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Fulltext Sensitive Detection of Dengue Virus Type 2 E-Proteins Signals Using Self-Assembled Monolayers/Reduced Graphene Oxide-PAMAM Dendrimer Thin Film-SPR Optical Sensor

Omar NAS, Fen YW, Abdullah J, Mustapha Kamil Y, Daniyal WMEMM, Sadrolhosseini AR, et al.

Sci Rep, 2020 02 11;10(1):2374.
PMID: 32047209 DOI: 10.1038/s41598-020-59388-3

In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM-1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.
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.
Three-dimensional analysis of reconstructed skulls using three different open-source software versus commercial software

Yap Abdullah J, Manaf Abdullah A, Zaim S, Hadi H, Husein A, Ahmad Rajion Z, et al.

Proc Inst Mech Eng H, 2024 Jan;238(1):55-62.
PMID: 37990963 DOI: 10.1177/09544119231212034

This study aimed to compare the 3D skull models reconstructed from computed tomography (CT) images using three different open-source software with a commercial software as a reference. The commercial Mimics v17.0 software was used to reconstruct the 3D skull models from 58 subjects. Next, two open-source software, MITK Workbench 2016.11, 3D Slicer 4.8.1 and InVesalius 3.1 were used to reconstruct the 3D skull models from the same subjects. All four software went through similar steps in 3D reconstruction process. The 3D skull models from the commercial and open-source software were exported in standard tessellation language (STL) format into CloudCompare v2.8 software and superimposed for geometric analyses. Hausdorff distance (HD) analysis demonstrated the average points distance of Mimics versus MITK was 0.25 mm. Meanwhile, for Mimics versus 3D Slicer and Mimics versus InVesalius, there was almost no differences between the two superimposed 3D skull models with average points distance of 0.01 mm. Based on Dice similarity coefficient (DSC) analysis, the similarity between Mimics versus MITK, Mimics versus 3D Slicer and Mimics versus InVesalius were 94.1, 98.8 and 98.3%, respectively. In conclusion, this study confirmed that the alternative open-source software, MITK, 3D Slicer and InVesalius gave comparable results in 3D reconstruction of skull models compared to the commercial gold standard Mimics software. This open-source software could possibly be used for pre-operative planning in cranio-maxillofacial cases and for patient management in the hospitals or institutions with limited budget.
Fulltext Liquid distribution study in a Katapak-SP12 column using X-ray tomography

Aferka, S., Abdullah, J., Olujic, Z., Saroha, A.K., Crine, M., Toye, D., et al.

Journal of Nuclear and Related Technologies, 2006;2006(1):25-34.
MyJurnal

This work focuses on the use of X-ray tomography in investigating the flow distribution in a structured packed bed. Cross sections of the liquid hold up distribution in a 10 cm diameter column packed with Katapak-SP12 are obtained at various column heights for different liquid flow rates. The repartition of the liquid hold up between baskets and corrugated sheets is quantified. Wall wipers and column wall effects are visualized. Results are obtained from an initially dry column without gas flow.
Voltammetric determination of iodide in iodized table salt using cetyltrimethylammonium bromide as ion-pairing

Jamilan MA, Abdullah J, Alang Ahmad SA, Md Noh MF

J Food Sci Technol, 2019 Aug;56(8):3846-3853.
PMID: 31413410 DOI: 10.1007/s13197-019-03855-x

