Now showing 1 - 10 of 11
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Impedimetric cardiac biomarker determination in serum mediated by epoxy and hydroxyl of reduced graphene oxide on gold array microelectrodes

2021-08-01 , Steven Taniselass , Mohd Khairuddin Md Arshad , Subash Chandra Bose Gopinath , Mohamad Faris Mohamad Fathil , Ibau C. , Anbu P.

A label-free chemical bonding strategy mediated by reduced graphene oxide (rGO) basal plane functional groups has been developed for cardiac Troponin I (cTnI) detection. Four different chemical strategies on respective electrode sensing surface were precedingly examined using electrochemical impedance spectroscopy. The impedimetric assessment was carried out by sweeping frequency at the range 0.1–500 kHz perturbated at a small amplitude of AC voltage (25 mV). The chemical strategy-4 denoted as S-4 shows a significant analytical performance on cTnI detection in spiked buffer and human serum, whereby the pre-mixture of rGO and (3-Aminopropyl)triethoxysilane (APTES) creates a large number of amine sites (−NH2), which significantly enhanced the antibody immobilization without excessive functionalization. The as-fabricated immunosensor exhibited an ultra-low limit of detection of 6.3 ag mL−1 and the lowest antigen concentration measured was at 10 ag mL−1. The immunosensor showed a linear and wide range of cTnI detection (10 ag mL−1–100 ng mL−1) in human serum with a regression coefficient of 0.9716, rapid detection (5 min of binding time), and stable and highly reproducible bioelectrode response with RSD < 5%. Hence, the demonstrated S-4 strategy is highly recommended for other downstream biosensors applications. Graphical abstract: [Figure not available: see fulltext.].

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Surface Morphology Analysis of graphene transfer on SiO2 with BPA aptasensor detection using Electrochemical Impedance Spectroscopy

2023-01-01 , Shukri N.I.A. , Norhayati Sabani , Mohamad Faris Mohamad Fathil , Syarifah Norfaezah Sabki , Ruslinda A. Rahim , Halim N.H.A. , Ismail N.S.

Bisphenol A or BPA is one of the highest produced chemicals in the world. The production of polycarbonate plastic and epoxy resin are used to make variety of consumer goods and it is frequently employed BPA as a raw material. BPA is one of the endocrine disruptors which is related to a wide range of adverse health effects that can cause reproductive disorders and many kinds of cancers. In the work, the novelty of electrochemical sensor of BPA was constructed on a graphene modified electrode using graphene transfer method. In this work, High-power microscope and scanning electron microscopy were used to study the production and characterization of the graphene, with two significant mapping graphene at 20% and 80%. The existence of graphene on silicon oxide was analyzed using Raman Spectroscopy while the composition of the materials was analyze using Fourier-Transform Infrared Spectroscopy. In this analysis, both analysis data from Raman and FTIR clearly shown that 80% mapping graphene is the best option which resulting to the high surface coverage. The electrochemical performance of the mapping 80% graphene electrode was examined using Electrochemical Impedance Spectra. The increase in charge transfer resistance (Rct) both before and after the addition of BPA denotes the development of the charge at the electrode surface. The equivalent circuit shows the Rct of graphene increased from 0.4 k Ω to 1.2 k Ω and drastically increased to 300 kΩ when the device was introduced with BPA due to the existence of a negative charge carrier and the repelling contact.

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Impact of buried oxide thickness in substrate-gate integrated silicon nanowire field-effect transistor biosensor performance for charge sensing

2021-07-21 , Tan Y.M. , Mohamad Faris Mohamad Fathil , Mohammad Nuzaihan Md Nor , Norhayati Sabani , Teoh X.Y. , Mohd Khairuddin Md Arshad , Subash Chandra Bose Gopinath , Rahman S.F.A. , Uda Hashim

The paper investigated on performance in charge sensing for substrate-gate integrated silicon nanowire field-effect transistor biosensor at different thickness of the buried oxide layer, sandwiched in between the top-silicon and substrate layers. The device structures with different buried oxide thickness ranging from 100 to 200 nm were designed and simulated using the Silvaco ATLAS device simulation software. The increase of buried oxide thickness reduced the strength of induced electric field that contributes to the formation of inversion layer for current flow through the silicon nanowire channel, hence contributed to the increase in threshold voltage. For simulation of charge sensing, the device demonstrated the ability to identify different interface charge values ranging from -5×1010 to -9×1010 e· cm-2 applied on the surface of the silicon nanowire channel to represent target charge biomolecules that bound to the biosensor in actual detection. Significant change in threshold voltage can be observed due to the applied interface charge density values and was evaluated to determine the sensitivity for charge sensing performance. The device shows better performance when designed with buried oxide thickness of 200 nm at sensitivity of 1.151 V/e· cm-2.

