Jing Hao

Thermally Controlled Release of Anticancer Drug from Self-Assembled γ-Substituted Amphiphilic Poly(ε-caprolactone) Micellar Nanoparticles

A thermo-responsive poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-ε-caprolactone}-b-poly(γ-octyloxy-ε-caprolactone) (PMEEECL-b-POCTCL) diblock copolymer was synthesized by ring-opening polymerization using tin octanoate (Sn(Oct)(2)) catalyst and a fluorescent dansyl initiator. The PMEEECL-b-POCTCL had a lower critical solution temperature (LCST) of 38 °C, and it was employed to prepare thermally responsive micelles. Nile Red and Doxorubicin (DOX) were loaded into the micelles, and the micellar stability and drug carrying ability were investigated. The size and the morphology of the cargo-loaded micelles were determined by DLS, AFM, and TEM. The Nile-Red-loaded polymeric micelles were found to be stable in the presence of both fetal bovine serum and bovine serum albumin over a 72 h period and displayed thermo-responsive in vitro drug release. The blank micelles showed a low cytotoxicity. As comparison, the micelles loaded with DOX showed a much higher in vitro cytotoxicity against MCF-7 human breast cancer cell line when the incubation temperature was elevated above the LCST. Confocal laser scanning microscopy was used to study the cellular uptake and showed that the DOX-loaded micelles were internalized into the cells via an endocytosis pathway.

Synthesis and Characterization of a Block Copolymer Containing Regioregular Poly(3‐hexylthiophene) and Poly(γ‐benzyl‐L‐glutamate)

Poly(3-hexylthiophene)-b-poly(γ-benzyl-L-glutamate) (P3HT-b-PBLG) rod-rod diblock copolymer was synthesized by a ring-opening polymerization of γ-benzyl-L-glutamate-N-carboxyanhydride using a benzylamine-terminated regioregular P3HT macroinitiator. The opto-electronic properties of the diblock copolymer have been investigated. The P3HT precursor and the P3HT-b-PBLG have similar UV-Vis spectra both in solution and solid state, indicating that the presence of PBLG block does not decrease the effective conjugation length of the semiconducting polythiophene segment. The copolymer displays solvatochromic behavior in THF/water mixtures. The morphology of the diblock copolymer depends upon the solvent used for film casting and annealing results in morphological changes for both films deposited from chloroform and trichlorobenzene.

Electronic Properties-Morphology Correlation of a Rod–Rod Semiconducting Liquid Crystalline Block Copolymer Containing Poly(3-hexylthiophene)

The influence of the solvent and annealing temperature on the field-effect mobilities and morphologies of poly(3-hexylthiophene)-b-poly(γ-benzyl-L-glutamate) (P3HT-b-PBLG) rod-rod diblock copolymer has been investigated. Thin film X-ray diffraction studies show peaks originating from both P3HT and PBLG indicating that the crystalline nature of both the blocks is conserved after the formation of the block copolymer. It has been observed that the field-effect mobilities of the diblock copolymer are independent of the annealing temperatures for thin films deposited from both 1,2,4-trichlorobenzene and chloroform solvents. The correlation between the field-effect mobility and morphology indicates that the P3HT block self-assembles at the surface SiO(2) dielectric.

Temperature-sensitive aliphatic polyesters: synthesis and characterization of γ-substituted caprolactone monomers and polymers

Synthesis and ring-opening polymerization of γ-substituted e-caprolactone monomers containing octyloxy and 2-[2-(2-methoxyethoxy)ethoxy]ethoxy functional groups is reported. An amphiphilic block copolymer containing hydrophobic poly(γ-octyloxy-e-caprolactone) and hydrophilic poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-e-caprolactone} forms micelles in aqueous solution above the critical micellar concentration of 1.74 × 10−3 g L−1. Poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-e-caprolactone} and its block copolymer with poly(γ-octyloxy-e-caprolactone) are thermoresponsive polymers. The LCST measured for poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-e-caprolactone} is 47.5 °C, while the LCST decreased to 37.5 °C for the amphiphilic block copolymer poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-e-caprolactone}-b-poly(γ-octyloxy-e-caprolactone).

Zinc Undecylenate Catalyst for the Ring‐Opening Polymerization of Caprolactone Monomers

The ring-opening polymerization of two caprolactone monomers catalyzed by zinc undecylenate (ZU) is reported. Polymerizations were performed in bulk with benzyl alcohol (BnOH) as an initiator at 90 and 110 °C, respectively. A slower polymerization rate was observed for γ-octyloxy-ε-caprolactone as compared to ε-caprolactone. Diblock copolymers were synthesized by the sequential monomer addition at 90 and 110 °C. The kinetic studies performed for the ring-opening polymerization of ε-caprolactone and γ-octyloxy-ε-caprolactone and the successful synthesis of diblock copolymers by the sequential monomer addition confirmed the controlled/living nature of zinc undecylenate catalyzed reactions.