Displaying publications 1 - 20 of 141 in total

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  1. Fulltext Growth promoting effects of Pluronic F-68 on callus proliferation of recalcitrant rice cultivar
    Kok AD, Wan Abdullah WMAN, Tan NP, Ong-Abdullah J, Sekeli R, Wee CY, et al.
    3 Biotech, 2020 Mar;10(3):116.
    PMID: 32117677 DOI: 10.1007/s13205-020-2118-5
    This study was undertaken to evaluate growth-promoting effects of Pluronic F-68 (PF-68) on recalcitrant MR 219 rice callus. Our study shows that calli grown on Murashige and Skoog medium supplemented with 0.04% PF-68 significantly increased callus proliferation by 58.80% (fresh weight) and 23.98% (dry weight) while root formation from callus was enhanced by 28.57%. Enhanced callus proliferation was supported by biochemical analysis, whereby highest amount of soluble sugar (1.77 mg/mL) and protein (0.17 mg/mL) contents were recorded in calli grown on 0.04% PF-68. Furthermore, enhanced expression of sucrose synthase (2.65-folds) and NADH-dependent glutamate synthase (1.86-folds) genes in calli grown on 0.04% PF-68 also correlates with enhanced callus proliferation. In contrast, high concentration of PF-68 (0.10%) recorded highest amount of phenolic (0.74 mg/mL), flavonoid (0.08 mg/mL), and hydrogen peroxide content (0.06 mg/mL) as compared to other treatment groups indicates activation of plant defence mechanism towards stress. Similarly, high expression of 4-coumarate:CoA ligase 3 (1.28-folds), chalcone-flavonone isomerase (1.65-folds) and ascorbate peroxidase (1.61-folds) genes were observed in calli grown on 0.10% PF-68 further supports increasing stress caused by the high concentration of PF-68. Taken together, our study revealed that optimum concentration of PF-68 could improve recalcitrant rice callus proliferation via enhanced sugar metabolism and amino acid biosynthesis which are crucial towards plant growth and development. However, at high concentration, PF-68 induces stress in plant which enhance the production of secondary metabolite to maintain cellular homeostasis.
  2. Fulltext A simple, portable, electrochemical biosensor to screen shellfish for Vibrio parahaemolyticus
    Nordin N, Yusof NA, Abdullah J, Radu S, Hushiarian R
    AMB Express, 2017 Dec;7(1):41.
    PMID: 28205102 DOI: 10.1186/s13568-017-0339-8
    An earlier electrochemical mechanism of DNA detection was adapted and specified for the detection of Vibrio parahaemolyticus in real samples. The reader, based on a screen printed carbon electrode, was modified with polylactide-stabilized gold nanoparticles and methylene blue was employed as the redox indicator. Detection was assessed using a microprocessor to measure current response under controlled potential. The fabricated sensor was able to specifically distinguish complementary, non-complementary and mismatched oligonucleotides. DNA was measured in the range of 2.0 × 10(-8)-2.0 × 10(-13) M with a detection limit of 2.16 pM. The relative standard deviation for 6 replications of differential pulse voltammetry (DPV) measurement of 0.2 µM complementary DNA was 4.33%. Additionally, cross-reactivity studies against various other food-borne pathogens showed a reliably sensitive detection of the target pathogen. Successful identification of Vibrio parahaemolyticus (spiked and unspiked) in fresh cockles, combined with its simplicity and portability demonstrate the potential of the device as a practical screening tool.
  3. Computed tomography of the brain in predicting outcome of traumatic intracranial haemorrhage in Malaysian patients
    Azian AA, Nurulazman AA, Shuaib L, Mahayidin M, Ariff AR, Naing NN, et al.
    Acta Neurochir (Wien), 2001;143(7):711-20.
