Displaying publications 1 - 20 of 41 in total

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  1. Adzhri R, Md Arshad MK, Gopinath SC, Ruslinda AR, Fathil MF, Ayub RM, et al.
    Anal Chim Acta, 2016 Apr 21;917:1-18.
    PMID: 27026595 DOI: 10.1016/j.aca.2016.02.042
    Field-effect transistors (FETs) have succeeded in modern electronics in an era of computers and hand-held applications. Currently, considerable attention has been paid to direct electrical measurements, which work by monitoring changes in intrinsic electrical properties. Further, FET-based sensing systems drastically reduce cost, are compatible with CMOS technology, and ease down-stream applications. Current technologies for sensing applications rely on time-consuming strategies and processes and can only be performed under recommended conditions. To overcome these obstacles, an overview is presented here in which we specifically focus on high-performance FET-based sensor integration with nano-sized materials, which requires understanding the interaction of surface materials with the surrounding environment. Therefore, we present strategies, material depositions, device structures and other characteristics involved in FET-based devices. Special attention was given to silicon and polyaniline nanowires and graphene, which have attracted much interest due to their remarkable properties in sensing applications.
  2. Haarindraprasad R, Hashim U, Gopinath SC, Perumal V, Liu WW, Balakrishnan SR
    Anal Chim Acta, 2016 Jun 21;925:70-81.
    PMID: 27188319 DOI: 10.1016/j.aca.2016.04.030
    Diabetes is a metabolic disease with a prolonged elevated level of glucose in the blood leads to long-term complications and increases the chances for cardiovascular diseases. The present study describes the fabrication of a ZnO nanowire (NW)-modified interdigitated electrode (IDE) to monitor the level of blood glucose. A silver IDE was generated by wet etching-assisted conventional lithography, with a gap between adjacent electrodes of 98.80 μm. The ZnO-based thin films and NWs were amended by sol-gel and hydrothermal routes. High-quality crystalline and c-axis orientated ZnO thin films were observed by XRD analyses. The ZnO thin film was annealed for 1, 3 and 5 h, yielding a good-quality crystallite with sizes of 50, 100 and 110 nm, and the band gaps were measured as 3.26, 3.20 and 3.17 eV, respectively. Furthermore, a flower-modeled NW was obtained with the lowest diameter of 21 nm. Our designed ZnO NW-modified IDE was shown to have a detection limit as low as 0.03 mg/dL (correlation coefficient = 0.98952) of glucose with a low response time of 3 s, perform better than commercial glucose meter, suitable to instantly monitor the glucose level of diabetes patients. This study demonstrated the high performance of NW-mediated IDEs for glucose sensing as alternative to current glucose sensors.
  3. Fathil MF, Md Arshad MK, Ruslinda AR, Nuzaihan M N M, Gopinath SC, Adzhri R, et al.
    Anal Chim Acta, 2016 Sep 07;935:30-43.
    PMID: 27543013 DOI: 10.1016/j.aca.2016.06.012
    A real-time ability to interpret the interaction between targeted biomolecules and the surface of semiconductors (metal transducers) into readable electrical signals, without biomolecular modification involving fluorescence dyes, redox enzymes, and radioactive labels, created by label-free biosensors has been extensively researched. Field-effect transistor (FET)- and capacitor-based biosensors are among the diverse electrical charge biosensing architectures that have drawn much attention for having charge transduction; thus, enabling the early and rapid diagnosis of the appropriate cardiac biomarkers at lower concentrations. These semiconducting material-based transducers are very suitable to be integrated with portable electronic devices for future online collection, transmission, reception, analysis, and reporting. This overview elucidates and clarifies two major electrical label-free systems (FET- and capacitor-based biosensors) with cardiac troponin (cTn) biomarker-mediated charge transduction for acute myocardial infarction (AMI) diagnosis. Advances in these systems are highlighted by their progression in bridging the laboratory and industry; the foremost technologies have made the transition from benchtop to bedside and beyond.
  4. Gopinath SC, Lakshmipriya T, Chen Y, Arshad MK, Kerishnan JP, Ruslinda AR, et al.
    Appl Microbiol Biotechnol, 2016 Aug;100(16):6955-69.
