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November 2017 - July 2019
Nanyang Technological University
- Project Officer
- Developed paper-based assays for point of care (POC) diagnosis
September 2014 - August 2017
The Hong Kong University of Science and Technology (HKUST)
Field of study
- Electronic and Computer Engineering
February 2008 - December 2012
Bangladesh University of Professionals affiliated with Military Institute of Science and Technology (MIST), Dhaka, Bangladesh
Field of study
- Electrical, Electronic and Communication Engineering
A flow-through colorimetric assay for detection of nucleic acids in plasma is reported. The proposed assay features an array of four polyvinylidene fluoride (PVDF) membranes impregnated with cationic poly (3-alkoxy-4-methylthiophene) (PT) as an optical reporter. The sensing strategy is based on monitoring the changes in optical properties of PT, up...
This paper presents an integrated nanofluidic diode biosensor based on a single asymmetric nanoslit with a nominal width of 30 nm. The nanoslit dimension is fine-tuned by the highly conformal atomic layer deposition (ALD) of Al2O3. The surface of the nanoslit is further modified with an ultra-thin layer of SiO2 that is placed onto the Al2O3 layer f...
Monitoring of glucose levels in non-invasive biofluids, such as saliva and sweat, can advance personal health tracking. However, the approach remains challenging due to the low glucose concentration in saliva and sweat, about 100 times lower than in the blood. Commercial glucose sensors rely on glucose oxidase to measure blood glucose levels with e...
Rapid and continuous tracking of the stress hormone cortisol's circadian rhythm is vital for diagnosing diseases related to chronic stress and adrenal gland disorders . Commercial cortisol sensors relying on labeled enzyme and antibodies suffer from limited stability, lengthy reaction time, and cross-reactivity with analogous molecules . To a...
We present a photoinduced reconfigurable metasurface to enable high spatial resolution terahertz (THz) wave modulation. Conventional photoinduced THz wave modulation uses optically induced conductive patterns on a semiconductor substrate to create programmable passive THz devices. The technique, albeit versatile and straightforward, suffers from li...
Rapid and sensitive detection of steroid hormone cortisol can benefit the diagnosis of diseases related to adrenal gland disorders and chronic stress. We report a molecularly imprinted polymer (MIP)-based electrochemical sensor that utilized nano gold-doped poly o-phenylenediamine (poly-o-PD) film to selectively determine trace level cortisol with...
Sensitive detection of hydrogen peroxide (H2O2) residue in aseptic packaging at point of use is critical to food safety. We present a sensitive non-enzymatic, amperometric H2O2 sensor based on ferrocene-functionalized multi-walled carbon nanotubes (MWCNT-FeC) and facile screen-printed carbon electrodes (SPCEs). The sensor utilizes the covalently gr...
Serotonin, or 5-hydroxytryptamine (5-HT), is a neurotransmitter that plays a crucial role in neural activities. 5-HT deficiency is clinically related to several psychiatric disorders. Therefore, sensitive 5-HT detection is critical in the diagnosis of diseases associated with neurological disorders. Here we developed a sensitive electrochemical sen...
A label-free and reagentless molecularly imprinted polymer (MIP)-based sensor is reported for electrochemical detection of steroid as doping material in sports. The sensor was constructed with one-step electropolymerization of MIP film in the presence of steroid analyte dehydroepiandrosterone (DHEA). MIP features redox-active polymer for direct ele...
We report nitrogen-doped yellow-emitting carbon dots (Y-CDs) with 25% quantum yield for sensitive ferric ions (Fe3+) detection. The Y-CDs prepared by a one-step microwave synthesis method exhibit an emission peak at 572 nm under 412 nm excitation. The Y-CDs showed superior water solubility, fluorescence intensity, and chemical stability. Fe3+ ions...
Insufficient or elevated hormone cortisol levels triggered by physical or psychological stress can cause several health problems, such as Addison's disease, Cushing's syndrome, and chronic fatigue syndrome. High serum cortisol levels are also related to increased mortality in COVID-19 patients. Thus, sensitive cortisol detection can provide an earl...
Abnormal dopamine levels lead to severe diseases and disorders, including Parkinson's disease, Alzheimer's disease, and schizophrenia . There is a need for sensitive and cost-effective dopamine sensors to provide rapid diagnosis at the point of care. Several approaches, such as high-performance liquid chromatography-mass spectrometry, fluorescen...
We report a highly sensitive DNA fluorescence sensor using molecular beacon-functionalized magnetoplasmonic nanoparticles. The sensor possesses both plasmonic and magnetic properties to enhance the sensing signal. The limit of detection of 1 pM was achieved.
Over the past few decades, colorimetric assays have been developed for cost-effective and rapid on-site urinalysis. Most of these assays were employed for detection of biomarkers such as glucose, uric acid, ions, and albumin that are abundant in urine at µM to mM levels. In contrast, direct assaying of urinary biomarkers such as glycated proteins,...
We discovered that several types of steroid hormones quench the fluorescence of quantum dots (QDs) at close proximity. Inspired by the finding, we developed a new type of biosensor for sensitive detection of cortisol via direct fluorescence quenching of functionalized QD probes directly induced by the capture of target cortisol without additional r...
In the past decade, advances in nanofluidics have opened up the possibility of rapid and sensitive biomolecule analysis based on unique ionic transport, specifically the rectification of ionic current through a nanochannel as in the rectification of an electronic current through a solid-state diode. A nanofluidic diode shows asymmetric ionic conduc...
My sample contains a thin film containing redox-active species. Redox-active species are electrodeposited with a polymer. I am wondering can I determine the concentration of redox-active species from cyclic voltammetry?
Ferrocene (Fc) has been regarded as a helpful catalyst for the electro-oxidation of dopamine, ascorbic acid, Levodopa, etc., at different potentials.
If anyone suggests to me any literature about why ferrocene works as a catalyst for particular analogs (e.g., dopamine, ascorbic acid, uric acid), not for others (e.g., glucose), that will be helpful.
In MIP sensors, monomer and target molecules are mixed together, and electropolymerization initiates polymerization to create molecularly imprinted polymers (MIP). The literature says a hydrogen bond is formed between the monomer and target molecule.
Is this hydrogen bond spontaneous or requires incubation time?
I appreciate any help you can provide.
I am preparing molecularly imprinted polymer (MIP) with electropolymerized polypyrrole. I am taking advantage of overoxidized pyrrole (by applying potential) for template removal. I want to control the overoxidation.
Is there any chemical way (e.g., doping) to reduce/control the overoxidation of pyrrole?
In the diffusion-controlled process, peak currents are linearly proportional to the square root of the scan rate. In surface controlled (also known as an adsorption-controlled) process, peak currents are linearly proportional to scan rate. Wha is the physical meaning behind this explanation?