Nano -structures Enhanced Bio -sensingdocuments.epfl.ch/groups/s/si/si-unit/www/nano-bio-sensing/Carrara... · Nano -Bio -Sensing Summer School Lausanne, Ju ly 1st, 2009 Nano -structures

S.Carrara, EPFL Lausanne

(Switzerland)1

Sandro Carrara

Integrated System Laboratory – EPFL, Lausanne (Switzerland)

NanoNano--BioBio--Sensing Summer School Lausanne, JuSensing Summer School Lausanne, July 1st, 2009ly 1st, 2009

NanoNano--structures structures

Enhanced BioEnhanced Bio--sensingsensing

((Electrochemical SensorsElectrochemical Sensors))


(Switzerland)2

What is Nanotechnology?What is Nanotechnology?

““Biology is not simply writing Biology is not simply writing

information; it is doing something information; it is doing something

about it. A biological system can about it. A biological system can

be exceedingly small. Many of be exceedingly small. Many of

the cells are very tiny, but they the cells are very tiny, but they

are very activeare very active””R.P.FeynmanR.P.Feynman

PlentyPlenty of Room at the of Room at the bottombottom, MIT , MIT lessonlesson, , DecDec. 1959. 1959

BioBio--inspired, so: inspired, so:

NanoNano--BIOBIO--technologytechnology


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The MotivationThe Motivation

� 50 $ (machinery)

� 0.05 $ the single strip

� 100.000 $ (machinery)

� 1.000 $ the single µ-array

for DNAfor DNA

for Glucosefor Glucose


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The MotivationThe Motivation

� 0.08 $/mm the single on-board CMOS bio-chip22

for DNAfor DNA


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Point-of-Care in Personalized Therapy

New systems for Drugs Monitoring in personalized therapies are an important frontier challenge


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Which are the building blocks?Which are the building blocks?

““the science of the science of objectsobjects withwith

smallestsmallest dimensionsdimensions rangingranging

fromfrom a few nanometers a few nanometers toto lessless

thanthan 100 nanometers100 nanometers””

G.M.WithesidesG.M.Withesides

SmallSmall 1(2005) 1721(2005) 172--179179


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Building Building blocksblocks under 100 under 100 nmnm sizesize

WhitesidesWhitesides definitiondefinition!!


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The proteins size

1.7 nm1.7 nm

3.8 nm3.8 nm

2.8 nm2.8 nm

Cytochrome P450Cytochrome P450

14.8nm14.8nm

12.8nm12.8nm

9.3 nm9.3 nm

HIV antibodyHIV antibody

8.2 nm8.2 nm

4.6 nm4.6 nm

Lactate OxidaseLactate Oxidase


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How nano?How nano?

The dimension drives the phenomenaThe dimension drives the phenomena

zz→→nmnm

zz→→nmnm

yy→→nmnm

zz→→nmnm

yy→→nmnm

xx→→nmnm

1D: Quantum wells1D: Quantum wells

2D: Quantum wires2D: Quantum wires

3D: Quantum dots3D: Quantum dots

Molecular MonoMolecular Mono--

MultiMulti--layerslayers

Carbon NanotubesCarbon Nanotubes

Metallic and semiconductingMetallic and semiconducting

NanoparticlesNanoparticles


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How nano?How nano?

The dimension drives the phenomenaThe dimension drives the phenomena

1D nano regions: Quantum well1D nano regions: Quantum well

2D nano region: Quantum wire2D nano region: Quantum wire

3D nano regions: Quantum dots3D nano regions: Quantum dots

polymerpolymer’’s layers + Carbon Nanotubess layers + Carbon Nanotubes

ProteinProtein’’s layers + metallic nanoparticless layers + metallic nanoparticles

Arachidate layers + semiArachidate layers + semi--conducting nanoparticlesconducting nanoparticles


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Examples of NanoExamples of Nano--BioBio--sensing?sensing?

� DNA biosensors enhanced by 1D

nanostructures.

