Fluorescent silica nanoparticles through silica densification

• US 8,961,825 B2
• Filed: 04/15/2010
• Issued: 02/24/2015
• Est. Priority Date: 04/15/2009
• Status: Active Grant

• Current Assignee: Cornell University
• Original Assignee: Cornell University
• Inventors: Wiesner, Ulrich B., Herz, Erik, Ow, Hooisweng
• Primary Examiner(s): Koslow, Carol M
• Application Number:
  US13/264,569
• Publication Number:
  US 20120223273A1
• Time in Patent Office: 1,776 Days
• Field of Search: 252/301.4 F, 428/404, 977/811, 977/834, 427/213.34, 427/213.3
• US Class Current: 252/301.4F
• CPC Class Codes: B01J 13/18 In situ polymerisation with all reactants being present in the same phase
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 33/18 Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C
• CPC Class Codes: C01P 2004/32 Spheres
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2004/90 Other morphology not specified above
• CPC Class Codes: C09B 67/0007 with inorganic coatings
• CPC Class Codes: C09B 69/008 Dyes containing a substituent, which contains a silicium atom
• CPC Class Codes: C09B 69/10 Polymeric dyes; Reaction products of dyes with monomers or with macromolecular compounds addition products of alkylene oxide to dyes, C09B69/00; dyeing with polymeric dyes D06P1/0056
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/06 containing organic luminescent materials
• CPC Class Codes: Y10S 977/811 Of specified metal oxide composition, e.g. conducting or semiconducting compositions such as ITO, ZnOx
• CPC Class Codes: Y10S 977/834 Optical properties of nanomaterial, e.g. specified transparency, opacity, or index of refraction
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Abstract

Provided herein are core-shell silica nanoparticles with a dense silica shell. The nanoparticles have improved properties such as, for example, increased photo luminescence and stability. Also provided are methods for making the nanoparticles.

Claims

1. A method for producing core-shell silica nanoparticles comprising the steps of:

a) preparing a silica core by combining a silica precursor and a silica precursor covalently bound to a light-absorbing material and/or light-emitting fluorescent or phosphorescent material, under conditions such that the silica precursors are hydrolyzed resulting in formation of a silica core, wherein the light-emitting material and/or light-absorbing material is covalently bound to the silica network of the core; and

b) forming a silica shell encapsulating the silica core by adding a silica precursor at a temperature of at least 50°

C., under conditions such that formation of new silica nanoparticles is not observed.

2. The method of claim 1, wherein the core-shell silica nanoparticles exhibit a density of at least 1.4 g/cm³.

3. The method of claim 1, wherein the silica precursor is TEOS and/or TMOS.

4. The method of claim 1, wherein the ratio of mass of light-absorbing material and/or light-emitting material to mass of silica is from 1 to 50 to 1 to 2000.

5. The method of claim 1, wherein in step b) the silica precursors are added in the form of at least 10 aliquots of silica precursor at a temperature of at least 50°

C. over a period of at least 1 hour, wherein the time between addition of the aliquots is at least 6 minutes.

6. The method of claim 1, wherein step b) is carried out at a temperature of from 50 to 100°

C.

7. The method of claim 1, wherein the silica core has a diameter of from 1 to 300 nanometers.

8. The method of claim 1, wherein the silica shell has a thickness of from 1 to 300 nanometers.

9. The method of claim 1, wherein the core-shell silica nanoparticle has a diameter of from 1 to 1000 nanometers.