    PMID: 11534693
    Head injury is a significant economic, social and medical problem all over the world. Road accidents are the most frequent cause of head injury in Malaysia with highest risk in the young (15 to 24 years old). The associated outcomes include good recovery, possibility of death for the severely injured, which may cause disruption of the lives of their family members. It is important to predict the outcome as it will provide sound information to assist clinicians in Malaysia in providing prognostic information to patients and their families, to assess the effectiveness of different modes of treatment in promoting recovery and to document the significance of head injury as a public health problem.

    RESULTS: A total of 103 cases with intracranial haemorrhage i.e. intracerebral haemorrhage, extradural haemorrhage, subdural haemorrhage, intraventricular haemorrhage, haemorrhagic contusion and subarachnoid haemorrhage, following motor vehicle accidents was undertaken to study factors contributing to either good or poor outcome according to the Glasgow Outcome Scale. Patients below 12 years of age were excluded. The end point of the study was taken at 24 months post injury. The selected variables were incorporated into models generated by logistic regression techniques of multivariate analysis to see the significant predictors of outcome as well as the correlation between the CT findings with GCS.

    CONCLUSION: Significant predictors of outcome were GCS on arrival in the accident emergency department, pupillary reflex and the CT scan findings. The CT predictors of outcome include ICH, EDH, IVH, present of SAH, site of ICH, volumes of EDH and SDH as well as midline shift.

  4. Association of p53 tumor suppressor gene with paraclinical and clinical modalities of gliomas patients in Malaysia
    Yusoff AA, Abdullah J, Abdullah MR, Mohd Ariff AR, Isa MN
    Acta Neurochir (Wien), 2004 Jun;146(6):595-601.
    PMID: 15168228
    Alteration of the tumor suppressor gene p53 is considered to be a critical step in the development of human cancer. Changes in this gene have been detected in a wide range of human tumours, including gliomas. In glioma, the presence of p53 gene alterations has been associated with worse prognosis.
  5. Preliminary report on spiegelberg pre and post-operative monitoring of severe head-injured patients who received decompressive craniectomy
    Abdullah J, Zamzuri I, Awang S, Sayuthi S, Ghani A, Tahir A, et al.
    Acta Neurochir. Suppl., 2005;95:311-4.
    PMID: 16463872
    The monitoring of craniospinal compliance is uncommonly used clinically despite it's value. The Spiegelberg compliance monitor calculates intracranial compliance (C = deltaV/deltaP) from a moving average of small ICP perturbations (deltaP) resulting from a sequence of up to 200 pulses of added volume (deltaV = 0.1 ml, total V = 0.2 ml) made into a double lumen intraventricular balloon catheter. The objective of this study was thus to determine the effectiveness of the decompressive craniectomy done on the worst brain site with regard to compliance (Cl), pressure volume index (PVI), jugular oximetry (SjVo2), autoregulation abnormalties, brain tissue oxygen (TiO2) and cerebral blood flow (CBF). This is a prospective cohort study of 17 patients who were enrolled after consent and approval of the ethics committee between the beginning of the year 2001 and end of the year 2002. For pre and post assessment on compliance and PVI, all 12 patients who survived were reported to become normal after decompressive craniectomy. There is no significant association between pre and post craniectomy assessment in jugular oxymetry (p > 0.05), autoregulation (p > 0.05), intracranial brain oxymetry (p = 0.125) and cerebral blood flow (p = 0.375). Compliance and PVI improved dramatically in all alive patients who received decompressive craniectomy. Compliance and PVI monitoring may be crucial in improving the outcome of severe head injured patients after decompressive craniectomy.
  6. Stacked films immobilization of MBTH in nafion/sol-gel silicate and horseradish peroxidase in chitosan for the determination of phenolic compounds
    Abdullah J, Ahmad M, Heng LY, Karuppiah N, Sidek H
    Anal Bioanal Chem, 2006 Nov;386(5):1285-92.
