Displaying publications 21 - 40 of 41 in total

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  1. 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.
  2. Gopinath SC, Lakshmipriya T, Chen Y, Phang WM, Hashim U
    Biotechnol Adv, 2016 May-Jun;34(3):198-208.
    PMID: 26876017 DOI: 10.1016/j.biotechadv.2016.02.003
    Aptamers are single-stranded oligonucleotides that can be artificially generated by a method called Systematic evolution of ligands by exponential enrichment (SELEX). The generated aptamers have been assessed for high-performance sensing applications due to their appealing characteristics. With either aptamers alone or complementing with antibodies, several high sensitive and portable sensors have been demonstrated for use in 'point-of-care testing'. Due to their high suitability and flexibility, aptamers are conjugated with nanostructures and utilized in field applications. Moreover, aptamers are more amenable to chemical modifications, making them capable of utilization with most developed sensors. In this overview, we discuss novel, portable, and aptamer-based sensing strategies that are suitable for 'point-of-care testing'.
  3. 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.
  4. Anbu P, Gopinath SC, Chaulagain BP, Tang TH, Citartan M
    Biomed Res Int, 2015;2015:816419.
    PMID: 26161416 DOI: 10.1155/2015/816419
  5. Haarindraprasad R, Hashim U, Gopinath SC, Kashif M, Veeradasan P, Balakrishnan SR, et al.
    PLoS One, 2015;10(7):e0132755.
    PMID: 26167853 DOI: 10.1371/journal.pone.0132755
    The performance of sensing surfaces highly relies on nanostructures to enhance their sensitivity and specificity. Herein, nanostructured zinc oxide (ZnO) thin films of various thicknesses were coated on glass and p-type silicon substrates using a sol-gel spin-coating technique. The deposited films were characterized for morphological, structural, and optoelectronic properties by high-resolution measurements. X-ray diffraction analyses revealed that the deposited films have a c-axis orientation and display peaks that refer to ZnO, which exhibits a hexagonal structure with a preferable plane orientation (002). The thicknesses of ZnO thin films prepared using 1, 3, 5, and 7 cycles were measured to be 40, 60, 100, and 200 nm, respectively. The increment in grain size of the thin film from 21 to 52 nm was noticed, when its thickness was increased from 40 to 200 nm, whereas the band gap value decreased from 3.282 to 3.268 eV. Band gap value of ZnO thin film with thickness of 200 nm at pH ranging from 2 to 10 reduces from 3.263eV to 3.200 eV. Furthermore, to evaluate the transducing capacity of the ZnO nanostructure, the refractive index, optoelectric constant, and bulk modulus were analyzed and correlated. The highest thickness (200 nm) of ZnO film, embedded with an interdigitated electrode that behaves as a pH-sensing electrode, could sense pH variations in the range of 2-10. It showed a highly sensitive response of 444 μAmM-1cm-2 with a linear regression of R2 =0.9304. The measured sensitivity of the developed device for pH per unit is 3.72μA/pH.
  6. 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.
  7. Perumal V, Hashim U, Gopinath SC, Haarindraprasad R, Foo KL, Balakrishnan SR, et al.
    Sci Rep, 2015 Jul 16;5:12231.
    PMID: 26178973 DOI: 10.1038/srep12231
    Hybrid gold nanostructures seeded into nanotextured zinc oxide (ZnO) nanoflowers (NFs) were created for novel biosensing applications. The selected 'spotted NFs' had a 30-nm-thick gold nanoparticle (AuNP) layer, chosen from a range of AuNP thicknesses, sputtered onto the surface. The generated nanohybrids, characterized by morphological, physical and structural analyses, were uniformly AuNP-seeded onto the ZnO NFs with an average length of 2-3 μm. Selective capture of molecular probes onto the seeded AuNPs was evidence for the specific interaction with DNA from pathogenic Leptospirosis-causing strains via hybridization and mis-match analyses. The attained detection limit was 100 fM as determined via impedance spectroscopy. High levels of stability, reproducibility and regeneration of the sensor were obtained. Selective DNA immobilization and hybridization were confirmed by nitrogen and phosphorus peaks in an X-ray photoelectron spectroscopy analysis. The created nanostructure hybrids illuminate the mechanism of generating multiple-target, high-performance detection on a single NF platform, which opens a new avenue for array-based medical diagnostics.
  8. Soo Yean CY, Selva Raju K, Xavier R, Subramaniam S, Gopinath SC, Chinni SV
    PLoS One, 2016;11(7):e0158736.
    PMID: 27367909 DOI: 10.1371/journal.pone.0158736
    Non-protein coding RNA (npcRNA) is a functional RNA molecule that is not translated into a protein. Bacterial npcRNAs are structurally diversified molecules, typically 50-200 nucleotides in length. They play a crucial physiological role in cellular networking, including stress responses, replication and bacterial virulence. In this study, by using an identified npcRNA gene (Sau-02) in Methicillin-resistant Staphylococcus aureus (MRSA), we identified the Gram-positive bacteria S. aureus. A Sau-02-mediated monoplex Polymerase Chain Reaction (PCR) assay was designed that displayed high sensitivity and specificity. Fourteen different bacteria and 18 S. aureus strains were tested, and the results showed that the Sau-02 gene is specific to S. aureus. The detection limit was tested against genomic DNA from MRSA and was found to be ~10 genome copies. Further, the detection was extended to whole-cell MRSA detection, and we reached the detection limit with two bacteria. The monoplex PCR assay demonstrated in this study is a novel detection method that can replicate other npcRNA-mediated detection assays.
  9. 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.
  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. Ge Y, Lakshmipriya T, Gopinath SC, Anbu P, Chen Y, Hariri F, et al.
    Int J Nanomedicine, 2019;14:7851-7860.
    PMID: 31632005 DOI: 10.2147/IJN.S222238
    BACKGROUND: Gestational diabetes mellitus is a commonly occurring metabolic disorder during pregnancy, affecting >4% of pregnant women. It is generally defined as the intolerance of glucose with the onset or initial diagnosis during pregnancy. This illness affects the placenta and poses a threat to the baby as it affects the supply of proper oxygen and nutrients.

