The objective of this study was to characterize the differences in electrophoretic behavior between linear and branched PEG‐conjugated proteins. Human growth hormone and alpha‐lactalbumin modified by linear or branched PEGs with molecular weight of 10 kDa were analyzed by SEC, MALDI‐TOF MS, SDS‐PAGE, and microchip CGE (MCGE). Chromatographic and mass spectrometric differences between the linear and branched PEG‐proteins on SEC and MALDI‐TOF MS were small, but their electrophoretic behaviors on SDS‐PAGE and MCGE were significantly different. In particular, MCGE showed significant differences in the peak width and the migration times of linear and branched PEG‐proteins, in which the branched PEG‐proteins exhibited a narrower peak and longer migration time than the linear PEG‐proteins. This phenomenon may explain the longer circulation half‐life for the branched PEG‐proteins observed in previously reported in vivo studies. Consequently, this study indicates that MCGE may be a valuable tool for differentiating linear and branched PEG‐proteins. 相似文献
Amino acid N‐thiocarboxyanhydride (NTA), the thioanalog of N‐carboxyanhydride (NCA), is much more stable than NCA against moisture and heat. The convenient monomer synthesis without rigorous anhydrous requirements makes the ring‐opening polymerization of NTA a competitive alternative to prepare polypeptoid‐containing materials with potential of large‐scale production. Polysarcosines (PSars) with high yields (>90%) and low polydispersities (<1.2) are synthesized from sarcosine N‐thiocarboxyanhydride (Sar‐NTA) at 60 °C initiated by primary amines including poly(ethylene glycol) amine (PEG–NH2). The lengths of PSar segments are controlled by various feed ratios of Sar‐NTA to initiator. PEG‐b‐PSar products, a class of novel double‐hydrophilic diblock copolymers, are effective in stabilizing oil‐in‐water emulsions at nano‐ and microscale, which demonstrates promising encapsulation applications in food, cosmetics, and drug delivery. Due to the different solubility of PEG and PSar blocks, PEG‐b‐PSar copolymers form micelles in organic solvents with the capability to incorporate metal cations including Cu2+ and Ni2+.
Gel formation was discovered in an aqueous mixture of enantiomeric triblock copolymers, PLLA‐PEG‐PLLA and PDLA‐PEG‐PDLA. This system is characteristic in that an interesting sol–gel transition was induced by the stereo‐complexation of the PLLA and PDLA segments of the block copolymers around 37°C. The process of gel formation was clearly monitored by the rheological change, and the responsibility of the stereo‐complex formation for the gelation was confirmed by wide‐angle X‐ray scattering. The mechanism of this gel formation is discussed in relation to its potential applications. 相似文献
Interactive materials being responsive to a biocompatible stimulus represent a promising approach for future therapeutic applications. In this study, we present a novel biohybrid material synthesized from biocompatible components being stimulus‐responsive to the pharmaceutically approved small‐molecule novobiocin. The hydrogel design is based on the gyrase B (GyrB) protein, which is covalently grafted to multi‐arm polyethylene glycol (PEG) using a Michael‐type addition reaction. Upon addition of the GyrB‐dimerizing substance coumermycin, stable hydrogels form which can be dissolved in a dose‐adjustable manner by the antibiotic novobiocin. The switchable properties of this PEG‐based hydrogel are favorable for future applications in tissue engineering and as externally controlled drug depot. 相似文献
Biodegradable hydrogels were synthesized by the click reaction of 4‐arm azido‐terminated PEG differing in molecular weight (2 100 and 8 800) and two alkyne‐terminated peptides: [alkyne]‐GFLGK‐[alkyne] and ([alkyne]‐GFLG)2K. The physical properties of in situ formed hydrogels were examined. The hydrogels were highly elastic as determined by rheological and microrheological studies. Swelling degree and enzymatic degradation by papain were dependent on the molecular weight of the PEG, but not the peptide. For PEG8800‐based hydrogels, time‐course analysis of degradation showed that the molecular weight of the soluble fraction quickly reached the PEG precursor value. These findings may guide future design of hydrogels with controllable mechanical properties and enzymatic degradability.
To great (monodisperse) lengths : An improved synthesis of purer ethylene glycol (EG) oligomers allows access to 16‐ and 32‐mers pure enough for multiple incorporation, and also to the longest (48‐mer) discrete EG oligomer yet reported. The high purity enables the first crystallizations and hence the first glimpses of secondary 310‐helical PEG structures.
