Now showing 1 - 10 of 18
  • Publication
    Facile electrical DNA genosensor for human papillomavirus (HPV 58) for early detection of cervical cancer
    ( 2023-07)
    F. Nadhirah Jaapar
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    ; ; ; ; ;
    Sh. Nadzirah
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    ; ;
    Wei Chern Ang
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    Iffah Izzati Zakaria
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    Zulida Rejali
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    Amilia Afzan
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    Azrul Azlan Hamzah
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    Chang Fu Dee
    ;
    F. Syakirah Halim
    For decades, a Pap smear test has been applied as a conventional method in detecting Human Papillomavirus caused cervical cancer. False-positive results were also recorded while using it as conventional method. Current biosensor such as Hybrid (II) Capture resulted in higher time consumption and cost. s Meanwhile, in this study we provided facile, mini, rapid, highly sensitive, eco-friendly, and cost-effective sensing system focusing on HPV strain 58 (HPV58) in a nano-size lab-on-chip technology genosensor. 30-mer of virus ssDNA designed and analyzed as a probe via bioinformatics tools such as GenBank, Basic Local Alignment Searching Tools (BLAST) and ClustalW. Nanotechnology-developed colloidal Gold-nanoparticles (AuNPs) are used in the biosensor fabrication to produce high stability and electron efficient transmission during electrical measurement. AuNPs-APTES modified on active sites of IDEs, followed by immobilization of specific probe ssDNA for HPV 58. Hydrogen binding during hybridization with its target produce electrical signals measured by KEITHLEY 2450 (Source Meter). The genosensor validated with different types of targets such as complimentary, non-complementary and single mismatch oligonucleotides. The serial dilution of target concentration has been experimented triplicate (n=3) range from 1fM to 10μM. The slope of calibration curve resulted 2.389E-0 AM-1 with regression coefficient (R2) = 0.97535.
  • Publication
    Fabrication of Graphene Electrode via Graphene Transfer Method for Bisphenol A (BPA) Detection
    Exposure of BPA is a concern as BPA can seep into food or beverages from containers and can possibly effects on human health especially endocrine systems. An electrochemical-based aptasensor utilizing graphene was developed in detecting endocrine disrupting compound Bisphenol A (BPA, 4,4'-(propane-2,2-diyl) diphenol). The graphene modified electrode was developed via graphene transfer. Fabrication and characterization of graphene transfer was studied in this paper using Scanning Electron Microscopy (SEM) and High-Power Microscope (HPM). In this research, the investigation of interfacial characteristic modified graphene with aptasensor and recognition of BPA with aptasensor had been done using electrochemical impedance spectroscopy (EIS). The increment of charge transfer resistance (Rct) before and after recognition of BPA denoting the accumulation of charge at the electrode surface in this research.
  • Publication
    Synthesis of TiO*2 structure at low hydrothermal temperature for biosensor application
    (Universiti Malaysia Perlis (UniMAP), 2018-12)
    Mayasarah Fauzan
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    Nurul Bariah Idris
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    Y. S. Lee
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    Sharipah Nadzirah Syed Ahmad Ayob
    Synthesis of TiO₂ wires was prepared by using two steps method. TiO₂ seed layer was prepared using sol-gel method while TiO₂ wires were grown by using hydrothermal method. The annealing time and temperature during hydrothermal method were varied from 1, 4, and 5 hours and 110 and 120 °C respectively to analyze the effect towards the growth of TiO₂ wires. The morphology of TiO₂ wires formed was characterized using scanning electron microscope (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The electrical characterization of the TiO₂ wire based biosensor was conducted using electrochemical analysis. The cyclic voltammetry response was observed to analyze the performance of the glucose biosensor. The TiO₂ wires have shown a good response towards glucose detection.
  • Publication
    Immuno-probed graphene nanoplatelets on electrolyte-gated field-effect transistor for stable cortisol quantification in serum
    ( 2020-12-01)
    Nur Nasyifa M.M.
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    ; ;
    Zainol Abidin A.S.
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    Mohd Faudzi F.N.
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    Ahmad N.A.
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    Lockman Z.
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    Rezek B.
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    Kromka A.