    PMID: 27350620 DOI: 10.1007/s00253-016-7686-2
    Aptamers are single-stranded nucleic acids or peptides identified from a randomized combinatorial library through specific interaction with the target of interest. Targets can be of any size, from small molecules to whole cells, attesting to the versatility of aptamers for binding a wide range of targets. Aptamers show drug properties that are analogous to antibodies, with high specificity and affinity to their target molecules. Aptamers can penetrate disease-causing microbial and mammalian cells. Generated aptamers that target surface biomarkers act as cell-targeting agents and intracellular delivery vehicles. Within this context, the "cell-internalizing aptamers" are widely investigated via the process of cell uptake with selective binding during in vivo systematic evolution of ligands by exponential enrichment (SELEX) or by cell-internalization SELEX, which targets cell surface antigens to be receptors. These internalizing aptamers are highly preferable for the localization and functional analyses of multiple targets. In this overview, we discuss the ways by which internalizing aptamers are generated and their successful applications. Furthermore, theranostic approaches featuring cell-internalized aptamers are discussed with the purpose of analyzing and diagnosing disease-causing pathogens.
  5. Chen Y, Chan CK, Kerishnan JP, Lau YL, Wong YL, Gopinath SC
    BMC Infect Dis, 2015;15:49.
    PMID: 25656928 DOI: 10.1186/s12879-015-0786-2
    Plasmodium knowlesi was identified as the fifth major malaria parasite in humans. It presents severe clinical symptoms and leads to mortality as a result of hyperparasitemia in a short period of time. This study aimed to improve the current understanding of P. knowlesi and identify potential biomarkers for knowlesi malaria.
  6. Tan AA, Phang WM, Gopinath SC, Hashim OH, Kiew LV, Chen Y
    Biomed Res Int, 2015;2015:453289.
    PMID: 26167486 DOI: 10.1155/2015/453289
    Breast cancer is one of the major issues in the field of oncology, reported with a higher prevalence rate in women worldwide. In attempt to reveal the potential biomarkers for breast cancer, the findings of differentially glycosylated haptoglobin and osteonectin in previous study have drawn our attention towards glycoproteins of secretome from the MCF-7 cancer cell line. In the present study, further analyses were performed on the medium of MCF-7 cells by subjecting it to two-dimensional analyses followed by image analysis in contrast to the medium of human mammary epithelial cells (HMEpC) as a negative control. Carboxypeptidase A4 (CPA4), alpha-1-antitrypsin (AAT), haptoglobin (HP), and HSC70 were detected in the medium of MCF-7, while only CPA4 and osteonectin (ON) were detected in HMEpC medium. In addition, CPA4 was detected as upregulated in the MCF-7 medium. Further analysis by lectin showed that CPA4, AAT, HP, and HSC70 were secreted as N-glycan in the medium of MCF-7, with HP also showing differentially N-glycosylated isoforms. For the HMEpC, only CPA4 was detected as N-glycan. No O-glycan was detected in the medium of HMEpC but MCF-7 expressed O-glycosylated CPA4 and HSC70. All these revealed that glycoproteins could be used as glycan-based biomarkers for the prognosis of breast cancer.
  7. Anbu P, Gopinath SC, Chaulagain BP, Tang TH, Citartan M
    Biomed Res Int, 2015;2015:816419.
    PMID: 26161416 DOI: 10.1155/2015/816419
  8. Lee LP, Karbul HM, Citartan M, Gopinath SC, Lakshmipriya T, Tang TH
    Biomed Res Int, 2015;2015:820575.
    PMID: 26180812 DOI: 10.1155/2015/820575
    Lipases are of great interest for different industrial applications due to their diversity and versatility. Among different lipases, microbial lipases are preferable due to their broad substrate specificity, and higher stability with lower production costs compared to the lipases from plants and animals. In the past, a vast number of bacterial species have been reported as potential lipases producers. In this study, the lipases-producing bacterial species were isolated from an oil spillage area in the conventional night market. Isolated species were identified as Bacillus species by biochemical tests which indicate their predominant establishment, and further screened on the agar solid surfaces using lipid and gelatin as the substrates. Out of the ten strains tested, four potential strains were subjected to comparison analysis of the lipolytic versus proteolytic activities. Strain 10 exhibited the highest lipolytic and proteolytic activity. In all the strains, the proteolytic activity is higher than the lipolytic activity except for strain 8, suggesting the possibility for substrate-based extracellular gene induction. The simultaneous secretion of both the lipase and protease is a mean of survival. The isolated bacterial species which harbour both lipase and protease enzymes could render potential industrial-based applications and solve environmental issues.
  9. Gopinath SC, Anbu P, Lakshmipriya T, Tang TH, Chen Y, Hashim U, et al.
    Biomed Res Int, 2015;2015:140726.
