Publications Archives – Page 6 of 13 – Institute of Nano Electronic Engineering

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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Optical measurements on tailored zinc oxide thin films under optimal

March 24, 2016 By Editor

Abstract – ZnO is synthesized by using conventional chemical route which is known as the “sol-gel” method and deposited on glass and silicon substrate. Morphological and optical properties have been investigated using XRD, AFM, FESEM and UV-vis test. In order to optimize the synthesized ZnO thin film, the ZnO thin film is coated with thin film of different thickness associated with various annealing temperature. Thicknesses of ZnO thin film coated for 3, 5 and 9 coating cycles of coating are 40 nm2, 60 nm2 and 200 nm2, respectively. The data report that the grain size of the seed solution increases from 80 nm to 110 nm as the thickness of ZnO thin film increases. As the thin film is treated with annealing temperature from 200°C to 450°C, the grain size of thin film also increases from 100 nm2 to 450 nm2. The RMS value of thin film also increases due to intense surface roughness on ZnO thin film. The band gap value of thin film decreased from 3.26 eV to 3.18 eV for coating ZnO thin film with thickness 40 nm2-200 nm2.

Keywords – Band gap, Grain size, Thin film, UV-vis, XRD, ZnO

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

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A new nano-worm structure from gold-nanoparticle mediated random curving of zinc oxide nanorods

December 17, 2015 By Editor

Abstract – Creating novel nanostructures is a primary step for high-performance analytical sensing. Herein, a new worm like nanostructure with Zinc Oxide-gold (ZnO/Au) hybrid was fabricated through an aqueous hydrothermal method, by doping Au-nanoparticle (AuNP) on the growing ZnO lattice. During ZnO growth, fine tuning the solution temperature expedites random curving of ZnO nanorods and forms nano-worms. The nano-worms which were evidenced by morphological, physical and structural analyses, revealed elongated structures protruding from the surface (length: 1. μm; diameter: ~100. nm). The appropriate peaks for the face centred cubic gold were (111) and (200), as seen from X-ray diffractogram. The strong interrelation between Au and ZnO was manifested by X-ray photoelectron spectroscopy. The combined surface area increment from the nanoparticle radii and ZnO nanorod random curving gives raise an enhancement in detection sensitivity by increasing bio-loading. ‘Au-decorated hybrid nano-worm’ was immobilized with a probe DNA from Vibrio Cholera and duplexed with a target which was revealed by Fourier Transform Infrared Spectroscopy. Our novel Au-decorated hybrid nano-worm is suitable for high-performance bio-sensing, as evidenced by impedance spectroscopy, having higher-specificity and attained femtomolar (10. fM) sensitivity. Further, higher stability, reproducibility and regeneration on this sensing surface were demonstrated.

Keywords – Cholera, DNA, Gold nanoparticle, Nano-worm, Nanorod, Zinc Oxide

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

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Structural, electronic and thermodynamic properties of half-metallic Co2CrZ (Z=Ga, Ge and As) alloys: First-principles calculations

October 29, 2015 By Editor

Abstract – Abstract Using first principles calculations, the structural, electronic, and magnetic properties of ferromagnetic half-metallic full-Heusler Co2CrZ (Z=Ga,GeandAs) alloy via the FP-LAPW method in the generalized gradient (GGA) and GGA+U approximations are compared with other experimental and theoretical results. The calculated equilibrium lattice constants were in qualitative agreement with the previous results. The existence of the energy gap in the minority spin (DOS and band structure) of Co2CrZ (Z=Ga,GeandAs) are an indication of being a potential half-metallic ferromagnetic HMF. The half-metallicity of the obtained material may prove useful for applications in spin-polarizers and spin-injectors of magnetic nanodevices. The calculated total spin magnetic moments are almost exactly that expected from Slater-Pauling rule. Thermal effects on some macroscopic properties of Co2CrZ (Z=Ga,GeandAs) are predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account. The variations of the primitive cell volume, volume expansion coefficient, bulk modulus, heat capacity and Debye temperature with pressure and temperature in the ranges of 0-20 GPa and 0-3000 K, respectively are obtained successfully.

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

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Non-Protein Coding RNA Genes as the Novel Diagnostic Markers for the Discrimination of Salmonella Species Using PCR

September 30, 2015 By Editor

Abstract – Salmonellosis, a communicable disease caused by members of the Salmonella species, transmitted to humans through contaminated food or water. It is of paramount importance, to generate accurate detection methods for discriminating the various Salmonella species that cause severe infection in humans, including S. Typhi and S. Paratyphi A. Here, we formulated a strategy of detection and differentiation of salmonellosis by a multiplex polymerase chain reaction assay using S. Typhi non-protein coding RNA (sRNA) genes. With the designed sequences that specifically detect sRNA genes from S. Typhi and S. Paratyphi A, a detection limit of up to 10 pg was achieved. Moreover, in a stool-seeding experiment with S. Typhi and S. Paratyphi A, we have attained a respective detection limit of 15 and 1.5 CFU/mL. The designed strategy using sRNA genes shown here is comparatively sensitive and specific, suitable for clinical diagnosis and disease surveillance, and sRNAs represent an excellent molecular target for infectious disease.

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

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