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Current treatments for chronic diabetic wounds remain unsatisfactory due to the lack of ideal wound dressings that can integrate matching mechanical strength, fast self-healability, facile dressing change, and multiple therapeutic effects into one system. In this work, benefiting from the catechol groups and therapeutic effect of epigallocatechin-3-gallate (EGCG, green tea derivative), a smart hydrogel dressing can be conveniently obtained through copolymerization of the complex formed by EGCG and 3-acrylamido phenyl boronic acid (APBA) (the formation of boronate ester bond) and acrylamide. The resulting hydrogel features adequate mechanical properties, self-healing capability, and tissue adhesiveness. Otherwise, the substantial release of EGCG can not only realize anti-oxidation, antibacterial, anti-inflammatory and proangiogenic effect, and modulation of macrophage polarization to accelerate wound healing, but also facilitate easy dressing change. This advanced hydrogel provides a facile and effective way for diabetic chronic wound management and may be extended for the therapy of other complicated wound healings. [ABSTRACT FROM AUTHOR]

Vascular disrupting agents (VDAs) have great potential for cancer treatment. Poly(l-glutamic acid)-combretastatin A4 conjugate (PLG-CA4) is a novel class of VDAs. Though it has notable antitumor activity, it can induce host immune responses that promote tumor growth. Here, PLG-CA4 induces the polarization of tumor-associated macrophages (TAMs) toward the M2-like phenotype in 4T1 metastatic breast cancer (Control 30% vs PLG-CA4 53%; p < 0.05). Compared to the monotherapy of PLGCA4, inhibition of phosphoinositide 3-kinase gamma (PI3Kγ) attenuates the immunosuppressive effect of PLG-CA4 treatment by decreasing the number of M2-like TAMs (2.0 × 104 to 1.5 × 104 per tumor) and potential enhancement of cytotoxic T lymphocyte (3.0 × 104 to 5.7 × 104 per tumor). Importantly, PI3Kγ inhibitor synergizing with PLG-CA4 significantly extends the mean survival time from 52 days in monotherapy-treated mice to 61.8 days. Additionally, the combination of PLG-CA4 and PI3Kγ inhibitor improves the tumor therapeutic effect of NLG919, an inhibitor of immune checkpoint indoleamine 2,3-dioxygenase (IDO). As far as it is known, this is the first demonstrated study that VDAs induce the reshaping of macrophages to the M2-like phenotype. The findings also indicate a potential therapeutic strategy of the combination VDAs with an accurate immune modifier in the tumor to reverse the immune resistance. [ABSTRACT FROM AUTHOR]

A zinc-based catalyst zinc bis[bis(trimethylsilyl)amide] was used for the polymerization of cyclic esters including -lactide (-LA) and 2-methyl-2-carboxyl-propylene carbonate (MBC). The polymerization of -lactide in THF could be carried out successfully under mild conditions in very short time by using the zinc catalyst and alcohols as the initiators. Kinetic study in solution polymerization prooved the polymerization has high monomer conversion degree close to 100% and the molecular weight of the resulting polyester has linear increase with the increase of [ M] /[ I] (molar ratio of monomer to initiator). Sequential polymerization of -LA and MBC in THF also showed high MBC conversion of 94% with a narrow molecualr weight maintained, indicating a living nature of this polymerization. The zinc catalyst system has also been used for the -LA bulk polymerization with a high monomer conversion. C NMR indicated the polymer possesses high regioregularity and the minor regioirregular component was owing to the -LA in the monomer inserted into the polymer mainchain during the transesterifcation. Interaction between monomer and zinc catalyst has been found to be a key factor to sustain a homogenous solution during the initiating procedure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

