Superparamagnetic colloidal photonic structures
First Claim
1. A method of forming chain-like colloidal assemblies that diffract light, consisting of:
- mixing an iron salt precursor, a polar solvent, and a surfactant to form a first mixture;
introducing a precipitation agent into the first mixture to initiate a hydrolysis reaction, wherein the precipitation agent is a base;
controlling the hydrolysis reaction to occur at a temperature ranging from about 100°
C. to about 320°
C.;
obtaining monodisperse superparamagnetic magnetite colloidal particles from the hydrolysis reaction, wherein each of the superparamagnetic magnetite colloidal particles is formed from a plurality of nanocrystals;
controlling a size of the monodisperse superparamagnetic magnetite colloidal particles from about 30 nanometers to about 300 nanometers based on a concentration of the base;
dispersing the monodisperse superparamagnetic magnetite colloidal particles in a polar solution; and
applying an external magnetic field on the monodisperse superparamagnetic magnetite colloidal particles so as to assemble the magnetite colloidal particles in chain-like structures that diffract light in the polar solution,wherein the colloidal particles within the chain-like structures are periodically arranged, with tunable periodicity and diffraction frequency by varying the external magnetic field.
1 Assignment
0 Petitions
Accused Products
Abstract
Monodisperse colloidal nanocrystal clusters of magnetite (Fe3O4) with tunable sizes from about thirty to about three hundred nanometers have been synthesized using a high-temperature hydrolysis process. The colloidal nanocrystal clusters are capped with polyelectrolytes, and highly water soluble. Each cluster is composed of many single magnetite crystallites, thus retaining the superparamagnetic behavior at room temperature. The combination of superparamagnetic property, high magnetization, and high water dispersibility makes the colloidal nanocrystal clusters ideal candidates for various important biomedical applications such as drug delivery and bioseparation. The present invention is further directed to methods for forming colloidal photonic crystals from both aqueous and nonaqueous solutions of the superparamagnetic colloidal nanocrystal clusters with an external magnetic field applied thereto. The diffraction of the photonic crystals can be tuned from near infrared to visible and further ultraviolet spectral region by varying the external magnetic field.
-
Citations
19 Claims
-
1. A method of forming chain-like colloidal assemblies that diffract light, consisting of:
-
mixing an iron salt precursor, a polar solvent, and a surfactant to form a first mixture; introducing a precipitation agent into the first mixture to initiate a hydrolysis reaction, wherein the precipitation agent is a base; controlling the hydrolysis reaction to occur at a temperature ranging from about 100°
C. to about 320°
C.;obtaining monodisperse superparamagnetic magnetite colloidal particles from the hydrolysis reaction, wherein each of the superparamagnetic magnetite colloidal particles is formed from a plurality of nanocrystals; controlling a size of the monodisperse superparamagnetic magnetite colloidal particles from about 30 nanometers to about 300 nanometers based on a concentration of the base; dispersing the monodisperse superparamagnetic magnetite colloidal particles in a polar solution; and applying an external magnetic field on the monodisperse superparamagnetic magnetite colloidal particles so as to assemble the magnetite colloidal particles in chain-like structures that diffract light in the polar solution, wherein the colloidal particles within the chain-like structures are periodically arranged, with tunable periodicity and diffraction frequency by varying the external magnetic field. - View Dependent Claims (2, 3, 4, 10, 11, 14, 16, 17, 18, 19)
-
-
5. A method of forming chain-like colloidal assemblies, consisting of:
-
mixing an iron salt precursor, a polar solvent, and a surfactant to form a first mixture; introducing a precipitation agent into the first mixture to initiate a hydrolysis reaction, wherein the precipitation agent is a base; controlling the hydrolysis reaction to occur at a temperature ranging from about 100°
C. to about 320°
C.;obtaining monodisperse superparamagnetic magnetite colloidal particles from the hydrolysis reaction, wherein each of the superparamagnetic magnetite colloidal particles is formed from a plurality of nanocrystals; controlling a size of the superparamagnetic magnetite colloidal particles from about 30 nanometers to about 300 nanometers based on a concentration of the base; rendering a surface of the superparamagnetic magnetite colloidal particles to be dispersible in nonaqueous solvents; dispersing the superparamagnetic magnetite colloidal particles in a nonaqueous polar solution; and applying an external magnetic field on the superparamagnetic magnetite colloidal particles so as to assemble the magnetite colloidal particles in chain-like structures that diffract light in the nonaqueous solution, wherein the colloidal particles within the chain-like structures are periodically arranged, with tunable periodicity and diffraction frequency under varying the external magnetic field. - View Dependent Claims (6, 7, 8, 9, 12, 13, 15)
-
Specification