A biomolecule-free electrochemical sensing approach based on a novel electrode modification technique: Detection of ultra-low concentration of Δ⁹-tetrahydrocannabinol in saliva by turning a sample analyte into a sensor analyte.

Cannabis is currently one of the most consumed drugs in many countries. Δ⁹-tetrahydrocannabinol (THC) is the principal psychoactive component of this drug and is present in saliva after consumption. This paper reports a novel biomolecule-free electrochemical approach to detect an ultra-low level of THC in saliva using modified electrodes with molecules of the same analyte (THC) that are detected later via square wave voltammetry.

Nanovehicles for Plant Modifications towards Pest- and Disease-Resistance Traits.

In agriculture, plant transformation is a versatile platform for crop improvement with the aim of increased pest resistance and an improved nutrient profile. Nanotechnology can overcome several challenges that face conventional methods of gene delivery. Specifically, nanomaterials offer an optimal platform for biomolecule delivery with unique physiochemical properties as well as the ability to traverse the challenging barrier of the plant cell wall.

Noninvasive Label-Free Detection of Cortisol and Lactate Using Graphene Embedded Screen-Printed Electrode.

Abstract: A sensitive and specific immunosensor for the detection of the hormones cortisol and lactate in human or animal biological fluids, such as sweat and saliva, was devised using the label-free electrochemical chronoamperometric technique. By using these fluids instead of blood, the biosensor becomes noninvasive and is less stressful to the end user, who may be a small child or a farm animal. Electroreduced graphene oxide (e-RGO) was used as a synergistic platform for signal amplification and template for bioconjugation for the sensing mechanism on a screen-printed electrode.

A novel approach for amine derivatization of MoS nanosheets and their application toward label-free immunosensor.

The application of molybdenum disulfide (MoS) nanosheets has assumed great significance in the design of next-generation biosensors. The immobilization of biomolecules on MoS nanosheets has generally been achieved via hydrophobic interactions or through other complicated surface modifications. In this work, we report a novel strategy for electrochemically assisted amine derivatization of MoS nanosheets.

A comprehensive review on nano-molybdenum disulfide/DNA interfaces as emerging biosensing platforms.

The development of nucleic acid-based portable platforms for the real-time analysis of diseases has attracted considerable scientific and commercial interest. Recently, 2D layered molybdenum sulfide (2D MoS from here on) nanosheets have shown great potential for the development of next-generation platforms for efficient signal transduction. Through combination with DNA as a biorecognition medium, MoS nanostructures have opened new opportunities to design and construct highly sensitive, specific, and commercially viable sensing devices.

Exploration of two-dimensional bio-functionalized phosphorene nanosheets (black phosphorous) for label free haptoglobin electro-immunosensing applications.

We report on the development of an antibody-functionalized interface based on electrochemically active liquid-exfoliated two-dimensional phosphorene (Ph) nanosheets-also known as black phosphorous nanosheets-for the label-free electrochemical immunosensing of a haptoglobin (Hp) biomarker, a clinical marker of severe inflammation. The electrodeposition has been achieved over the screen-printed electrode (SPE) using liquid-assisted ultrasonically exfoliated black phosphorus nanosheets. Subsequently, Ph-SPEs bioconjugated with Hp antibodies (Ab), using electrostatic interactions via a poly-L-lysine linker for biointerface development.

Graphene-based multiplexed disposable electrochemical biosensor for rapid on-farm monitoring of NEFA and βHBA dairy biomarkers.

Elevated circulating concentrations of non-esterified fatty acids (NEFA) and beta hydroxy butyrate (βHBA) in biological fluids are recognized as critical biomarkers for early diagnosis of negative energy balance (NEB) in dairy cows. Herein, we report the development of a cost-effective, bio-friendly and electrochemically active dual screen printed electrode (SPE) sensor platform composed of electro-reduced graphene oxide nanosheets (E-rGO) modified with specific antibodies against NEFA and βHBA. The chemically synthesized graphene oxide (GO) was reduced directly on the screen printed electrode (SPE) surface via a green electrochemical approach without using toxic chemicals.

A highly efficient 2D exfoliated metal dichalcogenide for the on-farm rapid monitoring of non-esterified fatty acids.

Herein, we report on the development of an electrochemically active liquid exfoliated 2D MoS nanosheet based biointerface for the on-farm monitoring of non-esterified fatty acid (NEFA) biomarkers.

Liquid exfoliation of 2D MoS nanosheets and their utilization as a label-free electrochemical immunoassay for subclinical ketosis.

We report the step-by-step fabrication of a 2D MoS nanostructure-based disposable electrochemical immunosensor to detect β-hydroxybutyrate (βHBA), a novel subclinical ketosis biomarker. The MoS nanosheets were exfoliated in the liquid phase by ultrasonication, and then followed by deposition on gold colloid modified screen-printed electrodes (Au-SPE). The MoS-modified electrodes were thoroughly characterized by physical, electrochemical as well as spectroscopic techniques, and the obtained results indicate the successful and irreversible electrodeposition of MoS nanosheets.

