A method for releasing viruses includes the steps of: preparing a first negatively charged complex, comprising a plurality of viruses, a plurality of polyethyleneimine particles, and a copolymer transferring the complex to an acidic region, thereby transforming the complex into a positively charged complex to release a portion of the viruses in the acidic region and transferring the complex to a non-acidic region, thereby transforming the positively charged complex into a negatively charged complex. One embodiment of the copolymer has the following chemical formula:wherein R1 represents aliphatic compounds or aromatic compounds, and R2 includes at least one negatively charged group.本揭露係關於一種釋放病毒的方法,其包含下列步驟:準備一第一負電荷複合物,其包含複數個病毒、複數個聚乙烯亞胺(polyethyleneimine)粒子及一共聚物;傳送該複合物至一酸性區域,藉由於該酸性區域使得該第一負電荷複合物轉變為一正電荷複合物而釋出部分病毒於該酸性區域;傳送該第一負電荷複合物至一非酸性區域,而使得帶有正電荷之複合物轉變為負電荷複合物。共聚物之實施例具有下列化學式:其中R1代表脂肪族化合物或芳香族化合物,R2包含至少一負電荷官能基。10‧‧‧複合物11‧‧‧共聚物13‧‧‧正電荷聚合物15‧‧‧病毒21‧‧‧酸性環境23‧‧‧癌細胞
