Now showing 1 - 10 of 78
  • Publication
    Synthesis of zinc oxide nanoparticles via cellar spider extract for enhanced functional properties in antimicrobial activities
    This study explores the green synthesis of zinc oxide nanoparticles (ZnO NPs) using cellar spider extracts as a sustainable alternative to traditional methods involving hazardous chemicals and radiation. The spider extracts effectively reduced zinc acetate dihydrate, yielding white precipitates indicative of ZnO NPs. Characterization through SEM revealed diverse morphologies, including spherical, rod-like, hexagonal, and uneven particles forming platelet-like aggregates. Further analyses, such as HPM, 3D nanoprofiler, and EDS, provided insights into size, shape, morphology, surface chemistry, thermal stability, and optical characteristics, quantifying the intended properties of the synthesized ZnO NPs. Antibacterial assays against E. coli and B. subtilis demonstrated significant antibacterial activity, affirming the nanoparticles' potential for antimicrobial applications. This green synthesis approach, validated through comprehensive characterization and quantitative measurements, offers a promising and environmentally friendly route for producing functional ZnO NPs.
  • Publication
    Molecular-imprinting assisted polydopamine-aptasensor on carbon and gold nanomaterials construct for the haemophilia B biomarker detection
    ( 2024-06)
    Hemavathi Krishnan
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    ; ;
    Makram A. Fakhri
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    Evan T. Salim
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    Narendra Patil
    The study presents a comprehensive approach for enhancing the performance of a spiral micro-interdigitated electrode (spiral-μIDE) sensor for the detection of FIX protein. Electropolymerization using dopamine resulted in a molecular-imprinted polymer (polyDOP-μIDE-MIP) layer, which encapsulated the aptamer-FIX complex and was later leached to create cavities. Cyclic and linear-sweep voltammetry techniques were utilized for the MIP development and rebinding assessment. Linear sweep voltammetry demonstrated a linear relationship between FIX concentration and peak current reduction, with a limit of detection (LOD) of 0.250 picomolar. The sensor's sensitivity was determined as 2.613E-10 A.fM-1.μm-2. This work highlights the importance of nanomaterials integration, and electropolymerization in improving sensor performance. The integration of carbon and gold nanomaterials and the use of molecular imprinting contribute to the sensor's enhanced sensitivity and selective detection of FIX protein.
  • Publication
    Comparative analysis on aluminium interdigitated electrode surface influence of ionic strength and electrolytes changes
    ( 2024-06)
    Hussaini Adam
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    ; ;
    Makram A. Fakhri
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    Evan T. Salim
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    The field of generating surface thin films in sensing applications is emerging, and the incorporation of thin film technology into sensor development for enhanced sensing is becoming increasingly significant in various industries such as healthcare, environmental monitoring, and food safety. However, in order to achieve higher specificity in biosensing, advances in nanomaterial biofunctionalization are crucial. This research focuses on the fabrication and characterization of nanobiosensors with surface modification using two different sensing materials: zinc oxide and gold nanorod nanocomposites. The aim of this study was to enhance the sensing capabilities of nanobiosensors by incorporating surface modification with different sensing materials. The fabrication of nanobiosensors involved using silicon as the base material and conventional photolithography to fabricate aluminium interdigitated electrodes with three different structures and gap sizes. AutoCAD software was utilized to create three different photo masks with varying gap sizes. Physical characterization of the fabricated ALIDEs was conducted using atomic force microscope, high power microscope, scanning electron microscope, and 3D-profilormeter. The electrical characterization of the ALIDEs was performed using a Keithley 6487 picoammeter. I-V measurements were conducted on bare ALIDEs as well as surface modified ALIDEs with zinc oxide and gold nanorod. I-V measurements were also performed for pH scouting. The I-V measurements on bare ALIDEs revealed that ALIDEs modified with gold nanorod conducted the least current compared to ALIDEs modified with zinc oxide. Furthermore, the ALIDEs modified with gold nanorod were found to be stable under various electrolytes environments after undergoing pH scouting.