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    Physiological and emotional stress affects the regulation of cortisol secretion, a routine process in circadian rhythm. Regular monitoring of cortisol level as a biomarker in the blood stream becomes vital to determine cortisol-related diseases. This study reports immuno-probed graphene nanoplatelets on electrolyte-gated field-effect transistor (EGFET) biosensor for cortisol determination in human serum. Solution-processed graphene nanoplatelets were evidenced on the surface by Raman spectroscopy analysis and utilized as the transducing element on the field-effect transistor. Further, confirmed the binding events of the antibody on graphene nanoplatelets using X-Ray Photoelectron Spectroscopy and characterized the electrostatic gating effect of cortisol and intermediate functionalization on graphene nanoplatelets-EGFET. The biosensor exhibited good sensitivity of 72.30 µA.(g/mL)−1 in a linear range between 1.00 pg/mL to 10.00 ng/mL, with a limit of detection (LOD) of 0.85 pg/mL. Confirmation with binding events on the biosensor was done using the relevant molecules, progesterone, cortisone, and corticosterone, and found to be selective towards cortisol. Cortisol was also successfully detected with interference by the human serum, suggesting the capability of graphene nanoplatelets-EGFET sensor for determining cortisol in a complex matrix.
      5  24
  • Publication
    Fabrication and simulation of silicon nanogaps pH sensor as preliminary study for Retinol Binding Protein 4 (RBP4) detection
    (Universiti Malaysia Perlis (UniMAP), 2025-01)
    M. I. Hashim
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    ; ;
    M. Shaifullah A.S
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    C. Y. Chean
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    M. Syamsul
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    Rozaimah A.T.
    In this research, a silicon nanogap biosensor has the potential to play a significant role in the field of biosensors for detecting Retinol Binding Protein 4 (RBP4) molecules due to its unique nanostructure morphology, biocompatibility features, and electrical capabilities. Additionally, as preliminary research for RBP4, a silicon nanogap biosensor with unique molecular gate control for pH measurement was developed. Firstly, using conventional lithography followed by the Reactive-ion etching (RIE) technique, a nanofabrication approach was utilized to produce silicon nanogaps from silicon-on-insulator (SOI) wafers. The critical aspects contributing to the process and size reduction procedures were highlighted to achieve nanometer-scale size. The resulting silicon nanogaps, ranging from 100 nm to 200 nm, were fabricated precisely on the device. Secondly, pH level detection was performed using several types of standard aqueous pH buffer solutions (pH 6, pH 7, pH 12) to test the electrical response of the device. The sensitivity of the silicon nanogap pH sensor was 7.66 pS/pH (R² = 0.97), indicating that the device has a wide range of pH detecting capacity. This also includes the silicon nanogap biosensor validated by simulation, with the sensitivity obtained being 3.24 μA/e.cm² (R² = 0.98). The simulation of the sensitivity is based on the interface charge (Qf) that represents the concentration of RBP4. The results reveal that the silicon nanogap biosensor has excellent characteristics for detecting pH levels and RBP4 with outstanding sensitivity performance. In conclusion, this silicon nanogap biosensor can be used as a new electrical RBP4 biosensor for biomedical diagnostic applications in the future.
      3  21
  • Publication
    Electrical simulation on silicon nanowire field-effect transistor biosensor at different substrate-gate voltage bias conditions for charge detection
    In this work, the impact of different substrate-gate voltage bias conditions (below and above the device threshold voltage) on current-voltage characteristics and sensitivity of a silicon nanowire field-effect transistor (SiNW-FET) biosensor was investigated. A 3-dimensional device structure with n-type SiNW channel and a substrate gate electrode was designed and electrically simulated In the Silvaco ATLAS. Next, the SiNW channel was covered with a range of interface charge density to mimic the charged target biomolecule captured by the device. The outcome was translated into a drain current versus interface charge semi-log graph and the device sensitivity was calculated using the linear regression curve’s slope of the plotted data. The device’s electrical characteristic shown higher generation of output drain current values with the increase of negative substrate-gate voltage bias due to the hole carriers’ accumulation that forms a conduction channel in the SiNW. Application of higher negative interface charge density increased the change in drain current, with the device biased with higher substrate-gate voltage shows more significant change in drain current. The device sensitivity increased when biased with higher substrate-gate voltage with highest sensitivity is 75.12 nA/dec at substrate-gate voltage bias of –1.00 V.