� Enzymes biosensors enhanced by 2D

nanostructures.


nanostructures.


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11--D Nanostructures for DNA D Nanostructures for DNA

detectiondetection

� Surface Wettability

� Surface Electrical Properties


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Electrochemical InterfaceElectrochemical Interface

Ion planes are formed at the interface when

electrodes immersed in solution are polarized

AVERAGE IONS POSITION


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Electrochemical InterfaceElectrochemical Interface

Ion planes are formed at the interface when

electrodes immersed in solution are polarized

New IONS POSITION

Previous IONS POSITION

IONS DISPLACEMENT


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The DNA Detection PrincipleE

LE

CT

RO

DE

Rct

Cdl

RS

EL

EC

TR

OD

E

Applied voltage

(e.g. V<0)

Ionsdisplacement

DNA molecules

Cd

A∝

Unlabeled Unlabeled ssDNAssDNA may be detected withmay be detected with capacitance capacitance

measurements as due to charge displacementmeasurements as due to charge displacement


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Method for a precise Capacitance measurementMethod for a precise Capacitance measurement

fCVI

I stepdc

AVG +=2

THE CAPACITANCE !THE CAPACITANCE !

)()( tiIti Cdc +=

∫+=2/

0

)(1

2

T

Cdc

AVG dttiT

II

Frequency!Frequency!

Current Based Capacitance Current Based Capacitance

Measurement (CBCM)Measurement (CBCM)


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Liquid Measurement setLiquid Measurement set--upup

Chip is glued on a PCB

Bonding wiresOutput PCB pads

Fluidic cell

Two different Chambers 1mmX1mm


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Large time driftLarge time drift

The problem of time instabilityThe problem of time instability

Capacitance variation during DNA hybridizationCapacitance variation during DNA hybridization


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Detection of DNA sequences by using peptide nucleic acid as

probe molecules immobilized on Silicon with silane linkers

Large time driftLarge time drift

The problem of time instabilityThe problem of time instability


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The problem of The problem of

largely scattered data pointslargely scattered data points

Large Standard deviationLarge Standard deviation

Capacitance variation during DNA hybridizationCapacitance variation during DNA hybridization


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The Average Capacitance Drift in timeThe Average Capacitance Drift in time

Results in a too large standard deviations on the DNA detectionResults in a too large standard deviations on the DNA detection

Large Standard deviationLarge Standard deviation3 3 σσσσσσσσ: no detection with a : no detection with a

confidence level up to 99.7%confidence level up to 99.7% WhyWhy??

The problem of large errors in detectionThe problem of large errors in detection


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The average capacitance upon the frequencies may shows us The average capacitance upon the frequencies may shows us

the DNA interface layer behaviorthe DNA interface layer behavior

0

100

200

300

400

500

600

0.01 0.1 1 10 100

Frequency [KHz]

Cap

acit

an

ce [

pF

] .

Targets and probes hybridized onto Gold electrodes

How to understand the reason How to understand the reason

of the time instability?of the time instability?

@ 1KHz@ 1KHz

Charge transfer pathways through the DNA layer affect the ideal Charge transfer pathways through the DNA layer affect the ideal

Capacitance behavior of the layer at interface with the solutionCapacitance behavior of the layer at interface with the solution samplesample


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Charge transfer pathways Charge transfer pathways

through the probe layerthrough the probe layer

The frequency and time dependence of the Average Capacitance The frequency and time dependence of the Average Capacitance

are similar to those observed on clean electrodesare similar to those observed on clean electrodes

Ions transport through nanometer size layer apertures


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CoCo--immobilized Thiols as Pathway Blockersimmobilized Thiols as Pathway Blockers

Repelling molecules may be used to improve the interfaceRepelling molecules may be used to improve the interface

behavior of Hybridized DNA monobehavior of Hybridized DNA mono--layerslayers

No layer apertures of direct access of the bare gold

MercaptoMercapto--HexanolHexanol


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Improved insulating behaviorImproved insulating behavior

