Publications Archives – Page 5 of 13 – 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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A direct detection of human papillomavirus 16 genomic DNA using gold nanoprobes

December 8, 2016 By Editor

Abstract – Nanoparticles have been investigated as flagging tests for the sensitive DNA recognition that can be utilized as a part of field applications to defeat restrictions. Gold nanoparticles (AuNPs) have been widely utilized due to its optical property and capacity to get functionalized with a mixed bag of biomolecules. This study exhibits the utilization of AuNPs functionalized with single-stranded oligonucleotide (AuNP-oligo test) for fast the identification of Human Papillomavirus (HPV). This test is displayed on interdigitated electrode sensor and supported by colorimetric assay. DNA conjugated AuNP has optical property that can be controlled for the applications in diagnostics. With its identification abilities, this methodology incorporates minimal effort, strong reagents and basic identification of HPV.

Keywords – Colorimetric detection, DNA detection, Gold nanoparticles, Human Papillomavirus, Interdigitated electrode sensor

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

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Formation of nanocrystalline GeSn thin film on Si substrate by sputtering and rapid thermal annealing

September 25, 2016 By Editor

Abstract – Nanocrystalline Ge1-xSnx thin films have been formed after rapid thermal annealing of sputtered GeSn layers. The alloy films were deposited onto the Silicon (100) substrate via low cost radio frequency magnetron sputtering. Then, the films were annealed by rapid thermal annealing at 350 °C, 400 °C, and 450 °C for 10 s. The morphological, structural, and optical properties of the layers were investigated with field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, and high-resolution X-ray diffraction (HR-XRD). The Raman analysis showed that the only observed phonon mode is attributed to Ge-Ge vibrations. Raman phonon intensities of GeSn thin films were enhanced with increasing the annealing temperature. The results clearly revealed that by increasing the annealing temperature the crystalline quality of the films were improved. The XRD measurements revealed the nanocrystalline phase formation in the annealed films with (111) preferred orientation. The results showed the potentiality of using the sputtering technique and rapid thermal anneal to produce crystalline GeSn layer.

Keywords – Germanium-tin, HR-XRD, Nanocrystalline materials, Raman spectroscopy, Sputtering, Thin films

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

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Cell-targeting aptamers act as intracellular delivery vehicles

July 25, 2016 By Editor

Abstract – Aptamers are single-stranded nucleic acids or peptides identified from a randomized combinatorial library through specific interaction with the target of interest. Targets can be of any size, from small molecules to whole cells, attesting to the versatility of aptamers for binding a wide range of targets. Aptamers show drug properties that are analogous to antibodies, with high specificity and affinity to their target molecules. Aptamers can penetrate disease-causing microbial and mammalian cells. Generated aptamers that target surface biomarkers act as cell-targeting agents and intracellular delivery vehicles. Within this context, the “cell-internalizing aptamers” are widely investigated via the process of cell uptake with selective binding during in vivo systematic evolution of ligands by exponential enrichment (SELEX) or by cell-internalization SELEX, which targets cell surface antigens to be receptors. These internalizing aptamers are highly preferable for the localization and functional analyses of multiple targets. In this overview, we discuss the ways by which internalizing aptamers are generated and their successful applications. Furthermore, theranostic approaches featuring cell-internalized aptamers are discussed with the purpose of analyzing and diagnosing disease-causing pathogens.

Keywords – Aptamer, Internalization, Receptor, SELEX, Surface antigen

Corresponding Author: Subash C B Gopinath
Corresponding Author’s Email: subash@unimap.edu.my

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Electrical detection of dengue virus (DENV) DNA oligomer using silicon nanowire biosensor with novel molecular gate control

June 21, 2016 By Editor

Abstract – In this paper, a silicon nanowire biosensor with novel molecular gate control has been demonstrated for Deoxyribonucleic acid (DNA) detection related to dengue virus (DENV). The silicon nanowire was fabricated using the top-down nanolithography approach, through nanostructuring of silicon-on-insulator (SOI) layers achieved by combination of the electron-beam lithography (EBL), plasma dry etching and size reduction processes. The surface of the fabricated silicon nanowire was functionalized by means of a three-step procedure involving surface modification, DNA immobilization and hybridization. This procedure acts as a molecular gate control to establish the electrical detection for 27-mers base targets DENV DNA oligomer. The electrical detection is based on the changes in current, resistance and conductance of the sensor due to accumulation of negative charges added by the immobilized probe DNA and hybridized target DNA. The sensitivity of the silicon nanowire biosensors attained was 45.0 μA M-1, which shows a wide-range detection capability of the sensor with respect to DNA. The limit of detection (LOD) achieved was approximately 2.0 fM. The demonstrated results show that the silicon nanowire has excellent properties for detection of DENV with outstanding repeatability and reproducibility performances.

Keywords – Dengue fever (DF); Deoxyribonucleic acid (DNA); Electrical detection; Molecular gate control; Nanolithography; Silicon nanowire biosensor

Corresponding Author: Mohammad Nuzaihan Md Nor
Corresponding Author’s Email: m.nuzaihan@unimap.edu.my

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