Saurav Saha from the Centre for Biotechnology and Molecular Biology proposes developing a biosensor for virus detection using gold nanorods. The document outlines the components and working principle of biosensors, including how an analyte interacts with the biological component and transducer to create an electronic signal. It then describes synthesizing gold nanorods, forming a self-assembled monolayer on a glass substrate, and conjugating antibodies to functionalize the surface for antigen detection and characterization. The goal is to create a biosensor using graphene oxide decorated with gold nanorod-antibody conjugates to detect viruses.

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Dévelopment Of Biosensor For Virus Détection
Saurav Saha
Centre For Biotechnology And Molecular Biology
Kerala 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 PRINCIPLE
Analyte 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/W
L
W

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Introduction to Gold Nanorod
9
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 in
gold 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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