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A disposable screen-printed carbon electrode (SPCE) functionalized reduced graphene oxide (rGO) was successfully fabricated for electrochemical detection of stress biomarker cortisol. Firstly, graphene oxide (GO) suspension was drop-casted onto carbon electrode surface before being electrochemically reduced into rGO-modified SPCE. Secondly, the rGO-modified SPCE was treated with N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) solution to activate carboxylic group (COOH) on the rGO surface which then reacts with amines (NH3) group of cortisol specific monoclonal antibody (C-Mab) to form an amide bonding. Finally, the electrochemical response of C-Mab/rGO-modified electrode towards cortisol was recorded by cyclic voltammetry (CV) techniques using5 mM (Fe3[CN]6) as a redox probe. The significant change of current was observed with and without the presence of cortisol using our fabricated electrode, C-Mab/rGO-modified SPCE becomes the main principle in this cortisol electrochemical immunosensor. The incorporation of rGO onto SPCE surface exhibited an enhancement of electrocatalytic of electrochemical oxidation of Fe3[CN]6for the detection of cortisol. It was shown that the peaks current of Fe3[CN]6 was significantly reduced in the presence of cortisol onto the C-Mab/rGO-modified electrode surface. Several parameters were optimised for improving electrochemical detection of cortisol including rGO concentration, C-Mab concentration and immobilisation time of cortisol. Under optimal condition, our developed immunosensor was able to detect cortisol in a wide linear range of 0.001 µg/mL to 10 µg/mL which covers the human cortisol levels in normal and stressful environments. These findings would help in the development of biosensor to monitor the stress level among military personnel. [ABSTRACT FROM AUTHOR]

The aim of this cross sectional case control study was to examine the serofrequency and serointensity of Toxoplasma gondii (Tg) IgG, IgM, and DNA among patients with schizophrenia. A total of 101 patients with schizophrenia and 55 healthy controls from Sungai Buloh Hospital, Selangor, Malaysia and University Malaya Medical Center (UMMC) were included in this study. The diagnosis of schizophrenia was made based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). The presence of Tg infection was examined using both indirect (ELISA) and direct (quantitative real-time PCR) detection methods by measuring Tg IgG and IgM and DNA, respectively. The serofrequency of Tg IgG antibodies (51.5%, 52/101) and DNA (32.67%, 33/101) among patients with schizophrenia was significantly higher than IgG (18.2%, 10/55) and DNA (3.64%, 2/55) of the controls (IgG, P = 0.000, OD = 4.8, CI =2.2-10.5; DNA, P=0.000, OD=12.9, CI=2.17-10.51). However, the Tg IgM antibody between patients with schizophrenia and controls was not significant (P> 0.005). There was no significant difference (P> 0.005) in both serointensity of Tg IgG and DNA between patients with schizophrenia and controls. These findings have further demonstrated the strong association between the active Tg infection and schizophrenia. [ABSTRACT FROM AUTHOR]