In this work, voltammetric study based on cetyltrimethylammonium bromide (CTAB) as an ion-pairing agent for the determination of iodine level in iodized table salt has been explored. CTAB was used as an intermediate compound between iodide (I-) and the electrode due to its ability to dissociate to produce cetyltrimethylammonium ions ([CTA]+). The [CTA]+ with a long hydrophobic alkyl chain can be directly adsorbed onto the surface of the working electrode, and this in turns coated the electrode with cationic charge and enhance the electrode ability to bind to iodide (I-) and other molecular iodine ions. A mixture of iodide and CTAB ([CTA]+I-) was prepared and potential of 1.0 V for 60.0 s was applied to pre-concentrate the solution on the working electrode causing the [CTA]+I- to oxidize to iodine (I2). The produced I2 immediately react with chloride ion (Cl-) from the electrolyte of hydrochloric acid (HCl) to produce I2Cl- and form ion-pair with CTA+ as [CTA]+I2Cl-. The linear calibration curve of the developed method towards iodide was in the concentration range of 0.5-4.0 mg/L with sensitivity of - 1.383 µA mg/L-1 cm-2 (R2 = 0.9950), limit of detection (LOD) of 0.3 mg/L and limit of quantification (LOQ) of 1.0 mg/L, respectively. The proposed method indicates good agreement with the standard method for iodine determination with recovery range from 95.0 to 104.3%. The developed method provided potential application as a portable on-site iodine detector.
Fulltext Sandwich Electrochemical Immunosensor for Early Detection of Tuberculosis Based on Graphene/Polyaniline-Modified Screen-Printed Gold Electrode

Mohd Azmi UZ, Yusof NA, Kusnin N, Abdullah J, Suraiya S, Ong PS, et al.

Sensors (Basel), 2018 Nov 14;18(11).
PMID: 30441776 DOI: 10.3390/s18113926

A rapid and sensitive sandwich electrochemical immunosensor was developed based on the fabrication of the graphene/polyaniline (GP/PANI) nanocomposite onto screen-printed gold electrode (SPGE) for detection of tuberculosis biomarker 10-kDa culture filtrate protein (CFP10). The prepared GP/PANI nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The chemical bonding and morphology of GP/PANI-modified SPGE were studied by Raman spectroscopy and FESEM coupled with energy dispersive X-ray spectroscopy, respectively. From both studies, it clearly showed that GP/PANI was successfully coated onto SPGE through drop cast technique. Cyclic voltammetry was used to study the electrochemical properties of the modified electrode. The effective surface area for GP/PANI-modified SPGE was enhanced about five times compared with bare SPGE. Differential pulse voltammetry was used to detect the CFP10 antigen. The GP/PANI-modified SPGE that was fortified with sandwich type immunosensor exhibited a wide linear range (20⁻100 ng/mL) with a low detection limit of 15 ng/mL. This proposed electrochemical immunosensor is sensitive, low sample volume, rapid and disposable, which is suitable for tuberculosis detection in real samples.
Orbital Morphometry: A Computed Tomography Analysis

Singh J, Rahman RA, Rajion ZA, Abdullah J, Mohamad I

J Craniofac Surg, 2017 Jan;28(1):e64-e70.
PMID: 27922969 DOI: 10.1097/SCS.0000000000003218

INTRODUCTION: The human orbit is a complex anatomic region, which plays predominant role in the evaluation of craniofacial complex. A thorough understanding of the relationship of the distance from orbital rim to the important vital structures of the orbital apex is required for the surgeon to perform safe and effective surgery.
OBJECTIVES: To evaluate and compare the depth and distances from various points of the orbital rim to the fissures and foramina of the orbital apex between genders in the local population.
METHODOLOGY: Linear measurements were conducted on 60 orbits from 30 patients who had undergone head computed tomography scan. These measurements were done utilizing the multiplanar reconstruction modes on computed tomography images with minimum slice thickness of 1 mm.
RESULTS: Males have statistically significant larger orbits than females with higher mean measurements in all parameters, except for the distance from posterior ethmoidal foramen to the optic canal which was the same. However, there were no significant differences in all parameters between the right and left orbits.
CONCLUSION: This study provides the absolute limit of safe internal orbital dissection in respect to the local population. Despite males having larger orbits than females, it is clinically negligible.
Rapid detection of Salmonella Typhi by loop-mediated isothermal amplification (LAMP) method

Abdullah J, Saffie N, Sjasri FA, Husin A, Abdul-Rahman Z, Ismail A, et al.