Redox reaction of K3Fe(CN)6 on gold electrode (a),

ss-DNA onto gold (b) and ss-DNA + 1-dodecanethiol onto gold (c)

Not enough Insulating


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Further Thiols as Pathway BlockersFurther Thiols as Pathway Blockers

Other repelling molecules may be used to improve the interfaceOther repelling molecules may be used to improve the interface

Behavior of Hybridized DNA monoBehavior of Hybridized DNA mono--layerslayers

No layer apertures of direct access of the bare gold

MercaptoMercapto--HexanolHexanol

LipaLipa--DEA moleculeDEA molecule


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N,NN,N--bis(2bis(2--hydroxyethyl)hydroxyethyl)--αα--lipoamide (lipoamide (LipaLipa--DEA)DEA) may be used as more efficient blocking agents

LipaLipa--DEA blockersDEA blockers

Different kind of thiols developed by Inger Different kind of thiols developed by Inger VikholmVikholm


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Monolayer of ssDNA with blocking agents still

present deep groves crossing the film

13 nm

0.7 nm

200nm

Lipa-DEA

400nm

Mercapto-Hexanol

3,9 nm

ssDNAssDNA MonoMono--layers with layers with

blocking agentsblocking agents


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Increased stability by using Increased stability by using LipaLipa--DEA as blocking agentDEA as blocking agent

Improved Capacitance StabilityImproved Capacitance Stability

Mercapto-Hexanol

Lipa-DEA


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Improved surface for capacitance detectionImproved surface for capacitance detection

Highly packed thiols monolayer may be used Highly packed thiols monolayer may be used

to improve the DNA detection capabilityto improve the DNA detection capability

No ways of direct access of the bare gold

CovalentCovalent

bindingbinding Well formed Well formed

SAMSAM


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Covalently linked by using EthyleneCovalently linked by using Ethylene--Glycol Glycol carboxyl terminated alkyl Thiolscarboxyl terminated alkyl Thiols

EthyleneEthylene--Glycol BlockersGlycol Blockers

ToTo preventprevent nonnon--specificspecific bindingbinding

Different kind of thiols developed by Different kind of thiols developed by G.M.WhitesidesG.M.Whitesides

Just entered the market in 2006Just entered the market in 2006


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EthyleneEthylene--glycol Monoglycol Mono--layerslayers

Monolayer of alkanethiols with ethylene-glycol chains

does not present deep groves crossing the film

Non-EG

EG

3.75 nm

0.5 nm


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Increased stability by using EthyleneIncreased stability by using Ethylene--Glycol thiolsGlycol thiols

Improved Capacitance StabilityImproved Capacitance StabilityThiols without glycole segment

0

50

100

150

200

250

300

350

400

450

500

0 2 4 6 8 10 12

time [min]

cap

acit

an

ce[n

F]

.

87 nF87 nFThiols with glycol segment

0

10

20

30

40

50

60

70

0 2 4 6 8 10

time [min]

Cap

acit

an

ce [

nF

] .

2 nF !2 nF !

non-EG

EG


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Improved insulating behaviorImproved insulating behavior

Redox reaction of K3Fe(CN)6 on gold electrode (a),

non-EG-thiols film (b) and EG-thiols film (c)

Highly Insulating


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Improved DNA arrayImproved DNA array

Capacitance vs frequency of NH2-terminated ss-DNA immobilized onto EG-Thiols precursor layer

Better Ideal capacitor behaviorBetter Ideal capacitor behavior


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Why the EGWhy the EG--Thiols improve the Thiols improve the

capacitance detection?capacitance detection?

Large detection

errors reduction

DNA detection based on ss-DNA-SH terminated directly immobilized onto gold and ss-DNA-NH2 terminated immobilized onto EG-Thiols


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Space filling of the EG thiols Space filling of the EG thiols

to close nanoto close nano--aperturesapertures

Space filling molecular model illustration of EG-thiols film presenting

a 1:1 mixture of -CON(CH2CH2O)nH (n ) 1, 3, or 6)

and O2H/CO2- groups.

