Z X Zhang

Publications (2)10.96 Total impact

• Article: Star-shaped cationic polymers by atom transfer radical polymerization from beta-cyclodextrin cores for nonviral gene delivery.

  F J Xu, Z X Zhang, Y Ping, J Li, E T Kang, K G Neoh
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  ABSTRACT: Cationic polymers with low cytotoxicity and high transfection efficiency have attracted considerable attention as nonviral carriers for gene delivery. Herein, well-defined and star-shaped CDPD consisting of beta-CD cores and P(DMAEMA) arms, and CDPDPE consisting of CDPD and P(PEGEEMA) end blocks (where CD = cyclodextrin, P(DMAEMA) = poly(2-(dimethylamino)ethyl methacrylate), P(PEGEEMA) = poly(poly(ethylene glycol)ethyl ether methacrylate)) for gene delivery were prepared via atom transfer radical polymerization (ATRP) from the bromoisobutyryl-terminated beta-CD core. The CDPD and CDPDPE exhibit good ability to condense plasmid DNA (pDNA) into 100-200 nm size nanoparticles with positive zeta potentials of 25-40 mV at nitrogen/phosphate (N/P) ratios of 10 or higher. CDPD and CDPDPE exhibit much lower cytotoxicity and higher gene transfection efficiency than high molecular weight P(DMAEMA) homopolymers. A comparison of the transfection efficiencies between CDPD and P(DMAEMA) homopolymer indicates that the unique star-shaped architecture involving the CD core can enhance the gene transfection efficiency. In addition to reducing cytotoxicity, the introduction of a biocompatible P(PEGEEMA) end block to the P(DMAEMA) arms in CDPDPE can further enhance the gene transfection efficiency.
  Biomacromolecules 02/2009; 10(2):285-93. · 5.48 Impact Factor
• Article: Thermo-responsive porous membranes of controllable porous morphology from triblock copolymers of polycaprolactone and poly(N-isopropylacrylamide) prepared by atom transfer radical polymerization.

  F J Xu, J Li, S J Yuan, Z X Zhang, E T Kang, K G Neoh
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  ABSTRACT: Stimuli-responsive polymers are of crucial importance in the design of smart biomaterials. The thermo-responsive triblock copolymers of polycaprolactone (PCL) and poly( N-isopropylacrylamide) (P(NIPAAm)), or P(NIPAAm)- b-PCL- b- P(NIPAAm) copolymers, were synthesized in this work via atom transfer radical polymerization (ATRP). The P(NIPAAm)- b-PCL- b-P(NIPAAm) copolymers were cast by phase inversion in water into porous membranes with well-defined and uniformly distributed pores. The P(NIPAAm) content in the P(NIPAAm)- b-PCL- b- P(NIPAAm) copolymers and the temperature of the aqueous medium for phase inversion could be used to control the pore size and porosity of the membranes. The thermo-responsive characteristics of the membranes were illustrated in the controlled water uptake and temperature-dependent glucose transport through the membranes. These temperature-sensitive membranes with controllable morphology have potential applications in biomedical engineering, drug delivery, and tissue engineering.
  Biomacromolecules 02/2008; 9(1):331-9. · 5.48 Impact Factor