Houbo Zhou,Yi Chen,Christopher M. Plummer,Huahua Huang,Yongming Chen
This article demonstrates a new post-modification method to synthesize well-defined brominated polymers based on the bromination of hydroxyl-containing polymers. Bromination conditions for poly(2-hydroxylethyl methacrylate) (PHEMA) with diethylaminodifluorosulfinium tetrafluoroborate (XtalFluor-E), including solvents, bromine sources, additives, feeding ratios and reaction times were studied in detail. It was found that all –OH groups of PHEMA were quantitatively transformed to –Br groups and that the product maintained a narrow molecular weight distribution with a combination of XtalFluor-E, tetrabutylammonium bromide (TBAB) and 1,8-diazabicyclo(5.4.0)undec-7-ene( DBU) in dichloromethane for 24 h, at a feed ratio of [OH] : [XtalFluor-E] : [TBAB] : [DBU] = 1 : 5 : 5 : 5. Thus, well-defined poly(2-bromoethyl methacrylate) (PBEMA) and its copolymer poly(BEMA-co-MMA) were readily prepared via post-modification of the corresponding PHEMA and poly(HEMA-co-MMA) copolymer at room temperature followed by a simple precipitation procedure. This methodology was additionally applied to obtain α,ω-dibromo and mono-bromo terminated poly(ethylene glycol)s (PEGs) from the corresponding hydroxyl-capped PEGs. The facile and efficient bromination of hydroxyl-containing polymers has the potential to be a universal methodology for the synthesis of a diverse range of brominated polymers.
Ting Su,Furong Cheng,Yuji Pu,Jun Cao,Shuibin Lin,Guizhi Zhu,Bin He
Cancer has been one of the major healthcare burdens, which demands innovative therapeutic strategies to improve the treatment outcomes. Combination therapy hold great potential to leverage multiple synergistic pathways to improve cancer treatment. Cancer cells often exhibit an increased generation of reactive oxygen species (ROS) and antioxidant species compared with normal cells, and the levels of these species can be further elevated by common therapeutic modalities such as photodynamic therapy (PDT) or chemotherapy. Taking advantage that cancer cells are vulnerable to further oxidative stress, we aim to design a drug delivery system by simultaneously increasing the cellular ROS level, reducing antioxidative capacity, and inducing anticancer chemotherapy in cancer cells. Here, we designed a star-shape polymer, PEG(- b -PCL-Ce6)- b -PBEMA, based on the Passerini three-component reaction, which can both enhance ROS generation during PDT and decrease the GSH level in cancer cells. The polycaprolactone conjugated with photosensitizer Ce6 served as hydrophobic segments to promote micelle formation, and Ce6 was used for PDT. The H 2 O 2 -labile group of arylboronic esters pendent on the third segment was designed for H 2 O 2 -induced quinone methide (QM) release for GSH depletion. We thoroughly investigated the spectral properties of blank micelle during its assembling process, ROS generation, and H 2 O 2 -induced QM release in vitro . Moreover, this polymeric micelle could successfully load hydrophobic anti-cancer drug Doxorubicin (DOX) and efficiently deliver DOX into cancer cells. The triple combination of ROS generation, GSH elimination, and chemotherapy dramatically improved antitumor efficiency relative to each of them alone in vitro and in vivo .
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