N,N′-Bis(benzoyl) suberic acid dihydrazide (NA) as nucleating agent for poly(-lactic acid) (PLLA) was synthesized from benzoyl hydrazine and suberoyl chloride, which was deprived from suberic acid via acylation. PLLA/NA samples were prepared by melt blending and a hot-press forming process. The nonisothermal and isothermal crystallization, spherulite morphology, and melting behavior of PLLA/NA with different contents of NA were investigated with differential scanning calorimetry, depolarized-light intensity measurement, scanning electron microscopy, polarized optical microscopy, and wide-angle X-ray diffraction. With the incorporation of NA, the crystallization peak became sharper and shifted to a higher temperature as the degree of supercooling decreased at a cooling rate of 1°C/min from the melt. Nonisothermal crystallization indicated that the presence of NA accelerated the overall PLLA crystallization. In isothermal crystallization from the melt, the presence of NA affected the isothermal crystalline behaviors of PLLA remarkably. The addition of NA led to a shorter crystallization time and a faster overall crystallization rate; this meant that there was a heterogeneous nucleation effect of NA on the crystallization of PLLA. With the addition of 0.8% NA, the crystallization half-time of PLLA/NA decreased from 26.5 to 1.4 min at 115°C. The Avrami theory was used to describe the kinetics of isothermal crystallization of the PLLA/NA samples. Also, with the presence of NA, the spherulite number of PLLA increased, and the spherulite size decreased significantly. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Novel hydrogels, physically crosslinked by hydrogen bonding of component polymers, were obtained by mixing aqueous solutions of carboxymethylchitosan (CMCS) with cellulose ethers including hydroxyethylcellulose (HEC) and methylcellulose (MC). The hydrogels were characterized by IR, XPS, WAXD, and SEM. The swelling and controlled drug release behaviors of hydrogels were also studied. The results indicate that intermacromolecular hydrogen bonding in CMCS/HEC is stronger than that in CMCS/MC. The swelling and drug release rate of hydrogels decrease as the interaction of component polymers increases. Both the swelling and drug release from hydrogels can be controlled by component polymer ratio. The hydrogels may be potential candidates for biomedical applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

A novel approach to selfassembled and shellcrosslinked SCL micelles from the diblock copolymer polyLlactideblockpolyLcysteine to be used as drug and protein delivery carriers is described. Rifampicin was used as a model drug. The drugloaded SCL micelles were obtained by selfassembly of the copolymer in the presence of the drug in aqueous media. Their morphology and size were studied with dynamic light scattering and field emission scanning electron microscopy. The rifampicin loading capacity and encapsulation efficiency were studied with ultraviolet–visible spectrophotometry. The drugrelease rate in vitrodepended on the oxidizing and reducing environment. Moreover, a straightforward approach to the conjugation of the copolymer with bovine serum albumin BSA was developed, and a gel electrophoresis test demonstrated that this conjugated BSA could be reversibly released from the copolymer substrate under reducing conditions. In conclusion, this Lcysteine copolymer can be used in drug delivery and in protein fixation and recovery. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

The polycaprolactone PCLstarch blends were prepared with a coextruder by using the starch graftedPLLA copolymer StgPLLA as compatibilizers. The thermal, mechanical, thermomechanical, and morphological characterizations were performed to show the better performance of these blends compared with the virgin PCLstarch blend without the compatibilizer. Interfacial adhesion between PCL matrix and starch dispersion phases dominated by the compatibilizing effects of the StgPLLA copolymers was significantly improved. Mechanical and other physical properties were correlated with the compatibilizing effect of the StgPLLA copolymer. With the addition of starch acted as rigid filler, the Youngs modulus of the PCLstarch blends with or without compatibilizer all increased, and the strength and elongation were decreased compared with pure PCL. Whereas when StgPLLA added into the blend, starch and PCL, the properties of the blends were improved markedly. The 5050 composite of PCLstarch compatibilized by 10 StgPLLA gave a tensile strength of 16.6 MPa and Youngs modulus of 996 MPa, respectively, vs. 8.0 MPa and 597 MPa, respectively, for the simple 5050 blend of PCLstarch. At the same time, the storage modulus of compatibilized blends improved to 2940 MPa. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

