Now showing 1 - 10 of 13
  • 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
    Surface characterization study of nanoporous anodic aluminium oxide thin film synthesized by single-step anodization
    Nanoporous anodic aluminium oxide (AAO) thin film electrodes were prepared by using a single step anodization method in 0.3 M oxalic acid at 40 V for 1 h. Electrolyte temperature was controlled and maintained at 15 °C by using ice water bath. After anodized, AAO surfaces were etched by using 5% phosphoric acid (H3PO4) solution at 30 °C to remove the AAO top rough surfaces and widening the pores. Effect of different etching duration to the pore widening was investigated at 10, 20 and 30 minutes, respectively. Regularity of the pores arrangements before and after etching were analysed by fast fourier transform (FFT) profile images that were generated from FESEM images. From observation, well ordered nanoporous structures were successfully revealed after top rough surfaces were removed by etching. Pores sizes were also found to be increased with the increasing of etching duration. Further investigations were done by x-ray diffraction (XRD) analysis and fourier transform infra-red spectroscopy (FTIR) to characterize and find out the crystallinity properties and functionalities of AAO thin film electrode surfaces.
  • 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
    Study on the effects of anodizing voltage to the AAO thin film dimensional properties synthesized by single step anodization method
    Anodic aluminium oxide (AAO) thin film electrodes were synthesized by using a single step anodizing method in 15 °C of 0.3 M oxalic acid at five different anodizing voltage ranging from 20 V to 60 V, respectively. The effect of anodizing voltage to the AAO dimensional properties were about to be investigated. Morphological observations were all done by FESEM where the measurements and calculation were made by using ImageJ and formulas. To ensure that the pore sizes were totally depended on the anodizing voltage, etching process were done at constant duration for all samples. The correlation between all AAO dimensional properties like pores size, interpore distance, wall thickness, pore density, percentage of porosity and nanoporous oxide thickness were presented in a linear graph.
  • Publication
    Gold-nanoparticle associated deep eutectic solution mediates early bio detection of ovarian cancer
    Gold nanoparticles (AuNPs) have indeed been extensively researched in biological and photothermal therapy applications in recent years. This study aims to enhance the sensitivity of biosensors for early detection of ovarian cancer biomarkers by investigating the efficacy of DES-mediated surface functionalization of AuNPs. Additionally, the impact of DES on the stability and dispersion of AuNPs on SiO2 support is assessed to optimize sensor performance. A simple DES-mediated synthesis method for efficient amine surface functionalization of silicon dioxide (SiO2) to incorporate tiny AuNPs for antibody biosensors. Physical characterization [Scanning Electron Microscope (SEM), Ultraviolet-Visible Spectrophotometer (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), and 3D Profiler] and electrical characterization (Keithley) have been done to determine the functionalization of the modified IDE surface. SEM analysis indicated the resultant nanoparticles have truncated spherical shapes. There is just a peak recorded by UV-Vis at 504-540 nm with AuNPs due to the formation of monodispersed AuNPs. When the conjugation of DES with samples is measured, the curves are identical in form, and the highest peak after conjugation has remained at 230 nm but the SPR absorption peak becomes narrower and moves toward greater wavelengths, indicating the conjugation between the molecules. Furthermore, when the DES is conjugated with AuNPs, 3-Aminopropyltriethoxysilane (APTES), antibody, and protein, the peaks gradually increased and became narrower, where O-H at 3280 cm-1, C-H at 2809 cm-1 and 2933 cm-1, CH2 at 1448 cm-1, CH3 at 1268 cm-1, C-OH at 1048 cm-1 and 1110 cm-1 and C-N+ at 844 cm-1 as analyzed by FTIR. Moreover, it can be observed that the 3D profilometer revealed a few red-colored areas, which are the portion that protrudes from the IDE surface. Based on the findings, it is possible to infer that this immunosensor does have the prospective to be used in clinical investigations for the precise detection of ovarian cancer or other biomarkers. The capacitance, transmittance, and resistivity profiles of the biosensor clearly distinguished between the antibody immobilization and the affinity binding. The presence of a DES-mediated synthetic approach increased the possibility of supporting different metal nanoparticles on SiO2 as the potential platform for biosensor applications.
