Abstract: Disclosed are methods for manufacturing a chitosan microflake. A chitosan microflake can be manufactured by two different ways. In the first method, chitosan is dissolved in a weak acidic solution to give a chitosan solution, which is then incubated for 1 to 30 days. The chitosan solution is then dried by a freeze-drying process, a thermal drying process, or a vacuum drying process so as to extract a solidified chitosan film. The solidified chitosan film is pulverized to yield a chitosan microflake which has a width at least ten fold greater than a thickness. In the second method, a multi-layered, air-gapped sheet of chitosan is manufactured first and pulverized so as to yield the chitosan microflake. The overall steps of the second method are similar to those of the fist method, and the only difference is a drying step. In the first method, drying is performed continuously without intermittence, but in the second method drying is conducted at substantially regular time intervals.

Abstract: Disclosed is a chitosan microflake which has a plate structure with a thickness between about 0.1 &mgr;m and about 50 &mgr;m and with a width between about 2 &mgr;m and about 2000 &mgr;m. The chitosan microflake in the present invention has a width at least ten fold larger than a thickness. It is a novel form of chitosan which can be effectively used as a clinical-pathological agent with high coatability onto skin, maximizing the medicinal efficacy of chitosan. In addition, the chitosan microflake of the present invention is highly suitable for use as a chitosan source for a broad spectrum of applications because it can be readily dissolved in water.

Abstract: Disclosed is a method for manufacturing a multi-layered, air-gapped sheet of chitosan, which is a novel form of chitosan. For the preparation of a multi-layered, air-gapped sheet of chitosan, chitosan is first dissolved in a weak acidic solution to form a chitosan solution. The chitosan solution is incubated at −5° C. to 50° C. for 1 to 30 days. The chitosan solution is than dried by a freeze-drying process, thermal drying process, or vacuum drying process. In freeze-drying, a freezing the chitosan solution at −10° C. to −60° C. and a heating it at 50° C. to 100° C. under a pressure of 100 Torr to 0.1 Torr are alternately repeated several times for about 10 minutes to about 120 minutes for each freezing or heating process. In thermal drying, a heating the chitosan solution at 50° C. to 200° C. and an incubating it at −5° C. to 50° C. are alternately repeated several times for about 10 minutes to about 120 minutes for each process.

Abstract: Disclosed is a multi-layered, air-gapped sheet of chitosan, which comprises a plurality of films of chitosan. The each film of chitosan is between 0.1 &mgr;m and 50 &mgr;m in thickness. Said each film of chitosan is stacked next to one another with a gap of 1 &mgr;m to 10,000 &mgr;m therebetween with the lower film surface facing the upper film surface of an adjacent film. The each film of chitosan is arranged in the direction substantially perpendicular or horizontal to the top surface of the multi-layered, air-gapped sheet, or slanting against the top surface of the sheet. Some multi-layered, air-gapped sheet of chitosan comprises a plurality of sub-sheets of chitosan. The each sub-sheet of chitosan itself is a multi-layered, air-gapped sheet of chitosan, and any two sub-sheets next to each other are not identical each other.