Optically encoded particles
The invention concerns a particle having a code embedded in its physical structure by refractive index changes between different regions of the particle. In preferred embodiments, a thin film possesses porosity that varies in a manner to produce a code detectable in the reflectivity spectrum.
1. A freestanding optically encoded particle, comprising:
a first porous layer having a predetermined first porosity and thickness; and
a plurality of n additional porous layers having predetermined thicknesses and porosities, at least one of which has a predetermined porosity differing from said first porosity; wherein
said predetermined porosities and thicknesses of said first porous layer and said n additional porous layers are configured to produce an interference pattern in the reflectivity spectrum having a distinct series of peaks such that the interference pattern forms an optical signature having a particular predetermined code determined by the porosities and thicknesses of said first porous layer and said n additional porous layers a receptor or targeting moiety for binding a predetermined analyte, wherein said receptor or targeting moiety is within one or more of said first porous layer and said n additional porous layers; and wherein
the particle has a diameter of a few hundred microns or less and is freestanding separated from any substrate.
2. The particle of claim 1 , wherein the particle has a diameter in the range from a few hundred nanometers to a few hundred microns.
3. The particle of claim 1 , wherein said first porous layer and said n additional porous layers have a matched optical thickness, wherein optical thickness comprises the product of refractive index and layer thickness.
4. The particle of claim 1 , wherein said interference pattern in the reflectivity spectrum extends beyond the visible spectrum.
5. The particle of claim 1 , wherein said first porous layer and said n additional porous layers alternate periodically and form a Bragg stack.
6. The particle of claim 1 , wherein said first porous layer and said n additional porous layers form a Rugate reflector.
7. The particle of claim 1 , wherein said first porous layer and said n additional porous layers are formed from a semiconductor.
8. The particle of claim 7 , wherein said semiconductor comprises silicon.
9. The particle of claim 1 , wherein said first porous layer and said n additional porous layers are formed from an insulator.
10. A method for identification of an analyte bound to an encoded particle of claim 1 , the method comprising steps of:
associating the encoded particle with the analyte;
generating an interference pattern in the reflectivity spectrum by illumination of the particle;
determining said particular predetermined code from the interference pattern;
identifying the analyte based upon said step of determining.
11. The method according to claim 10 , wherein the targeting moiety is a sugar or polypeptide.
12. The method according to claim 10 , further comprising a step of signaling binding of an analyte by fluorescence labeling or analyte autofluorescence.
13. A method for identification of an analyte bound to a particle of claim 1 , the method comprising steps of:
associating the encoded particle with the analyte;
generating an interference pattern in the reflectivity spectrum by illumination of the particle;
determining said particular predetermined code from the interference pattern; and
identifying the analyte based upon said step of determining, wherein the receptor or targeting moiety is a sugar or polypeptide.
14. A method for identification of an analyte bound to a particle of claim 1 , the method comprising steps of:
associating the encoded particle with the analyte;
generating an interference pattern in the reflectivity spectrum by illumination of the particle;
determining said particular predetermined code from the interference pattern; and
identifying the analyte based upon said step of determining, wherein the receptor or targeting moiety is a sugar or polypeptide.
15. A method for identification of an analyte bound to a particle of claim 1 , the method comprising steps of:
associating the encoded particle with the analyte;
binding of an analyte by fluorescence labeling or analyte autofluorescence;
generating an interference pattern in the reflectivity spectrum by illumination of the particle;
determining said particular predetermined code from the interference pattern; and
identifying the analyte based upon said step of determining, wherein the receptor or targeting moiety is a sugar or polypeptide.
16. A freestanding encoded micron-sized porous particle having a particular predetermined code embedded in its physical porous structure by refractive index changes between different porous regions of the particle and a receptor or targeting moiety within said porous structure, wherein the physical porous structure has a plurality of layers some of which have separate predetermined mismatched optical thicknesses and the particle has a diameter of a few hundred microns or less and is freestanding separated from any substrate.
17. The encoded micron-sized particle of claim 16 , wherein different regions of the particle have different thickness.
18. The particle of claim 16 , wherein said receptor is a receptor for a biological analyte.
19. The particle of claim 16 , wherein said receptor is a receptor for a chemical analyte.
20. The particle of claim 16 , wherein said receptor is a receptor for a gaseous analyte.
21. The particle of claim 16 , further comprising a fluorescence tag for assaying the particle.
22. The particle of claim 16 , wherein said porous structure consists of porous silicon.
23. A method for identification of an analyte bound to a particle of claim 16 , the method comprising steps of:
associating the encoded particle with the analyte;
generating an interference pattern in the reflectivity spectrum by illumination of the particle;
determining said particular predetermined code from the interference pattern; and
identifying the analyte based upon said step of determining.
24. A method for identification of an analyte bound to or a host including a particle of claim 16 , the method comprising steps of:
associating the encoded particle with the analyte;
generating an interference pattern in the reflectivity spectrum by illumination of the particle;
determining said particular predetermined code from the interference pattern; and
identifying the analyte based upon said step of determining, wherein the receptor or targeting moiety is a sugar or polypeptide.
25. A method for identification of an analyte bound to a particle of claim 16 , the method comprising steps of:
associating the encoded particle with the analyte;
binding of an analyte by fluorescence labeling or analyte autofluorescence;
generating an interference pattern in the reflectivity spectrum by illumination of the particle;
determining said particular predetermined code from the interference pattern; and
identifying the analyte based upon said step of determining, wherein the receptor or targeting moiety is a sugar or polypeptide.
26. An optically encoded particle consisting of:
a first porous layer having a predetermined first porosity; and
a plurality of n additional consecutive porous layers upon said first porous layer, said n additional consecutive porous layers having predetermined thicknesses and porosities and at least one of said n additional consecutive porous layers having a porosity differing from said first porosity and a receptor or targeting moiety within one or more of said first porous layer and said n additional consecutive porous layers; wherein
said first porous layer and said n additional porous layers are configured to produce an interference pattern in the reflectivity spectrum having a distinct series of peaks such that the interference pattern forms an optical signature having a particular predetermined code determined by the porosities and thicknesses of said first porous layer and said n additional porous layers, and wherein
the particle has a diameter of a few hundred microns or less and is freestanding separated from any substrate.
27. The particle of claim 1 , wherein said predetermined thickness of said first porous layer and said predetermined thicknesses of said n additional porous comprise a plurality of thicknesses that are varied with respect to each other.