    PMID: 26180780 DOI: 10.1155/2015/140726
    Keratinases are proteolytic enzymes predominantly active when keratin substrates are available that attack disulfide bridges in the keratin to convert them from complex to simplified forms. Keratinases are essential in preparation of animal nutrients, protein supplements, leather manufacture, textile processing, detergent formulation, feather meal processing for feed and fertilizer, the pharmaceutical and biomedical industries, and waste management. Accordingly, it is necessary to develop a method for continuous production of keratinase from reliable sources that can be easily managed. Microbial keratinase is less expensive than conventionally produced keratinase and can be obtained from fungi, bacteria, and actinomycetes. In this overview, the expansion of information about microbial keratinases and important considerations in keratinase production are discussed.
  10. Gopinath SC, Anbu P, Arshad MK, Lakshmipriya T, Voon CH, Hashim U, et al.
    Biomed Res Int, 2017;2017:1272193.
    PMID: 28280725 DOI: 10.1155/2017/1272193
    Amylase is an important and indispensable enzyme that plays a pivotal role in the field of biotechnology. It is produced mainly from microbial sources and is used in many industries. Industrial sectors with top-down and bottom-up approaches are currently focusing on improving microbial amylase production levels by implementing bioengineering technologies. The further support of energy consumption studies, such as those on thermodynamics, pinch technology, and environment-friendly technologies, has hastened the large-scale production of the enzyme. Herein, the importance of microbial (bacteria and fungi) amylase is discussed along with its production methods from the laboratory to industrial scales.
  11. Fatin MF, Ruslinda AR, Arshad MK, Tee KK, Ayub RM, Hashim U, et al.
    Biosens Bioelectron, 2016 Apr 15;78:358-66.
    PMID: 26655174 DOI: 10.1016/j.bios.2015.11.067
    Human immunodeficiency virus (HIV) has infected almost 35 million people worldwide. Various tests have been developed to detect the presence of HIV during the early stages of the disease in order to reduce the risk of transmission to other humans. The HIV-1 Tat protein is one of the proteins present in HIV that are released abundantly approximately 2-4 weeks after infection. In this review, we have outlined various strategies for detecting the Tat protein, which helps transcribe the virus and enhances replication. Detection strategies presented include immunoassays, biosensors and gene expression, which utilize antibodies or aptamers as common probes to sense the presence of Tat. Alternatively, measuring the levels of gene transcription is a direct method of analysing the HIV gene to confirm the presence of Tat. By detection of the Tat protein, virus transmission can be detected in high-risk individuals in the early stages of the disease to reduce the risk of an HIV pandemic.
  12. Toh SY, Citartan M, Gopinath SC, Tang TH
    Biosens Bioelectron, 2015 Feb 15;64:392-403.
    PMID: 25278480 DOI: 10.1016/j.bios.2014.09.026
    The application of antibodies in enzyme-linked immunosorbent assay (ELISA) is the basis of this diagnostic technique which is designed to detect a potpourri of complex target molecules such as cell surface antigens, allergens, and food contaminants. However, development of the systematic evolution of Ligands by Exponential Enrichment (SELEX) method, which can generate a nucleic acid-based probe (aptamer) that possess numerous advantages compared to antibodies, offers the possibility of using aptamers as an alternative molecular recognition element in ELISA. Compared to antibodies, aptamers are smaller in size, can be easily modified, are cheaper to produce, and can be generated against a wide array of target molecules. The application of aptamers in ELISA gives rise to an ELISA-derived assay called enzyme-linked apta-sorbent assay (ELASA). As with the ELISA method, ELASA can be used in several different configurations, including direct, indirect, and sandwich assays. This review provides an overview of the strategies involved in aptamer-based ELASA.
  13. Gopinath SC, Tang TH, Chen Y, Citartan M, Tominaga J, Lakshmipriya T
    Biosens Bioelectron, 2014 Nov 15;61:357-69.
    PMID: 24912036 DOI: 10.1016/j.bios.2014.05.024
    Influenza viruses, which are RNA viruses belonging to the family Orthomyxoviridae, cause respiratory diseases in birds and mammals. With seasonal epidemics, influenza spreads all over the world, resulting in pandemics that cause millions of deaths. Emergence of various types and subtypes of influenza, such as H1N1 and H7N9, requires effective surveillance to prevent their spread and to develop appropriate anti-influenza vaccines. Diagnostic probes such as glycans, aptamers, and antibodies now allow discrimination among the influenza strains, including new subtypes. Several sensors have been developed based on these probes, efforts made to augment influenza detection. Herein, we review the currently available sensing strategies to detect influenza viruses.
  14. Gopinath SC, Tang TH, Chen Y, Citartan M, Lakshmipriya T
    Biosens Bioelectron, 2014 Oct 15;60:332-42.
