Biological and Chemical Sensors

 

The unique chemical and physical properties of CNT have paved the way to the electrochemical biosensors. CNT-based electrochemical transducers offer substantial improvements in the performance of amperometric enzyme electrodes, immunosensors and nucleic-acid sensing devices. The greatly enhanced electrochemical reactivity of hydrogen peroxide and NADH at CNT-modified electrodes makes these nanomaterials extremely attractive for numerous oxidase and dehydrogenase based amperometric biosensors.
CNT act as molecular wires to allow efficient electron transfer between the underlying electrode and the redox centers of enzymes. Bioaffinity devices utilizing enzyme tags can greatly benefit from the enhanced response of the biocatalytic reaction product at the CNT transducer and from CNT amplification platforms carrying multiple tags. The successful realization of CNT-based biosensors requires proper control of their chemical and physical properties, as well as their functionalization and surface immobilization. These functionalized CNT based electrodes are useful in catalyzing the electrochemical reactions of dopamine, epinephrine and norepinephrin.

DNA-MWNT BIO-SENSOR :

 


Dopamine(DA) is an important neuro-transmitter and in the brain fluid, it coexists with ascoorbic acid (AA).Concentration of AA is much higher than that of DA and the oxidation potential of the AA is close to that of DA, making selective detection of DA a challenging task.CNTs(due to the large surface area and good charge-transport characterisitcs of the MWNTs) functionalized with DNA as electrode materials detect electrochemically the presence of minute concentrations of critical body fluids.

DNA is rich in active funcational groups (amino groups, carbonyl groups and carboxyl groups) which act as media for electron trransfer in redox reaction and catalyse the oxidation of DA and AA.

 

Peaks for DA and AA can be clearly identified at 0.304 and 0.055 V respectively with peak separation of 0.249 V with CNT-DNA.

 

The reduction in over potential for oxidation shifts to more negative values on the modified electrodes in the following order ss-DNA > f-MWNT/ss-DNA > Pt/f-MWNT/ss-DNA, with a considerable increase in oxidation currents. The low oxidation potential of the hybrid nanoparticle coated electrode allows low potential detection of dopamine in solution. Amperometric analysis of Pt/f-MWNT/ss-DNA/NA electrode, with increase in concentration of dopamine is shown. Inset shows the calibration curve of the biosensor. With the increase of DA concentration, the amperometric response increase linearly up to 315 µM for Pt/f-MWNT/ss-DNA modified electrode with detection limit 0.8 µM.
The time required to reach 95 % of the steady state current was less than 3s, indicating a fast response, which was mainly due to the excess electro active sites and good conducting nature of the Pt and MWNT.

CNT based Cancer Treatment and Drug Delievery

 

The development of functionalized Carbon nanotube (f-CNT) nanovehicles by covalent bond approach involves spacers for the attachment of drugs on the f-CNT. To overcome this spacer problem, it is essential that the drug molecules should directly be covalent bonded with f-CNT to reduce the diameter of the nanovector to pave way for easy penetration through the cell barrier with more drugs. In the present work, the drug attachment to the spacerless nanovectors was ensured by HRTEM and the compositions were analysis by CHN-S analytical techniques.The non-toxicity of MWNT based nanovectors was confirmed by MTT assay and confocal microscope images . 

This finding eliminates the need for the spacer and this novel route can be used as a good model for synthesizing spacerless targeted drug delivery system and for cancer treatment.

 

Recently, We have developed " Chemically Exfoliated Spacerless Graphene Oxide System" for Cancer Treatment and Drug Delivery.


Nanocomposite based Novel, Flexible, Nerve Guide Conduit


Neurons are highly influenced by electrical stimuli due to their inherent nature of transmitting electrical signals within nervous system. Nerve injuries occur through accidents, idiopathic damage, iatrogenic injuries, compression syndromes and systemic disease resulting in loss of significant functions such as control of movement and sensory information. Therefore, restoration of seered nerve pathways through artificial nerve guide conduit (NGC) is essential for proper functioning of human body.

 

 

 

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