Publications Archives &#8211; Page 3 of 13 &#8211; Institute of Nano Electronic Engineering

Design and fabrication of PDMS microfluidics device for rapid and label-free DNA detection

March 24, 2020 By Editor

Abstract – Microfluidics explores the manipulation of fluid in small volume, a multidisciplinary field is imperative for DNA extraction. This study offers a simple yet substantial methodology for the fabrication of microfluidics structure-based polydimethylsiloxane (PDMS) biopolymer on a glass substrate with SU-8 photoresist for label-free detection of pathogenic genomic DNA. Two microfluidics designs for DNA detection were based on AutoCAD software, both contain two inlets and one outlet, with dimensions of 28 mm wide, and 18 mm long, and total surface area of 504 mm2. The designs were patterned in such particular sizes and dimensions to test fluid delivery and enhancement in biochemical processes in DNA extraction, while maintaining economical values as a disposable chip. Both microfluidics devices showed no leakage during fluid delivery, have heights of 97.97 and 103.44 μm, and surface roughness of 0.15 and 0.07 μm, respectively. DNA extraction from pathogenic fungus Ganoderma boninense was run on PDMS microfluidic device and UV–Vis analysis confirmed successful extraction with peaks found at 260–280 nm. Current–voltage (I–V) measurement confirmed the accuracy of microfluidic device for the specific pathogen with both real and synthetic samples of G. boninense illustrating the similar graph values of only 0.000005 A difference at 1.0 V after hybridization.

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

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Fabrication of gold nanorod–zinc oxide nanocomposite on gap‑fingered integrated interdigitated aluminum electrodes and their response to electrolytes

December 5, 2019 By Editor

Abstract – This study describes the fabrication of three different gap-fingered aluminum-interdigitated electrodes (AlIDEs) on the silicon substrate based on photolithographic method, followed by integration of the gold nanorod–zinc oxide nanocomposite. The IDE masks were designed using AutoCAD software with the gaps of 10, 20, and 30 μm for design 1, 2, and 3, respectively. The morphological and electrical characterizations were subsequently performed using 3D-nanoprofiler, atomic force microscopy, high-power microscopy (HPM), scanning electron microscopy (SEM), and I–V. Validation of the fabricated surfaces (AlIDEs with/without gold nanorod–zinc oxide nanocomposite) against the electrolytes was performed at different pHs which are ranging from 1 to 12. SEM revealed the following gaps, 18.4, 20, and 40.5 μm for bare 1, 2, and 3, respectively. The measurements on I–V for bare AlIDEs indicated the electrolyte influences at different pH solutions, which were almost similar in terms of current variations except at highly acidic and alkaline. AlIDEs were well fabricated and the smaller the gap displayed the better the sensitivity, hence device 1 AlIDE has a good performance. Using different pH solutions which ranging from pH 1–12, before and after AlIDEs were coated with zinc oxide and gold nanorod. The responses of the devices were similar, fluctuating from highly acidic region to highly alkaline region in the cases of AlIDEs bare 1 and 3. Bare 2 AlIDE displayed similar responses with the AlIDE that was deposited with gold nanorod. With these results, we can conclude that deposition of gold nanorod on the device brought about the orderly response to the different pH and with the increment from acidic to alkaline increases, the proportional changes with the current were noticed.

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

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Co-ordinated split aptamer assembly and disassembly on Gold nanoparticle for functional detection of HIV-1 tat

September 22, 2019 By Editor

Abstract – Human immunodeficiency virus (HIV) is a life threatening, weakens the immune system upon infection, thus ultimately resulting in the fatal health issues. This situation necessitates the generation of different strategies for HIV detection. HIV-1 Tat, a transactivator of HIV gene expression, was chosen in this study as the target of a non-functional split aptamer. Implementation of split aptamer has been demonstrated in this work for colorimetric detection of HIV-1 Tat. An unmodified gold nanoparticle (GNP)-based colorimetric assay was used for the visible detection of the proof, displays color transitions from red to purple in relation to the dose-dependency of HIV-1 Tat against the split aptamer in ionic solutions. The visible color transition was characterized using UV–vis spectrophotometer showing spectrum shift and supported by Scanning Electron Microscopy observation. With addition of sodium chloride, the color of the solution started to change to purple and spectrum started to shift to higher wavelength due to aggregation at HIV-1 Tat concentration as low as 10 nM. Specificity test was conducted with duplexed split aptamer and HIV-1 p24 has shown slight color changes. With HIV-1 Nef, GNP solution retains the color similar to the control, which indicated the specific split aptamer interaction to HIV-1 Tat.

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

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Complementation of ELISA and an Interdigitated Electrode Surface in Gold Nanoparticle Functionalization for Effective Detection of Human Blood Clotting Defects

July 29, 2019 By Editor

Abstract – Developing an enhanced diagnosis using biosensors is important for the treatment of patients before disease complications arise. Improving biosensors would enable the detection of various low-abundance disease biomarkers. Efficient immobilization of probes/receptors on the sensing surface is one of the efficient ways to enhance detection. Herein, we introduced the pre-alkaline sensing surface with amine functionalization for capturing gold nanoparticle (GNP) conjugated to human blood clotting factor IX (FIX), and we demonstrated the excellent performance of the strategy. We have chosen the enzyme-linked immunosorbent assay (ELISA) and the interdigitated electrode (IDE), which are widely used, to demonstrate our method. The optimal amount for silanization has been found to be 2.5%, and 15-nm-sized GNPs are ideal and characterized. The limit of FIX detection was attained with ELISA at 100 pM with the premixed GNPs and FIX, which shows 60-fold improvement in sensitivity without biofouling, as compared to the conventional ELISA. Further, FIX was detected with higher specificity in human serum at a 1:1280 dilution, which is equivalent to 120 pM FIX. These results were complemented by the analysis on IDE, where improved detection at 25 pM was achieved, and FIX was detected in human serum at the dilution of 1:640. These optimized surfaces are useful for improving the detection of different diseases on varied sensing surfaces.

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

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Multidimensional (0D-3D) nanostructures for lung cancer biomarker analysis: Comprehensive assessment on current diagnostics

July 8, 2019 By Editor

Abstract – The pragmatic outcome of a lung cancer diagnosis is closely interrelated in reducing the number of fatal death caused by the world’s top cancerous disease. Regardless of the advancement made in understanding lung tumor, and its multimodal treatment, in general the percentage of survival remain low. Late diagnosis of a cancerous cell in patients is the major hurdle for the above circumstances. In the new era of a lung cancer diagnosis with low cost, portable and non-invasive clinical sampling, nanotechnology is at its inflection point where current researches focus on the implementation of biosensor conjugated nanomaterials for the generation of the ideal sensing. The present review encloses the superiority of nanomaterials from zero to three-dimensional nanostructures in its discrete and nanocomposites nanotopography on sensing lung cancer biomarkers. Recent researches conducted on definitive nanomaterials and nanocomposites at multiple dimension with distinctive physiochemical property were focused to subside the cases associated with lung cancer through the development of novel biosensors. The hurdles encountered in the recent research and future preference with prognostic clinical lung cancer diagnosis using multidimensional nanomaterials and its composites are presented.

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

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