Compositions and methods for enhanced fluorescence
This disclosure relates to the field of fluorescent dyes, and in particular, compositions and methods for increasing fluorescent signals and the reduction of fluorescent quenching.
1. A composition, comprising a first conjugated antibody comprising two to ten fluorescent labels and two or more spacer molecules covalently attached to a first antibody, wherein the fluorescent labels and spacer molecules are not covalently attached to each other and wherein the composition exhibits increased fluorescence relative to a composition comprising a second conjugated antibody that is the same as and has a same degree of fluorescent labeling as the first conjugated antibody but that is lacking spacer molecules covalently attached to the second conjugated antibody, wherein the spacer molecules, which are covalently attached to the first antibody, are selected from sulfo-NHS-acetate, MS(PEG) 4 , or NHS-Betaine.
2. The composition of claim 1 , wherein the first conjugated antibody exhibits higher fluorescent emission levels than the second conjugated antibody wherein the higher fluorescent emission levels are the result of the spacer molecules increasing fluorescence of the first conjugated antibody.
3. The composition of claim 1 , wherein the spacer molecules are conjugated to the first antibody to an amine group of a lysine residue.
4. The composition of claim 1 , wherein the spacer molecules are sulfo-NHS-acetate.
5. The composition of claim 1 , wherein the spacer molecules are MS-(PEG) 4 .
6. The composition of claim 1 wherein the fluorescent labels are positively charged.
7. The composition of claim 1 , wherein the fluorescent labels are dyes independently selected from a cyanine dye; a benzo-rhodamine dye; a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene dye; a fluorescein dye; a benzopyrillium dye, including derivatives thereof; a coumarin dye, a benzofuran dye; a quinoline dye; a quinazolinone dye; an indole dye; a furan dye; a benzazole dye; a borapolyazaindacene dye; or a xanthene dye.
8. The composition of claim 1 , wherein the fluorescent labels comprise a moiety selected from xanthene, coumarin, cyanine, pyrene, oxazine, borapolyazaindacene, benzopyrylium, or carbopyronine.
9. The composition of claim 1 , wherein the fluorescent labels comprise a moiety selected from is selected from dinitrophenyl, Fluorescein, hexachlorofluorescein, 4′,5′-dichloro-2′,7′-dimethoxy-5(6)-carboxyfluorescein, 6-carboxyl-X-rhodamine, tetrachlorofluorescein, tetramethyl rhodamine, or 7-hydroxy-9H-(1,3-dichloro-9,9-dimethylacridin-2-one) succinimidyl ester (DDAO-SE).
10. The composition of claim 1 , wherein a number of the fluorescent labels conjugated to the first antibody is from 2 to 6.
11. The composition of claim 1 , wherein a number of the spacer molecules conjugated to the first antibody is from 2 to 50.
12. The composition of claim 1 , wherein the spacer molecules are in molar excess to the fluorescent labels in an amount from 0.1 to 25 fold.
13. The composition of claim 1 , wherein the presence of the spacer molecules increases detectable fluorescence of the fluorescent labels by 20% to 500 5 .
14. The compistion of claim 1 , wherein the first conjugated antibody comprises one or more of the following characteristics:
(a) a Fluorescent Ratio on a per fluorescent label basis that is equal to or greater than 0.5,
(b) at least four fluorescent labels conjugated to the first antibody, and/or
(c) total fluorescence of the first conjugated antibody is at least 20 percent greater than fluorescence of an unconjugated fluorescent molecule.