Muhammad Zafir Mohamad Nasir

Two-Dimensional 1T-Phase Transition Metal Dichalcogenides as Nanocarriers To Enhance and Stabilize Enzyme Activity for Electrochemical Pesticide Detection

Single or few layers lithium-exfoliated transition metal dichalcogenides (TMDs) are found to exist predominantly in the conducting metallic 1T-polymorph, which makes it desirable for numerous applications due to its large surface area, good electrical conductivity, and enhanced electrocatalytic capabilities. We demonstrated the use of tert-butyllithium exfoliated TMDs (MoS2, MoSe2, WS2, WSe2) as a platform for the indirect electrochemical detection of an organophosphate pesticide, fenitrothion, via enzymatic inhibition pathway. All four reported materials enhanced the response of the enzymatic biosensor in comparison to the corresponding biosensor in the absence of TMDs. 1T-Phase WS2 outperforms all other TMD materials, and we proved that it serves as an excellent transducer for enhancing electron transfer in a robust model enzyme-based inhibition assay system using cross-linking immobilization with glutaraldehyde. The reported system showed a broad fenitrothion concentration range (1-1000 nM) with an excellent linearity (r = 0.987). Moreover, the system displayed high sensitivity with low limit of detection (2.86 nM) obtained, which far exceeds the required limit set by Food and Agriculture Organisation (FAO) of the United Nations (UN). The feasibility of the proposed system in real samples was demonstrated in apple juice samples with good recoveries of 80.2% and 80.3% obtained at 10 and 1000 nM fenitrothion, respectively.

3D Printed Electrodes for Detection of Nitroaromatic Explosives and Nerve Agents

Three-dimensional (3D) printing has proven to be a versatile and useful technology for specialized applications in industry and also for scientific research. We demonstrate its potential use toward the electrochemical detection of nitroaromatic compounds 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), and fenitrothion (FT). The detection of these compounds is of utmost importance in military and forensic applications. Stainless steel electrodes were fabricated by 3D printing, and the surface was electroplated with gold. The electrochemical performance of the 3D printed electrodes was compared to that of the conventionally employed glassy carbon electrode (GCE) and proved to be more sensitive toward the detection of all three nitroaromatic compounds. 3D printing of customizable electrodes provides a viable alternative to traditional electrodes for the analysis of samples with electrochemical methods.

Impact electrochemistry on screen-printed electrodes for the detection of monodispersed silver nanoparticles of sizes 10–107 nm

Impact electrochemistry provides a useful alternative technique for the detection of silver nanoparticles in solutions. The combined use of impact electrochemistry on screen-printed electrodes (SPEs) for the successful detection of silver nanoparticles provides an avenue for future on-site, point-of-care detection devices to be made for environmental, medicinal and biological uses. Here we discuss the use of screen-printed electrodes for the detection of well-defined monodispersed silver nanoparticles of sizes 10, 20, 40, 80, and 107 nm.

Detection of Amphipathic Viral Peptide on Screen-Printed Electrodes by Liposome Rupture Impact Voltammetry

Detection of infectious viruses and disease biomarkers is of utmost importance in clinical screening for effective identification and treatment of diseases. We demonstrate here the use of liposome rupture impact voltammetry for the qualitative detection of model amphipathic viral peptide on a screen-printed electrode. This novel, proof-of-concept method was proposed for the quick and reliable detection of viruses by nonfaradaic liposome rupture impact voltammetry with the aid of 1,2-dioleoyl-sn-glycero-3-phosphocholine liposomes. This provides an avenue for the development of future on-site, point-of-care detection devices for medical and biological applications.