    PMID: 24836016 DOI: 10.1016/j.bios.2014.04.014
    The ubiquitous nature of bacteria enables them to survive in a wide variety of environments. Hence, the rise of various pathogenic species that are harmful to human health raises the need for the development of accurate sensing systems. Sensing systems are necessary for diagnosis and epidemiological control of pathogenic organism, especially in the food-borne pathogen and sanitary water treatment facility' bacterial populations. Bacterial sensing for the purpose of diagnosis can function in three ways: bacterial morphological visualization, specific detection of bacterial component and whole cell detection. This paper provides an overview of the currently available bacterial detection systems that ranges from microscopic observation to state-of-the-art smartphone-based detection.
  15. Gopinath SC, Tang TH, Citartan M, Chen Y, Lakshmipriya T
    Biosens Bioelectron, 2014 Jul 15;57:292-302.
    PMID: 24607580 DOI: 10.1016/j.bios.2014.02.029
    Sensing applications can be used to report biomolecular interactions in order to elucidate the functions of molecules. The use of an analyte and a ligand is a common set-up in sensor development. For several decades, antibodies have been considered to be potential analytes or ligands for development of so-called "immunosensors." In an immunosensor, formation of the complex between antibody and antigen transduces the signal, which is measurable in various ways (e.g., both labeled and label-free based detection). Success of an immunosensor depends on various factors, including surface functionalization, antibody orientation, density of the antibody on the sensor platform, and configuration of the immunosensor. Careful optimization of these factors can generate clear-cut results for any immunosensor. Herein, current aspects, involved in the generated immunosensors, are discussed.
  16. Citartan M, Gopinath SC, Tominaga J, Tan SC, Tang TH
    Biosens Bioelectron, 2012 Apr 15;34(1):1-11.
    PMID: 22326894 DOI: 10.1016/j.bios.2012.01.002
    Aptamers are single stranded DNA or RNA oligonucleotides that have high affinity and specificity towards a wide range of target molecules. Aptamers have low molecular weight, amenable to chemical modifications and exhibit stability undeterred by repetitive denaturation and renaturation. Owing to these indispensable advantages, aptamers have been implemented as molecular recognition element as alternative to antibodies in various assays for diagnostics. By amalgamating with a number of methods that can provide information on the aptamer-target complex formation, aptamers have become the elemental tool for numerous biosensor developments. In this review, administration of aptamers in applications involving assays of fluorescence, electrochemistry, nano-label and nano-constructs are discussed. Although detection strategies are different for various aptamer-based assays, the core of the design strategies is similar towards reporting the presence of specific target binding to the corresponding aptamers. It is prognosticated that aptamers will find even broader applications with the development of new methods of transducing aptamer target binding.
  17. Perumal V, Hashim U, Gopinath SC, Haarindraprasad R, Poopalan P, Liu WW, et al.
    Biosens Bioelectron, 2016 Apr 15;78:14-22.
    PMID: 26584078 DOI: 10.1016/j.bios.2015.10.083
    Creating novel nanostructures is a primary step for high-performance analytical sensing. Herein, a new worm like nanostructure with Zinc Oxide-gold (ZnO/Au) hybrid was fabricated through an aqueous hydrothermal method, by doping Au-nanoparticle (AuNP) on the growing ZnO lattice. During ZnO growth, fine tuning the solution temperature expedites random curving of ZnO nanorods and forms nano-worms. The nano-worms which were evidenced by morphological, physical and structural analyses, revealed elongated structures protruding from the surface (length: 1 µm; diameter: ~100 nm). The appropriate peaks for the face centred cubic gold were (111) and (200), as seen from X-ray diffractogram. The strong interrelation between Au and ZnO was manifested by X-ray photoelectron spectroscopy. The combined surface area increment from the nanoparticle radii and ZnO nanorod random curving gives raise an enhancement in detection sensitivity by increasing bio-loading. 'Au-decorated hybrid nano-worm' was immobilized with a probe DNA from Vibrio Cholera and duplexed with a target which was revealed by Fourier Transform Infrared Spectroscopy. Our novel Au-decorated hybrid nano-worm is suitable for high-performance bio-sensing, as evidenced by impedance spectroscopy, having higher-specificity and attained femtomolar (10 fM) sensitivity. Further, higher stability, reproducibility and regeneration on this sensing surface were demonstrated.
  18. Balakrishnan SR, Hashim U, Gopinath SC, Poopalan P, Ramayya HR, Veeradasan P, et al.
    Biosens Bioelectron, 2016 Oct 15;84:44-52.