Recent advancement in biosensors technology for animal and livestock health management.

The term biosensors encompasses devices that have the potential to quantify physiological, immunological and behavioural responses of livestock and multiple animal species. Novel biosensing methodologies offer highly specialised monitoring devices for the specific measurement of individual and multiple parameters covering an animal's physiology as well as monitoring of an animal's environment. These devices are not only highly specific and sensitive for the parameters being analysed, but they are also reliable and easy to use, and can accelerate the monitoring process.

Graphene quantum dot modified screen printed immunosensor for the determination of parathion.

The widespread use of pesticides has immense effect on increased crop productions. However, they are also responsible for posing detrimental health hazards and/or for contaminating the environment with chemical residues. A routine and an on-field detection of pesticide residues in different food, water, and soil samples has become a need of the hour for which biosensors can offer a viable alternative.

A label-free electrochemical immunosensor for the detection of cardiac marker using graphene quantum dots (GQDs).

A label-free immunosensor based on electrochemical impedance spectroscopy has been developed for the sensitive detection of a cardiac biomarker myoglobin (cMyo). Hydrothermally synthesized graphene quantum dots (GQDs) have been used as an immobilized template on screen printed electrodes for the construction of an impedimetric sensor platform. The GQDs-modified electrode was conjugated with highly specific anti-myoglobin antibodies to develop the desired immunosensor.

A New Electrolytic Synthesis Method for Few-Layered MoS2 Nanosheets and Their Robust Biointerfacing with Reduced Antibodies.

We report an efficient method for the synthesis of few-layered MoS2 nanosheets and demonstrate their application in the label-free detection of the prostate-specific antigen (PSA) cancer marker. As a novel strategy, the electro-dissolution of molybdenum metal sheets in the presence of Na(+) and S(2-) ions led to the formation of Na(+) intercalated MoS2. Further exfoliation by ultrasonication yielded the desired formation of few-layered MoS2 nanosheets.

Graphene modified screen printed immunosensor for highly sensitive detection of parathion.

Due to indiscriminate use of pesticides, there is a growing need to develop sensors that can sensitively detect the trace amount of pesticides in food and water samples. Parathion, identified as an acetylcholinesterase inhibitor, had been one of the most widely used pesticides throughout the world. Symptoms of its poisoning are found to be diverse enough to include nausea, vomiting, diarrhea, muscle cramping/twitching, and shortness of breath.

One step in-situ synthesis of amine functionalized graphene for immunosensing of cardiac marker cTnI.

2-Aminobenzyl amine (2-ABA) functionalized graphene is proposed for the ultrasensitive immunosensing of Cardiac Troponin I (cTnI). 2-ABA was electrochemically polymerized on the graphene decorated interdigitated electrode to obtain the amine functionalized graphene (f-GN). The f-GN electrode was then modified with monoclonal anti-cTnI antibodies via Schiff reaction based chemistry.

Biofunctionalized rebar graphene (f-RG) for label-free detection of cardiac marker troponin I.

One-step microwave-assisted unscrolling of carbon nanotubes to form functionalized rebar graphene (f-RG) is reported. The well-characterized f-RG on an interdigitated electrode biochip in a FET configuration showed enhanced electronic properties, as demonstrated with I-V characteristics. The developed device was biofunctionalized with specific anti-cTnI antibodies exhibiting a shift of threshold voltage from -2.

Phosphinic acid functionalized carbon nanotubes for sensitive and selective sensing of chromium(VI).

Single-walled carbon nanotubes (SWCNTs) have been functionalized with a phosphinic acid derivative 'bis(2,4,4-trimethylpentyl) phosphinic acid' (PA/d). It has been achieved by treating the chlorinated SWCNTs with PA/d at 80°C. Successful functionalization and different nanomaterial properties have been investigated by UV-vis-NIR, FTIR, Raman spectroscopy, AFM and FE-SEM.

Graphene-gated biochip for the detection of cardiac marker Troponin I.

We report lithium ion intercalation mediated efficient exfoliation of graphite to form monolithic graphene sheets which have subsequently been investigated for the development of highly sensitive label-free electrochemical detection platform for cardiac biomarker, Troponin I (cTnI). The spectroscopic and morphological analysis demonstrated the formation of defect free graphene sheets which were successfully employed to fabricate an inter-digited microdevice in a drain-source configuration on a silicon biochip. The graphene gated biochip functionalized with anti-cTnI antibodies used in label free detection of cTnI which exhibited an excellent sensitivity in the picogram range (~1 pg mL(-1)) for cTnI without the use of any enzymatic amplification that promises its potential applicability for bio-molecular detection in clinical diagnosis.

Bio-functionalized graphene-graphene oxide nanocomposite based electrochemical immunosensing.

We report a novel in-situ electrochemical synthesis approach for the formation of functionalized graphene-graphene oxide (fG-GO) nanocomposite on screen-printed electrodes (SPE). Electrochemically controlled nanocomposite film formation was studied by transmission electron microscopy (TEM) and Raman spectroscopy. Further insight into the nanocomposite has been accomplished by the Fourier transformed infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) spectroscopy.