Polymeric micelles were prepared by dropping ethanol into solutions containing（poly（γ-benzyl L-）glutamate）-poly（ethylene oxide） block copolymer （PBLG-b-PEO）,chloroform（CHCl3） and trifluoroacetic acid（TFA）.Viscometry,transmission electron microscopy（TEM）,nuclear magnetic resonance（（）1H-NMR） spectroscopy and infra-red difference spectroscopy（IR） were used to investigate the influence of PBLG chain conformation on the self-assembly behavior of PBLG-b-PEO.The experimental results revealed that PBLG-b-PEO could associate into polymeric micelles in ethanol solutions.The introduction of TFA not only changes the conformation of PBLG segments,but also increases the critical micelle concentration,and further affects the morphologies of the formed micelles.
Polypeptide graft copolymers such as poly(γ-benzyl-L-glutamate)(PBLG)-poly(ethylene glycol)(PEG) and poly(γ-ethyl-L-glutamate)(PELG)-poly(ethylene glycol)(PEG) were introduced into self-setting calcium phosphate cement(CPC) system to improve its mechanical properties. The compression strength was improved considerably by the induction of polypeptide copolymers. It is about 22.3 higher for PBLG-g-PEG and 65.0 higher for PELG-g-PEG, respectively. The results also show that for the same polypeptide copolymer, higher compression strength of composites can be obtained by introducing copolymer micelles into the CPC. According to the results of scanning electron microscope(SEM), the crystallite shapes of CPC depend on the weight fraction of polypeptide copolymer in the composites.
Self-association behavior of an amphiphilic polypeptide graft copolymer,poly(γ-benzyl L-glutamate)-g-poly(ethylene glycol), and the drug carrier capability of the formed micelles were examined by fluorescence spectroscopy,transmission electron microscopy and UV spectroscopy.It was found that the hydrophobic inner core of the micelles formed by poly(γbenzyl L-glutamate)(PBLG) segments can act as an incorporation site for hydrophobic drugs.The drug-loading content of the graft copolymer micelles tends to be larger when the content of the PBLG segments in the copolymer increases.The results obtained from the drug-release studies showed that the drug-release rates were dependent on the chemical nature of the graft copolymer.