Novel temperature and pH dual‐responsive hydrogels were constructed by inclusion of poly(PEGMA)‐co‐poly(DMA) with α‐cyclodextrin in aqueous solution. The temperature‐ or pH‐induced sol/gel transition in the hydrogels was completely reversible. Studies on structure/property relationships show that chain uniformity, graft density and copolymer concentration affect the hydrogel behavior. A dual‐responsive mechanism is proposed. The in vitro release of a model drug from this hydrogel was studied. It was found that the release kinetics were greatly accelerated at higher temperature and at acidic pH conditions, indicating potential applications in controlled drug delivery.
PEG400 (polyethylene glycol, MW 400) biscyanoacrylate is synthesized and copolymerized with 2‐octyl cyanoacrylate for potential use as bioadhesive. PEG400 biscyanoacrylate is synthesized from the esterification of anthracenyl cyanoacrylic acid where the anthracene unit serves as vinyl‐protecting group. Copolymerization increases the plasticity, mechanical strength, and resilience of the resulted polymer as determined by dynamic mechanical analysis. Peeling test confirms its superior bioadhesive properties. Surface morphology is characterized by SEM imaging. The formulations are cytocompatible and safe. This cyanoacrylate composition may provide improved bioadhesive cyanoacrylates.
The covalent attachment of poly(ethylene glycol) (PEG) to therapeutically active proteins (PEGylation) has become an important method to deal with the pharmacological difficulties of these polypeptides, such as short body‐residence times and immunogenicity. However, the derivatives of PEG used for PEGylation lack further functional groups that would allow the addition of targeting or labeling moieties. Squaric acid diethyl ester was used for the chemoselective single‐step activation of poly(ethylene glycol)s into the respective ester amides. The resultant selective protein‐reactive poly(ethylene glycol)s were investigated with respect to their selectivity towards amino acid residues in bovine serum albumin (as a model protein). The presented procedure relies on a robust two‐step protocol and was found to be selective towards lysine residues; the activated polyethers are efficient and stoichiometric PEGylation agents with a remarkable hydrolytic stability over a period of several days. By adjusting the pD value of the conjugation mixture, the chemoselectivity of the activated PEGs towards the α‐ and ε‐amino groups of lysine methyl ester was effectively changed. 相似文献
An aqueous solution of a poly(ethylene glycol)‐polycaprolactone‐poly(ethylene glycol) (PEG‐PCL‐PEG) with a composition of EG13CL23EG13 undergoes multiple transitions, from sol‐to‐gel (hard gel)‐to‐sol‐to‐gel (soft gel)‐to‐sol, in the concentration range 20.0∼35.0 wt.‐%. Through dynamic mechanical analysis, UV‐vis spectrophotometry, small angle X‐ray scattering, differential scanning calorimetry, microcalorimetry and 13C NMR spectroscopy, the mechanism of these transitions was investigated. The hard gel and soft gel are distinguished by the crystalline and amorphous state of the PCL. The extent of PEG dehydration and the molecular motion of each block also played a critical role in the multiple transitions. This paper suggests a new mechanism for these multiple transitions driven by temperature changes.
A simple and efficient polymer grafting onto hydrothermal carbonization (HTC)‐derived materials is described. The method pertains to the Diels–Alder cycloaddition reaction of furan moieties present on the surface of a HTC material with the maleimide groups stemming from a maleimide protected poly(ethylene glycol) (Me‐PEG‐MI) by a retro Diels‐Alder reaction. The precursor polymer, HTC material, and final product are characterized. Successful grafting is confirmed by elemental analysis, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and dispersion studies.
Controllable synthesis of coordination polymer (CP) isomers and revealing their structure–property relationships remain enormous challenges. Three new supramolecular isomers have been synthesized by tuning the poly(ethylene glycol) (PEG) content in the feed. These supramolecular isomers have the same framework formula of [Cu2I2(tppe)] and different architectures from the classical 2D stacking framework to a 3D entangled system with the coexistence of interpenetration and polycatenation, and a 3D topological framework. Interestingly, these CPs could be utilized for capturing iodine molecules. According to multiple complementary experiments and crystallographic analyses, iodine capture is mainly based on halogen‐bond interactions in the inorganic {Cu2I2} building blocks of the framework. The present study describes a structure–property relationship in supramolecular isomerism with distinct topological structures. 相似文献