detection limit of DA to <10−11 M and the specifically distinguishing ability from other chemical analogues, such as ascorbic acid, catechol, phenethylamine, tyrosine, epinephrine, and norepinephrine. The MPC DA-specific aptamer/SiNW-FET was also employed to monitor DA release under hypoxic stimulation from living PC12 cells in real time. The experimental results revealed that the increase in intracellular Ca2+ that is required to trigger DA secretion is dominated by an extracellular Ca2+ influx, rather than the release of intracellular Ca2+ stores. The second project of the thesis focuses on the detection of neuropeptide Y (NPY) using a DNA-aptamer modified SiNW-FET. NPY is an important neurotransmitter and is related with several critical diseases. Two most common detection and quantification techniques for NPY are enzyme-linked immunosorbent assay (ELISA) and liquid chromatography–mass spectrometry (LC-MS/MS). However, both techniques lack the real-time detection ability for NPY and are not suitable for cellular investigation. Herein, we report a DNA-aptamer modified SiNW-FET (referred to as NPY-specific aptamer/SiNW-FET) applicable for the real-time and selective detection for NPY. The linear working range of the NPY-specific aptamer/SiNW-FET for NPY detection spanned from 10-7 to 10-5 M and the limit of NPY detection is 24 nM. The NPY-specific aptamer/SiNW-FET has shown a detection specificity that is able to distinguish NPY from other neurotransmitters, such as dopamine. Furthermore, this NPY-specific aptamer/SiNW-FET has been successfully applied for real-time monitoring DA release from living PC12 cells under hypoxic stimulation.
Subjects
SiNW-FET
dopamine
neuropeptide Y
aptamer
biosensor
SDGs
Type
thesis
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