Water-soluble thiol-capped nanocrystals

• US 6,426,513 B1
• Filed: 09/18/1998
• Issued: 07/30/2002
• Est. Priority Date: 09/18/1998
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Mikulec, Frederick V., Lee, Jin-Kyu, Bawendi, Moungi G.
• Primary Examiner(s): Jackson, Jr., Jerome
• Application Number:
  US09/156,457
• Time in Patent Office: 1,411 Days
• Field of Search: 257/13, 257/17
• US Class Current: 257/13
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 5/00 Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery
• CPC Class Codes: H10K 30/35 comprising inorganic nanostructures, e.g. CdSe nanoparticles

Abstract

A water soluble semiconductor nanocrystal capable of light emission is provided, including a quantum dot having a selected band gap energy, a layer overcoating the quantum dot, the overcoating layer comprised of a material having a band gap energy greater than that of the quantum dot, and an organic outer layer, the organic layer comprising a compound having the formula, SH(CH₂)_nX, where X is carboxylate or sulfonate. The particle size of the nanocrystal core is in the range of about 12 Å to about 150 Å, with a deviation of less than 10% in the core. The coated nanocrystal exhibits photoluminescence having quantum yields of greater than 10% in wate.

Claims

1. A water-soluble semiconductor nanocrystal capable of light emission comprising:

a quantum dot having a selected band gap energy;

a layer overcoating the quantum dot, wherein the overcoating layer comprises a material having a band gap energy greater than the band gap energy of the quantum dot; and

an outer layer, wherein the outer layer comprises a compound having a formula, SH(CH₂)_nX, where X is carboxylate or sulfonate and where n≧

8.

3. The water soluble nanocrystal of claim 1 or 2, wherein the quantum dot comprises YX, where Y is selected from the group consisting of Zn, Cd, and mixtures thereof and X is selected from the group consisting S, Se and Te and mixtures thereof.

4. The water soluble nanocrystal of claim 1 or 2, wherein the overcoating layer comprises AB, where A is selected from the group consisting of Zn, Cd, and mixtures thereof, and B is selected from the group consisting of S, Se and Te, such that AB is not identical to the quantum dot and wherein AB has a higher band gap energy than the quantum dot.

5. The water soluble nanocrystal of claim 4, wherein the overcoating layer comprises up to eight monolayers of AB.

6. The water soluble nanocrystal of claim 1 or 2, wherein a size of the quantum dot is between about 12 Å

and about 150 Å

.

2. A water-soluble semiconductor noncrystal capable of light emission comprising:

a quantum dot having a selected band gap energy;

a layer overcoating the quantum dot, wherein the overcoating layer comprises a material having a band gap energy greater than the band gap energy of the quantum dot; and

an outer layer, wherein the outer layer comprises a compound having a formula, SH(CH₂)_nX, where X is carboxylate or sulfonate and where n≧

10.

7. A composition, comprising:

a water soluble nanocrystal including a quantum dot having a band gap energy in the visible light range and at least one water-solubilizing moiety attached to the outer surface of the quantum dot, the moiety having the formula, SH(CH₂)_nX, where X is a hydrophilic moiety and where n≧

8, the water soluble nanocrystal dispersed or dissolved in an aqueous medium.

8. A composition, comprising:

a water soluble nanocrystal including a quantum dot having a band gap energy in the visible light range and at least one water-solubilizing moiety attached to the outer surface of the quantum dot, the moiety having the formula, SH(CH₂)_nX, where X is a hydrophilic moiety and where n≧

10, the water soluble nanocrystal dispersed or dissolved in an aqueous medium.