Braz J Microbiol, 2014;45(4):1385-91.
PMID: 25763045

An in-house loop-mediated isothermal amplification (LAMP) reaction was established and evaluated for sensitivity and specificity in detecting the presence of Salmonella Typhi (S. Typhi) isolates from Kelantan, Malaysia. Three sets of primers consisting of two outer and 4 inner were designed based on locus STBHUCCB_38510 of chaperone PapD of S. Typhi genes. The reaction was optimised using genomic DNA of S. Typhi ATCC7251 as the template. The products were visualised directly by colour changes of the reaction. Positive results were indicated by green fluorescence and negative by orange colour. The test was further evaluated for specificity, sensitivity and application on field samples. The results were compared with those obtained by gold standard culture method and Polymerase Chain Reaction (PCR). This method was highly specific and -10 times more sensitive in detecting S. Typhi compared to the optimised conventional polymerase chain reaction (PCR) method.
Fulltext Immuno Nanosensor for the Ultrasensitive Naked Eye Detection of Tuberculosis

Mohd Bakhori N, Yusof NA, Abdullah J, Wasoh H, Md Noor SS, Ahmad Raston NH, et al.

Sensors (Basel), 2018 Jun 14;18(6).
PMID: 29899214 DOI: 10.3390/s18061932

In the present study, a beneficial approach for the ultrasensitive and affordable naked eye detection and diagnosis of tuberculosis (TB) by utilizing plasmonic enzyme-linked immunosorbent assay (ELISA) via antibody-antigen interaction was studied. Here, the biocatalytic cycle of the intracellular enzymes links to the formation and successive growth of the gold nanoparticles (GNPs) for ultrasensitive detection. The formation of different colored solutions by the plasmonic nanoparticles in the presence of enzyme labels links directly to the existence or non-existence of the TB analytes in the sample solutions. For disease detection, the adapted protocol is based mainly on the conventional ELISA procedure that involves catalase-labeled antibodies, i.e., the enzymes consume hydrogen peroxide and further produce GNPs with the addition of gold (III) chloride. The amount of hydrogen peroxide remaining in the solution determines whether the GNPs solution is to be formed in the color blue or the color red, as it serves as a confirmation for the naked eye detection of TB analytes. However, the conventional ELISA method only shows tonal colors that need a high concentration of analyte to achieve high confidence levels for naked eye detection. Also, in this research, we proposed the incorporation of protein biomarker, Mycobacterium tuberculosis ESAT-6-like protein esxB (CFP-10), as a means of TB detection using plasmonic ELISA. With the use of this technique, the CFP-10 detection limit can be lowered to 0.01 µg/mL by the naked eye. Further, our developed technique was successfully tested and confirmed with sputum samples from patients diagnosed with positive TB, thereby providing enough evidence for the utilization of our technique in the early diagnosis of TB disease.
Teratocarcinosarcoma of the nasal cavity and ethmoid

Sharma HS, Abdullah JM, Othman NH, Muhamad M

J Laryngol Otol, 1998 Jul;112(7):682-6.
PMID: 9775307

Sinonasal teratocarcinosarcoma is very unusual malignant neoplasm histologically consisting of an epithelial element and one or more mesenchymal components. This is a report of teratocarcinosarcoma, in a 74-year-old male, involving the right nasal cavity and ethmoids with intracranial extension. The tumour was totally resected via the craniofacial approach and the patient was given post-operative chemotherapy. Extensive tumour necrosis, rapid growth and local destruction are the prominent features of this tumour. The clinical presentation, pathological features and clinical course of this rare malignancy are discussed with a review of the literature.
Referral of epileptic patients in North East Coast of West Malaysia an area with poor MRI coverage: an analysis

Mohamed Y, Alias NN, Shuaib IL, Tharakan J, Abdullah J, Munawir AH, et al.

Southeast Asian J. Trop. Med. Public Health, 2006 Nov;37(6):1199-208.
PMID: 17333778