  • Publication
    Synthesis and optimization of Anodic Aluminium Oxide thin film electrode for DNA sensing
    Recent years, anodic aluminum oxide (AAO) has been extensively explored as an inexpensive, portable and sensitive DNA biosensing device. Apart from their ability to self-grow into well-ordered nanoporous with high porosity and huge surface area, AAO has one special feature wherein their nanopores‘ dimension are capable to be altered and engineered by controlling the main anodizing parameters namely voltage, temperature, time and electrolyte concentration. Since sensitivity and limit of detection of AAO-DNA biosensor depends on the nanopores‘ dimension itself, therefore, many researchers have tried to understand the effect of each anodizing parameters to the nanopores‘ dimension while tried to optimize and improve the sensitivity of AAO in detecting DNA. However, those studies were only focused on the trend of single variable parameter at one time by one-factor-at-a-time method (OFAT), rather than investigating all the interactions between the anodizing parameters simultaneously. Hence, they only reported the improvement made to the sensitivity of their AAO-DNA biosensor at the particular parameter range that they have tested without providing the best of optimum combination levels of all anodizing parameters while the most critical and influential anodizing parameter is still remained unknown. As a contribution to solve these problems, Taguchi method has been proposed in this research as an optimization tool to study the existing interaction between the parameters while at the same time providing the best combination of all parameters levels to improve the AAO-DNA biosensor sensitivity at its optimum performance. Meantime, ANOVA analysis has been proposed to obtain the most influential anodizing parameter to the sensitivity of AAO-DNA biosensor. Prior to optimization, correlation study between the pores‘ dimension and resistance charge transfer (Rct) that affects the sensitivity of AAO-DNA biosensor has been conducted. For this research, AAO thin film-DNA biosensor electrode was synthesized using a single step anodization method in oxalic acid. FESEM was used to observe the AAO surface, while EIS was utilised to study the electrochemical system for DNA hybridization detection. From the first finding, sensitivity of AAO-DNA biosensor was found to be influenced by the ratio of AAO thickness to the pore size. Rct remained under 100 kΩ as long as the ratio of AAO thickness to the pore size was maintained in the range between 1:11 to 1:16. Exceeding the ratio of more than 1:25 will result to the sudden increased in Rct and hence affecting the sensitivity to be reduced. From the second finding, optimization through Taguchi method is the main novelty of this research. The optimum combinations of anodizing parameters were found at 40 V, 17 °C, 0.3 M of oxalic acid at 1 hour. A repetition in experiment was conducted to confirm the efficiency of Taguchi where the sensitivity of the optimized AAO-DNA biosensor electrode was successfully improved to 62.57 % at 0.278 kΩ/M (LOD at 6.497 x 10-15 M) compared to the nominal. From the third finding through ANOVA analysis, the sequences of the most influential anodizing parameter to the AAO-DNA biosensor sensitivity are following the order: anodizing voltage (34.13%) > anodizing time (29.85%) > temperature (20.27%) > electrolyte concentration (15.74%). At the end of this research, optimization of the synthesis of AAO thin film electrode by Taguchi method for DNA sensing was successfully achieved. Since this research had used nonspecific type of DNA target analytes for prototyping development purposed, therefore, it is targeted that this optimized and sensitivity improved AAO thin film electrode will have greater chance to be used widely in the future for detecting various types of DNA, such as dengue, E-coli, or salmonella. Besides, it is of great hope that the outcome from this research may help other researchers to synthesize AAO thin film at its optimum anodizing condition as to improve the sensitivity of the AAO-DNA biosensor
  • 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.
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  • Publication
    The optimization of multi-walled carbon nanotubes surface modification via nitric acid oxidation for DNA immobilization
    This thesis discussed on the optimization of MWCNTs surface modification via nitric acid oxidation for DNA immobilization. After acid oxidation treatment, the impurities in multi-walled carbon nanotube (MWCNTs) such as carbonaceous and metal catalyst particles are successfully reduced as has been analyzed by energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD) and thermogravimetric analyzer (TGA). Acid oxidation will caused to the opening of MWCNTs tips and structural defects formed on the MWCNTs surface due to the acid attack. Oxygen containing functional groups, mainly, carboxylic group (COOH) has been introduced on the MWCNTs opened tips and at the defect sites which are useful to interact with other molecules, in this case, aminated-ssDNA probe. The results from fourier transform infrared spectroscopy (FTIR) and Raman Spectroscopy have shown that the COOH amount is depended on the MWCNTs structure defects. Meanwhile, cyclic voltammetry (CV) results have indicated that the immobilization current is directly proportional to the COOH amount. However, structure defect will affect to the immobilization current when ID/IG ratio is increased. The acid oxidation parameter should be optimized, thus the amount of COOH can be increased with the minimal structure defect. Therefore, the main goal to have a maximum immobilization current can be achieved. L9 Taguchi orthogonal array has been used to optimize the acid oxidation parameters. From the result, 5 M of nitric acid concentration, 120 °C of treatment temperature and 6 hours of treatment time are selected as the most optimum combination of acid oxidation parameters. The percentage influence of each main factor is also calculated to be 46% xvi 35% and 18% for nitric acid concentration, treatment time and treatment temperature, respectively. The improvement is happened to be 11.6% of increment in the immobilization current.
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  • Publication
    Cost-Effective Fabrication of Polydimethylsiloxane (PDMS) Microfluidics for Point-of-Care Application
    Microfluidics fabrication pertains to the construction of small-scale devices and systems that manipulate and control small volumes of fluids. This process involves precise engineering and manufacturing procedures aimed at designing and producing these devices, which find applications in healthcare, environmental monitoring, and chemical analysis. The present study showcases an inexpensive approach to fabricate microfluidics channels using PDMS biopolymer and soft lithography technique to achieve laminar fluid flow. Initially, a robust and adhesive mold was created by fabricating a master template using several layers of SU-8 5 and SU-8 2015 negative photoresists. Subsequently, PDMS microfluidics channels were replicated and sealed onto a glass substrate through plasma bonding treatment. High-power microscopy images and profilometer analyses demonstrated successful fabrication with minimal deviation from the initial designs and the fabricated devices (less than 0.07 mm, less than 0.6°). Both the SU-8 master template and PDMS replicate displayed average microchannel height values and surface roughness of 100 μm and 0.26 µm or lower, respectively. Additionally, the fluid test confirmed laminar flow without any leakage post plasma oxidation, indicating the completion of an efficient and cost-effective fabrication process.
  • 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.