      3  62
  • Publication
    Optimization of gold nanoparticles electrodeposition duration on screen printed electrode to enhance electrochemiluminescence of nitrogen-doped carbon dots
    ( 2023-12)
    Nurul Izzati Akmal Mohd Azman
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    ; ; ; ;
    Toibah Abd Rahim
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    Siti Aisyah Shamsudin
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    Eiichi Tamiya
    In this work, the electrodeposition method was utilized to form gold nanoparticles on a carbon screen-printed electrode (SPE) using chronoamperometry at -0.4 V with various durations from 50 to 200 seconds. Scanning Electron Microscopy (SEM) images have proven that the electrodeposition method is capable of uniformly forming AuNPs on SPE (AuNPs- SPE). Apart from that, electrodeposition durations have increased the size of AuNPs by up to 66% based on average size measurements using ImageJ software. It can be observed that long electrodeposition durations permit the agglomeration of AuNPs on the electrode surface. The effect of electrodeposition duration on electrocatalytic performance in potassium ferricyanide and electrochemiluminescence (ECL) intensity of nitrogen-doped carbon dots (NCDs) was evaluated. Cyclic voltammetry (CV) of ferricyanide demonstrates that as the electrodeposition duration increases, AuNPs-SPE shows better electrochemical performance than bare SPE. ECL of NCDs displays that 100 s electrodeposition durations give the highest ECL intensity of 184% compared to bare SPE and have been chosen as the optimum parameter. The ECL mechanisms of bare SPE and AuNPs-SPE reveal that AuNPs- SPE has greater electrochemical and ECL performance than bare SPE, as evidenced by the CV of AuNPs-SPE having a faster reduction current, which rises to 87.2% ECL intensity and 510 mV faster ECL occurrence. These phenomena confirmed that the electrodeposition of AuNPs has improved the conductivity of SPE.
      6  3
  • Publication
    Fabrication and simulation of silicon nanowire pH sensor for Diabetes Mellitus detection
    Diabetes Mellitus (DM) is a disease failed to control the balance of blood sugar level due to lack of insulin thereby it effect human health. In Malaysia, there are around 3.9 millions people aged 18 years old and above have diabetes according to National Health and Morbidity Survey 2019. Silicon Nanowire is a nanostructure which has ultra-high sensitivity and non-radioactive that has potential given good performances when applied on pH sensor and biosensor. Silicon nanowire pH sensor and biosensor is an electronic sensor that investigated to improve the sensitivity and accuracy for detecting DM. This project consists of two parts, which are fabrication of silicon nanowire pH sensor and simulation of silicon nanowire biosensor as preliminary study. In fabrication, silicon nanowire of pH sensor is fabricated by conventional lithography process, reaction ion etching (RIE) and metallization to achieved the width of 100 nm silicon nanowire. The pH6, pH7, pH10 and DI water as analytes to analysis the current-voltage (I-V) characteristics of silicon nanowire pH sensor. In second part, the silicon nanowire biosensor as preliminary study is done simulation by Silvaco ATLAS devices simulator. The silicon nanowire with 30 nm in height and 20 nm in width of biosensor is designed and simulated to analyze the performance in terms of sensitivity. I-V characteristics of silicon nanowire biosensor according to different concentration of negative interface charge is determined. The negative interface charge represent as the Retinol Binding Protein 4 (RBP4) which is used to diagnose DM. The I-V characteristic based on the change in current, resistance and conductance to determine sensitivity. Lastly, the sensitivity of silicon nanowire pH sensor obtained 23.9 pS/pH while the sensitivity of simulated silicon nanowire biosensor obtained 3.91 nS/e.cm2. The results shown the more negative charge of concentration analyte attached on surface silicon nanowire has been accumulated more current flow from drain terminal to source terminal. It leads to the resistance becomes highest and obtained good sensitivity. In summary, the silicon nanowire pH sensor exhibited good performance and high sensitivity in detection pH level. The simulated silicon nanowire biosensor is capable of detecting biomolecular interactions charges to obtained high sensitive and accuracy result.
      3  25
  • Publication
    Mediatorless impedance studies with titanium dioxide conjugated gold nanoparticles for hydrogen peroxide detection
    ( 2017) ;
    Yook Lee
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    Radha Marugan
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    An impedimetric-based biosensor constructed using gold nanoparticles (AuNP) entrapped within titanium dioxide (TiO2) particles for hydrogen peroxide (H2O2) detection is the main feature of this research. The matrix of the biosensor employed the surface of TiO2, which was previously modified with an amine terminal group using 3-Aminopropyltriethoxysilane (APTS) at a low temperature to create a ready to immobilise surface for the biosensor application. Hemoglobin (Hb), which exhibits peroxidase-like activity, was used as the bioreceptor in the biosensor to detect H2O2 in solution. The analysis was carried out using an alternative impedance method, in which the biosensor exhibited a wide linear range response between 1 × 10−4 M and 1.5 × 10−2 M and a limit of detection (LOD) of 1 × 10−5 M without a redox mediator.
      1  16