Förster Resonance Energy Transfer (FRET)

Tina R. Amirtha

Supervisors: Antigoni AlexandrouDidier Casanova

Using Lanthanide-Ion Doped Oxide Nanoparticles as Donors to Organic Fluorophore Acceptors

Collaboration with PMC (D. Giaume, T. Gacoin, J.P.

Boilot

Agenda

Introduction Lanthanide-Ion Doped Oxide Nanoparticles FRET

Set-up of Microscope Results Discussion Conclusions

Time-Gated Detection Alternative Nanoparticles Nanoparticles as both donors and acceptors

Lanthanide-Ion Doped Oxide Nanoparticles: YVO4:Eu YVO4 Matrix, doped with Eu3+

ions (20%) 1-nm SiO2 Layer Excitation peak at 466nm Emission peak at 617nm

YVO4:Eu General Advantages

Synthesis in water Photostable, no blinking Narrow emission spectrum, large Stokes

shift

Förster Resonance Energy Transfer: FRET

Organic Flurophores Luminescent Lanthanide Chelates Quantum Dots Lanthanide-Ion Doped Oxide Nanoparticles

Donor Acceptor

15 – 100 Å

Absorption Emission

E617 nm 670 nm

Absorption Emission

E466 nm 617 nm

Förster Equation:

YVO4:Eu Cy5

R

YVO4:Eu to Cy5

Excite YVO4:Eu at 466nm

Eu 3+ emits at 617nm -- excites Cy5

Cy5 emits at 670nm

Excitation

Emission

Methods

SiO2 coverslip

Cy5 spin-coated over YVO4:Eu

Wide-Field Microscopy

Dichroic Mirror Two Interference

Filters (615nm, 670nm)

Cy5 with 670nm Interference Filter

Results

Observation 1

617nm 670nm

Observation 2

617nm 670nm

Efficiency of Energy Transfer (E)

Ro = distance (Å) at which E = 0.5

J = spectral overlap of donor and acceptor (M-1cm-1nm4)

Förster Equation:

Ro = 37.4672 Å

RYVO4:Eu

Cy5

Selvin, P., et. al. (2002)

FRET Efficiency YVO4:Eu-Cy5 vs. Distance Ro = 37.4672 Å

RYVO4:EuCy5

« FRET Photons »

« Sensitized » Emission of Cy5

More Cy5 = More FRET photons

IDA :measured NP emission in presence of Cy5

IADtotal :measured sensitized emission of Cy5

qA = 0.27

qD = 0.10

IAD :sensitized emission of 1 Cy5 molecule

RYVO4:Eu

Cy5

Conclusions

FRET is possible with lanthanide-ion doped oxide nanoparticles

Promising for single-molecule applications

Synthesis in water Good photostability; no blinking Large Stokes shifts

Perspectives: Time-Gated Detection Goal: To minimize background fluorescence

due to Cy5 TCy5 ~ns

TYVO4:Eu ~ms

Perspectives: Alternative Oxide Nanoparticles

LaPO4 Matrix Co-Doped NP’s (LaPO4:CeTb) Multi-Color Experiments NP’s as Donors and Acceptors

Abs

orpt

ion

NP Composition Options

Wavelength (nm)

Various Emission Wavelengths

Em

issi

on

Wavelength (nm)

Example: LaPO4:Ce to LaPO4:Tb Ro = 7.0662 Å

LaPO4:Ce LaPO4:TbR

Summary

FRET is possible with lanthanide-ion doped oxide nanoparticles

Time-gated techniques Multi-color experiments NP’s as donors and acceptors