Photo acoustic spectroscopy of beta amyloids - research overview

Group Meeting February 08

OTDRpulse width: 100ns-1μs

Scope

detector

10%

fibersplitter

Erbium Amplifier

90%

PZT

RF Amplifier

24V+ Voltage source

reference Photo-acoustic signal

First setup goal –generating and characterization of pa signal

Wavelength – 1550 nm

1. OTDR

TunableLaser

Polarization controller

Modulator Function Generator

Erbium Amplifier x2

Scope

PZT

RF Amplifier x3

24V+ Voltage sourcedetector

fibersplitter

Reference

95%

Signal

5%

2. Tunable Laser

Wavelength 1535 -1565 nm

~5 micro second

~5 micro second

PZT

abs coefficient

-10

10

30

50

70

90

110

130

1000 1200 1400 1600 1800 2000

nm

cm

^-1

ddw

ethanol

3.85ethanol

water

P

P

Water:

Abs coefficient =11.6 cm^-1

heat capacity = 4.184J cm-3 K-1   

Thermal expansion =20710-6/K

ethanol:Abs coefficient =5.7 cm^-1

heat capacity = 1.925J cm-3 K-1   Thermal expansion =75010-6/K

0PP

E

C

second peak amp of glucose in diff conentrations

0

20

40

60

80

100

0 20 40 60

glucose concentration in water(%)

amp

of

pea

k

Series1

•There is a change of 0.28% in sound velocity for a percent change of glucose concentration

200 800 2,000300 10,000

UV visible Near-IR IR

nm

1550

peptidic bond(190-250 nm)

aromatic residues(~280nm) starching vibration of aromatic residues(3.3, 6.25,6.6 μm )

starching vibration of amide bond (5.88-6.25 μm )

bending vibration of aromatic residues (11.1-14.5 μm)

Over tones (1000-2600)

Spectrum

0

0.5

1

1.5

2

2.5

3

3.5

180 200 220 240 260 280 300

insulin 200

insulin 400

Technion experiment :

Nd:YAG fourth harmonic 266nm laser:

1.Insulin

0 500 1000 1500 2000 2500-4

-3

-2

-1

0

1

2

3

4

5Insulin (-offset)

Insulin 200M

Insulin 400M

Insulin 100M

Insulin 50MBuffer Gly (with small ins c.)Native(400 M) Insulin in H2O

0 500 1000 1500 2000 2500-8

-6

-4

-2

0

2

4

6Lyso 50mg 1stH2OLyso 50mg 2ndLyso 25mgLyso 12.5mgLyso 6.25mgH2O(small protein concentration)H2O 2nd

2.lysosin

3.Beta amyloid

opo experiment:OPO -optical parametric oscillator

0

0.5

1

1.5

2

2.5

3

3.5

1000 1200 1400 1600 1800 2000

D2O 0.5

lysozyme D2O 0.5

insulin native D2O 0.5

insulin amyloid D2O 0.5

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

1600 1650 1700 1750 1800

D2O 0.5

lysozyme D2O 0.5

insulin native D2O 0.5

insulin amyloid D2O 0.5

Zoom in on first peak

1100 1200 1300 1400 1500 1600 1700 18000

5

10

15

20

25

30

35Water absorption & 1st peak of acoustic signals (multiplied by 50)

wavelength (nm)

water absorptionabsorption in gratings wavelength

1 .insulin

2 .water

Wavelength ~1660nm

Goals for the short future

improving the sensitivity of the measurements

Defining the concentration and absorption coefficient of solutions by pa measurement

Finding the amyloids over tones spectra , and characterize its pa signal

Examine the ability of performing pa measurements in the MIR

Completing the simulation of the pa signal