Publications Archives &#8211; Page 2 of 13 &#8211; Institute of Nano Electronic Engineering

A gold nanoparticles coated unclad single mode fiber-optic sensor based on localized surface plasmon resonance

June 10, 2023 By Editor

Abstract – In the last few decays, the fiber-optic was employed in the field of sensing because of its benefits in contrast to other types of sensors such as small size, easy to fabricate, high response, and flexibility. In this study, unclad single mode fiber-optic sensor is proposed to operate at 650 nm wavelength. COMSOL Multiphysics 5.1 finite element method (FEM) is used to design the sensor and tested it theoretically. The middle portion of the fiber cladding is removed and replaced by gold nanoparticles (Au NPs) of 50 nm thickness. Analytic layer of 3 μm thickness was immersed in different liquids in range of refractive index (RI) from 1.000281 to 1.39. These liquids are NaCl Deionized (DI) water solution, sucrose-Deionized (DI) water solution, and glycerol solution Deionized (DI) water. It was found that the highest obtained sensitivity and resolution are for glycerol-DI water solution with value of 3157.98 (nm/RIU) and 3.16 × 10–5 (RIU), respectively. Furthermore, it is easy to fabricate and of low cost. In experiments, pulsed laser ablation (PLA) was used to prepare Au NPs. X-ray diffraction (XRD) shown that the peak of the intensity grew as the ablated energy increased as well as the structure crystallization. Transmission electron microscopy (TEM) revealed an average diameter of 30 nm at the three ablated energies, while X-ray spectroscopy (EDX) spectrum has indicated the presence of Au NPs in the prepared solution. The photoluminescence (PL) and ultraviolet–visible UV–Vis transmission were used to study the optical properties of the prepared Au NPs. An optical spectrum analyzer was used to obtain the sensor’s output results. It has shown that best intensity was obtained for sucrose which confined with theoretical results.

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

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Link to Publication: https://doi.org/10.1038/s41598-023-32852-6

Faradaic electrochemical impedimetric analysis on MoS2/Au-NPs decorated surface for C-reactive protein detection

December 7, 2022 By Editor

Abstract – Background: A label-free Faradaic electrochemical impedimetric was developed for a highly sensitive detection of C-reactive protein using a gold interdigitated microelectrode bio-sensing platform enhanced by a gold nanoparticle-decorated molybdenum disulfide (Au-NPs/MoS2) nanosheet via selected chemical linking processes. C-reactive protein (C-RP), a crystalline protein, generates by the liver and hikes when there is inflammation throughout the patients’ body. The concentrations of C-RP plasma levels tend to increase rapidly when the patient facing major injury which will lead to cardiovascular disease (CVD). Methods: The 5 µm microelectrode and gap size g-IDE with the nanostructured materials was demonstrated to increase the impedimetric detection response in Faradaic-mode electrochemical impedance spectroscopy high performance detection environment. The high surface area-to-volume ratio of the modified Au-NPs/MoS2 nanocomposite increased the probes loading onto the transducer and enhanced the impedimetric detection response of the C-RP target post-binding due to an amplified net change in the charge transfer resistance. The developed immunoassay revealed a linear detection of C-RP biomarker in a logarithmic-scale from as low as 1 fg/mL up to 1 µg/mL, and a limit of detection of 0.01 fg/mL. The sensor shows great potential as an early warning risk for cardiovascular disease at a threshold concentration value of C-RP at 1 µg/mL. Significant findings: The biosensor demonstrates an excellent discrimination against other competing proteins in serum, exhibiting the highest predilection to C-RP spiked human serum target. The sensor’s reproducibility is reported within an acceptable range of relative standard deviation of 1–4% for n = 3.

