A particle includes a ferromagnetic material, a radiopaque material, and/or an MRI-visible material.
1. A particle, comprising
a polymeric matrix; and
a radiopaque material distributed in the polymeric matrix, wherein:
the particle has a diameter of from about ten microns to about 3,000 microns,
the particle has a center region with pores having a mean size of about 20 microns or more,
the particle has a surface region with pores having a mean size of about one micron or less, and
the polymeric matrix comprises a cross-linked polymer.
2. The particle of claim 1 , wherein the radiopaque material is selected from the group consisting of metals, metal alloys, and contrast agents.
3. The particle of claim 1 , wherein the radiopaque material comprises a member selected from the group consisting of titanium dioxide and bismuth subcarbonate.
4. The particle of claim 1 , wherein the radiopaque material comprises platinum or barium sulfate.
5. The particle of claim 1 , wherein the radiopaque material is substantially homogeneously distributed throughout the polymeric matrix.
6. The particle of claim 1 , wherein the polymeric matrix comprises a polysaccharide.
7. The particle of claim 1 , wherein the cross-linked polymer comprises a member selected from the group consisting of cross-linked polyvinyl alcohols, cross-linked polyacrylic acids, cross-linked polymethacrylic acids, cross-linked poly vinyl sulfonates, cross-linked carboxymethyl celluloses, cross-linked hydroxyethyl celluloses, cross-linked substituted celluloses, cross-linked polyacrylamides, cross-linked polyethylene glycols, cross-linked polyamides, cross-linked polyureas, cross-linked polyurethanes, cross-linked polyesters, cross-linked polyethers, cross-linked polystyrenes, cross-linked polysaccharides, cross-linked polylactic acids, cross-linked polyethylenes, cross-linked polymethylmethacrylates, cross-linked polycaprolactones, cross-linked polyglycolic acids, cross-linked poly(lactic-co-glycolic) acids, and combinations thereof.
8. The particle of claim 1 , wherein the particle further comprises a therapeutic agent.
9. The particle of claim 1 , wherein the polymeric matrix comprises a first polymer and a second polymer.
10. The particle of claim 9 , wherein the second polymer forms a coating over the first polymer.
11. The particle of claim 1 , wherein the particle is substantially spherical.
12. The particle of claim 1 , wherein the particle comprises from about 0.1 percent to about 50 percent by weight of the radiopaque material.
13. The particle of claim 1 , wherein the mean size of the pores of the center region is 30 microns or more.
14. The particle of claim 1 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
15. The particle of claim 1 , wherein the mean size of the pores of the surface region is from about 0.1 micron to about 0.01 micron.
16. The particle of claim 15 , wherein the mean size of the pores of the center region is 30 microns or more.
17. The particle of claim 15 , wherein the mean size of the pores of the center region is from 20 microns to about 35 microns.
18. The particle of claim 1 , wherein the particle includes a body region between the center region and the surface region.
19. The particle of claim 18 , wherein the mean size of the pores of the center region is about 30 microns or more.
20. The particle of claim 18 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
21. The particle of claim 18 , wherein the mean size of the pores of the surface region is from about 0.1 micron to about 0.01 micron.
22. The particle of claim 21 , wherein the mean size of the pores of the center region is 30 microns or more.
23. The particle of claim 21 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
24. The particle of claim 18 , wherein the body region has pores having a mean pore size of 18 microns or less.
25. The particle of claim 24 , wherein the mean size of the pores of the center region is 30 microns or more.
26. The particle of claim 24 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
27. The particle of claim 24 , wherein the mean size of the pores of the surface region is from about 0.1 micron to about 0.01 micron.
28. The particle of claim 27 , wherein the mean size of the pores of the center region is about 30 microns or more.
29. The particle of claim 27 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
30. The particle of claim 18 , wherein the body region has pores having a mean pore size of 15 microns or less.
31. The particle of claim 29 , wherein the mean size of the pores of the center region is about 30 microns or more.
32. The particle of claim 29 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
33. The particle of claim 29 , wherein the mean size of the pores of the surface region is from about 0.1 micron to about 0.01 micron.
34. The particle of claim 33 , wherein the mean size of the pores of the center region is 30 microns or more.
35. The particle of claim 33 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
36. The particle of claim 18 , wherein the body region has pores having a mean pore size of from about 18 microns to about two microns.
37. The particle of claim 36 , wherein the mean size of the pores of the center region is 30 microns or more.
38. The particle of claim 36 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
39. The particle of claim 36 , wherein the mean size of the pores of the surface region is from about 0.1 micron to about 0.01 micron.
40. The particle of claim 39 , wherein the mean size of the pores of the center region is 30 microns or more.
41. The particle of claim 39 , wherein the mean size of the pores of the center region is from about 20 microns to about 35 microns.
42. A particle, comprising:
a polymeric matrix; and
a radiopaque material distributed in the polymeric matrix,
wherein:
the particle has a diameter of from about ten microns to about 3,000 microns,
the particle has a center region having pores with a mean size,
the particle has a surface region having pores with a mean size,
the particle has a body region having pores with a mean size,
the body region is between the center region and the surface region,
the mean size of the pores of the center region is greater than the mean size of the pores of the surface region,
the mean size of the pores in the body region is from about 50 percent to about 70 percent of the mean size of the pores in the center region, and
the polymeric matrix comprises a cross-linked polymer.
43. The particle of claim 42 , wherein the mean size of the pores of the surface region is about 10 percent or less of the mean size of the pores of the body region.