Modified polyethyleneimine and its preparation method, pharmaceutical - gene vector system and a method for preparing

The present invention provides a modified polyethyleneimine, N- ([beta] maleimido acid) hydrazide, and the mercapto compound obtained by the reaction of polyethyleneimine. In the present invention provides a modified polyethyleneimine as an antitumor agent and a carrier supporting the gene, a gene complex obtained pharmaceutical carrier system. Gene complex pharmaceutical carrier system obtained can be administered directly to the lungs, and drug concentration to achieve high levels of gene quickly in the lung tumor tissue and decrease the distribution in other normal tissues, to achieve a low toxicity and dosing. The present invention provides a method for preparing a modified polyethyleneimine also provided a method for preparing a pharmaceutical gene complex vector system.