Nanobiosensors

By:

Atul Kumar

(imi2010009)

Definition for Biosensors:

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.

Components of a Biosensor

Detector

1ST Component: Biological Element

MicroorganismTissueCellOrganelleNucleic AcidEnzymeEnzyme Component ReceptorAntibody

The component used to bind the target molecule.

Must be highly specific, stable under storage conditions, immobilized.

2ND Component: Physiochemical Transducer

Acts as an interface, measuring the physical change that occurs with the reaction at the bioreceptor then transforming that energy into measurable electrical output.

3RD Component: Detector

Signals from the transducer are passed to a microprocessor where they are amplified and analyzed.

The data is then converted to concentration units and transferred to a display or/and data storage device.

Biosensors on the NanoscaleReceptorsFor purposes of biosensing , receptors are responsible for "receiving” as well as “sending” functions.

Schematic of a Si nanowire-based FET device configured as a sensor with antibody receptors (green), where binding of a protein with net positive charge (red) yields a decrease in the conductance

Types of Nanobiosensors Optical Biosensors Nanotube Based BiosensorsElectrical BiosensorsViral Nanosensors

Electrochemical BiosensorsNanoshell BiosensorsNanowire Biosensors

Nanobiosensors include following nanostructures NanoshellsNanoparticlesNanotubesNanowiresNanoscale CantileversNanorods

A nanoshell consists of a dielectric core surrounded by a thin metallic shellBecomes a quasiparticle called a plasmon – electrons simultaneously oscillate with respect to all of the ionsThis characteristic makes them tunable to electromagnetic radiation

Useful forBiomedical ImagingTherapeutic applicationsFluorescence enhancement

Nanoshells

Nanoparticles Similar to Nanoshells, but without the shell –

generally made of the same materialDepending on the material, different electrical and other

properties can be realized Nanoparticles are a bridge between the bulk material

and atomic or molecular structuresMany, many applications including

Quantum Dots to locate cancer cells in the bodyNanoparticles to deliver chemotherapy drugs directly

to cancer cellsGold Nanoparticles to allow heat from infrared lasers

to be targeted on tumor cells

Carbon NanotubesAllotropes of carbon with a cylindrical nanostructure.Length-to-diameter ratio significantly larger than any other materialNovel Electrical Properties for applications in

NanotechnologyElectronicsOpticsMaterial Sciences

NanowiresA nanostructure, with diameter of the order of a nanometerAt these scales, quantum mechanical effects are important Different types of Nanowires existMetallic (e.g., Ni, Pt, Au)Semiconducting (e.g., Si, InP, GaN, etc.)Insulating (e.g., SiO2, TiO2)

A cantilever naturally resonates depending on its mass and mechanical propertiesThe mass changes when contaminants land on the devices causing the resonant frequency to changeAn example application is that the levers are coated with antibodies to detect certain viruses

Nanoscale Cantilevers

Nanorods

Metallic Nanoparticles used in biosensing

Changing the shape from sphere to rod lowers the frequency to which the particles react

Allows for deeper penetration with near IR wavelengths instead of visible light

Thank You!