    PMID: 17031625
    The stacked-film immobilization of 3-methyl-2-benzothiazolinone hydrazone (MBTH) in hybrid nafion/sol-gel silicate film and horseradish peroxidase (HRP) in chitosan, performed in order to allow the determination of phenolic compounds, was investigated via an optical method. The stacked films were deposited onto a microscope glass slide by a spin-coating technique. The quinone or free radical product formed by the enzymatic reactions of phenolic compounds interacts with MBTH to form azo-dye products, which can be measured spectrophotometrically at a wavelength of 500 nm. The color intensity of the product was found to increase in proportion to the phenolic concentration after 5 min of exposure. The response of the biosensor was linear over concentration ranges of 0.025-0.500, 0.010-0.070 and 0.050-0.300 mM for guaiacol, resorcinol and o-cresol, respectively, and gave detection limits of 0.010, 0.005 and 0.012 mM. The sensor exhibited good sensitivity and stability for at least two months.
  7. Biosensor based on glutamate dehydrogenase immobilized in chitosan for the determination of ammonium in water samples
    Azmi NE, Ahmad M, Abdullah J, Sidek H, Heng LY, Karuppiah N
    Anal Biochem, 2009 May 1;388(1):28-32.
    PMID: 19454217 DOI: 10.1016/j.ab.2009.02.005
    An optical biosensor based on glutamate dehydrogenase (GLDH) immobilized in a chitosan film for the determination of ammonium in water samples is described. The biosensor film was deposited on a glass slide via a spin-coating method. The ammonium was measured based on beta-nicotinamide adenine dinucleotide (NADH) oxidation in the presence of alpha-ketoglutaric acid at a wavelength of 340 nm. The biosensor showed optimum activity at pH 8. The optimum chitosan concentrations and enzyme loading were found to be at 2% (w/v) and 0.08 mg, respectively. Optimum concentrations of NADH and alpha-ketoglutaric acid both were obtained at 0.15 mM. A linear response of the biosensor was obtained in the ammonium concentration range of 0.005 to 0.5 mM with a detection limit of 0.005 mM. The reproducibility of the biosensor was good, with an observed relative standard deviation of 5.9% (n=8). The biosensor was found to be stable for at least 1 month when stored dry at 4 degrees C.
  8. Fluorescence-based immunoassay for the detection of Xanthomonas oryzae pv. oryzae in rice leaf
    Awaludin N, Abdullah J, Salam F, Ramachandran K, Yusof NA, Wasoh H
    Anal Biochem, 2020 12 01;610:113876.
    PMID: 32750357 DOI: 10.1016/j.ab.2020.113876
    The identification of rice bacterial leaf blight disease requires a simple, rapid, highly sensitive, and quantitative approach that can be applied as an early detection monitoring tool in rice health. This paper highlights the development of a turn-off fluorescence-based immunoassay for the early detection of Xanthomonas oryzae pv. oryzae (Xoo), a gram-negative bacterium that causes rice bacterial leaf blight disease. Antibodies against Xoo bacterial cells were produced as specific bio-recognition molecules and the conjugation of these antibodies with graphene quantum dots and gold nanoparticles was performed and characterized, respectively. The combination of both these bio-probes as a fluorescent donor and metal quencher led to changes in the fluorescence signal. The immunoreaction between AntiXoo-GQDs, Xoo cells, and AntiXoo-AuNPs in the immuno-aggregation complex led to the energy transfer in the turn-off fluorescence-based quenching system. The change in fluorescence intensity was proportional to the logarithm of Xoo cells in the range of 100-105 CFU mL-1. The limit of detection was achieved at 22 CFU mL-1 and the specificity test against other plant disease pathogens showed high specificity towards Xoo. The detection of Xoo in real plant samples was also performed in this study and demonstrated satisfactory results.
  9. Distribution of prosaposin mRNA in the central nervous system of the pigeon (Columba livia)
    Islam MR, Abdullah JM, Atoji Y
    Anat Histol Embryol, 2013 Aug;42(4):257-65.
