Now showing 1 - 10 of 83
  • 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
    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
    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
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    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.
  • Publication
    High-performance data throughput analysis in wireless ad hoc networks for smart vehicle interconnection
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025)
    Alaa Kamal Yousif Dafhalla
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    Amira Elsir Tayfour Ahmed
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    Nada Mohamed Osman Sid Ahmed
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    Ameni Filali
    ;
    Lutfieh S. Alhomed
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    Fawzia Awad Elhassan Ali
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    Asma Ibrahim Gamar Eldeen
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    ;
    Vehicular Ad Hoc Networks play a crucial role in enabling Smart City applications by facilitating seamless communication between vehicles and infrastructure. This study evaluates the throughput performance of different routing protocols, specifically AODV, AODV:TOM, AODV:DEM, GPSR, GPSR:TOM, and GPSR:DEM, under various city and highway scenarios in complex networks. The analysis covers key parameters including traffic generation, packet sizes, mobility speeds, and pause times. Results indicate that TOM and DEM profiles significantly improve throughput compared to traditional AODV and GPSR protocols. GPSR:TOM achieves the highest throughput across most scenarios, making it a promising solution for high-performance data transmission in Smart Cities. For instance, GPSR:TOM achieves an average throughput of 3.2 Mbps in city scenarios compared to 2.8 Mbps for GPSR, while in highway scenarios, the throughput increases to 3.6 Mbps. Additionally, AODV:DEM records a throughput of 3.4 Mbps for high traffic generation, outperforming AODV:TOM at 3.1 Mbps and baseline AODV at 2.7 Mbps. The findings highlight the importance of optimizing data throughput to ensure reliability and efficiency in complex vehicle interconnection systems, which are critical for traffic management, accident prevention, and real-time communication in smart urban environments
  • Publication
    Selective detection of alpha synuclein amyloid fibrils by faradaic and non-faradaic electrochemical impedance spectroscopic approaches
    (Elsevier B.V., 2025-02)
    Hussaini Adam
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    ;
    Hemavathi Krishnan
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    ;
    Makram A. Fakhri
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    Evan T. Salim
    ;
    A. Shamsher
    ;
    Sreeramanan Subramaniam
    ;
    Yeng Chen
    This study utilized faradaic and non-faradaic electrochemical impedance spectroscopy to detect alpha synuclein amyloid fibrils on gold interdigitated tetraelectrodes (AuIDTE), providing valuable insights into electrochemical reactions for clinical use. AuIDE was purchased, modified with zinc oxide for increased hydrophobicity. Functionalization was conducted with hexacyanidoferrate and carbonyldiimidazole. Faradaic electrochemical impedance spectroscopy has been extensively explored in clinical diagnostics and biomedical research, providing information on the performance and stability of electrochemical biosensors. This understanding can help develop more sensitive, selective, and reliable biosensing platforms for the detection of clinically relevant analytes like biomarkers, proteins, and nucleic acids. Non-faradaic electrochemical impedance spectroscopy measures the interfacial capacitance at the electrode–electrolyte interface, eliminating the need for redox-active species and simplifying experimental setups. It has practical implications in clinical settings, like real-time detection and monitoring of biomolecules and biomarkers by tracking changes in interfacial capacitance. The limit of detection (LOD) for normal alpha synuclein in faradaic mode is 2.39-fM, The LOD for aggregated alpha synuclein detection is 1.82-fM. The LOD for non-faradaic detection of normal alpha synuclein is 2.22-fM, and the LOD for nonfaradaic detection of aggregated alpha synuclein is 2.40-fM. The proposed EIS-based AuIDTEs sensor detects alpha synuclein amyloid fibrils and it is highly sensitive.
  • Publication
    AI-optimized electrochemical aptasensors for stable, reproducible detection of neurodegenerative diseases, cancer, and coronavirus
    (Elsevier, 2025)
    Amira Elsir Tayfour Ahmed
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    Th.S. Dhahi
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    Tahani A. Attia
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    Fawzia Awad Elhassan Ali
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    ; ;
    AI-optimized electrochemical aptasensors are transforming diagnostic testing by offering high sensitivity, selectivity, and rapid response times. Leveraging data-driven AI techniques, these sensors provide a non-invasive, cost-effective alternative to traditional methods, with applications in detecting molecular biomarkers for neurodegenerative diseases, cancer, and coronavirus. The performance metrics outlined in the comparative table illustrate the significant advancements enabled by AI integration. Sensitivity increases from 60 to 75 % in ordinary aptasensors to 85–95 %, while specificity improves from 70-80 % to 90–98 %. This enhanced performance allows for ultra-low detection limits, such as 10 fM for carcinoembryonic antigen (CEA) and 20 fM for mucin-1 (MUC1) using Electrochemical Impedance Spectroscopy (EIS), and 1 pM for prostate-specific antigen (PSA) with Differential Pulse Voltammetry (DPV). Similarly, Square Wave Voltammetry (SWV) and potentiometric sensors have detected alpha-fetoprotein (AFP) at 5 fM and epithelial cell adhesion molecule (EpCAM) at 100 fM, respectively. AI integration also enhances reproducibility, reduces false positives and negatives (from 15-20 % to 5–10 %), and significantly decreases response times (from 10-15 s to 2–3 s). These advancements improve data processing speeds (from 10 to 20 min per sample to 2–5 min) and calibration accuracy (<2 % margin of error compared to 5–10 %), while expanding application scope to multi-target biomarker detection. This review highlights how these advancements position AI-optimized electrochemical aptasensors as powerful tools for personalized treatment, point-of-care testing, and continuous health monitoring. Despite a higher cost ($500-$1,500/unit), their enhanced portability and diagnostic performance promise to revolutionize healthcare, environmental monitoring, and food safety, ultimately improving public health outcomes.
