Small water-soluble quantum dots
View Patent ↗Water-soluble, stable fluorescent PEGylated alkanethiol-coated quantum dots are made by contacting quantum dots with PEGylated alkanethiol in a non-oxidative, water-immiscible organic reaction solvent under a non-oxidative gas, wherein the reaction solvent is in contact with an aqueous phase, at elevated temperature and time sufficient to coat the dots with the PEGylated alkanethiol, wherein resultant water-soluble, stable fluorescent PEGylated alkanethiol-coated dots enter the aqueous phase.
1. A method of making water-soluble, stable fluorescent PEGylated alkanethiol-coated quantum dots, the method comprising:
contacting quantum dots with PEGylated alkanethiol in a non-oxidative, water-immiscible organic reaction solvent under a non-oxidative gas, wherein the reaction solvent is in contact with an aqueous phase, at elevated temperature of 40-80° C. and time sufficient to coat the dots with the PEGylated alkanethiol, wherein resultant water-soluble, stable fluorescent PEGylated alkanethiol-coated dots enter the aqueous phase, wherein the PEGylated alkanethiol is in a mixture of the PEGylated alkanethiol and functionalized PEGylated alkanethiol.
2. The method of claim 1 wherein the elevated temperature is about 60 C and the time is about 4 hours.
3. The method of claim 1 wherein the gas comprises inert gas that is nitrogen.
4. The method of claim 1 wherein the reaction solvent comprises toluene, chlorobenzene, or octane.
5. The method of claim 1 wherein the aqueous phase comprises tetraethylammonium hydroxide (20% wt) in water.
6. The method of claim 1 wherein:
the elevated temperature is about 60 C and the time is about 4 hours;
the gas comprises inert gas that is nitrogen;
the reaction solvent comprises toluene; and
the aqueous phase comprises tetraethylammonium hydroxide (20% wt) in water.
7. The method of claim 1 wherein the dots comprise a nanocrystal metal core of CdSe, HgCdSe, CdTe, ZnTe, ZnS, CdS or InAs.
8. The method of claim 1 wherein the dots further comprise a shell of ZnS or CdS.
9. The method of claim 1 wherein the coated dots have a diameter less than 10 nm.
10. The method of claim 1 wherein:
the dots comprise a nanocrystal metal core of CdSe, CdTe, ZnTe, or ZnS;
the dots further comprise a shell of ZnS or CdS; and
the coated dots have a diameter less than 10 nm.
11. The method of claim 1 wherein the PEGylated alkanethiol is in a mixture of the PEGylated alkanethiol and functionalized PEGylated alkanethiol, wherein the functionalized PEGylated is 10% or less of the mixture.
12. The method of claim 1 wherein the PEGylated alkanethiol is in a mixture of the PEGylated alkanethiol and functionalized PEGylated alkanethiol, wherein the functionalized PEGylated alkanethiol is carboxyl PEGylated alkanethiol or amine PEGylated alkanethiol.
13. The method of claim 1 wherein the PEGylated alkanethiol is in a mixture of the PEGylated alkanethiol and functionalized PEGylated alkanethiol, wherein the functionalized PEGylated alkanethiol is a corresponding carboxyl PEGylated alkanethiol.
14. The method of claim 1 wherein the PEGylated alkanethiol is in a mixture of the PEGylated alkanethiol and functionalized PEGylated alkanethiol, wherein the functionalized PEGylated alkanethiol is a corresponding carboxyl PEGylated alkanethiol, wherein the mixture is HSC11(EG)4-OH/HSC11(EG)4-COOH (2.5%).
15. The method of claim 1 wherein the functionalized PEGylated alkanethiols of the coated dots are further functionalized with an affinity tag.
16. The method of claim 1 further comprising isolating the coated dots with anion exchange chromatography.
17. The method of claim 1 further comprising washing the aqueous phase containing the coated dots with a water-immiscible organic wash solvent and then isolating the coated dots with anion exchange chromatography.
18. The method of claim 1 further comprising isolating the coated dots and (a) storing the isolated dots in refrigeration for over one month, and/or (b) storing the isolated dots in a mixture comprising at least 50% ethylene glycol.
19. A composition comprising an organic phase comprising quantum dots and PEGylated alkanethiol, at elevated temperature of 40-80° C. under a non-oxidative gas, in contact with an aqueous phase comprising water-soluble, stable fluorescent corresponding PEGylated alkanethiol-coated quantum dots, wherein the PEGylated alkanethiol is in a mixture of the PEGylated alkanethiol and functionalized PEGylated alkanethiol.
20. The composition of claim 19 wherein the coated dots have a diameter less than 10 nm.