    PMID: 22994540 DOI: 10.1111/ahe.12009
    Bioassay and immunohistochemical studies have detected the presence of prosaposin in the central nervous system (CNS) of mammals. Here, first time, we have determined the partial cDNA sequence of pigeon prosaposin and mapped the distribution of its mRNA in the pigeon CNS. The predicted amino acid sequence of pigeon prosaposin showed 93 and 60% identity to chicken and human prosaposin, respectively. In situ hybridization, autoradiograms showed that the prosaposin mRNA expression was found in the olfactory bulb, prepiriform cortex, Wulst, mesopallium, nidopallium, hippocampal formation, thalamus, tuberis nucleus, pre-tectal nucleus, nucleus mesencephalicus lateralis, pars dorsalis, nucleus isthmi, pars parvocellularis and magnocellularis, Edinger-Westphal nucleus, optic tectum, cerebellar cortex and nuclei, vestibular nuclei and gray matter of the spinal cord. These results suggest that the cDNA sequence of pigeon prosaposin is comparable to other vertebrates, and the general distribution pattern of prosaposin mRNA resembles those are found in mammals.
  10. Uniaxial and Multiaxial Fatigue Life Prediction of the Trabecular Bone Based on Physiological Loading: A Comparative Study
    Fatihhi SJ, Harun MN, Abdul Kadir MR, Abdullah J, Kamarul T, Öchsner A, et al.
    Ann Biomed Eng, 2015 Oct;43(10):2487-502.
    PMID: 25828397 DOI: 10.1007/s10439-015-1305-8
    Fatigue assessment of the trabecular bone has been developed to give a better understanding of bone properties. While most fatigue studies are relying on uniaxial compressive load as the method of assessment, in various cases details are missing, or the uniaxial results are not very realistic. In this paper, the effect of three different load histories from physiological loading applied on the trabecular bone were studied in order to predict the first failure surface and the fatigue lifetime. The fatigue behaviour of the trabecular bone under uniaxial load was compared to that of multiaxial load using a finite element simulation. The plastic strain was found localized at the trabecular structure under multiaxial load. On average, applying multiaxial loads reduced more than five times the fatigue life of the trabecular bone. The results provide evidence that multiaxial loading is dominated in the low cycle fatigue in contrast to the uniaxial one. Both bone volume fraction and structural model index were best predictors of failure (p 
  11. Use of bovine xenograft in reconstruction of traumatic anterior cranial fossa bone defects involving the frontal sinus
    Abdullah J, Rushdan A, Hamzah M, Ariff AR, Rani A
    Ann. Transplant., 1999;4(3-4):28-31.
    PMID: 10853777
    Four patients underwent reconstruction of anterior cranial fossa of skull defects between November 1997 and January 1998. All of them had traumatic anterior cranial fossa defect and were reconstructed with lyophilised bovine cortical bone graft. There was no cerebrospinal fluid leakage, meningitis, extradural abscess or other infections. This study demonstrates that the use of bovine bone graft in the reconstruction of anterior base defects is safe.
  12. Preparation and quantification of radioactive particles for tracking hydrodynamic behavior in multiphase reactors
    Yunos MA, Hussain SA, Yusoff HM, Abdullah J
    Appl Radiat Isot, 2014 Sep;91:57-61.
    PMID: 24907683 DOI: 10.1016/j.apradiso.2014.05.015
    Radioactive particle tracking (RPT) has emerged as a promising and versatile technique that can provide rich information about a variety of multiphase flow systems. However, RPT is not an off-the-shelf technique, and thus, users must customize RPT for their applications. This paper presents a simple procedure for preparing radioactive tracer particles created via irradiation with neutrons from the TRIGA Mark II research reactor. The present study focuses on the performance evaluation of encapsulated gold and scandium particles for applications as individual radioactive tracer particles using qualitative and quantitative neutron activation analysis (NAA) and an X-ray microcomputed tomography (X-ray Micro-CT) scanner installed at the Malaysian Nuclear Agency.
