Now showing 1 - 5 of 5
  • 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
    Advancing COVID-19 detection high-performance RNA biosensing via electrical interactions
    ( 2024-06) ;
    Muhammad Nur Afnan Uda
    ;
    ; ;
    Nur Hulwani Ibrahim
    ;
    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
    Aluminium interdigitated electrode with 5.0 μm gap for electrolytic scooting
    ( 2024-06) ; ; ; ;
    Ismail Saad
    ;
    ; ; ;
    G. Yashni
    ;
    Nur Hulwani Ibrahim
    ;
    N. Parimon
    ;
    M. F. H. Rani
    The goal of the research project is to design, fabricate, and characterize an extremely sensitive biosensor for use in healthcare. Using AutoCAD software, a novel IDE pattern with a 5 μm finger gap was created. Conventional photolithography and regular CMOS technology were used in the fabrication process. A 3D nano profiler, scanning electron microscopy (SEM), high-power microscopy (HPM), and low-power microscopy (LPM) were used to physically characterize the manufactured IDE. Chemical testing was done using several pH buffer solutions, and electrical validation was performed using I-V measurements. The Al IDE was produced, with a tolerance of 0.1 μm between the fabricated IDEs and the design mask. Electrical measurements verified the flawless fabrication of the IDE, and the device's repeatability was validated by the outcomes of comparable IDE samples. For each pH buffer solution, a modest additional volume of 2 μl was used to quantitatively detect slight current fluctuations in the microampere range. Through pH calibration for advanced applications in the realm of chemical sensors using an amperometric method, this research study has verified the chemical behavior of the IDE.
  • Publication
    Conductometric immunosensor for specific Escherichia coli O157:H7 detection on chemically funcationalizaed interdigitated aptasensor
    ( 2024)
    Muhammad Nur Afnan Uda
    ;
    Alaa Kamal Yousif Dafhalla
    ;
    Thikra S. Dhahi
    ;
    ; ;
    Asral Bahari ambek
    ;
    ; ;
    Nur Hulwani Ibrahim
    ;
    Escherichia coli O157:H7 is a strain of Escherichia coli known for causing foodborne illness through the consumption of contaminated or raw food. To detect this pathogen, a conductometric immunosensor was developed using a conductometric sensing approach. The sensor was con-structed on an interdigitated electrode and modified with a monoclonal anti-Escherichia coli O157: H7 aptamer. A total of 200 electrode pairs were fabricated and modified to bind to the target molecule replica. The binding replica, acting as the bio-recognizer, was linked to the electrode surface using 3-Aminopropyl triethoxysilane. The sensor exhibited excellent performance, detecting Escherichia coli O157:H7 in a short time frame and demonstrating a wide detection range of 1 fM to 1 nM. Concentrations of Escherichia coli O157:H7 were detected within this range, with a minimum detection limit of 1 fM. This innovative sensor offers simplicity, speed, high sensitivity, selectivity, and the potential for rapid sample processing. The potential of this pro-posed biosensor is particularly beneficial in applications such as drug screening, environmental monitoring, and disease diagnosis, where real-time information on biomolecular interactions is crucial for timely decision-making and where cross-reactivity or interference may compromise the accuracy of the analysis.
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  • Publication
    Silica and graphene mediate arsenic detection in mature rice grain by a newly patterned current–volt aptasensor
    ( 2021-12-01) ; ; ;
    Halim N.H.
    ;
    ;
    Muhammad Nur Afnan Uda
    ;
    Anbu P.
    ;
    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.
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