A triblock poly(lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(lactic acid) (PLA–PEG–PLA)/paclitaxel (PTX) conjugate was synthesized by the reaction of carboxyl‐terminated copolymer PLA–PEG–PLA with PTX in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine. Carboxyl‐terminated copolymer PLA–PEG–PLA was prepared by the reaction of the hydroxyl end groups in copolymer PLA–PEG–PLA with succinic anhydride. Its structure was confirmed by NMR and gel permeation chromatography. The PLA–PEG–PLA/PTX conjugates could self‐assemble into micelles in aqueous solutions with a low critical micelle concentration. Dynamic light scattering and environmental scanning electron microscopy analyses of the PLA–PEG–PLA/PTX micelles revealed their spherical structure and size of 220 nm. The antitumor activity of the conjugate against woman Hela cancer cells, evaluated by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide method, showed that the conjugates had an antitumor activity similar to that of pure PTX. The obtained PLA–PEG–PLA/PTX conjugates are expected to be used in clinical practice. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [ABSTRACT FROM AUTHOR]

A novel amphiphilic biodegradable triblock copolymer (PGL‐PLA‐PGL) with polylactide (PLA) as hydrophobic middle block and poly(glutamic acid) (PGL) as hydrophilic lateral blocks was successfully synthesized by ring‐opening polymerization (ROP) of L‐lactide (LA) and N‐carboxy anhydride (NCA) consecutively and by subsequent catalytic hydrogenation. The results of cell experiment of PGL‐PLA‐PGL suggested that PGL could improve biocompatibility of polyester obviously. The copolymer could form micelles of spindly shape easily in aqueous solution. The pendant carboxyl groups of the triblock copolymer were further activated with N‐hydroxysuccinimide and combined with a cell‐adhesive peptide GRGDSY. Incorporation of the oligopeptide further enhanced the hydrophilicity and led to formation of spherical micelles. PGL‐PLA‐PGL showed better cell adhesion and spreading ability than pure PLA and the GRGDSY‐containing copolymer exhibited even further improvement in cell adhesion and spreading ability, indicating that the copolymer could find a promising application in drug delivery or tissue engineering. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3218–3230, 2007 [ABSTRACT FROM AUTHOR]

A novel biodegradable aliphatic poly(L‐lactide‐co‐carbonate) bearing pendant acetylene groups was successfully prepared by ring‐opening copolymerization of L‐lactide (LA) with 5‐methyl‐5‐propargyloxycarbonyl‐1,3‐dioxan‐2‐one (PC) in the presence of benzyl alcohol as initiator with ZnEt2 as catalyst in bulk at 100 °C and subsequently used for grafting 2‐azidoethyl β‐D‐glucopyranoside and 2‐azidoethyl β‐lactoside by the typical “click reaction,” that is Cu(I)‐catalyzed cycloaddition of azide and alkyne. The density of acetylene groups in the copolymer can be tailored by the molar ratio of PC to LA during the copolymerization. The aliphatic copolymers grafted with sugars showed low cytotoxicity to L929 cells, improved hydrophilic properties and specific recognition and binding ability with lectins, that is Concanavalin A (Con A) and Ricinus communis agglutinin (RCA). Therefore, this kind of sugar‐grafted copolymer could be a good candidate in variety of biomedical applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3204 –3217, 2007 [ABSTRACT FROM AUTHOR]

