Nanosensors

A part of nanotechnology. Nanosensors is very hot topic for research. As nanosensor has immense applications in the fields like medical, analysis, research etc. Nanosensor recude the cost and also the time require for analysis.

1. NANOSENSORS BY POOJA SEVAK MSc -II BIOTECH

2. INTRODUCTION A particle that is able to sense a physical or environmental property at the nanoscale known as a NanoSensor . It is able to sense the properties of environmental conditions at very small and gaseous level.

3. TYPES OF NANOSENSORS Classification based on Structure Optical Nanosensors Electrochemical Nanosensors

4. APPLICATION OF NANOSENSING Glucose Monitoring Asthma Detection Microorganism Detection Detection of Bacteria Detection of Viruses Cancer Diagnosis Cell Monitoring

5. Glucose Monitoring The incorporation of nanomaterials into these sensors offers a variety of advantages including increased surface area, more efficient electron transfer from enzyme to electrode and the ability to include additional catalytic steps. Nanostructured polymers can improve the development of glucose sensors.

6. Fluorescent polymeric nanosensors This approach often involves a ‘‘smart tattoo’’ for the patient, because sensors would be implanted into the skin of the patient similar to regular tattoos. The sensors would change fluorescence properties in response to blood glucose. Sensors are based on polymeric nanosensors incorporating boronic acid derivatives to recognize glucose. Alizarin was used as the reporting group. It can track blood glucose throughout the physiological range (from 66 mg/deciliter ( dL ) or 3.7 mM to 427 mg/ dL or 23.7 mM )

7. Advantages of Nanosensor in Glucose monitoring Higher surface areas (yielding larger currents and faster responses) and improved catalytic activities. Continuous monitoring The small size of these sensors, they could potentially avoid the foreign body response of the immune system. Therefore, have longer useful lives.

8. Asthma detection Nitric oxide level are found to be increased in asthma patients. The base of surface sensor is polymer coated Nano Tube Field Effect Transistor (NTFET). NTFET containing a random network of single-walled carbon nanotube between source and drain gold electrode on silicon oxide substrate.

9. CANCER DETECTION Semiconductor nanocrystals , also known as  quantum dots  (QDs) DNA nanosensor that detects target sequences via DNA hybridization and fluorescence resonance energy transfer (FRET) using QDs as energy donors. Aberrant DNA hypermethylation is observed at classic tumor-suppressor genes, which are known to be genetically mutated and cause inherited forms of cancer.

10. Detection of Bacteria The rapid & sensitive detection of pathogenic bacteria can be done using nanosensors . Limitation of most of conventional diagnosis lack of ultra sensitivity and delay in getting result can be over come. Single bacterium can be detected. Eg . detection of small number of salmonella enteric bacteria is achieved due to change in surface stress on silicon nitrate cantiliver .

11. REFERENCES Francla GD, AlfonoB and Ferrara VL (2009). Conductometric gas nanosensors . Journal of sensors, Hindawii Publishing Corporation: 659275 Fehr , Frommer WB and Lalonde S (2002). Visualization of maltose uptake in living yeast cells by using fluorescent nansensors.PNAS99(15): 98469851 Zenkl , G. and Klimant , I. (2009) Fluorescent acrylamide nanoparticles for boronic acid based sugar sensing - from probes to sensors. Microchim . Acta 166, 123–131 Billingsley, K. et al. (2010) Fluorescent nano-optodes for glucose detection. Anal. Chem. 82, 3707–3713 http://www.me.jhu.edu/thwang/quantumdots.htm