Water molecules adsorptionWater molecules adsorption


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Water Adsorption in thin filmsWater Adsorption in thin films

Film Water adsorption on alkyl thiol film chains

7 water molecules


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Molecular conformations driven by terminal groups in EG-thiols

OH-terminated



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Water adsorption and Molecular conformation

in EG-thiols Film



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Covalently linked by using threeCovalently linked by using three--glycol glycol

carboxyl terminated alkyl Thiolscarboxyl terminated alkyl Thiols

OH-terminated

for probes binding


helical conformation helical conformation


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QCM measurements on dried EG-thiols film conditioned with water buffer



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� Antibodies and DNA biosensors enhanced

by 1D nanostructures.


nanostructures.


nanostructures.


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22--D Nanostructures for D Nanostructures for

Enzymes bioEnzymes bio--sensingsensing

� Surface Polarization

� Surface charging

� Electron Transfer Efficiency


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Different kind of CNTs present different characteristics ranging from Metallic to

Semiconducting conductivity based on its chirality of the walls

What a CNT is?What a CNT is?

Courtesy: K. Banerjee/California Univ.


(Switzerland)46

Electron Transfer Mediated by Electron Transfer Mediated by

2D nanostructures2D nanostructures

Carbon Nanotubes may be used in Electrochemical Interfaces


(Switzerland)47

Redox reactions from VoltammetryRedox reactions from Voltammetry

( )( )

−=

tC

tC

nF

RTEE

O

R

,0

,0ln0

II

VV

Oxidation peakOxidation peakOxidation peakOxidation peakOxidation peakOxidation peakOxidation peakOxidation peak

Peak currentPeak currentPeak currentPeak currentPeak currentPeak currentPeak currentPeak current

Reduction peakReduction peakReduction peakReduction peakReduction peakReduction peakReduction peakReduction peak Reduction PotentialReduction PotentialReduction PotentialReduction PotentialReduction PotentialReduction PotentialReduction PotentialReduction Potential

Oxidation PotentialOxidation PotentialOxidation PotentialOxidation PotentialOxidation PotentialOxidation PotentialOxidation PotentialOxidation Potential

Standard PotentialStandard PotentialStandard PotentialStandard PotentialStandard PotentialStandard PotentialStandard PotentialStandard Potential

Nernst equationNernst equation

),0(),0(

2/1

tCRT

DnFnFADti

∝

νRandles-Sevcik equation

S.Carrara, EPFL - Lausanne

(Switzerland)48

Redox reactions from Redox reactions from AmperometryAmperometry

I

t

[C1]

[2C1]

[3C1]

V=Vo

2

2 ),(),(

x

txCD

t

txC

∂

∂=

∂

∂

∞→=

=

=

∞→

ttC

CtxC

CxC

o

x

o

,0),0(

),(

)0,(

lim

Linear diffusion equation

Boundary conditions

Cottrell equation

2/12/1

2/1 ),(),(

t

txCnFADtxi

π=

I

C(x,t)

Linear relationship


(Switzerland)49

Carbon Nanotubes contribute Carbon Nanotubes contribute

to Redox Reactions Efficiencyto Redox Reactions Efficiency

Cottrell equation

( )( )

−=

tC

tC

nF

RTEE

O

R

,0

,0ln0

2/12/1

2/1 ),(),(

t

txCnFADtxi

π=

Randles-Sevcik equation

Nernst equation

),0(),0(

2/1

tCRT

DnFnFADti

∝

ν


(Switzerland)50

The peak potential is shifted toward lower potentials in case

of electrons-transfer is mediated by carbon nanotubes

Nernst Effect on Electrochemical H2O2

detection with Nano-structured Electrodes


(Switzerland)51

Carbon nanotubes contributions to Carbon nanotubes contributions to

Surface Concentration and LayeringSurface Concentration and Layering

( )( )

