Embolization

Abstract

A composition includes a plurality of particles. At least some of the plurality of particles include cross-linked polyvinyl alcohol and have a diameter of about 500 microns or less. The particles have a first average pore size in an interior region, and a second average pore size at a surface region. The first average pore size being greater than the second average pore size. The composition also includes a carrier fluid. The plurality of particles being in the carrier fluid.

1 .- 31 . (canceled) 
     
     
         32 . A particle having a diameter of about 500 microns or less, wherein the particle comprises a cross-linked polymer, the particle has a first density of pores in an interior region and a second density of pores at a surface region, and the first density is different from the second density. 
     
     
         33 . The particle of  claim 32 , wherein the polymer comprises polyvinyl alcohol. 
     
     
         34 . The polymeric particle of  claim 32 , wherein the first density is greater than the second density. 
     
     
         35 . The polymeric particle of  claim 32 , wherein the particle has a first average pore size in the interior region and a second average pore size at the surface region, the first average pore size being different from the second average pore size. 
     
     
         36 . The polymeric particle of  claim 35 , wherein the first average pore size is greater than the second average pore size. 
     
     
         37 . The polymeric particle of  claim 32 , wherein the particle has a diameter of about 10 microns or more. 
     
     
         38 . The polymeric particle of  claim 32 , wherein the particle has a diameter of about 100 microns or more. 
     
     
         39 . The polymeric particle of  claim 37 , wherein the particle has a diameter of about 300 microns or less. 
     
     
         40 . The polymeric particle of  claim 32 , wherein the particle has a diameter of about 300 microns or more. 
     
     
         41 . The polymeric particle of  claim 32 , wherein the polymer comprises at least one polymer selected from the group consisting of polyvinyl alcohols, polyacrylic acids, polymethacrylic acids, poly vinyl sulfonates, carboxymethyl celluloses, hydroxyethyl celluloses, substituted celluloses, polyacrylamides, polyethylene glycols, polyamides, polyureas, polyurethanes, polyesters, polyethers, polystyrenes, polysaccharides, polylactic acids, polyethylenes, polymethylmethacrylates, polycaprolactones, polyglycolic acids, and poly(lactic-co-glycolic) acids. 
     
     
         42 . The polymeric particle of  claim 32 , wherein the particle is at least partially coated with a substantially bioabsorbable material. 
     
     
         43 . The polymeric particle of  claim 32 , wherein the particle has a density of from about 1.1 grams per cubic centimeter to about 1.4 grams per cubic centimeter. 
     
     
         44 . The polymeric particle of  claim 32 , wherein the particle has a sphericity of about 0.9 or more. 
     
     
         45 . The polymeric particle of  claim 32 , wherein, after compression to about 50 percent, the particle has a sphericity of about 0.9 or more. 
     
     
         46 . The polymeric particle of  claim 32 , wherein the particle comprises about 2.5 weight percent or less polysaccharide. 
     
     
         47 . The polymeric particle of  claim 46 , wherein the polysaccharide comprises alginate. 
     
     
         48 . The polymeric particle of  claim 47 , wherein the alginate has a guluronic acid content of about 60 percent or greater. 
     
     
         49 . The polymeric particle of  claim 32 , wherein the particle is substantially insoluble in DMSO. 
     
     
         50 . The polymeric particle of  claim 32 , wherein the particle is substantially free of animal-derived compounds. 
     
     
         51 . A composition, comprising:
 a plurality of particles comprising a cross-linked polymer, at least some of the plurality of particles having a diameter of about 500 microns or less, wherein at least some of the particles having a diameter of about 500 microns or less have a first density of pores in an interior region and a second density of pores at a surface region, the first density being different from the second density; and   a carrier fluid, the plurality of particles being in the carrier fluid.