A series of biodegradable polylactide‐based polyurethanes (PLAUs) were synthesized using PLA diol (Mn = 3200) as soft segment, 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluene diisocyanate (TDI), and isophorone diisocyanate (IPDI) as hard segment, and 1,4‐butanediol as chain extender. The structures and properties of these PLAUs were studied using infrared spectroscopy, differential scanning calorimetry, tensile testing, and thermomechanical analysis. Among them, the MDI‐based PLAU has the highest Tg, maximum tensile strength, and restoration force, the TDI‐based PLAU has the lowest Tg, and the IPDI‐based PLAU has the highest tensile modulus and elongation at break. They are all amorphous. The shape recovery of the three PLAUs is almost complete in a tensile elongation of 150% or a twofold compression. They can keep their temporary shape easily at room temperature (20 °C). More importantly, they can deform and recover at a temperature below their Tg values. Therefore, by selecting the appropriate hard segment and adjusting the ratio of hard to soft segments, they can meet different practical demands for shape memory medical devices. Copyright © 2007 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A series of biodegradable polyurethanes (PUs) are synthesized from the copolymer diols prepared from L‐lactide and ɛ‐caprolactone (CL), 2,4‐toluene diisocyanate, and 1,4‐butanediol. Their thermal and mechanical properties are characterized via FTIR, DSC, and tensile tests. Their Tgs are in the range of 28–53°C. They have high modulus, tensile strength, and elongation ratio at break. With increasing CL content, the PU changes from semicrystalline to completely amorphous. Thermal mechanical analysis is used to determine their shape‐memory property. When they are deformed and fixed at proper temperatures, their shape‐recovery is almost complete for a tensile elongation of 150% or a compression of 2‐folds. By changing the content of CL and the hard‐to‐soft ratio, their Tgs and their shape‐recovery temperature can be adjusted. Therefore, they may find wide applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4182–4187, 2007 [ABSTRACT FROM AUTHOR]

Novel poly(ester carbonate)s were synthesized by the ring‐opening polymerization of L‐lactide and functionalized carbonate monomer 9‐phenyl‐2,4,8,10‐tetraoxaspiro[5,5]undecan‐3‐one derived from pentaerythritol with diethyl zinc as an initiator. 1H NMR analysis revealed that the carbonate content in the copolymer was almost equal to that in the feed. DSC results indicated that Tg of the copolymer increased with increasing carbonate content in the copolymer. Moreover, the protecting benzylidene groups in the copolymer poly(L‐lactide‐co‐9‐phenyl‐2,4,8,10‐tetraoxaspiro[5,5]undecan‐3‐one) were removed by hydrogenation with palladium hydroxide on activated charcoal as a catalyst to give a functional copolymer, poly(L‐lactide‐co‐2,2‐dihydroxylmethyl‐propylene carbonate), containing pendant primary hydroxyl groups. Complete deprotection was confirmed by 1H NMR and FTIR spectroscopy. The in vitro degradation rate of the deprotected copolymers was faster than that of the protected copolymers in the presence of proteinase K. The cell morphology and viability on a copolymer film evaluated with ECV‐304 cells showed that poly(ester carbonate)s derived from pentaerythritol are good biocompatible materials suitable for biomedical applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45:1737 –1745, 2007 [ABSTRACT FROM AUTHOR]

Poly(ɛ‐caprolactone)‐based segmented polyurethanes (PCLUs) were prepared from poly(ɛ‐caprolactone) diol, diisocyanates (DI), and 1,4‐butanediol. The DIs used were 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluenediisocyanate (TDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI). Differential scanning calorimetry, small‐angle X‐ray scattering, and dynamic mechanical analysis were employed to characterize the two‐phase structures of all PCLUs. It was found that HDI‐ and MDI‐based PCLUs had higher degree of microphase separation than did IPDI‐ and TDI‐based PCLUs, which was primarily due to the crystallization of HDI‐ and MDI‐based hard‐segments. As a result, the HDI‐based PCLU exhibited the highest recovery force up to 6 MPa and slowest stress relaxation with increasing temperature. Besides, it was found that the partial damage in hard‐segment domains during the sample deformation was responsible for the incomplete shape‐recovery of PCLUs after the first deformation, but the damage did not develop during the subsequent deformation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 557–570, 2007 [ABSTRACT FROM AUTHOR]