Advances in neuroimaging techniques, particularly Magnetic Resonance Imaging (MRI), have proved invaluable in detecting structural brain lesions in patients with epilepsy in developed countries. In Malaysia, a few electroencephalography facilities available in rural district hospitals run by trained physician assistants have Internet connections to a government neurological center in Kuala Lumpur. These facilities are more commonly available than MRI machines, which require radiological expertise and helium replacement, which may problematic in Southeast Asian countries where radiologists are found in mainly big cities or towns. We conducted a cross-sectional study over a two year period begining January 2001 on rural patients, correlating EEG reports and MRI images with a clinical diagnosis of epilepsy to set guidelines for which rural patients need to be referred to a hospital with MRI facilities. The patients referred by different hospitals without neurological services were classified as having generalized, partial or unclassified seizures based on the International Classification of Epileptic Seizures proposed by the International League Against Epilepsy (ILAE). The clinical parameters studied were seizure type, seizure frequency, status epilepticus and duration of seizure. EEG reports were reviewed for localized and generalized abnormalities and epileptiform changes. Statistical analysis was performed using logistic regression and area under the curve. The association between clinical and radiological abnormalities was evaluated for sensitivity and specificity. Twenty-six males and 18 females were evaluated. The mean age was 20.7 +/- 13.3 years. Nineteen (43.2%) had generalized seizures, 22 (50.0%) had partial seizures and 3 (6.8%) presented with unclassified seizures. The EEG was abnormal in 30 patients (20 with generalized abnormalities and 10 localized abnormalities). The MRI was abnormal in 17 patients (38.6%); the abnormalities observed were cerebral atrophy (5), hippocampal sclerosis (4), infarct/gliosis (3), cortical dysgenesis (2) and tumors (2). One patient had an arachnoid cyst in the right occipital region. Of the 17 patients with an abnormal MRI, 14 had an abnormal EEG, this difference was not statistically significant. There was no significant associaton between epileptographic changes and MRI findings (p = 0.078). EEG findings were associated with MRI findings (p = 0.004). The association between an abnormal EEG and an abnormal MRI had a specificity of 82.4%, while epileptogenic changes had a specificity of 64.7% in relation to abnormal MRI findings. This meants that those patients in rural hospitals with abnormal EEGs should be referred to a neurology center for further workup and an MRI to detect causes with an epileptic focus.
Fulltext The prognostic value of early follow-up computerized tomography of the brain in adult traumatic brain injury

Kiflie A, Alias NA, Abdul-Kareem MM, Mar W, Abdullah J, Naing NN

Med J Malaysia, 2006 Oct;61(4):466-73.
PMID: 17243525 MyJurnal

A total of 31 adult patients with moderate and severe head injury were assessed clinically on admission for Glasgow Coma Scale (GCS) and short test of mental status (STMS) on follow-up and compared to their initial and follow up CT scan. Good predictors were admission GCS, midline shift, volume of subdural haemorrhage in the initial CT scan of the brain as well as the presence of post-traumatic hydrocephalus, gliosis and site of gliosis in the follow-up CT scan. There was no direct correlation between the significant predictors on the first CT scan and the follow-up CT scan of the brain.
A study of the factors related to intima-media thickness of the common carotid artery amongst rural middle age individuals in Hospital Universiti Sains Malaysia

Yunus R, Ariff AR, Shuaib IL, Jelani AM, Alias NA, Abdullah J, et al.

Southeast Asian J. Trop. Med. Public Health, 2006 Jul;37(4):806-11.
PMID: 17121310

There is very little data regarding the factors related to intima-media thickness (IMT) of the common carotid artery in normal individuals in those with non-insulin diabetes mellitus and perimenopausal women in Southeast Asian countries. Ultrasound imaging evaluating the carotid artery IMT in those with diabetes and those on hormone replacement therapy (HRT) was performed beginning in August 2000 for a period of nearly two years at the Department of Radiology, Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. A total of 153 participants were included. Significant differences between the women on HRT and not on HRT were IMT and systolic blood pressure. When comparing those with non-insulin dependent diabetes mellitus (NIDDM) and normal individuals, the significant differences were IMT, total cholesterol level, systolic blood pressure and diastolic blood pressure. IMT was high in those with NIDDM but not in those on HRT. Both those with NIDDM and those on HRT had associated dyslipidemia and systolic hypertension.
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.
CT scan in minor head injury: a guide for rural doctors

Abdul Latip LS, Ahmad Alias NA, Ariff AR, Shuaib IL, Abdullah J, Naing NN

J Clin Neurosci, 2004 Nov;11(8):835-9.
PMID: 15519858 DOI: 10.1016/j.jocn.2003.12.017