−=

tC

tC

nF

RTEE

O

R

,0

,0ln0

Nernst equation

-Zi

Zr

RS

CDL

RL Wr

CPE

fo


(Switzerland)52

PolyPoly--((orthoortho))--anisidineanisidine (POAS)(POAS)

Nyquist impedance diagram of a POAS film. Experimental data

are showed by boxes. Data are acquired in the frequency range

from 100 mHz up to 1KHz. The solid line shows the best fitting

0

1000

2000

3000

4000

5000

6000

0 2000 4000 6000

Z'(ohm)

-Z"(

oh

m)

polyaniline derivatives have not the tendency to form well

organized films, as it was shown by AFM microscopy

Ram M.K., et al., Synthetic Metals 100(1999) 249-259


(Switzerland)53

0

500

1000

1500

2000

2500

3000

3500

4000

0 1000 2000 3000 4000

Z'(ohm)

-Z"(

oh

m)

Nyquist impedance diagram of a POAS film. Experimental data are showed by

boxes. Data are acquired in the frequency range from 1KHz down to 100mHz.

The solid line shows the best fitting

Charge transfer resistance

coherently decreases with

the Lundberg Theory of

conducting mixtures

Conducting Polymer +Conducting Polymer + Carbon ParticlesCarbon Particles


(Switzerland)54

0

50

100

150

200

250

300

350

400

0 100 200 300 400

Z'(ohm)

-Z"(

oh

m)

� Nyquist impedance diagrams of a POAS film synthesized with Carbon Nanotubes.

Experimental data are showed by boxes. Data are acquired in the frequency range

from 1KHz down to 100 mHz. The solid line shows the best fitting

Conducting Polymer + Multi Walled Conducting Polymer + Multi Walled CNTsCNTs

Pure electrostatic attraction

in the double layer and

faradic reaction are

responsible for the super-

capacitance phenomena in

Carbon Nanotube

structures


(Switzerland)55

0

5

10

15

20

25

0 1 2 3 4 5

[H2O2] (mM)

Cu

rren

t (µ

A)

Bare electrode

Nanostructured electrode

sensitivity = 51.9 µA/mM cm2

sensitivity = 0.7 µA/mM cm2

~ 75 times more!!!!~ 75 times more!!!!

Cottrel Effects on H2O2 detection with Nano-

structured Electrodes


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Peroxide DetectionPeroxide Detection

The peroxide detection is highly improved

by using carbon nanotubes

2 order of magnitude!!!


(Switzerland)57

R-OH

P450 for Drugs MonitoringP450 for Drugs Monitoring

RH (e.g. benzphetaminebenzphetamine )

H-O-H

NADPH+H+

NADP+

Cytochrome

P450 2B4

Oxidized formmore soluble

then

faster secreted

O2

From electrode

Drugs detection !

2e -

3.6 nm3.6 nm

5.2 nm5.2 nm

4.9 nm4.9 nm


(Switzerland)58

BZ BZ

TK

EE

B

F

e

Ef−

+

=

1

1)(

φ

)(Ef

φφ

)(EfLUMO LUMO

G

==

h2

2

0

ennGG

e - e -

P1P2>P1

Electron Transfer Enhancer

An improved P450/Electrode coupling An improved P450/Electrode coupling

by Ballistic Nanotubesby Ballistic Nanotubes


(Switzerland)59

Shift in Peak PotentialShift in Peak PotentialE

Nernst EffectNernst Effect

A shift in the Peak Potential is observed when the P450 Activity is mediated by Single Walled Carbon Nanotubes


