Experimental Setup

Nd:YAG OPO

MonochromatorDetector

PMT

Sample

1.0

1.2

0.8

0.6

0.4

0.2

10 20 30 40 50

Time (ms)

10mM [Dy(DOTA)]-

10mM Dy3+

1.0

1.2

0.8

0.6

0.4

0.2

10 20 30 40 50

Time (ms)

10mM [Dy(DOTA)]-

0.4mM [Dy(DOTA)]-

0.08mM [Dy(DOTA)]-

1mM [Dy(DOTA)]-

10mM[Dy(DOTA)]-

10nM [Dy(DOTA)]-

570 670wavelength (nm)

450 556 660 670 838 Two Photon Absorption Wavelength (nm)

s2

s1

(x 10-3)10

8

6

4

2

AMCANTS

EdensLucifer Yellow

CS124

(x 10-4)

E2 (mJ)E1 (mJ)

24.5��

1.736.0�

�15.0

30.0��

1.047.0�

�0.1

20.0��

0.2

450452

454456

458

570Absorption wavelength (nm) Emission

wavelength (nm)

525.3 526.5nm

Eu3+ absorptionNo Pf1

Eu3+ absorptionWith Pf1

596 620nm

Eu3+ emissionNo Pf1

Eu3+ emissionWith Pf1

400 500 600 700 800

Dy3+ Emission Spectrum

500 520 540 560 580 600

Eu3+ Absorption Spectrum

450 700660Wavelength (nm)

Absorption CS124

Example of the emission spectrum of Dysprosium 3+ taken at 355 nm absorption.

Emission spectra of [Dy(DOTA)]- following one photon absorption. The dependence of the 570 nm emission wavelength on absorption wavelength intensity is easily seen.

Excited state lifetimes with and without the DOTA chelate. The absence of water molecules surrounding the chelated Dy3+ eliminates vibrational energy transfer, resulting in longer excited state lifetimes.

Concentration dependence of [Dy(DOTA)]- showing the decrease in signal intensity with decreasing lanthanide concentration.

How low can we go?A low detection limit is an important aspect with in vivo experiments. Using this experimental setup signals were obtainable with Dy3+ concentrations as low as 10 nM.

This table shows the ratio of the two photon to one photon cross sections vs. the two photon absorption wavelength. Lucifer Yellow's higher cross section ratio can be attributed to its higher one photon wavelength of 432 nm.

Two photon absorption spectrum of carbostyril-124 with detection wavelength of 440 nm.

Future Experiments

Unable to drive the two photon process with the chelated dye, experimental modifications are needed to excite [Eu(DOTA)]- at the 590 nm absorption maximum and detect at 810 nm emission.

A Stark shift was shown for both the absorption and emission of Eu3+ when present with the Pf1 virus. This shift is due to the interaction of the electric field of the Pf1 with the dipole moment of the lanthanide. Using the model shown above the shift can be obtained by calculating the derivative of the potential with respect to the distance from Pf1.

-25 -15 -5 5kHz

23Na 39K

-6 -4 -2 0kHz

V(r) = aK0(r) +Voffr+(r) ¹ r-(r)

This simple model shows the electric potential surrounding the pseudomonas phage Pf1.

Stark Shift pE ·=

The liquid NMR spectra above shows the splittings of sodium and potassium ions due to the electric field gradient near the Pf1 virus. While isotropic tumbling eliminates quadrupolar effects in liquids NMR, electrical alignment of ions in the Pf1 fields allows recovery of these quadrupolar splittings.

Acknowledgements

Scott RileyShashi Vyas

Claude MearesPaul Whetstone

rVE

¶¶=

Experimental setup consisting of a Spectra Physics GCR-270 Nd:YAG laser, Spectra Physics Quanta-Ray MOPO-700 Optical Parametric Oscillator, and detection system. The OPO is pumped with the frequency tripled 355 nm output of the Nd:YAG and has a tunable signal output from 400-690 nm and an idler output from 710-2000 nm. To detect lanthanide lifetimes a Tekronix TDS 724C digitizing oscilloscope is used. Absorption and emission spectra are acquired and digitized using a Stanford Research Systems boxcar averager and Tecmag data acquisition system.

Axially symmetric lanthanide (III) complex of the macrocyclic ligand 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetate, DOTA.

N N

NN

-OOC

-OOC

COO-

COO-

Ln3+

Introduction

Biotechnical researchers have recently demonstrated the ability to site specifically attach large molecules to target cells inside the body. Current research involves tethering luminescent dyes to these molecules through a lanthanide doped chelating agent. While many of these lanthanides' electronic transitions fall within 700 to 1000 nm, their long excited state lifetimes allow for easy luminescence detection. Skin is largely transparent to these wavelengths, which encouraged the investigation of one- and two-photon energy transfer between various dyes and the chelated lanthanide. This approach will lead to a less damaging and less costly method to image soft tissue in vivo.

2

2

2

rV ÷

÷ø

öççè

æ

¶¶

2

2

rV

¶¶

Possible luminescent probes.

Emission Wavelength 620

Tb3+7F5-7F2

850

Dy3+6F3/2-6H5/2

810

Eu3+5D0-7F6

700

Tm3+3F3-3H6

Eu3+5D0-7F6

615

Towards In Vivo Ion ImagingApril J. Weekley, Sarah M. Cureton, Matthew P. Augustine

Department of ChemistryUniversity of California

Davis, CA 95616