Sandwich Structure-like Meshes Fabricated via Electrospinning for Controllable Release of Zoledronic Acid

Novel sandwich structure-like nanofiber multilayered meshes were fabricated via electrospinning. The purpose of the present work was to control zoledronic acid release via the novel structure of sandwich structure-like meshes. The in vitro release experiments reveal that the drug release speed and initial burst release were controllable by adjusting the thicknesses of electrospun barrier mesh and drug-loaded mesh. Compared with those of other drug delivery systems, the main advantages of the sandwich structure-like fiber meshes are facile preparation conditions and the generality for hydrophobic and hydrophilic pharmaceuticals.

Synthesis and Characterization of Chitosan-Albumin Conjugates as pH-Sensitive Biodegradable Hydrogels

A new kind of biodegradable pH-sensitive drug delivery system was developed via chitosan-albumin conjugate hydrogel. Through changing the feeding modes of reactants, two types of hydrogels（comb-type and reticular-type） were synthesized by amidation reactions between 6-O-succinoylated N-phthaloyl chitosan and albumin. The structures and morphologies of the hydrogels were characterized by SEM. And their water swelling capacity, drug loading and releasing properties at different pH values were also investigated. It was found that the comb-type of hydrogels with looser space construction had better water swelling ratio（more than 400% of its original mass） than the reticular-type of ones did（about 180% of its original mass）. In vitro release experiments of Rifampicin show that the hydrogels provided the controlled release of the entrapped drug for more than 50 h. The drug release rates of both types of hydrogels under acidic condition were lower than those under neutral or basic condition. The introduction of albumin not only improved the hydrophilicity of chitosan, but also provided the possibility of the carrier system combining other biologically active materials more easily to fulfill the delivery and therapy functions.

Preparation of Poly（serine ester）s by Ring-opening Polymerization of N-Trityl Serine Lactone Under Catalysis of ZnEt2

Poly（N-trityl serine lactone）（PTSL） and mPEG-block-poly（N-trityl serine lactone）（mPEG-b-PTSL, PEG= polyethylene glycol） were synthesized via the ring-opening polymerization of N-trityl serine lactone（TSL） with diethyl zinc（ZnEt2） as catalyst. The structures of these polymers were confirmed with hydrogen nuclear magnetic resonance（IH NMR） spectroscopy, carbon nuclear magnetic resonance（13C NMR） spectroscopy and infrared（IR） spectrometer. The thermal decomposition temperature and glass transition temperature of PTSL were 241 and 161 ℃, respectively. A series of mPEG-b-PTSL with different molecular weights（Mn＇s from 7000 to 32000） was obtained by tuning the TSL/mPEG feed ratio. After the removal of the trityl groups, mPEG-block-poly（serine lactone）（mPEG- b-PSL） was obtained as a new kind of cationic block copolymer. Low cytotoxicity of these polymers to L929 cells was confirmed via 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide（MTT） assay.