  13. Prevalence of BCR-ABL T315I Mutation in Malaysian Patients with Imatinib-Resistant Chronic Myeloid Leukemia
    Mat Yusoff Y, Abu Seman Z, Othman N, Kamaluddin NR, Esa E, Zulkiply NA, et al.
    Asian Pac J Cancer Prev, 2018 Dec 25;19(12):3317-3320.
    PMID: 30583336
    Objective: Chronic Myeloid Leukemia (CML) is caused by a reciprocal translocation between chromosomes 9
    and 22, t(9;22) (q34;q11) which encodes for the BCR-ABL fusion protein. Discovery of Imatinib Mesylate (IM) as
    first line therapy has brought tremendous improvement in the management of CML. However, emergence of point
    mutations within the BCR-ABL gene particularly T315I mutation, affects a common BCR-ABL kinase contact residue
    which impairs drug binding thus contribute to treatment resistance. This study aims to investigate the BCR-ABL T315I
    mutation in Malaysian patients with CML. Methods: A total of 285 patients diagnosed with CML were included in this
    study. Mutation detection was performed using qualitative real-time PCR (qPCR). Results: Fifteen out of 285 samples
    (5.26%) were positive for T315I mutations after amplification with real-time PCR assay. From the total number of
    positive samples, six patients were in accelerated phase (AP), four in chronic phase (CP) and five in blast crisis (BC).
    Conclusion: Mutation testing is recommended for choosing various tyrosine kinase inhibitors (TKIs) to optimize
    outcomes for both cases of treatment failure or suboptimal response to imatinib. Therefore, detection of T315I mutation
    in CML patients are clinically useful in the selection of appropriate treatment strategies to prevent disease progression.
  14. Fulltext Identification of FLT3 and NPM1 Mutations in Patients with Acute Myeloid Leukaemia
    Mat Yusoff Y, Abu Seman Z, Othman N, Kamaluddin NR, Esa E, Zulkiply NA, et al.
    Asian Pac J Cancer Prev, 2019 06 01;20(6):1749-1755.
    PMID: 31244296 DOI: 10.31557/APJCP.2019.20.6.1749
    Objective: The most frequent acquired molecular abnormalities and important prognostic indicators in patients
    with Acute Myeloid Leukaemia (AML) are fms-like tyrosine kinase-3 gene (FLT3) and nucleophosmin-1 (NPM1)
    mutations. Our study aims to develop a cost effective and comprehensive in-house conventional PCR method for
    detection of FLT3-ITD, FLT3-D835 and NPM1 mutations and to evaluate the frequency of these mutations in patients
    with cytogenetically normal (CN) AML in our population. Methods: A total of 199 samples from AML patients (95
    women, 104 men) were included in the study. Mutation analyses were performed using polymerase chain reaction
    (PCR) and gene sequencing. Result: Sixty-eight patients were positive for the mutations. FLT3-ITD mutations were
    detected in 32 patients (16.1%), followed by FLT3-D835 in 5 (2.5%) and NPM1 in 54 (27.1%). Double mutations of
    NPM1 and FLT3-ITD were detected in 23 cases (11.6%). Assays validation were performed using Sanger sequencing
    and showed 100% concordance with in house method. Conclusion: The optimized in-house PCR assays for the
    detection of FLT3-ITD, FLT3-D835 and NPM1 mutations in AML patients were robust, less labour intensive and cost
    effective. These assays can be used as diagnostic tools for mutation detection in AML patients since identification of
    these mutations are important for prognostication and optimization of patient care.
  15. Malignant paraganglioma of frontoethmoidal region
    Sharma HS, Madhavan M, Othman NH, Muhamad M, Abdullah JM
    Auris Nasus Larynx, 1999 Oct;26(4):487-93.
