nanomaterials in the design of chemical sensors and biosensors: a bottom up approach ·...

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University of CreteDepartment of Chemistry

Laboratory of Analytical ChemistryIraklion, Crete, GREECE

Nanomaterials in the Design ofChemical Sensors and Biosensors:

Nikos A. Chaniotakis

Chemical Sensors and Biosensors:A bottom up Approach

E-MRS Spring 2006. N. A. Chaniotakis University of Crete

Top Down Vs Bottom Up Approach in Bio-Sensors


Selectivity Detection Limit

The Controlling Parameters of Bio-Sensors

NanomaterialsSensitivity

Reproducibility Stability

CostNanomaterials

Disciplines Involved in the Design of Bio-Sensors

CHEMISTRY

Inorganic

Organic

Macromolecular

Physical

MATERIALS

PolymersNanoparticles

Semi-conductors

BIOLOGY

DNAEnzymes

CellsDEVICES

Bio-SensorsE-MRS Spring 2006. N. A. Chaniotakis University of Crete

Schematic Diagram of Bio-Sensors

DisplayElectrode

Signal Conditioning:

Analyte

100

200

300

400

500

600

0

250

500

1250

P t ti l C t

Nanomaterials

Signal Transduction

Analyte Recognizing SystemEnzyme, Ionophore

Potential, Current,Impedance, Light


Nanomaterials must have unique and novel physicaland/or chemical characteristics which can aid in the designof bio-sensors with improved analytical characteristics:

Nanomaterials in Bio-Sensors

High surface ratio

Novel electro-optical properties

Increased catalytic activity

Enhanced electron transfer


2

High surface ratio

Novel electro-optical properties

Increased catalytic activity

Enhanced electron transfer

Immobilization matricesStabilization matricesOptical & electrochemical Mediators Transduction platforms


Quantum Dots

Nano Materials


Enzyme Glucose oxidase

+800 mV

GlucoseFADH2O2

Operational Principles of BiosensorsThe example of Glucose Oxidase

Gluconic acidFADH

e-O2


NanomaterialsQuantum Dots?

MaterialsImmobilization and stabilization of proteins and other biologicalmolecules


GaN Quantum DotsFunctionalization with inorganic and biological molecules


-180

-200

-220

l (m

V)

Stabilization in Nano Spaces

0 30 60 90 120 150 180 210 240

-140

-160Pote

ntia

l

Time (days)

M. Vamvakaki, N.A. Chaniotakis, Anal. Chim. Acta 320 (1996) 53-61

Stabilization of Proteins in Confined SpacesEffect of confinement on the folding free energy as a function of the cage size

The radius of the protein in the native state (aN) was given by 3.73N1/3

Cage size (in units of 2aN) is given on a log scale.

Ν = 100Ν = 200

H.X. Zhou, K.A. Dill Biochemistry, 2001, 40 (38), 11289

Active Surface

Protein and Cage SizeMaximum stabilization of proteins in spherical cages with diameter of 2 to 6 times the diameter of the native protein

~20 -100 nm

~7 nm Glucose

Gluconic Acid

Enzyme

Enzyme withpolyelectrolyte


3

Enzyme StabilizationStabilization of Glucose Oxidase into nanoporous carbon

V. Gavalas, N.A. Chaniotakis, Anal. Chim. Acta 2000, 404, 67

AChE

Acetylcholine

Pesticide Biosensor

Peripheral Site

Acylation Site

W279

W84

Acetylcholine receptors

CH O P

O

OMeOMeC

Cl

Cl

Dichlorvos

O2N O P

O

OCH3

OCH 3

Paraoxon-methyl


50

60

70 dichlorvos paraoxon

Calibration Curve

Mutant (E69Y, Y71D) Drosophila melanogaster AChE+350 mV 25 oC

Porous Carbon Pesticide Biosensor

Continuous Operation

100

120

140

Act

ivity

free m-AChEm-AChE in carbon nanopores

8 10 12 14 16 18 20

0

10

20

30

40

50

% In

hibi

tion

-log[pesticide], M

S. Sotiropoulou, N.A. Chaniotakis, Biosens.Bioelectron. 2005, 20, 2347S. Sotiropoulou, N.A. Chaniotakis, Anal.Chim. Acta 2005, 530, 199

0 20 40 60 800

20

40

60

80

100

% R

emai

ning

A

time (hr)

Nano Biosensors

Lipids

300 ± 4 nm

enzymefluorescentindicatorporin substrate

Insertion of the porin OmpF in the

liposome membrane to allow substrate

entrance

Encapsulation ofAChE in liposomes

Encapsulation of the pH sensitive

fluorescent indicator, pyranine

The enzymatic reaction lowers the pH value which is correlated to substrate

concentration

AChEAcetylcholine + H2O choline + acetic acid

B. Chaize, M. Winterhalter, D. Fournier, BioTechniques 2003, 34, 1158

Pesticide Biosensor

Detection Limit:7.5 x 10-11 M

60

70

80

90

Calibration Curve

V. Vamvakaki, N.A. Chaniotakis, Anal. Chim. Acta submitted

6 7 8 9 10 11 12

0

10

20

30

40

50

I (%

)

-log[dichlorvos], M

Fullerenes

Fullerene C60multiple redox stateslow solubility in aqueous solutionsstable in many redox forms

Enzyme Glucose oxidase

Glucose

Gluconic acid

FAD

FADHMediator(ox)

Mediator(red)

+350 mV

e-


4

Fullerenes

V. Gavalas, N.A. Chaniotakis, Anal. Chim. Acta 2000, 409, 131

Calibration curve of the glucose biosensorcontaining 1.7µg C60/mg of electrodematerial. Measurements were performedin 10mM phosphate buffer, pH=7.5 underargon, at +350mV vs. Ag/AgCl.

