Abstract: A series of cross-linking PEI were synthesized by low molecular weight PEI-{1800} and dimethyl-3,3'-dithio-bis(propionimidate) dihydrochloride(DTBP). The properties of the cross-linking PEI/DNA gene supramolecular assembly were influenced by the structure of gene support and assembly conditions, such as the N/P, pH value and salt concentration. Under the conditions of c(NaCl)=20 mmol/L, N/P=5, pH=7.4, CLPEI_<sup>50 /DNA gene assembly shows uniform spheres with particle size about 170 nm determined by AFM, better than the CLPEI_<sup>100 and CLPEI_<sup>33 as gene supports. In the presence of GSH at a concentration comparable to the intracellular environment, the -S-S-bonds of CLPEI_<sup>50 were cleavaged and the gene assembly was unpacked. Glutathione-response gene supramolecular assembly was developed via the complex of DNA and DTBP cross-linked PEI.

Key words: Non-viral gene support, Biomimetics, Supramolecular assembly