AENL – Alternative Energy and Nanotechnology

Bio Sensors

Cholesterol & HDL Biosensor

Cholesterol is an essential lipid for human body and possesses a potential threat when the level is greater than 240 mg/dL. It is a fundamental parameter in the diagnosis of coronary heart disease and excessive cholesterol causes poor cardiovascular conditions leading to coronary heart disease, myocardial infarction. However along with cholesterol level, quantification of HDL, LDL, triglycerides are also necessary to avoid heart problems. Optimum level of HDL in human body should be in within the range from 40 mg/dL to 60 mg/dL. Our group is working on the quantification of cholesterol and HDL incorporating metal-oxide/ carbon composite in electrochemical method. Variable valency of metal-oxide and interaction between analyte and odified electrode influence the sensing mechanism for nonenzymatic detection. Further, incorporation of ChOx and ChEt on modified electrode surface using physical adsorption and chemical immobilization method improved the selectivity and sensitivity of nanocomposite based sensor. For enzyme based analysis, quantification of cholesterol and HDL is done by measuring the amount of produced during reaction mechanism. We have shown that metal-oxide nanocomposite can be probed as suitable electrochemical biosensor for its biocompatibility, sensitivity, and electrical properties.

Organophosphorus Biosensor

Organophosphorus compounds are highly toxic to humans, chiefly affecting the central nerves system (CNS). AChE is an important cholinesterase enzyme, which maintains the levels of the neurotransmitter acetylcholine by catalyzing the hydrolysis reaction of acetythiolcholine to thiocholine in CNS. In the presence of trace amount of OP compounds, the catalytic activity of AChE can be drastically inhibited. Due to its acute toxicity, even at trace levels, there is increasing interest in the development of sensors to detect, monitor and quantify for public security and health protection. Our group works on green synthesis procedure for preparing zinc oxide nanoparticle (NP)-decorated multiwalled carbon nanotube-graphene hybrid composite (ZnO-MWCNTs-sG) by using solar energy and its application as a transducer candidate for organophosphorus biosensor.The fabricated biosensor shows a high affinity (AChE) with a Km constant value of 0.8 mM

Glucose Biosensors

Diabetes mellitus is a worldwide public health problem. The patient suffers from insulin deficiency and hyperglycemia, which is reflected by blood glucose concentrations higher or lower than the normal range of 70-130 mg/dL (3.9-7.1 mM). Noble metal nanoparticles on graphene or MWCNTs surfaces have been reported to be efficient sensing platform for their distinguished physical and chemical attributes such as excellent biocompatibility, catalytic activity and chemical stability. The synergistic effect between Au nanoparticles and MWCNTs-sG resulted in superior sensitivity and excellent selectivity on AuMWCNTs-sG hybrid nanocomposites modified electrodes towards glucose sensing

Non-Enzymatic Glucose Biosensor

A pH driven self assembly process was employed to decorate 1D narrow sized Cu(OH)₂ nanorods on 2D functionalized graphene sheets (fGS) and the nanorods were further reassembled to CuO. When we have employed this composite for glucose detection, CuO NRs-fGS@GCE showed high sensitivity, good reproducibility and a fast amperometric response

Flexible Strain Sensor

Researchers started testing polymer nanocomposites for strain sensing applications. A majority of past studies on the effect of strain on electrical properties of conducting polymer composites (CPCs) involved the usage of polymer composites dispersed with carbon black and carbon fibers. Our group is working on the development of carbon nanotubes–graphene hybrid polymer nanocomposite strain sensors. We have developed a process for controlling the dispersion of carbon nanotubes, graphene, carbon nanotubes-graphene hybrid and selective metal oxide decorated carbon based materials in polymers. A method was developed for the coating and alignment process for the application of these composites in multi-layer configurations, using both large area and small area (sensor patch) coatings on to metal and composite substrates. The piezoresistive property of the conducting polymer nanocomposites is investigated and the mechanism behind strain sensing of the polymer nanocomposites is studied. We have shown that by this method, development of sensor films and coatings that can be used to monitor environmental and chemical hazards can also be performed.

Gas Sensor

Combustion of hydrogen can provide nearly three times the energy produced from gasoline, diesel and petroleum gas of the same weight. However, it is a highly inflammable gas with wide flammability range from 4% to 75% in air and very low ignition energy of 0.017 mJ. Therefore production, storage and transport of H pose more safety challenges. Most of the expensive sensors available commercially are made of semiconducting metal oxides, which operate at higher temperatures. Low cost sensors with high sensitivity at room temperature at these concentrations are desirable. We have explored graphitic carbon nitride (g-C₃N₄ ) as a room temperature hydrogen sensor. (g-C₃ N₄ ) is a semiconducting material with band gap of 2.7 eV and it is highly stable and nontoxic. Nanostructured palladium modified graphitic carbon nitride (g-C₃ N₄ ) shows a very high H sensitivity at room temperature.