(Switzerland)60

Layering affects total ChargingLayering affects total Charging

Different Total Charges as calculated from Cyclic Voltammetry with electrodes not structured and structured

by using SW or MW Carbon Nanotubes


(Switzerland)61

The Peak Current is larger when the P450 Activity is mediated The Peak Current is larger when the P450 Activity is mediated

by Multi Walled Carbon Nanotubesby Multi Walled Carbon Nanotubes

Peak current enhancementPeak current enhancement

RandlesRandles EffectEffect


(Switzerland)62

Cottrell EffectCottrell Effect

Electron Transfer Electron Transfer

EnhancementEnhancement

The Sensitivity is enhanced when the P450 Activity is mediated The Sensitivity is enhanced when the P450 Activity is mediated

by Multi Walled Carbon Nanotubesby Multi Walled Carbon Nanotubes


(Switzerland)63

OxidaseOxidase

OxygenOxygenProductProduct

Oxidases based detection: Oxidases based detection:

the working principlethe working principle

Oxygen peroxideOxygen peroxide

2e2e--AmperometricAmperometric

Detection !!!!!Detection !!!!!

Glucose, or Lactate, or Glutamate, or Glucose, or Lactate, or Glutamate, or ……


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Sensitivity Enhancement in Glucose detection by using GOD

immobilized onto Multi Walled Carbon Nanotubes

Glucose detection by Oxidase and CNTGlucose detection by Oxidase and CNT


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Sensitivity Enhancement in Lactate detection by using LOD

immobilized onto Multi Walled Carbon Nanotubes

Sensitivity enhancementSensitivity enhancement

Lactate detection by Oxidase and CNTLactate detection by Oxidase and CNT


(Switzerland)66


� Antibodies and DNA biosensors enhanced

by 1D nanostructures.


nanostructures.


nanostructures.


(Switzerland)67

33--D Nanostructures for D Nanostructures for

Enzymes bioEnzymes bio--sensingsensing

� Single Electron Trapping

� Electron Transfer Efficiency


(Switzerland)68

The CdS nanoparticle formationArachidic Acid

Cd

The final particle is surrounded by a insulating barrier The final particle is surrounded by a insulating barrier

also in case of other formation techniques!also in case of other formation techniques!

Semiconducting particles fabrication in Semiconducting particles fabrication in

Thin Solid FilmsThin Solid Films


(Switzerland)69

Sulfide based NanoSulfide based Nano--particlesparticles

Mass variation during the grown of CdS nanoparticles in H2S atmosphere

0

5

10

15

20

25

0 5 10 15 20 25 30 35 40 45 50

tempo [minuti]

Massa c

om

ple

ssiv

a

delle n

an

op

art

icelle [

ng

]


(Switzerland)70

They act as electron-traps

Tunneling barrier

Potential hole for the

charge carriersTrapped electron

The Two Barriers SystemsThe Two Barriers Systems


(Switzerland)71

CdS nanoparticles (close to 5 nm in size) in Arachidic matrix

STM imaging and spectroscopy on STM imaging and spectroscopy on

nanoparticlesnanoparticles

Negative Differential Resistance (NDR) regionsNegative Differential Resistance (NDR) regions !!!!!!

Coulomb Coulomb StaircaseStaircase!!

Just a Just a tunnelingtunneling!!


(Switzerland)72

A semi-classical theory

SingleSingle--electron conductivityelectron conductivity

mediated by a nanoparticlemediated by a nanoparticle


(Switzerland)73

Bias Voltage [V]

0

2

4

6

8

10

12

0 0.5 1

Bias Voltage [V]

0

2

4

6

8

10

12

0 0.5 1

Bias Volta ge [V]

0

5

10

15

20

25

30

35

0 0.5 1

Bias Voltage [V]

0

2

4

6

8

10

12

0 0.5 1

SingleSingle--electron conductivity on electron conductivity on

single nanoparticlesingle nanoparticle

LikharevLikharev TheoryTheory

LimitLimit (1983)(1983)

More evident NDR when n increaseMore evident NDR when n increase

new Theorynew Theory

LimitLimit (1996)(1996)

The size drives the phenomena !!!The size drives the phenomena !!!


(Switzerland)74

Metallic particles fabrication in solutionMetallic particles fabrication in solution

A A gold nuggetgold nugget is formed!is formed!