Minor head injury in a developing country like Malaysia is managed by primary care physicians and/or medical assistants in district hospitals. These patients are seen initially in their local hospitals, which have at least an X-ray machine for the purpose of screening. This study aimed to guide these physicians to manage these patients at a primary care level. A cross-sectional study was conducted and the study revealed significant predictors of significant computed tomographic (CT) findings. The presence of a Glasgow coma scale (GCS) score of 14 or 13 was associated with the risk of developing significant CT findings compared to patients with a GCS of 15 (p<0.001). Thirty-seven out of 50 patients with GCS of 14 or 13 developed clinically significant brain injury on CT scan. Similarly, the presence of skull fracture was associated with the risk of developing CT abnormalities (p<0.001). Forty-two out of 51 patients with skull fracture developed clinically significant CT findings. Vomiting was associated with developing CT abnormalities (p=0.017). Twenty-seven out of 40 patients with vomiting showed significant CT findings. Soft tissue injury was also found to be associated with developing CT abnormalities (p=0.007). Therefore, we propose reclassifying minor head injury based on the GCS score. Patients with a GCS score of 15 were classified as having mild head injury, while patients with a GCS score of 13 or 14 were at higher risk of developing brain injury and therefore categorized as high risk mild head injury. This group requires emergency CT scan examination, especially when associated with non-motor vehicle accidents, abnormal central nervous system (CNS) examination, craniofacial injuries or skull fractures. They should be referred to a general surgical unit which can treat head injuries or a neurosurgical tertiary centre.
Stereotactic neuroendoscopic management of hydrocephalus: a three-year follow-up and analysis of Malaysian children with aqueduct stenosis

Abdullah J, Ariff AR, Ghazaime G, Naing NN

Stereotact Funct Neurosurg, 2001;76(3-4):175-80.
PMID: 12378096

The beneficial effects of stereotactic third ventriculostomy versus ventriculoperitoneal shunt were evaluated in 62 paediatric patients and analysed in relation to age, sex, clinical history, presence of meningomyelocele, magnetic resonance imaging measurements of hydrocephalus and third ventricle floor size. The third ventriculostomy were done on 50 patients using the Richard-Wolf Caemaert Endoscope and the Leksell Stereotactic Frame Model G. These patients were operated using the 4-French Fogarty catheter to open the base of the third ventricle. During the same period of study 12 paediatric patients with aqueduct stenosis who were managed by ventriculoperitoneal shunt were included. Both surgical procedures were compared. Statistically univariate analysis revealed that those patient with an age group of more than six months undergoing ventriculostomy had good outcome. Multivariate analysis revealed that past history of haemorrhage and/or meningitis were predictors of poor outcome. Sex, size of lumbar meningocele at birth, abnormal ventricular anatomy or narrow third ventricular floor size were non predictors of bad outcome in these patients. There was no difference in outcome in both the shunt or ventriculostomy group.
Fulltext Computed tomography perfusion of ischaemic stroke patients in a rural Malaysian tertiary referral centre

Man K, Kareem AM, Ahmad Alias NA, Shuaib IL, Tharakan J, Abdullah JM, et al.

Singapore Med J, 2006 Mar;47(3):194-7.
PMID: 16518552

Computed tomography (CT) perfusion is a new method to diagnose ischaemic stroke especially in developing countries. It identifies the area and is useful to predict the size of final infarction. The aim of this study was to assess cerebral ischaemia with CT perfusion (CTP) among patients with acute ischaemic stroke in Hospital Universiti Sains Malaysia, a tertiary referral centre in a rural setting.
Hydrocephalic children presenting to a Malaysian community-based university hospital over an 8-year period

Abdullah J, Naing NN

Pediatr Neurosurg, 2001 Jan;34(1):13-9.
PMID: 11275782

There are few local statistics on the incidence of hydrocephalus and the outcome of hydrocephalic shunts in the South East Asian region. We report a retrospective study on 285 hydrocephalic patients who underwent shunting procedures between 1990 and 1998 at the University Hospital Science Malaysia, a regional referral center. Multiple logistic regression analysis was applied to predict determinants of outcome in relation to the timing of diagnosis, other congenital abnormalities associated with the hydrocephalus, timing of surgery and cortical thickness from CT scan. The relationship of shunt infection was correlated to the age of the patient and surgical procedure. The predictors for developmental outcome reported by this study were age at diagnosis, type of brain abnormalities and gender. Time of operation and cortical thickness did not contribute to the outcome.
Fulltext Thiolate-Capped CdSe/ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose

Abd Rahman S, Ariffin N, Yusof NA, Abdullah J, Mohammad F, Ahmad Zubir Z, et al.

