Development of Microfluidic Graphene-Aptamer Biosensor for Cardiac Troponin-I Detection
Date Issued
2015
Date
2015
Author(s)
Huang, Cheng-Chun
Abstract
The topic of this dissertation is to develop a biosensor for detecting cardiac troponin-I (cTnI). In clinical, it is pathognostic to have acute coronary syndrome (ACS) in two abnormalities of three items that are clinical symptoms assessment, electrocardiography (ECG) diagnosis, and detection of the concentration of cardiac enzymes. However, it is sometimes not easy to determine clinical symptoms, such as the dementia and apoplexy suffered patients, or the ECG without obviously specific characteristic. Therefore, it is taken more attention to diagnose ACS with cardiac enzymes. Cardiac troponin I (cTnI) is one kind of cardiac enzymes. cTnI has been proved as the gold-standard and an attractive biomarker for presymptomatic diagnosis and suitable for long-term monitoring. The biochip with application in point of care system is expected convenient usage, low concentration detection and high sensitivity. Testing solution flows in biochip via capillary force for self-driving is performed without external equipment requirement. The dynamic equation of capillary flow in rectangular channel is derived. The surface tension, coefficient of viscosity and contact angle are parameters. The equation is available for design of channel dimension and location of biosensor in channel. Different mixing ratios of glycerol and deionized water to be testing solutions with different coefficients of viscosities are served into the parylene coated polydimethylsiloxane (PDMS) microchannel in the capillary force driving experiment. According to the relation of meniscus position and time, the variation of advancing contact angle can be obtained, and then the velocity can be calculated as well. The viscous shear stress and shear force near the surface of microchannel can be estimated. The information is provided to appraise if the binding of molecules would be broken and to design the location of biosensor in microchannel. The back-gate filed effect transistor (FET) is fabricated with graphene as transport channel (detecting area). The cTnI aptamer is immobilized on the surface of graphene for functionalization to enhance performance of low limit detection (LOD). All the characteristics of FET biosensors are p-type after fabrication process and bio-functionalization. Under the detecting test, the transconductance and carrier mobility in electrical characteristic of FET changes as the concentration of testing solution due to n-doping effect. When the concentration is greater, the variation of transconductance becomes larger. As a result, transconductance can be used to determine the concentration level of biomarkers in testing solution. The LOD in this research achieves at 0.01 ng/mL. The final part of this dissertation is to fabricate a microcone with build-in magnetic field in microchannel. It has functions of mixing microfluid and capturing microbeads.
Subjects
Acute coronary syndrome
biomarker
cardiac troponin
aptamer
graphene
biosensor
microfluid
capillary force
contact angle
viscous shear force
magnetic microbeed
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-104-D98522018-1.pdf
Size
23.54 KB
Format
Adobe PDF
Checksum
(MD5):2725aa4ba08e6b963b71122c7e410cd7