    PURPOSE: Due to the high percentage of affected pregnant women, it should be mandatory to evaluate glucose levels during pregnancy and there is a need for a continuous monitoring system.

    METHODS: Herein, the investigators modified the interdigitated (di)electrodes (IDE) sensing surface to detect the glucose on covalently immobilized glucose oxidase (GOx) with the graphene. The characterization of graphene and gold nanoparticle (GNP) was performed by high-resolution microscopy.

    RESULTS: Sensitivity was found to be 0.06 mg/mL and to enhance the detection, GOx was complexed with GNP. GNP-GOx was improved the sensitive detection twofold from 0.06 to 0.03 mg/mL, and it also displayed higher levels of current changes at all the concentrations of glucose that were tested. High-performance of the above IDE sensing system was attested by the specificity, reproducibility and higher sensitivity detections. Further, the linear regression analysis indicated the limit of detection to be between 0.02 and 0.03 mg/mL.

    CONCLUSION: This study demonstrated the potential strategy with nanocomposite for diagnosing gestational diabetes mellitus.

  12. Kerishnan JP, Gopinath SC, Kai SB, Tang TH, Ng HL, Rahman ZA, et al.
    Int J Med Sci, 2016;13(6):424-31.
    PMID: 27279791 DOI: 10.7150/ijms.14475
    The association between human papillomavirus type 16 (HPV16) and oral cancer has been widely reported. However, detecting anti-HPV antibodies in patient sera to determine risk for oral squamous cell carcinoma (OSCC) has not been well studied. In the present investigation, a total of 206 OSCC serum samples from the Malaysian Oral Cancer Database & Tissue Bank System, with 134 control serum samples, were analyzed by enzyme-linked immunosorbant assay (ELISA) to detect HPV16-specific IgG and IgM antibodies. In addition, nested PCR analysis using comprehensive consensus primers (PGMY09/11 and GP5(+)/6(+)) was used to confirm the presence of HPV. Furthermore, we have evaluated the association of various additional causal factors (e.g., smoking, alcohol consumption, and betel quid chewing) in HPV-infected OSCC patients. Statistical analysis of the Malaysian population indicated that OSCC was more prevalent in female Indian patients that practices betel quid chewing. ELISA revealed that HPV16 IgG, which demonstrates past exposure, could be detected in 197 (95.6%) OSCC patients and HPV16-specific IgM was found in a total of 42 (20.4%) OSCC patients, indicating current exposure. Taken together, our study suggest that HPV infection may play a significant role in OSCC (OR: 13.6; 95% CI: 3.89-47.51) and HPV16-specific IgG and IgM antibodies could represent a significant indicator of risk factors in OSCC patients.
  13. 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.
  14. 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.
  15. Perumal V, Hashim U, Gopinath SC, Rajintra Prasad H, Wei-Wen L, Balakrishnan SR, et al.
    Nanoscale Res Lett, 2016 Dec;11(1):31.
    PMID: 26787050 DOI: 10.1186/s11671-016-1245-8