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The thiols shell prevents further aggregations The thiols shell prevents further aggregations

and this allows monoand this allows mono--disperse nanoparticles!disperse nanoparticles!

Metallic particles fabrication in solutionMetallic particles fabrication in solution


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TEM provides the metallic core size

while SAXS provides the organic coating size

Transmission Electron MicroscopyTransmission Electron Microscopy

5 nm5 nm

Small Angle XSmall Angle X--ray Scattering (SAXS)ray Scattering (SAXS)

9 nm9 nm


(Switzerland)77

radius by TEM Radius by SAXS= 3.1 nm4.4 nm

Gold Nanoparticles SizeGold Nanoparticles Size


(Switzerland)78

Conducting coreInsulating layer

Gold nanoparticles as Quantum DotsGold nanoparticles as Quantum Dots

This nanoThis nano--system is very useful system is very useful

for quantum effects !!!for quantum effects !!!

Potential hole for Potential hole for

charge carrierscharge carriers Tunneling barrierTunneling barrier

2 nm2 nm22 22


(Switzerland)79

BZ BZ

TK

EE

B

F

e

Ef−

+

=

1

1)(

φ

)(Ef

φφ

)(EfLUMO LUMO

e -

P1

P2>P1

Electron Transfer Enhancer

e -

An improved P450/Electrode An improved P450/Electrode

coupling by Quantum Dotscoupling by Quantum Dots


(Switzerland)80

P450+Riboflavin+phospholipids+Albumine+

Glutaraldehyde

only NPs !only NPs !

Cottrell EffectCottrell Effect

Electron Transfer Electron Transfer

EnhancementEnhancement

The Sensitivity is enhanced when the P450 Activity is mediated The Sensitivity is enhanced when the P450 Activity is mediated

by gold nanoby gold nano--particlesparticles


(Switzerland)81

Nano affects Detection Nano affects Detection

Sensitivity and LimitSensitivity and Limit

Sensitivity

Detection Limit


(Switzerland)82

Sensitivity Sensitivity vsvs Detection limitDetection limit

The case of Glucose

Nano!


(Switzerland)83


The case of lactate

Nano!


(Switzerland)84


The case of Hydrogen Peroxide

Nano!


(Switzerland)85


The case of Cholesterol

Nano!


(Switzerland)86

“Nano” Improves Bio-Sensing

Conclusions (1)Conclusions (1)

11--5 nm5 nm

22--10 nm10 nm

2 nm2 nm


(Switzerland)87

Conclusions (2)Conclusions (2)� 1D-nanostructures made by ethylene-glycol layers highly

improve insulating property of electrochemical interfaces

� 1D-nanostructures made by ethylene-glycol mono-layers highly improve DNA label-free detection

� 2D-nanostructures by carbon nanotubes improve charging effect and electron-transfer in electrochemical interfaces

� 2D-nanostructures by carbon nanotubes improve sensitivity and detection limit in enzymes based bio-sensing

� 3D-nanostructures by metallic or semiconducting particles assure single-electron trapping

� 3D-nanostructures by metallic particles improve sensitivity and detection limit in enzymes based bio-sensing

� Nanotechnology is useful

not only for Nanobamafabrication!!!


(Switzerland)88

CoordinatesSandro Carrara Ph.D

EPFL - Swiss Federal Institute of Technology

in Lausanne

Web: http://si2.epfl.ch/~scarrara/

email: [email protected]

Dedicated to Janos Fendler, a great pioneer in the field of Nano-particle technology

Thanks to all the peoples helping me Thanks to all the peoples helping me

on this research and thank to all of on this research and thank to all of

you for your kindly attention!you for your kindly attention!

Documents

Nano -structures Enhanced Bio -sensingdocuments.epfl.ch/groups/s/si/si-unit/www/nano-bio-sensing/Carrara... · Nano -Bio -Sensing Summer School Lausanne, Ju ly 1st, 2009 Nano -structures