    PMID: 10530746
    Nonchromaffin paragangliomas are unusual tumours arising from widely distributed paraganglionic tissues probably of neural crest origin. In the head and neck region they are usually seen as carotid body or jugulotympanic tumours. Other rarely reported sites in the head and neck region are the orbit, nose and larynx. This report deals with a case of sinonasal paraganglioma which was initially treated with surgery and radiotherapy. Twenty two years later the tumour recurred and showed a rapid growth due to malignant transformation which we believe is late effect of radiotherapy. The clinical features, histopathology and role of radiotherapy in sinonasal paragangliomas together with a review of the medical literature have been discussed.
  16. Fulltext Training simulated patients: evaluation of a training approach using self-assessment and peer/tutor feedback to improve performance
    Perera J, Perera J, Abdullah J, Lee N
    BMC Med Educ, 2009;9:37.
    PMID: 19563621 DOI: 10.1186/1472-6920-9-37
    BACKGROUND: Most medical schools use simulated patients (SPs) for teaching. In this context the authenticity of role play and quality of feedback provided by SPs is of paramount importance. The available literature on SP training mostly addresses instructor led training where the SPs are given direction on their roles. This study focuses on the use of peer and self evaluation as a tool to train SPs.
    METHODS: SPs at the medical school participated in a staff development and training programme which included a) self-assessment of their performance while observing video-tapes of their role play using a structured guide and b) peer group assessment of their performance under tutor guidance. The pre and post training performance in relation to authenticity of role play and quality of feedback was blindly assessed by students and tutors using a validated instrument and the scores were compared. A focus group discussion and a questionnaire assessed acceptability of the training programme by the SPs.
    RESULTS: The post-training performance assessment scores were significantly higher (p < 0.05) than the pre-training scores. The degree of improvement in the quality of feedback provided to students was more when compared to the improvement of role play. The acceptability of the training by the SPs was very satisfactory scoring an average of 7.6 out of 10. The majority of the SPs requested the new method of training to be included in their current training programme as a regular feature.
    CONCLUSION: Use of structured self-reflective and peer-interactive, practice based methods of SP training is recommended to improve SP performance. More studies on these methods of training may further refine SP training and lead to improvement of SP performance which in turn may positively impact medical education.
  17. Mouse model of intracerebellar haemorrhage
    Tijjani Salihu A, Muthuraju S, Aziz Mohamed Yusoff A, Ahmad F, Zulkifli Mustafa M, Jaafar H, et al.
    Behav Brain Res, 2016 10 01;312:374-84.
    PMID: 27327104 DOI: 10.1016/j.bbr.2016.06.034
    The present study aimed to investigate the behavior and neuronal morphological changes in the perihaemorrhagic tissue of the mouse intracerebellar haemorrhage experimental model. Adult male Swiss albino mice were stereotactically infused with collagenase type VII (0.4U/μl of saline) unilaterally in to the cerebellum, following anaesthesia. Motor deficits were assessed using open field and composite score for evaluating the mouse model of cerebellar ataxia at 1, 3, 7, 14 and 21 days after collagenase infusion. The animals were sacrificed at the same time interval for evaluation of perihaematomal neuronal degeneration using haematoxylin and eosin staining and Annexin V-FITC/Propidium iodide assay. At the end of the study, it was found that infusion of 0.4U collagenase produces significant locomotor and ataxic deficit in the mice especially within the first week post surgery, and that this gradually improved within three weeks. Neuronal degeneration evident by cytoplasmic shrinkage and nuclear pyknosis was observed at the perihaematomal area after one day; especially at 3 and 7 days post haemorrhage. By 21 days, both the haematoma and degenerating neurons in the perihaematomal area were phagocytosed and the remaining neuronal cells around the scar tissue appeared normal. Moreover, Annexin-V/propidium iodide-positive cells were observed at the perihaematomal area at 3 and 7 days implying that the neurons likely die via apoptosis. It was concluded that a population of potentially salvageable neurons exist in the perihaematomal area after cerebellar haemorrhage throughout a wide time window that could be amenable to treatment.
