Study of Stimuli-Sensitivities of Amphiphilic Modified Star Poly[N,N-(Dimethylamino)ethyl Methacrylate] and Its Ability of DNA Complexation

Abstract

Cationic star polymers as drug/gene carriers have attracted increasing attention. Herein, environmental sensitivities and star-shaped architecture were combined into a well-defined gene carrier system, and further amphiphilic modification was conducted. The thermo- and pH-sensitive behaviors of poly[N,N-(dimethyl amino)ethyl methacrylate] (PDMAEMA) star polymers before and after amphiphilic modification in aqueous solutions were investigated. The observed lower critical solution temperature (LCST) increased with increasing arm length due to the increase of hydrophilicity. A significant decrease of the LCSTs with increasing pH and ionic-strength of the solution was found. The incorporation of MMA and BA lipophilic moieties decreased the LCST of the cationic star polymer due to enhanced hydrophobic interaction. As a potential gene carrier, the performance of star polymers on binding DNA was primarily evaluated via particle size, zeta potential, and gel retardation measurements. All the complexes formed stable small particles with diameter of 100∼150 nm at N/P ratio higher than 3.0. The electrostatic screening effect and facilitation for the interaction of complexes with cell membrane induced by the incorporation of lipophilic units were expected to enhance the gene transfection efficiency.

Keywords:

• Thermo- and pH-sensitivities
• amphiphilic modification
• star block copolymer
• gene carrier
• DMAEMA

Supplemental Data

Supplemental data for this article can be accessed at www.tandfonline.com/lmsa.

Additional information

Funding

This work was financially supported by the Shanghai Natural Science Foundation (No.12ZR1407800), Shanghai Leading Academic Discipline Project (B502) and Shanghai Key Laboratory Project (08DZ2230500).