  • Publication
    Revisiting the optoelectronic properties of graphene : a DFT approach
    ( 2024-01)
    L.O Agbolade
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    Alaa Kamal Yousif Dafhalla
    ;
    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.
      48  2
  • Publication
    Quantitative lead (Pb+) ion detection via modified silicon nanowire
    ( 2021-05-03) ; ;
    Nuri A KH Ehfaed
    ;
    Muhammad Nur Afnan Uda
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    The study presented a functionalized silicon with (3-aminopropyl) triethoxysilane (APTES) to serve as a sensor for heavy metal detection. The amino-functionalized Si nanowires were tested against the heavy metal, lead (Pb). Due to the silicon electrochemical response towards the heavy metal ions, linear response to four different sources of water was observed. The results indicated that Pb can be detected with a high precision. Furthermore, confirmation was demonstrated using atomic absorption spectroscopy to determine the level lead content in the collected water source. Tab water (H2O), River H2O, Treated (H2O), DI (deionized) H2O and found the levels of 0.0859 mg/L, 0.0929 mg/L, 0.0052mg/L, 0.0023 mg/L with 5.8pA, 7.2pA, 4.6pA, 3.3pA current responses, respectively. Thus, with this high capability to discriminate water samples, the sensor potential can be employed for effective heavy metal detections and further be extended to a large sensor network in water treatment plant. A new microfluidic bonding material based on SU8 to implement electrical Nano chemical sensors for ions sensing, and an investigation of direct electrical measurement allowed for label free detection.. Thus, the study developed new room temperature bonding method using SU8 as an intermediate adhesive layer. The SU8 modified bonding was compared with non modified. The bond strength of SU8 modified was found to be stronger than ordinary plasma bonding under the same curing conditions. Overnight room temperature curing yields an average burst pressure of 420 kPa, which is more than adequate for many PDMS sensor devices. In contrast, non SU8 coated plasma bonded resulted in a burst pressure of only 174 KPa.
      2
  • Publication
    Plant-based green synthesis of silver nanoparticle via chemical bonding analysis
    ( 2023-01-01)
    Azwatul H.M.
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    ; ;
    Arsat Z.A.
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    Abdullah F.
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    Muttalib M.F.A.
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    Hashim M.K.R.
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    ; ;
    Uda M.N.A.
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    Radi Wan Yaakub A.
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    Ibrahim N.H.
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    Parmin N.A.
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    Nanotechnology that involves the biological synthesis of nanoparticles is a relatively recent subject with advantages over chemical and physical synthesis procedures with respect to the economics and the environment. This study is the first to use the brown sea algae Sargassum muticum (S. muticum) as a reducing agent to generate nanostructured silver particles (AgNP). Using FTIR, XRD, and UV–vis spectroscopy, the structure, shape, and optical features of the synthesized nanoparticles have been exhaustively characterized. Using a UV–visible spectrophotometer, a clear absorption peak at 390 nm demonstrated the synthesis of AgNP. By crystallizing chemicals, nanoparticles were formed. The XRD pattern validated the results.
      1  21
  • Publication
    Insight on the structural aspect of ENR-50/TiO2 hybrid in KOH/C3H8O medium revealed by NMR spectroscopy
    ( 2020-01-01)
    Dahham O.S.
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    Hamzah R.
    ;
    Abu Bakar M.
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    Zulkepli N.N.
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    Alakrach A.M.
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    ;
    Omar M.F.
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    ;
    Al-rashdi A.A.
    The ring-opening reactions (ROR) of epoxide groups in epoxidized natural rubber/titania (ENR-50/TiO2) hybrid in potassium hydroxide/isopropanol medium were examined using NMR spectroscopy and supported by the FTIR technique. The thermal behaviour of the hybrid was also studied using TG/DTG and DSC analyses. The 1H NMR results suggested that 16.82% of ROR occurred in the hybrid, while the 13C NMR results exhibited five new peaks at δ 19.5, 71.0, 73.7, 91.7 and 94.4 ppm in the hybrid. 2D NMR, such as HMQC, HMBC and COSY techniques, further scrutinized these assignments. The FTIR spectrum exhibited Ti-O-C characteristics via the peak at 1028 cm−1. The TG/DTG results showed four steps of thermal degradation at 44–148, 219–309, 331–489 and 629–810 °C due to the existence of Ti moieties along with a polymer chain mixture (intact and ring-opened epoxide groups) of ENR-50, which in turn led to an increase in the Tg value of the hybrid to 27 °C compared to that of purified ENR-50 at −17.72 °C.
      2