CPC A61K 9/16 (2013.01) [A61K 9/1682 (2013.01); A61K 33/00 (2013.01); A61K 33/26 (2013.01); A61K 45/06 (2013.01); A61P 35/00 (2018.01)] | 12 Claims |
1. A method for forming hollow silica spheres incorporating Fe3O4 (“Fe-HSS”), comprising:
dissolving a hydrolyzable aryl silane in an aqueous solution comprising Fe3O4, water and an acid to form a hydrolyzed silane solution, wherein a molar ratio of the hydrolyzable aryl silane to the Fe3O4 ranges from 100:1 to 1:100;
mixing the hydrolyzed silane solution with a hydroxide base to form a precipitate; and
calcining the precipitate using a multi-stage calcination to form the Fe-HSS;
wherein surfaces of the Fe-HSS comprise no more than 0.1 mol. % phenyl or aryl groups relative to an average uncalcined Fe-HSS,
wherein the multi-stage calcination comprises a first stage and a second stage, the first stage including heating the precipitate to a first temperature of 180° C. to 240° C. by a first ramp rate of 3° C. to 10° C. per minute, and holding at the first temperature for about 15 minutes to 45 minutes; and the second stage including heating the precipitate to a second temperature of 600° C. to 740° C. by a second ramp rate of 0.8° C. to 2.5° C. per minute, and holding at the second temperature for about 12 hours to 24 hours,
wherein the Fe-HSS have a hollow core space containing plural individual particles of Fe3O4 having an average diameter in a range of from 9.5 nm to 21.3 nm and the Fe3O4 has a spinel structure,
wherein the hollow silica spheres of the Fe3O4 hollow silica spheres have a core-shell structure with shells larger in thickness than cores, and the hollow silica spheres have an average diameter in a range of from 415 to 615 nm,
wherein the hollow silica spheres of the Fe3O4 hollow silica spheres have an average diameter less than the average diameter of the corresponding uncalcined Fe-HSS: and
wherein the particles of Fe3O4 are present in an amount of from 0.1 to 10 wt. % of a combined weight of the HSS and Fe3O4 in the Fe-HSS.
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