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Lectin bioreceptor approach in capacitive biosensor for prostate-specific membrane antigen detection in diagnosing prostate cancer

2021-03-01 , Subramani I.G. , Ramzan Mat Ayub , Subash Chandra Bose Gopinath , Perumal V. , Mohamad Faris Mohamad Fathil , Mohd Khairuddin Md Arshad

This research reports a new approach with lectin-based capacitive non-faradaic biosensor for the detection of prostate-specific membrane antigen (PSMA) as a promising diagnostic marker for determining prostate cancer. PSMA expression is significantly higher in malign hyperplasia, thus can be effectively employed to discriminate other benign prostatic diseases. Herein, the aluminium interdigitated electrode was fabricated and modified by a linker, 2-mercaptoacetate to form the self-assembled monolayer. Gold nanoparticles were used as a signal amplifier and supported the conjugation of Concanavalin A, for efficient capacitive sensing of PSMA. Scanning electron microscope observation effectively captured the surface modification on the aluminium surface by revealing the specific adherence of gold nanoparticles with Concanavalin A. Moreover, the successful surface modification was further validated by atomic force microscopy, Fourier transforms infrared spectroscopy, and X-ray photoelectron spectroscopy. The interaction analysis of Concanavalin A with PSMA by capacitive non-faradaic measurement exhibited a linear detection range from 10 pM to 100 nM and attained the detection limit and sensitivity of 10 pM and 1.65 nF/pM respectively as the comparable performance to the current sensing strategies. Furthermore, the fabrication and quantification of PSMA as demonstrated here are relatively simple and can be employed for the straightforward detection of other biomarkers.

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Glycosylated biomarker sensors: advancements in prostate cancer diagnosis

2021-09-28 , Siti Fatimah Abd Rahman , Mohd Khairuddin Md Arshad , Subash Chandra Bose Gopinath , Mohamad Faris Mohamad Fathil , Sarry F. , Ibau C.

Prostate cancer is currently diagnosed using the conventional gold standard methods using prostate-specific antigen (PSA) as the selective biomarker. However, lack of precision in PSA screening has resulted in needless biopsies and delays the treatment of potentially fatal prostate cancer. Thus, identification of glycans as novel biomarkers for the early detection of prostate cancer has attracted considerable attention due to their reliable diagnostic platform compared with the current PSA systems. Therefore, biosensing technologies that provide point-of-care diagnostics have demonstrated the ability to detect various analytes, including glycosylated micro- and macro-molecules, thereby enabling versatile detection methodologies. This highlight article discusses recent advances in the biosensor-based detection of prostate cancer glycan biomarkers and the innovative strategies for the conjugation of nanomaterials adapted to biosensing platforms. Finally, the article is concluded with prospects and challenges of prostate cancer biosensors and recommendations to overcome the issues associated with prostate cancer diagnosis.

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Molybdenum disulfide—gold nanoparticle nanocomposite in field-effect transistor back-gate for enhanced C-reactive protein detection

2020-11-01 , Dalila N.R. , Mohd Khairuddin Md Arshad , Subash Chandra Bose Gopinath , Mohammad Nuzaihan Md Nor , Mohamad Faris Mohamad Fathil

Nanofabricated gold nanoparticles (Au-NPs) on MoS2 nanosheets (Au-NPs/MoS2) in back-gated field-effect transistor (BG-FET) are presented, which acts as an efficient semiconductor device for detecting a low concentration of C-reactive protein (C-RP). The decorated nanomaterials lead to an enhanced electron conduction layer on a 100-μm-sized transducing channel. The sensing surface was characterized by Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), atomic force microscopy (AFM), scanning electron microscopy (SEM), and high-power microscopy (HPM). The BG-FET device exhibits an excellent limit of detection of 8.38 fg/mL and a sensitivity of 176 nA/g·mL−1. The current study with Au-NPs/MoS2 BG-FET displays a new potential biosensing technology; especially for integration into complementary metal oxide (CMOS) technology for hand-held future device application. [Figure not available: see fulltext.]

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Femtomolar Dengue Virus Type-2 DNA Detection in Back-gated Silicon Nanowire Field-effect Transistor Biosensor

2022-01-01 , Abidin W.A.B.Z. , Nor M.N.M. , Mohd Khairuddin Md Arshad , Mohamad Faris Mohamad Fathil , Nor Azizah Parmin , Sisin N.A.H.T. , Ibau C. , Azlan A.S.

Background: Dengue is known as the most severe arboviral infection in the world spread by Aedes aegypti. However, conventional and laboratory-based enzyme-linked immunosorbent as-says (ELISA) are the current approaches in detecting dengue virus (DENV), requiring skilled and well-trained personnel to operate. Therefore, the ultrasensitive and label-free technique of the Silicon Nanowire (SiNW) biosensor was chosen for rapid detection of DENV. Methods: In this study, a SiNW field-effect transistor (FET) biosensor integrated with a back-gate of the low-doped p-type Silicon-on-insulator (SOI) wafer was fabricated through conventional photo-lithography and Inductively Coupled Plasma – Reactive Ion Etching (ICP-RIE) for Dengue Virus type-2 (DENV-2) DNA detection. The morphological characteristics of back-gated SiNW-FET were examined using a field-emission scanning electron microscope supported by the elemental analysis via energy-dispersive X-ray spectroscopy. Results and Discussion: A complementary (target) single-stranded deoxyribonucleic acid (ssDNA) was recognized when the target DNA was hybridized with the probe DNA attached to SiNW surfaces. Based on the slope of the linear regression curve, the back-gated SiNW-FET biosensor demonstrated the sensitivity of 3.3 nAM-1 with a detection limit of 10 fM. Furthermore, the drain and back-gate voltages were also found to influence the SiNW conductance changed. Conclusion: Thus, the results obtained suggest that the back-gated SiNW-FET shows good stability in both biosensing applications and medical diagnosis throughout the conventional photolithography method.