    Generation of hybrid nanostructures has been attested as a promising approach to develop high-performance sensing substrates. Herein, hybrid zinc oxide (ZnO) nanorod dopants with different gold (Au) thicknesses were grown on silicon wafer and studied for their impact on physical, optical and electrical characteristics. Structural patterns displayed that ZnO crystal lattice is in preferred c-axis orientation and proved the higher purities. Observations under field emission scanning electron microscopy revealed the coverage of ZnO nanorods by Au-spots having diameters in the average ranges of 5-10 nm, as determined under transmission electron microscopy. Impedance spectroscopic analysis of Au-sputtered ZnO nanorods was carried out in the frequency range of 1 to 100 MHz with applied AC amplitude of 1 V RMS. The obtained results showed significant changes in the electrical properties (conductance and dielectric constant) with nanostructures. A clear demonstration with 30-nm thickness of Au-sputtering was apparent to be ideal for downstream applications, due to the lowest variation in resistance value of grain boundary, which has dynamic and superior characteristics.
  16. 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.
  17. Nithya R, Ahmed SA, Hoe CH, Gopinath SC, Citartan M, Chinni SV, et al.
    PLoS One, 2015;10(3):e0118668.
    PMID: 25774907 DOI: 10.1371/journal.pone.0118668
    Salmonellosis, a communicable disease caused by members of the Salmonella species, transmitted to humans through contaminated food or water. It is of paramount importance, to generate accurate detection methods for discriminating the various Salmonella species that cause severe infection in humans, including S. Typhi and S. Paratyphi A. Here, we formulated a strategy of detection and differentiation of salmonellosis by a multiplex polymerase chain reaction assay using S. Typhi non-protein coding RNA (sRNA) genes. With the designed sequences that specifically detect sRNA genes from S. Typhi and S. Paratyphi A, a detection limit of up to 10 pg was achieved. Moreover, in a stool-seeding experiment with S. Typhi and S. Paratyphi A, we have attained a respective detection limit of 15 and 1.5 CFU/mL. The designed strategy using sRNA genes shown here is comparatively sensitive and specific, suitable for clinical diagnosis and disease surveillance, and sRNAs represent an excellent molecular target for infectious disease.
  18. 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.
  19. 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.
  20. Arshad MK, Bin Mohamad Fathil MF, Gopinath SC, Ruslinda AR, Md Nor MN, Lam HY, et al.
    Curr Med Chem, 2016;23(37):4270-4284.
    PMID: 27719655
    Cardiovascular disease (CVD) is a major threat to global health, estimated to be the cause 30 % (17.3 million in 2008) of deaths every year, and the number of deaths caused by CVD is expected to increase further, reaching 23.3 million by 2030. Hence, there is a growing demand for simpler sample extraction, rapid screening results, and intervention of the subsequent analysis in emergency units. In this paper, we reviewed CVD biomarkers in blood- and saliva-based specimens. The history of cardiac biomarkers indicates that in the beginning, cardiac troponin I (cTnI) was a widely accepted 'gold standard' marker due to its high specificity and selectivity. Considering the advantages of salivary-based cardiac biomarkers, we examined correlations between non-invasive (salivary) and invasive (blood) diagnoses, and it was found that C-reactive protein (CRP) provides a better correlation. Despite the low abundance of salivary CRP, several reports displayed the detection limit down to pg/ml using existing technologies. Thus, salivary CRP has the potential to be used for future forefront diagnostics for the early assessment of cardiac risks.
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