Green polymer chemistry VIII: synthesis of halo-ester-functionalized poly(ethylene glycol)s via enzymatic catalysis.

Halo-ester-functionalized poly(ethylene glycol)s (PEGs) are successfully prepared by the transesterification of alkyl halo-esters with PEGs using Candida antarctica lipase B (CALB) as a biocatalyst under the solventless conditions. Transesterifications of chlorine, bromine, and iodine esters with tetraethylene glycol monobenzyl ether (BzTEG) are quantitative in less than 2.5 h.

Sustained release of bovine serum albumin using implantable wafers prepared by MPEG-PLGA diblock copolymers.

MPEG-PLGA diblock copolymers, consisting of methoxy polyethylene glycol (MPEG) and poly(L-lactic-co-glycolic acid) (PLGA), were synthesized by ring-opening polymerization of L-lactide and glycolide in the presence of MPEG as an initiator. Implantable wafers, using diblock copolymers as a drug carrier, were fabricated by direct compression method after freeze milling of the diblock copolymers and bovine serum albumin-fluorescein isothiocyanate (BSA-FITC) as a model protein drug. The wafers prepared with MPEG-PLGA diblock copolymers exhibited initial burst in the release of BSA.

Co-effect of aqueous solubility of drugs and glycolide monomer on in vitro release rates from poly(D,L-lactide-co-glycolide) discs and polymer degradation.

The objective of this study was to investigate the effect of aqueous solubility of model drugs and glycolide monomer (GM) from poly(D,L-lactide-co-glycolide) (PLGA) discs on in vitro release rates and polymer degradation. 5-Fluorouracil (5-FU), a water-soluble compound, and dexamethasone in a water-insoluble base form were selected as model drugs. Glycolide monomer, that has moderate solubility in water, was a non-toxic and biodegradable additive as a derivative material of hydrolysis of PLGA in order to obtain desirable drugs release rates.

Enhancement of the stability of BCNU using self-emulsifying drug delivery systems (SEDDS) and in vitro antitumor activity of self-emulsified BCNU-loaded PLGA wafer.

The main purpose of this study was to develop self-emulsifying drug delivery systems (SEDDS) for the improvement of the stability of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) after released from poly (D,L-lactide-co-glycolide) (PLGA) wafer and to evaluate its in vitro antitumor activity against 9L gliosarcoma cells. The in vitro stability test of BCNU was characterized by the BCNU amount in phosphate buffered saline (PBS, pH 7.4) at 37 degrees C.

Characterization of degradation behavior for PLGA in various pH condition by simple liquid chromatography method.

The aim of this study was to detect the amount of lactic acid (LA) and glycolic acid (GA) in poly(D,L-lactide-co-glycolide) (PLGA) by development a simple HPLC method and to determine the pH of media, which can influence on degradation of PLGA and drug release. Analysis of in vitro degradation behavior of PLGA with two different molecular weights as 8000 and 33,000 g/mol were performed in various media conditions (pH 3.0, 5.

Synthesis and characterization of polyanhydride for local BCNU delivery carriers.

p-Carboxyphenoxy propane (CPP) prepolymer consisting of 4 units and sebacic acid (SA) prepolymer consisting of about 10 units were synthesized by reacting CPP and SA in the presence of excess acetic anhydride, respectively. Polyanhydride, poly(CPP-SA) copolymers were copolymerized by a melt polycondensation process with a mixture of CPP and SA prepolymer. Copolymers of average molecular weight up to 110,000 g/mol were achieved.

First preparation of biotinylated gradient polyethylene surface to bind photoactive caged streptavidin.

A gradient polyethylene (PE) surface was created through corona treatment, in which the corona power increased along the 5 cm length of the PE. The gradient surface was treated with polyethyleneimine and then biotin. Fluorescein-conjugated streptavidin (SAV) caged within 5-carboxymethoxy-2-nitrobenzyl (CMNB) adsorbed onto the biotinylated gradient PE surface following molecular recognition principles.

Preparation of a gradient biotinylated polyethylene surface to bind streptavidin-FITC.

A novel biotinylated gradient surface was designed to bind a streptavidin-FITC. The gradient polyethylene (PE) surface was prepared by a corona treatment with a power increase along the PE length, and successively, biotinylated gradient PE surface was prepared by the reaction of polyethylenimine (PEI) and biotin. Surface properties of the gradient PE surface changed according to PE length and chemical modification.

Preparation of poly(ethylene glycol)-block-poly(caprolactone) copolymers and their applications as thermo-sensitive materials.

The polymerization of epsilon-caprolactone (epsilon-CL) was initiated by the terminal alcohol of methoxy poly(ethylene glycol) (MPEG) as an initiator via activated ring-opening polymerization in the presence of HCl. Et2O as a monomer activator. The molecular weights of the poly(epsilon-caprolactone) (PCL) in MPEG-PCL diblock copolymers controlled with the feed ratio of epsilon-CL to MPEG.