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Faradaic electrochemical impedimetric analysis on MoS2 /Au-NPs decorated surface for C-reactive protein detection

2022-09-01 , Dalila R N. , Mohd Khairuddin Md Arshad , Subash Chandra Bose Gopinath , Ibau C. , Mohammad Nuzaihan Md Nor , Mohamad Faris Mohamad Fathil , Azmi U.Z.M. , Anbu P.

Background: A label-free Faradaic electrochemical impedimetric was developed for a highly sensitive detection of C-reactive protein using a gold interdigitated microelectrode bio-sensing platform enhanced by a gold nanoparticle-decorated molybdenum disulfide (Au-NPs/MoS2) nanosheet via selected chemical linking processes. C-reactive protein (C-RP), a crystalline protein, generates by the liver and hikes when there is inflammation throughout the patients’ body. The concentrations of C-RP plasma levels tend to increase rapidly when the patient facing major injury which will lead to cardiovascular disease (CVD). Methods: The 5 µm microelectrode and gap size g-IDE with the nanostructured materials was demonstrated to increase the impedimetric detection response in Faradaic-mode electrochemical impedance spectroscopy high performance detection environment. The high surface area-to-volume ratio of the modified Au-NPs/MoS2 nanocomposite increased the probes loading onto the transducer and enhanced the impedimetric detection response of the C-RP target post-binding due to an amplified net change in the charge transfer resistance. The developed immunoassay revealed a linear detection of C-RP biomarker in a logarithmic-scale from as low as 1 fg/mL up to 1 µg/mL, and a limit of detection of 0.01 fg/mL. The sensor shows great potential as an early warning risk for cardiovascular disease at a threshold concentration value of C-RP at 1 µg/mL. Significant findings: The biosensor demonstrates an excellent discrimination against other competing proteins in serum, exhibiting the highest predilection to C-RP spiked human serum target. The sensor's reproducibility is reported within an acceptable range of relative standard deviation of 1–4% for n = 3.

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Interdigitated impedimetric-based Maackia amurensis lectin biosensor for prostate cancer biomarker

2024-02-01 , Rahman S.F.A. , Mohd Khairuddin Md Arshad , Subash Chandra Bose Gopinath , Mohamad Faris Mohamad Fathil , Sarry F. , Ibau C. , Elmazria O. , Hage-Ali S.

Highly specific detection of tumor-associated biomarkers remains a challenge in the diagnosis of prostate cancer. In this research, Maackia amurensis (MAA) was used as a recognition element in the functionalization of an electrochemical impedance-spectroscopy biosensor without a label to identify cancer-associated aberrant glycosylation prostate-specific antigen (PSA). The lectin was immobilized on gold-interdigitated microelectrodes. Furthermore, the biosensor’s impedance response was used to assess the establishment of a complex binding between MAA and PSA-containing glycans. With a small sample volume, the functionalized interdigitated impedimetric-based (IIB) biosensor exhibited high sensitivity, rapid response, and repeatability. PSA glycoprotein detection was performed by measuring electron transfer resistance values within a concentration range 0.01–100 ng/mL, with a detection limit of 3.574 pg/mL. In this study, the ability of MAA to preferentially recognize α2,3-linked sialic acid in serum PSA was proven, suggesting a potential platform for the development of lectin-based, miniaturized, and cost effective IIB biosensors for future disease detection. Graphical Abstract: [Figure not available: see fulltext.].

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Impedimetric Lectin Biosensor for Prostate Cancer Detection

2021-01-01 , Abd Rahman S.F. , Mohd Khairuddin Md Arshad , Subash Chandra Bose Gopinath , Mohamad Faris Mohamad Fathil , Sarry F. , Md Nor M.N.

There is considerable attention on the determination of prostate-specific antigen (PSA) glycosylation patterns for the early detection of prostate cancer, as it is one of the most reliable tumor biomarkers. In this study, the highly effective lectin-based biosensor utilizing gold interdigitated microelectrode was developed as a sensing transducer, coupled with electrochemical impedance spectroscopy (EIS) for the sensitive detection of biomolecules event on the device. The self-assembled monolayer using 11-mercaptoundecanoic acid was utilized to modify the sensor surface for the conjugation of Maackia amurensis lectin as biorecognition elements. The analytical analysis of the developed lectin biosensor with PSA glycosylation through impedimetric measurement exhibited a linear detection ranging from 100 pg/mL to 100 ng/mL and attained a detection limit of 27.6 pg/mL.