Corresponding Author: Assoc. Prof. Ir. Dr. Mohd Khairuddin Md Arshad
Corresponding Author’s Email: mohd.khairuddin@unimap.edu.my

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Link to Publication: https://doi.org/10.1016/j.jtice.2022.104450

An investigation on GaN/ porous-Si NO2 gas sensor fabricated by pulsed laser ablation in liquid

June 30, 2022 By Editor

Abstract – Pulsed-laser ablation in liquid was used to prepare GaN nanostructure. The P-type GaN nanostructure was deposited onto the porous-silicon substrate through the drop-casting method for NO2 gas-sensor fabrication. Ablation was performed in ethanol using two laser wavelengths, namely, 532 and 1064 nm. The XRD pattern showed a high and sharp peak at 2θ= 29.49°, indicating enhanced GaN formation using a 532 nm laser wavelength. AFM and FESEM analyses confirmed increased GaN grain growth at the same wavelength. The optical reflectance of the GaN sample showed higher reflectance at 532 nm than at 1064 nm. The optical-energy bandgap was more elevated at 532 nm than at 1064 nm. Photoluminescence analysis revealed that the 532 nm sample had a higher-intensity peak than the 1064 nm one. Device-performance studies showed the most enhanced sensor response (158.49%), highest sensitivity (2.109 ppm), and best response time (13.5 s) at 250 °C for the sample prepared using 532 nm laser wavelength.

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

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Link to Publication: https://doi.org/10.1016/j.snb.2022.132163

MiR-133a-3p overexpression-induced elevation of cisplatin-mediated chemosensitivity to non-small cell lung cancer by targeting replication factor C3

December 17, 2021 By Editor

Abstract – Investigated the role of miR-133a-3p expression in NSCLC resistance to cisplatin (DDP) treatment and elucidate the possible mechanisms. MiR-133a-3p expression levels in DDP-resistant cells (SPC-1/DPP and A549/DDP) were measured using quantitative reverse-transcription polymerase chain reaction. Cell proliferation, cell apoptosis, cell cycle distribution, and DDP sensitivity were detected through flow cytometry, Cell Counting Kit-8 (CCK-8) and western blot analysis. In addition, databases were used to predict the miR-133a-3p targets, confirmed by dual-luciferase reporter assay. The miR-133a-3p expression levels obviously decreased in the A549/DDP and SPC-1/DPP cells [**P < 0.01; (n = 3)]. Upregulation of the miR-133a-3p expression notably suppressed cell growth, enhanced cell apoptosis, and resulted in cell cycle arrest in the SPC-1/DPP and A549/DDP cells. CCK-8 assay for the detection of proliferation of the miR-133a-3p mimic-transfected A549/DDP and SPC-A1/DDP cells treated with different DDP doses revealed IC50 values of NC mimic group: 6.85 μg/mL; miR-133a-3p mimic: 3.9 μg/mL and NC mimic group: 6.9 μg/mL; miR-133a-3p mimic: 3.99 μg/mL, respectively]. By contrast, it elevated DDP sensitivity in the A549/DDP cells and DDP resistance in the SPC-1/DPP cells. Mechanically, miR-133a-3p negatively regulated replication factor C3 and promoted DDP sensitivity in the SPC-1/DPP and A549/DDP cells, 94 potential targets that might bind to miR-133a-3p were identified.

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

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Link to Publication: https://doi.org/10.1016/j.procbio.2021.10.026

Fabrication and characterizations of Al nanoparticles doped ZnO nanostructures-based integrated electrochemical biosensor

June 15, 2020 By Editor

Abstract – The benefits of the electrical-based biosensor include cheap production and fast response time of detecting diseases. An interdigitated electrode (IDE) is fabricated using silver (Ag) as a metal contact that is deposited on aliminium (Al) nanoparticles doped with both zinc oxide (ZnO) and Silicon (Si) forming AZO/Si nanostructures by vacuum coater in a thermal evaporator. The electrical properties are studied as a function of frequency and voltage using I–V characteristics. Sol–gel method under annealing temperature, 500 °C is utilized to generate Al nanoparticles doped ZnO nanostructures. UV–vis spectrophotometer, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD) are used for analyzing optical, topographical, morphological and structural studies of AZO nanostructure, respectively. Specific empirical models of optical dielectric constant, bulk modulus and refractive index are also verified.

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

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Link to Publication: https://doi.org/10.1016/j.jmrt.2019.11.025