    PMID: 26560969 DOI: 10.1016/j.bios.2015.10.075
    Rationally designed biosensing system supports multiplex analyses is warranted for medical diagnosis to determine the level of analyte interaction. The chemically functionalized novel multi-electrode polysilicon nanogap (PSNG) lab-on-chip is designed in this study, facilitates multiplex analyses for a single analyte. On the fabricated 69nm PSNG, biocompatibility and structural characteristics were verified for the efficient binding of Human Chorionic Gonadotropin (hCG). With the assistance of microfluidics, hCG sample was delivered via single-injection to 3-Aminopropyl(triethoxy)silane (APTES) and Glycidoxypropyl(trimethoxy)silane (GPMS) modified PSNG electrodes and the transduced signal was used to investigate the dielectric mechanisms for multiplex analyses. The results from amperometric response and impedance measurement delivered the scale of interaction between anti-hCG antibody and hCG that exhibited 6.5 times higher sensitivity for the chemical linker, APTES than GPMS. Under optimized experimental conditions, APTES and GPMS modified immunosensor has a limit of detection as 0.56mIU/ml and 2.93mIU/ml (at S/N=3), with dissociation constants (Kd) of 5.65±2.5mIU/ml and 7.28±2.6mIU/ml, respectively. These results suggest that multiplex analysis of single target could enhance the accuracy of detection and reliable for real-time comparative analyses. The designed PSNG is simple, feasible, requires low sample consumption and could be applied for any given multiplex analyses.
  19. Fathil MF, Md Arshad MK, Gopinath SC, Hashim U, Adzhri R, Ayub RM, et al.
    Biosens Bioelectron, 2015 Aug 15;70:209-20.
    PMID: 25841117 DOI: 10.1016/j.bios.2015.03.037
    Acute myocardial infarction or myocardial infarction (MI) is a major health problem, due to diminished flow of blood to the heart, leads to higher rates of mortality and morbidity. Data from World Health Organization (WHO) accounted 30% of global death annually and expected more than 23 million die annually by 2030. This fatal effects trigger the need of appropriate biomarkers for early diagnosis, thus countermeasure can be taken. At the moment, the most specific markers for cardiac injury are cardiac troponin I (cTnI) and cardiac troponin T (cTnT) which have been considered as 'gold standard'. Due to higher specificity, determination of the level of cardiac troponins became a predominant indicator for MI. Several ways of diagnostics have been formulated, which include enzyme-linked immunosorbent assay, chemiluminescent, fluoro-immunoassays, electrical detections, surface plasmon resonance, and colorimetric protein assay. This review represents and elucidates the strategies, methods and detection levels involved in these diagnostics on cardiac superior biomarkers. The advancement, sensitivity, and limitations of each method are also discussed. In addition, it concludes with a discussion on the point-of care (POC) assay for a fast, accurate and ability of handling small sample measurement of cardiac biomarker.
  20. Ten ST, Hashim U, Gopinath SC, Liu WW, Foo KL, Sam ST, et al.
    Biosens Bioelectron, 2017 Jul 15;93:146-154.
    PMID: 27660016 DOI: 10.1016/j.bios.2016.09.035
    Surface acoustic wave mediated transductions have been widely used in the sensors and actuators applications. In this study, a shear horizontal surface acoustic wave (SHSAW) was used for the detection of food pathogenic Escherichia coli O157:H7 (E.coli O157:H7), a dangerous strain among 225 E. coli unique serotypes. A few cells of this bacterium are able to cause young children to be most vulnerable to serious complications. Presence of higher than 1cfu E.coli O157:H7 in 25g of food has been considered as a dangerous level. The SHSAW biosensor was fabricated on 64° YX LiNbO3 substrate. Its sensitivity was enhanced by depositing 130.5nm thin layer of SiO2 nanostructures with particle size lesser than 70nm. The nanostructures act both as a waveguide as well as a physical surface modification of the sensor prior to biomolecular immobilization. A specific DNA sequence from E. coli O157:H7 having 22 mers as an amine-terminated probe ssDNA was immobilized on the thin film sensing area through chemical functionalization [(CHO-(CH2)3-CHO) and APTES; NH2-(CH2)3-Si(OC2H5)3]. The high-performance of sensor was shown with the specific oligonucleotide target and attained the sensitivity of 0.6439nM/0.1kHz and detection limit was down to 1.8femto-molar (1.8×10(-15)M). Further evidence was provided by specificity analysis using single mismatched and complementary oligonucleotide sequences.
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