Sensors (Basel), 2017 Jul 01;17(7).
PMID: 28671559 DOI: 10.3390/s17071537

A semiconducting water-soluble core-shell quantum dots (QDs) system capped with thiolated ligand was used in this study for the sensitive detection of glucose in aqueous samples. The QDs selected are of CdSe-coated ZnS and were prepared in house based on a hot injection technique. The formation of ZnS shell at the outer surface of CdSe core was made via a specific process namely, SILAR (successive ionic layer adsorption and reaction). The distribution, morphology, and optical characteristics of the prepared core-shell QDs were assessed by transmission electron microscopy (TEM) and spectrofluorescence, respectively. From the analysis, the results show that the mean particle size of prepared QDs is in the range of 10-12 nm and that the optimum emission condition was displayed at 620 nm. Further, the prepared CdSe/ZnS core shell QDs were modified by means of a room temperature ligand-exchange method that involves six organic ligands, L-cysteine, L-histidine, thio-glycolic acid (TGA or mercapto-acetic acid, MAA), mercapto-propionic acid (MPA), mercapto-succinic acid (MSA), and mercapto-undecanoic acid (MUA). This process was chosen in order to maintain a very dense water solubilizing environment around the QDs surface. From the analysis, the results show that the CdSe/ZnS capped with TGA (CdSe/ZnS-TGA) exhibited the strongest fluorescence emission as compared to others; hence, it was tested further for the glucose detection after their treatment with glucose oxidase (GOx) and horseradish peroxidase (HRP) enzymes. Here in this study, the glucose detection is based on the fluorescence quenching effect of the QDs, which is correlated to the oxidative reactions occurred between the conjugated enzymes and glucose. From the analysis of results, it can be inferred that the resultant GOx:HRP/CdSe/ZnS-TGA QDs system can be a suitable platform for the fluorescence-based determination of glucose in the real samples.
Label-free optical spectroscopy for characterizing binding properties of highly sensitive nanocrystalline cellulose-graphene oxide based nanocomposite towards nickel ion

Daniyal WMEMM, Fen YW, Abdullah J, Sadrolhosseini AR, Saleviter S, Omar NAS

Spectrochim Acta A Mol Biomol Spectrosc, 2019 Apr 05;212:25-31.
PMID: 30594850 DOI: 10.1016/j.saa.2018.12.031

Surface plasmon resonance (SPR) is a label-free optical spectroscopy that is widely used for biomolecular interaction analysis. In this work, SPR was used to characterize the binding properties of highly sensitive nanocrystalline cellulose-graphene oxide based nanocomposite (CTA-NCC/GO) towards nickel ion. The formation of CTA-NCC/GO nanocomposite has been confirmed by FT-IR. The SPR analysis result shows that the CTA-NCC/GO has high binding affinity towards Ni2+ from 0.01 until 0.1 ppm with binding affinity constant of 1.620 × 103 M-1. The sensitivity for the CTA-NCC/GO calculated was 1.509° ppm-1. The full width at half maximum (FWHM), data accuracy (DA), and signal-to-noise ratio (SNR) have also been determined using the obtained SPR curve. For the FWHM, the value was 2.25° at 0.01 until 0.08 ppm and decreases to 2.12° at 0.1 until 10 ppm. The DA for the SPR curves is the highest at 0.01 until 0.08 ppm and lowest at 0.1 until 10 ppm. The SNR curves mirrors the curves of SPR angle shift where the SNR increases with the Ni2+ concentrations. For the selectivity test, the CTA-NCC/GO has the abilities to differentiate Ni2+ in the mixture of metal ions.

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