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Dévelopment Of Biosensor For Virus Détection

Saurav Saha

Centre For Biotechnology And Molecular BiologyKerala Agriculture University

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Biosensor

A sensor that integrates a biological element with a physiochemical transducer to produce an electronic signal proportional to a single analyte which is then conveyed to a detector.

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Component

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WORKING PRINCIPLEAnalyte diffuses from the solution to the surface of the Biosensor.Analyte reacts specifically & efficiently with the Biological Component of the Biosensor.This reaction changes the physicochmical properties of the Transducer surface.This leads to a change in the optical/electronic properties of the Transducer Surface.The change in the optical/electronic properties is measured/converted into electrical signal, which is detected.

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Introduction To Virus

•Green or red streaks or spindle-shaped lesions can appear on leaf petioles

•Chlorotic streaks on the leaf blade can also indicate infection. 

•Sometime red colour strip appear on the psudostem

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Outline of Experimental procedure

• Synthesis of gold-nanorod • Formation SAM layer on the glass substrate

• Immobilization nanorod on the glass substrate

• Conjugation of antibody on Au-rod modified glass substrate

• Check the antigen concentration of test sample

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Gold nanorod synthesis• CTAB solution mixed with HAuCl4 ice-cold NaBH4. • Formation of a brownish yellow solution.

• To grow the gold nanorod, HAuCl4 and AgNO3 were added to followed by the addition of ascorbic acid.

• Finally, of the seed solution was added to the growth solution

• Colure will be change ruby red

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Characterization

Aspect Ratio (AR) = L/WL

W

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Introduction to Gold Nanorod

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Under electromagnetic field of light, the conduction band electrons undergo a collective coherent oscillation in resonance with the frequency of the incident light. This is known as the localized surface plasmon resonance (LSPR).

Due to their anisotropic shape, 2 extinction peaks can be observed from gold nanorods.

Huang et al. Adv Mater. 2009, 21, 4880-4910.

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SPR(Surface Plasmon Resonance)•Surface plasmons are those plasmons that are confined to the surface of the metal.

•When the light is totally reflected in a certain angle it is called total reflective index.

•Surface plasmon (electron) are create electric field this is called evanescent wave,

•Optical energy is coupled into the Au surface. As a result, reflection is decreased at this resonance angle.

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Formation of SAM

• Glass substrate was incubated for 13 hr 1% MPTMS for 13 h • Formation of a thiol-terminated self- assembled monolayer

(SAM)

• Mercaptosilane-modified glass substrate was then incubate ingold nanorod solution for 2 hr

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Conjugation of antibody on Au-rod modified glass substrate

• For the binding of antibody

• AuNR-modified optical fiber immersed in the MUA and MCH ethanol solution for 18 hr

• MUA/MCHmodified AuNR glass sub stare immersed in(EDC)and N-hydroxy- succinimide (NHS) for 2h.

• Then incubate it in antibody solution for 2 hr.

• Characterized it in UV-Vis spectroscopy for the binding

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Characterization of gold nanorod glass substrate

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Antigen concentration

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Biosensor based on graphene oxide decorated with gold nanorod–antibody

conjugates

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Graphene oxide (GO)

• Strongly oxygenated, highly hydro- philic layered material

• Abun- dant oxygen-containing functional groups

• Interact with varieties of biomolecules through covalent, noncovalent or electrostatic interactions

• Effectiveness in quenching fluorescence affords advantages over alternative carbon material

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Experiment procedure

• Synthesis of GO and AuNR–antibody conjugates

-EDC/NHS linking chemistry was applied for the attachment of AuNR- antibody

- Mixture of EDC and NHS was added into the gold nanorod

- Then the antibody was added into the sollution and gently shaking

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GO decorated with AuNR–antibody conjugates

• Glass slide with Au film was fixed under the reactor.

• 2-mercaptoethylamine (MEA) was injected into the reactor to form amino-modified Au film

• GO was injected and assembled on the Au film via electrostatic interaction

• NHS/EDC was added to activated the carboxyl groups

• AuNR– antibody conjugates were injected into the reactor to covalently attach to the GO surface.

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Schematic diagram of experiment

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