Optical biosensor

Biosensor consists of an biological material and a transducer.

1. OPTICAL BIOSENSOR Submitted by Kannan Vasudev @32

2. CONTENTS Introduction Types Advantages & Disadvantages Recent developments Future Applications Conclusion Bibliography

3. Optical Biosensor consists of biological equipment, detector element and transducer associated with both components. The biological component is generally a protein target (bio receptors) which is immobilized on the surface of the transducer. The OBs are coupled with microfluidics which introduces an analyte as well as separates unbound molecules and is a powerful biophysical tool for characterization quantitatively. Introduction

4. Physical phenomenon for which the electrons in thin gold film can be excited into collective oscillation by bombarding it with photons (light) of particular frequency. These occurs on the surface of metal at the interface of two media (usually glass and liquid) when it is illuminated by polarized light at a specific angle . This generates surface Plasmon and consequently a reduction of the intensity of reflected light at a specific angle known as the resonance angle. This effect is proportionate to the mass on the surface.  SPR sensing is an exceedingly powerful and quantitative probe of the interactions. These interactions of variety of biopolymers with various ligands, biopolymers and membranes including protein:ligand,protein:protein,protein:DNA and protein: membrane.   The SPR phenomenon enables direct, label-free and real-time changes of refractive index at the sensor surface, which is proportionate to the biomolecule concentration . Surface Plasmon Resonance TYPES OF OB

5. To measure a ligand–analyte interaction, one interacting molecule must be immobilized on the sensor surface . The SPR chip contains a functional layer which enables the immobilization of interacting molecules . The first commercial SPR-based biosensor instrument was launched by Pharmacia Biosensor AB, which was later renamed Biacore .

6. Analytical devices in which fibre optic device serves as transduction element and it is to produce a signal that is proportional to the concentration of chemical or biochemical to which the biological element reacts. Transmits light on the basis of the principle of Total Internal Reflection(TIR). These are based on the transmission of light along with silica glass fibre or plastic fibre optic to the site of analysis. Classified into 2 different categories: Intrinsic sensors: the internal property of optical fiber itself converts the environmental changes into a modulation of light signal. This modulation of light signal may be in form of intensity, phase and frequency or may be polarization . Fibre Optic Biosensor

7. Extrinsic sensors: In contrast to intrinsic sensing, in extrinsic sensing; the fiber may be used as information carriers that lead to a black box and that will generate a light signal depending on the information arrived at black box. This black box may be made of mirrors, gas, liquid cell, or many other mechanisms that will proceed to generate an optical signal.

8. Low technology Colorimetric test strips C ellulose pads embedded with enzymes and reagents U sed in diabetes regulation: glucose oxidase 1 glucose + O2-----------------------  gluconic acid + H2O2 peroxidase 2 chromogen(2H ) + H2O2 ---------------  dye + 2H2O Strip includes: glucose oxidase, horseradish peroxidase, and a chromogen When oxidized, the chromogen will be colored ABSORBANCE BASED

9. Luminescence-light that is not primarily generated from heat. Light output from a biochemical reaction. Can be used in detection of bacteria --Uses Firefly luciferase(from the tails of wild fireflies). -- Bacteria is lysed and yellow light is given off. LUMINESCENCE BASED ATP + Luciferin + O2 ---  AMP + PPi + Oxyluciferin + CO2 + h γ

10. Small Flexible Fast Safe , no electrical device interacts with the body Good biocompatibility (fibers are glass ) ADVANTAGES

11. H igh cost of some instrumentation May be Invasive Fluorescent signal may not be strong enough DISADVANTAGES

12. Optical biosensor in the last decade has developed to a great extent in every field but there is still a long way to replace completely the conventional methods of the optical biosensor technology in many fields and, specially, in biomedical field . To achieve such objective, we still need to develop optical biosensors able to detect, in a direct way at very low levels (picomolar to femtomolar) of a great number of substances in the areas of environmental monitoring, industrial and food process, health care, biomedical technology, clinical analysis,etc.  There are various technical difficulties for fabrication of optical biosensor but still more research efforts are needed for finding out better alternatives Some of them are as follows: Immobilization of biomaterials is the hardest difficulty in the process of fabrication of optical biosensor. Material losses are observed during the process of immobilization of biomolecules on solid substrate . Recent Developments

13. 2) Contamination There is a big problem of biomolecules and chemicals used in the biosensors leaking out of the biosensor which may create contamination. To avoid contamination, biomolecules should be attached to the transducer as strongly as possible. 3) Uniformity Optical biosensors that are fabricated by different processes can be easily reproduced if they are uniform.  4) Selection Range The selection range should be large in order to detect a lot of variety of biomaterials . 5) Sterilization Sensor’s biomolecules may get destroyed if nonsterile probes are used. 6) Expensive Low-cost optical biosensors have to be developed for mass use and to have a better equipment to fight out different medical and technological problems.

14. TEST FOR TUBERCULOSIS Cough into the tube and sputum is brought up. Give positive reading if TB is present in the lungs. Future Applications

15. OPTICAL BIOPSY SENSOR Detects if tumor in esophagus is cancerous or Benin. When illuminated, normal tissue and cancerous tissue will emit light at different wavelengths. Diagnosis is accurate over 98 %.

16. MEDICAL TELESENSOR Universal sensing chip. Multiple bio-sensing applications. Measure blood-oxygen levels. Color of hemoglobin is transmitted w hen illuminated by light.

17. Optical Biosensors are expected to grow most in importance in the healthcare, biomedical and biopharmaceutical sectors. They can provide new analytical tools with reduced size as well as successfully tested in many fields such as medicine,pharmacy,food safety,environment ,biotechnology ,..etc The broad practical application of optical biosensors is still under development and is limited mostly to academic and pharmaceutical environments. CONCLUSION

18. Biosensors and Bioelectronics by D.Dharaneeswara Reddy,O.M.Hussain,D.V.R Sai Gopal, D. Muralidhara Rao ,K.S Sastry www.ncb.nlm.n ih.gov www.mdp i.com BIBLIOGRAPHY