Hydrodynamic voltammogram for theglucose biosensors constructed usingcarbon incubated for: 0 ( ), 4 ( ), 5 ( )cycles in the toluene-C60 solution

Fullerenes

Fullerene MediatorEnzyme

Glucose Oxidase

GlucoseFAD

+350mV+100mV

Flowchart of the processes involved in a light induced fullerene mediated electrochemical biosensor. The operating potential has dropped to +100 mV.

Gluconic acid

e-FADH


Fullerenes

0.0

-0.2

-0.4

Light ONΑ)

-1 0 1 2 3 4 50.8

0.6

0.4

0.2Light OFF∆

Ι (µΑ

[Glucose], mM


Carbon Nanotubes

Pt Transducer

Glucose

Gluconic acid

e-

EnzymeGlucose Oxidase

The carbon nanotubes were grown by the CVD method on a platinum substrate, thusproviding an array of MWNT, 15-20 microns long and with an internal diameter of150nm.

S. Sotiropoulou, N.A. Chaniotakis, Anal. Bioanal. Chem. 2003, 375, 103

Carbon Nanotubes

SEM images of the Carbon Nanotubes

Initial Carbon Nanotube Array

Acid oxidation (HNO3/H2SO4)

Air oxidation(600 0C, 5min)


1.0

1.5

2.0

(µΑ

)

Carbon Nanotube Biosensor

Linear range: 0.05 - 2.5 MSensitivity: 93.9 ± 0.4 µA mM-1 cm-2

0.0 0.5 1.0 1.5 2.0 2.5

0.0

0.5

∆Ι

[glucose] (mM)


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Carbon Nanofiber Biosensor

Carbon NanotubesCarbon NanofibersV. Vamvakaki, K. Tsagaraki, N.A. Chaniotakis, Anal. Chem. Is press

Carbon Nanofiber BiosensorTable 1. Carbon nanofiber physical characteristics

Nanofiber Grade LHT HTE GFE

Diameter (nm) 70-150 80-150 80-150

N2 Surface Area (m2/g) 43 80-100 > 50

Density (g/cm3) > 1.95 1.98 2.17

Heat treatment (o C) 1000 1000 3000

Metal Content (wt. %) < 0.50 < 0.50 < 0.01

Electrical Resistivity (Ohm/cm) < 10-3 < 10-3 < 10-3

SEM image of HTE Nanofibersmean diameter ~ 110 nmlength ~ tenths of nanometers

V. Vamvakaki, K. Tsagaraki, N.A. Chaniotakis, Anal. Chem. Is press

Carbon Nanofiber Sensor

0.0

5.0x10-4

1.0x10-3

A)

GFE HTE LHT NANOTUBES GRAPHITE

-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

-1.0x10-3

-5.0x10-4

I (A

E (V)

V. Vamvakaki, K. Tsagaraki, N.A. Chaniotakis, Anal. Chem. Is press

120

130

140

150

ing

Act

ivity

Carbon Nanofiber BioSensor

Stability Study

0 20 40 60 80 100

70

80

90

100

110

% R

emai

ni

t (hours)

GFE HTE LHT NANOTUBES GRAP HITE

Reproducibility: RSD value < 1% (N = 3)V. Vamvakaki, K. Tsagaraki, N.A. Chaniotakis, Anal. Chem. Is press

GaN Quantum DotsBy altering the particle size and the chemicalcomposition of the QDs the fluorescent emissionchanges.


A quantum dot

Quantum Dots


6

Photoluminescence spectra

6000

7000

8000

9000

10000

11000

ty (a

. u.)

GaN QDs GaN QDs - KCl 1M GaN QDs - KCl 2M

Optical Properties of GaN quantum dots

Depending on the KCl concentration • Blue shift

400 450 500 550 600 650 700 750

1000

2000

3000

4000

5000

Inte

nsit

Wavelength (nm)

The particle size and the chemical composition altered

QDs fluorescent emission changes

• Rise of intensity


Conclusions-Future Directions

Nanomaterilas have unique properties that are ideal for the development of

highly stable,reproduciblereproducible,and sensitive

chemical sensors andbiosensors

Acknowledgments

Sofia SotiropoulouVicky VamvakakiMaria FouskakiJiannis AlifragisAntonis Volosirakis

This work is being supported by the European Commission Programs “GANANO” and “SAFEGARD”, “IRAKLITOS” and “ARCHIMIDIS” of the Greek Ministry of

Education.

Antonis VolosirakisKleri Karapidaki

ColaborationsMicroelectronics Group FORTHProf. Ambacher and his group TUI

nanomaterials in the design of chemical sensors and biosensors: a bottom up approach ·...

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