  • Publication
    Advancing COVID-19 detection high-performance RNA biosensing via electrical interactions
    ( 2024-06) ;
    Muhammad Nur Afnan Uda
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    ; ;
    Nur Hulwani Ibrahim
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    Chai Chang Yii
    ;
    Lorita Angeline
    This research paper investigated the detection of COVID-19 using an Aluminum Interdigitated Electrode (Al-IDE) sensor based on electrical conductivity. The silanization process involved the functionalization step, employing (3-Aminopropyl) triethoxysilane (APTES), while the immobilization process was facilitated by the RNA Probe specific to COVID-19. To verify its specificity in detection, the functionalized biosensor was tested against single-base mismatches, non-complementary sequences, and complementary sequences. The physical characteristics of the Al-IDE biosensor were examined using both low-power microscopy (LPM) and high-power microscopy (HPM). Additionally, the morphological properties of the biosensor were assessed using atomic force microscopy (AFM). To assess its diagnostic potential, the biosensor's sensitivity was evaluated by exposing it to a range of complementary targets, spanning from 1 femtomolar (fM) to 1 micromolar (μM). The current-voltage (I-V) characteristics of the biosensor were meticulously analyzed at each stage of functionalization bare Al-IDE, silanization, immobilization, and hybridization. This I-V characterization was carried out using a picoammeter voltage source (Keithley 2450), Kickstart software, and a probe station. The results confirmed the biosensor's capability to effectively detect COVID-19 targets within the nanoampere concentration range, demonstrating its success in detecting specific COVID-19 targets at the nanoampere level.
  • Publication
    Arthropods-mediated green synthesis of Zinc oxide nanoparticles using cellar spider extract a biocompatible remediation for environmental approach
    ( 2024-06) ; ;
    M. A. R. Irfan
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    ; ; ;
    MRM Huzaifah
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    Maimunah Mohd Ali
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    Nur Hulwani Ibrahim
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    Muaz Mohd Zaini Makhtar
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    ; ; ; ; ;
    Mahfuz Affif Mohd Ruslan
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    This study presents an eco-friendly approach to synthesizing zinc oxide nanoparticles (ZnO NPs) using extracts from cellar spiders, addressing environmental and health concerns associated with conventional methods. The spider extract efficiently reduced zinc acetate dihydrate, and the synthesized ZnO NPs underwent comprehensive quantitative characterization, including size, shape, morphology, surface chemistry, thermal stability, and optical properties using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zeta potential measurements, thermogravimetric analysis (TGA), and UV-vis spectroscopy. The nanoparticles exhibited intended characteristics, and their adsorption capability for methylene blue (MB) was quantitatively assessed using the Freundlich isotherm model and pseudo-second-order kinetic model, providing numerical insights into MB removal efficiency. The study demonstrates the potential of these green-synthesized ZnO NPs for applications in environmental remediation, wastewater treatment, and antibacterial therapies, contributing to both sustainable nanomaterial development and quantitative understanding of their functional properties.
  • Publication
    Silica and graphene mediate arsenic detection in mature rice grain by a newly patterned current–volt aptasensor
    ( 2021)
    M. N. A. Uda
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    ; ;
    N. H. Halim
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    N. A. Parmin
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    M. N. Afnan Uda
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    ;
    Periasamy Anbu
    Arsenic is a major global threat to the ecosystem. Here we describe a highly accurate sensing platform using silica nanoparticles/graphene at the surface of aluminum interdigitated electrodes (Al IDE), able to detect trace amounts of arsenic(III) in rice grain samples. The morphology and electrical properties of fabricated Al IDEs were characterized and standardized using AFM, and SEM with EDX analyses. Micrometer scale Al IDEs were fabricated with silicon, aluminum, and oxygen as primary elements. Validation of the bare Al IDE with electrolyte fouling was performed at different pH levels. The sensing surface was stable with no electrolyte fouling at pH 7. Each chemical modification step was monitored with current–volt measurement. The surface chemical bonds were characterized by fourier transform infrared spectroscopy (FTIR) and revealed different peaks when interacting with arsenic (1600–1000 cm−1). Both silica nanoparticles and graphene presented a sensitive limit of detection as measured by slope calibration curves at 0.0000001 pg/ml, respectively. Further, linear regression was established using ΔI (A) = 3.86 E−09 log (Arsenic concentration) [g/ml] + 8.67 E−08 [A] for silica nanoparticles, whereas for graphene Y = 3.73 E−09 (Arsenic concentration) [g/ml] + 8.52 E−08 on the linear range of 0.0000001 pg/ml to 0.01 pg/ml. The R2 for silica (0.96) and that of graphene (0.94) was close to the maximum (1). Modification with silica nanoparticles was highly stable. The potential use of silica nanoparticles in the detection of arsenic in rice grain extract can be attributed to their size and stability.
