# US 9,752,986 B2 · Spectro-temporal optical encoding of information using a time-gated fluorescence resonance energy transfer (FRET)

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- Number: US 9,752,986 B2
- Document ID: US9752986B2
- Status: Granted
- Kind: B2
- Application number: 13/911,157
- Filed: 2013-06-06
- Published: 2013-11-21
- Granted: 2017-09-05
- Earliest claimed: 2012-05-18
- Assignees: The United States of America as represented by the Secretary of the Navy
- Applicants: W. Russ Algar; Niko Hildebrandt; Alan L. Huston; Igor L. Medintz
- Inventors: W. Russ Algar; Niko Hildebrandt; Alan L. Huston; Igor L. Medintz
- Web page: https://patentgrep.com/patent/US9752986B2

## CPC

- G01N 21/6486: {Measuring fluorescence of biological material, e.g. DNA, RNA, cells (G01N21/6428 takes precedence)}
- B82Y 15/00: Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
- B82Y 20/00: Nanooptics, e.g. quantum optics or photonic crystals
- G01N 21/6408: {with measurement of decay time, time resolved fluorescence}
- G01N 21/6428: {Measuring fluorescence of fluorescent products of reactions or of fluorochrome labelled reactive substances, e.g. measuring quenching effects, using measuring "optrodes" (in vivo A61B5/00; immunoassay G01N33/53)}
- G01N 33/542: with steric inhibition or signal modification, e.g. fluorescent quenching
- G01N 33/588: {with semiconductor nanocrystal label, e.g. quantum dots}
- G01N 2021/6441: {with two or more labels}
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

Described herein is a time-gated, two-step FRET relay effective to provide temporal transference of a prompt FRET pathway, or provide spectro-temporal encoding analytical signals and other information. A FRET relay assembly includes a long lifetime FRET donor (for example, a lanthanide complex), a semiconductor quantum dot (QD) configured as an intermediate acceptor/donor in FRET, and a fluorescent dye configured as a terminal FRET acceptor, wherein the long lifetime FRET donor has an excited state lifetime of at least one microsecond and the QD and fluorescent dye each have excited state lifetimes of less than 100 nanoseconds.

## Claims

### Claim 1

A method of using a FRET relay assembly, the method comprising:
providing a FRET relay assembly comprising:
a long lifetime FRET donor,
a semiconductor quantum dot (QD) configured as an intermediate acceptor/donor in FRET and assembled to the long lifetime FRET donor in sufficient proximity thereto so as to allow for a first FRET process between the long lifetime FRET donor and the QD and
a fluorescent dye configured as a terminal FRET acceptor and assembled to the QD in sufficient proximity thereto so as to allow for a second FRET process between the QD and the fluorescent dye,
wherein the long lifetime FRET donor has an excited state lifetime of at least one microsecond and the QD and fluorescent dye each have excited state lifetimes of less than 100 nanoseconds;
spectrally exciting the FRET relay assembly; and
receiving a spectral emission from the FRET relay assembly.

### Claim 2 (depends on 1)

The method of claim 1, wherein at least two distinct FRET relay assemblies are provided.

### Claim 3 (depends on 1)

The method of claim 1, wherein spectral emissions are received in observation windows 0-250 ns and 55-1055 μs after said spectrally exciting.

### Claim 4 (depends on 1)

The method of claim 1, wherein said long lifetime FRET donor comprises Tb3+, Eu3+, Sm3+, Tm3+, or Ru2+.

### Claim 5 (depends on 1)

The method of claim 1, wherein said long lifetime FRET donor and/or said fluorescent dye are bound to said QD using peptides and/or oligonucleotides.

### Claim 6 (depends on 1)

The method of claim 1, wherein at least one His6 motif is adapted to bind said long lifetime FRET donor and/or said fluorescent dye to said QD.

### Claim 7 (depends on 1)

The method of claim 1, wherein the QD is functionalized with carboxylate, amine, or poly(ethylene glycol).