Biosensor Archives – Institute of Nano Electronic Engineering

Substrate-gate coupling in ZnO-FET biosensor for cardiac troponin I detection

March 17, 2017 By Editor

Abstract – Currently, field-effect transistor (FET)-based biosensors have been implemented in several portable sensors with the ultimate application in point-of-care testing (POCT). In this paper, we have designed substrate-gate coupling in FET-based biosensor for the detection of cardiac troponin I (cTnI) biomarker. In the device structure, zinc oxide nanoparticles (ZnO-NPs) thin film were deposited through sol-gel and spin coating techniques on the channel. The p-type silicon was used as a substrate, while ZnO is an n-type nanomaterial, thus creates p-n-p junction between source, channel, and drain. The deposited thin films exhibited hexagonal wurtzite phase of ZnO, suitable for biomolecular interaction as revealed in X-ray diffraction (XRD) analysis. The surface of the thin film was then functionalized with 3-aminopropyltriethoxysilane (APTES), followed by glutaraldehyde (GA) as a bi-functional linker to immobilize the cTnI monoclonal antibody (MAb-cTnI) as bio-receptor for capturing cTnI biomarker and proven by the Fourier transform-infrared (FT-IR) spectra. Lastly, we demonstrated a new strategy, the integration of FET-based biosensors with substrate-gate showed differences between before (immobilization) and after cTnI target biomarker interaction by significant changes in drain current (ID) and change of threshold voltage (VT), which improved the sensitive detection, with the limit of detection down to 3.24 pg/ml.

Keywords – Biosensor, Cardiac troponin I, Electrical-based, Field-effect transistor, Substrate-gate coupling, Zinc oxide nanoparticles

Corresponding Author: Uda Hashim
Corresponding Author’s Email: uda@unimap.edu.my

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2-Day Course on Nano-Biosensor

October 17, 2014 By Editor

Date: November 24 & 25, 2014
Time: 9.00 a.m. – 5 p.m.
Venue: Institute of Nano Electronic Engineering, UniMAP

Course Background

Biosensor is a short form for “biological sensor”. The device is made up of a transducer and a biological element that may be an enzyme, an antibody or a nucleic acid. The bio-element interacts with the analyte being tested and the biological response is converted into an electrical signal by the transducer. Depending on their particular application, biosensors are also known as immunosensors, optrodes, resonant mirrors, chemical canaries, biochips, glucometers and biocomputers.

The Objectives

Provide an overview on the important aspects and principles of nano biosensor design, fabrication and characterization.
Assist the participants in understanding major fabrication steps and their underlying theories.
Exposure to the sophisticated and state-of-the art nano devices fabrication equipment and tools.

Any inquiry, kindly contact:
Dr Ramzan b Mat Ayub
Mobile: +6012-274 9986
Email: ramzan@unimap.edu.my

Aptamer-based biosensor for sensitive PDGF detection using diamond transistor

May 2, 2013 By Editor

Abstract – The detection of platelet-derived growth factor (PDGF) via a solution-gate field-effect transistor (SGFET) has been demonstrated for the first time using aptamers immobilized on a diamond surface. Upon introduction of PDGF to the immobilized aptamer, a shift of 31.7mV in the negative direction is observed at a source-drain current of −50µA. A shift of 32.3mV in the positive direction is detected after regeneration by SDS solution, indicating that the static measurement returns to its original value. These SGFETs operate stably within the large potential window of diamond (>3.0 V), and hence the surface channel does not need passivating with a thick insulating layer. Thereof, the immobilized aptamer channels have been exposed directly to the electrolyte solution without a gate insulator. Immobilization is achieved via aptamers covalently bonding to amine sites, thereby increasing the sensitivity of the biosensors. Diamond SGFETs have potential for the detection of PDGF and show durability against biological degradation after repeated usage and regeneration.

Keywords – Aptamer, Diamond transistor, Platelet-derived growth factor, Biosensor

Corresponding Author: Ruslinda Abdul Rahim
Corresponding Author’s Email: ruslinda@unimap.edu.my

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Effects of diamond-FET-based RNA aptamer sensing for detection of real sample of HIV-1 Tat protein

April 29, 2013 By Editor

Abstract – Diamond is a promising material for merging solid-state and biological systems owing to its chemical stability, low background current, wide potential window and biocompatibility. The effects of surface charge density on human immunodeficiency virus type 1 Trans-activator transcription (HIV-1 Tat) protein binding have been investigated on a diamond field-effect transistor (FET) using ribonucleic acid (RNA) aptamers as a sensing element on a solid surface. A change in the gate potential of 91.6 mV was observed, whereby a shift in the negative direction was observed at a source-drain current of -8µA in the presence of HIV-1 Tat protein bound to the RNA aptamers. Moreover, the reversible change in gate potential caused by the binding and regeneration cycles was very stable throughout cyclical detections. The stable immobilization is achieved via RNA aptamers covalently bonded to the carboxyl-terminated terephtalic acids on amine sites, thereby increasing the sensitivity of the HIV-1 Tat protein sensor. The reliable use of a real sample of HIV-1 Tat protein by an aptamer-FET was demonstrated for the first time, which showed the potential of diamond biointerfaces in clinical biosensor applications.

Keywords – RNA aptamer, Diamond FET, HIV-1 Tat protein, Biosensor

Corresponding Author: Ruslinda Abdul Rahim
Corresponding Author’s Email: ruslinda@unimap.edu.my

Full text: PDF