  • Publication
    Analysis on silica and graphene nanomaterials obtained from rice straw for antimicrobial potential
    This study focuses on the encapsulation of silica and graphene nanoparticles and their potential applications. The encapsulation enhances the properties and effectiveness of these nanoparticles, with silica providing stability and graphene contributing to high surface area and electrical conductivity. Characterization of silica-graphene nanoparticles was conducted using various techniques including High Power Microscope (HPM), Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), and 3D Nano Profiler. The antimicrobial activity of silica, graphene, and silica-graphene nanoparticles was evaluated using a disc diffusion assay against E. coli and B. subtilis at varying concentrations. Results showed significant antimicrobial activity, with the inhibition zone being directly proportional to the concentration. Silica-graphene nanoparticles demonstrated higher efficacy against E. coli compared to B. subtilis, attributed to differences in cell wall structure. Statistical analysis using ANOVA confirmed significant differences in antimicrobial activity among the tested components.
  • Publication
    Revisiting the optoelectronic properties of graphene : a DFT approach
    ( 2024-01)
    L.O Agbolade
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    Alaa Kamal Yousif Dafhalla
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    A.Wesam Al-Mufti
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    ; ; ; ; ;
    Understanding the atomic behaviour of pure graphene is crucial in manipulating its properties for achieving optoelectronics with high absorption indexes and efficiencies. However, previous research employing the DFT approach emphasised its zero-band gap nature, not its unique optical properties. Therefore, this study employed ab initio calculations to revisit the electronic, magnetic, and optical properties of pristine graphene using the WIEN2K code. The results reveal that the PBE-GGA valence and conduction bands cross at -0.7 eV. Our calculations demonstrated that the absorption coefficient of graphene has the strongest light penetration in the parallel direction. Furthermore, our results not only present the best possible propagation of light in pure graphene but also reveal that the linear relationship between the formation of the free electron carriers and the energy absorption is responsible for the high optical conductivity observed in pure graphene, as indicated by the peaks. Lastly, the metallic properties of graphene are reflected by the variation in spin up and down that appears, as evidenced by the total and partial densities of states, and the large refractive index attributed to its high electron mobility confirms its metallic nature.
  • Publication
    Modular architecture of a non-contact pinch actuation micropump
    ( 2012)
    Pei Song Chee
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    Rashidah Arsat
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    ; ;
    Ruzairi Abdul Rahim
    ;
    Pei Ling Leow
    This paper demonstrates a modular architecture of a non-contact actuation micropump setup. Rapid hot embossing prototyping was employed in micropump fabrication by using printed circuit board (PCB) as a mold material in polymer casting. Actuator-membrane gap separation was studied, with experimental investigation of three separation distances: 2.0 mm, 2.5 mm and 3.5 mm. To enhance the micropump performance, interaction surface area between plunger and membrane was modeled via finite element analysis (FEA). The micropump was evaluated against two frequency ranges, which comprised a low driving frequency range (0–5 Hz, with 0.5 Hz step increments) and a nominal frequency range (0–80 Hz, with 10 Hz per step increments). The low range frequency features a linear relationship of flow rate with the operating frequency function, while two magnitude peaks were captured in the flow rate and back pressure characteristic in the nominal frequency range. Repeatability and reliability tests conducted suggest the pump performed at a maximum flow rate of 5.78 mL/min at 65 Hz and a backpressure of 1.35 kPa at 60 Hz.