Focus on polymer chemistry papers in Science in China Series B:Chemistry of the year 2009

The journal Science in China Series B:Chemistry published 11 and 37 papers in polymer fields in 2008 and 2009,respectively,leading to a percentage increase of 236% and thereby a great historic breakthrough of the journal.These papers mainly focus on three fields:(1) polymer synthesis,(2) functional polymer materials and (3) biomedical polymers.Several research groups published a series of papers in Science in China Series B:Chemistry and detailedly introduced their works in the related fields.

Stem cell differentiation and human liver disease

Human stem cells are scalable cell populations capable of cellular differentiation.This makes them a very attractive in vitro cellular resource and in theory provides unlimited amounts of primary cells.Such an approach has the potential to improve our understanding of human biology and treating disease.In the future it may be possible to deploy novel stem cell-based approaches to treat human liver diseases.In recent years,eff icient hepatic differentiation from human stem cells has been achieved by several research groups including our own.In this review we provide an overview of the f ield and discuss the future potential and limitations of stem cell technology.

Dispersity Regulation in Photo-controlled Radical Polymerization by Merging Aryl Sulfonyl Chloride Initiators and Mixed Disulfide Agents

On-demand regulation of molecular weight distribution(MWD)is crucial to influence the properties of polymers.In this work,we reported an organocatalyzed photo-controlled radical polymerization(photo-CRP)from the tosyl chloride initiator by combining two disulfides as chain transfer agents.This novel synthetic protocol allows facile access toward well-defined polymers with tunable MWDs and predetermined molecular weights.Experiments including structural characterization,kinetic investigation and chain-extension polymerization exhibited good chain-growth control for polymers of different dispersities.Given the easy accessibility of the initiating site(sulfonyl chloride)on many aromatic sources,this work presents a promising avenue to modify such substances with polymers of tailored MWDs,chain lengths and repeating units under metal-free and mild conditions driven by light.

Supramolecular Single-Chain Polymeric Nanoparticles

Nature has unparalleled control over the conforma-tion and dynamics of its folded macromolecular structures.Nature’s ability to arrange amino acids into a precise spatial organization by way of folding allows proteins to fulfill specific functions in an ex-tremely efficient manner.

Thermoresponsive dendronized copolymers for protein recognitions based on biotin-avidin interaction

Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interaction investigated.Both first（PG1） and second generation（PG2） dendronized copolymers were designed to examine possible thickness effects on the interaction between biotin and avidin.Inherited from the outstanding thermoresponsive properties from OEG dendrons,these biotinylated cylindrical copolymers show characteristic thermoresponsive behavior which provides an envelope to capture avidin through switching temperatures above or below their phase transition temperatures（T_（cp）s）.Thus,the recognition of polymer-supported biotin with avidin was investigated with UV/vis spectroscopy and dynamic laser light scattering.In contrast to the case for PG1,the increased thickness for copolymer PG2 hinders partially and inhibits the recognition of biotin moieties with avidin either below or above its T_（cp）.This demonstrates the significant architecture effects from dendronized polymers on the biotin moieties to shift onto periphery of the collapsed aggregates,which should be a prerequisite for protein recognition.These kinds of novel thermoresponsive copolymers may pave a way for the interesting biological applications in areas such as reversible activity control of enzyme or proteins,and for controlled delivery of drugs or genes.

Facile preparation of antibacterial polymer coatings via thiol-yne click photopolymerization

Novel antibacterial polymer coatings were prepared by a facile thiol-yne click photopolymerization of 1-propargyl-3-allYl-l,3-diazanyl-2,4-cyclopentadiene bromide （[PAIMIBr） and tetra（3-mercapto-pro- pionate）pentaerythritol （PETMP） （2：1 molar ratio） using 2,2-dimethoxy-2-phenylacetophenone （DMPA） as initiator. The antibacterial activity of the coatings was tested against Staphylococcus aureus （ATCC 292130） and Escherichia coli （ATCC 25922） by the dynamic shake method. The evaluation results revealed the antibacterial polymer coatings exhibited excellent inhibitory activity against S. aureus and E. coil, especially for S. aureus.