  18. Fulltext Promoter Cis-Element Analyses Reveal the Function of αVPE in Drought Stress Response of Arabidopsis
    Tang CN, Wan Abdullah WMAN, Wee CY, Balia Yusof ZN, Yap WS, Cheng WH, et al.
    Biology (Basel), 2023 Mar 10;12(3).
    PMID: 36979122 DOI: 10.3390/biology12030430
    Vacuolar processing enzyme (VPE) is a cysteine protease responsible for vacuolar proteins' maturation and regulation of programmed cell death (PCD). Four isoforms of Arabidopsis thaliana VPEs were identified previously, but only the functions of βVPE, γVPE, and δVPE were determined. The specific function of a gene is linked to the cis-acting elements in the promoter region. A promoter analysis found repetitive drought-related cis-elements in αVPE, which highlight its potential involvement in drought regulation in A. thaliana. The further co-expression network portraying genes interacting with αVPE substantiated its drought-regulation-related function. Expression of αVPE was upregulated after drought treatment in A. thaliana. To confirm the role of αVPE, a loss of function study revealed that αVPE knockout mutants remained green compared with WT after drought treatment. The mutants had reduced proline activity, decreased sucrose content, and lower MDA content, but increased photosynthetic pigments, indicating that αVPE negatively regulates drought tolerance in A. thaliana. Taken together, our findings serve as important evidence of the involvement of αVPE in modulating drought tolerance in A. thaliana.
  19. Fulltext Advances in Aptamer-Based Biosensors and Cell-Internalizing SELEX Technology for Diagnostic and Therapeutic Application
    Gan Z, Roslan MAM, Abd Shukor MY, Halim M, Yasid NA, Abdullah J, et al.
    Biosensors (Basel), 2022 Oct 25;12(11).
    PMID: 36354431 DOI: 10.3390/bios12110922
    Aptamers are a group of synthetic single-stranded nucleic acids. They are generated from a random library of single-stranded DNA or RNA by a technology named systematic evolution of ligands by exponential enrichment (SELEX). SELEX is a repetitive process to select and identify suitable aptamers that show high affinity and specificity towards target cells. Great strides have been achieved in the design, construction, and use of aptamers up to this point. However, only a small number of aptamer-based applications have achieved widespread commercial and clinical acceptance. Additionally, finding more effective ways to acquire aptamers with high affinity remains a challenge. Therefore, it is crucial to thoroughly examine the existing dearth and advancement in aptamer-related technologies. This review focuses on aptamers that are generated by SELEX to detect pathogenic microorganisms and mammalian cells, as well as in cell-internalizing SELEX for diagnostic and therapeutic purposes. The development of novel aptamer-based biosensors using optical and electrical methods for microbial detection is reported. The applications and limitations of aptamers are also discussed.
  20. A simple and sensitive fluorescence based biosensor for the determination of uric acid using H2O2-sensitive quantum dots/dual enzymes
    Azmi NE, Ramli NI, Abdullah J, Abdul Hamid MA, Sidek H, Abd Rahman S, et al.
    Biosens Bioelectron, 2015 May 15;67:129-33.
    PMID: 25113659 DOI: 10.1016/j.bios.2014.07.056
    A novel optical detection system consisting of combination of uricase/HRP-CdS quantum dots (QDs) for the determination of uric acid in urine sample is described. The QDs was used as an indicator to reveal fluorescence property of the system resulting from enzymatic reaction of uricase and HRP (horseradish peroxidase), which is involved in oxidizing uric acid to allaintoin and hydrogen peroxide. The hydrogen peroxide produced was able to quench the QDs fluorescence, which was proportional to uric acid concentration. The system demonstrated sufficient activity of uricase and HRP at a ratio of 5U:5U and pH 7.0. The linearity of the system toward uric acid was in the concentration range of 125-1000 µM with detection limit of 125 µM.
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