A process for optimizing the recoverability of lyophilized microspheres for emboli and chitosan microspheres to which a drug-containing carrier is bound are disclosed. Specifically, a process for optimizing the recoverability, which includes adding trehalose as a lyophilization protectant prior to a lyophilization process for stable storage of the microspheres, and vortexing the lyophilized microspheres in order to rehydrate the microspheres, is provided. Also, microspheres capable of precisely controlling the release of the drug since the quantity of a drug released from the chitosan microspheres having a drug-containing nano-carrier bound thereto is adjusted according to the drug/chitosan ratio, and a method of preparing the same are provided. The optimization process can be useful in maintaining the physical properties, shapes, and the drug release level of the microspheres for emboli even after lyophilization of the microspheres. The chitosan microspheres having the drug-containing nano-carrier bound thereto can be useful in stably causing emboli in blood vessels, and precisely adjusting the release of the drug, and thus can be used in anticancer treatment.
