Archive for September, 2013

Paper of the week: Cell-penetrating albumin conjugates for enhanced doxorubicin delivery

Albumin-based drug delivery has been demonstrated to be useful for achieving improved cancer therapy, largely due to its passive target toward tumor via the enhanced permeability and retention effect and the increased demand for albumin by tumor cells as source of energy and amino acids. However, albumin lacks not only the active mechanism to overcome the cell membrane barrier, but also the ability to penetrate into tumor tissues. Herein, a cell-penetrating albumin-based delivery strategy was developed, in which a cell-penetrating peptide was chemically conjugated to albumin in order to enhance the efficiency of intracellular delivery and tumor penetration. Doxorubicin (DOX) molecules were loaded into the carrier via cleavable disulfide bonds, which are responsive to the highly reducing environment in the cytosol of tumor cells, thus archiving prodrug-type targeted drug release. The cell-penetrating albumin–DOX conjugates displayed significantly higher antitumor activity than DOX. More interestingly, the conjugates also efficiently killed the drug-resistant tumor cells, in sharp contrast to the ineffective DOX. The studies with human xenograft tumors in nude mice further demonstrated the enhanced antitumor efficacy and reduced side effects of the cell-penetrating albumin-assisted DOX delivery strategy, indicating the promise of this delivery system.

Cell-penetrating albumin conjugates for enhanced doxorubicin delivery by Qianqian GuoHuiyuan WangYongxing ZhaoHuixin Wang,Feng ZengHaiying HuaQin Xu and  Yongzhuo Huang Polym. Chem., 2013,4, 4584-4587

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Author of the Week: Prof. Hanying Zhao

Hanying Zhao received his bachelor’s degree in Chemical Engineering from HeFei University of Technology in China in 1988, his MS degree in Chemical Engineering from Tianjin University in 1993, and a PhD in Polymer Chemistry and Physics from Changchun Institute of Applied Chemistry, Chinese Academy of Sciences in 1997. From 1997 to 2004, he conducted postdoctoral research in Fudan University, Institute of Polymer Research in Dresden, University of Florida and Clarkson University. He joined the Department of Chemistry at Nankai University in 2004, and now he is a professor of chemistry. His current research interests include: (1) synthesis and self-assembly of macromolecules with different topological structures, (2) synthesis of polymer brushes on solid surfaces, (3) synthesis and self-assembly of shape amphiphiles (gold nanoparticles, single-chain nanoparticles, Janus structures).

Webpage: http://chem.nankai.edu.cn/teachers/echo-1.php?id=zhaohanying

What was your inspiration in becoming a chemist?

Actually, until I received my master degree, I was not sure what job I should take, to be a chemist or an engineer? I thought it was not a bad thing to have a PhD degree, so I went to Changchun to pursue my PhD. I studied under Professor Baotong Huang at Changchun Institute of Applied Chemistry, Chinese Academy of Sciences. Prof. Huang was an eminent polymer chemist at that time. In my research, I synthesized block copolymers by anionic polymerization, I found polymer chemistry is so beautiful and I never left this field since then. Now all the research conducted in our group is related to polymer chemistry.

What was the motivation to write your Polymer Chemistry article? (DOI: 10.1039/C3PY00516J)

Usually polymeric micelles are composed of hydrophobic cores and hydrophilic coronae. The hydrophobic cores can be used as nanosized vehicles for hydrophobic compounds. In our article, we described a method to prepare hydrophilic interface-crosslinked polymeric micelles. The interfaces of the micelles are crosslinked by atom transfer radical coupling reaction, and the stability of the micelles is improved. The cores and the coronae of the micelles are hydrophilic, and the hydrophilic micelles can be used as nanoreactors for the synthesis of CdS quantum dots, and nanocarriers for the absorption of methylene blue, a positively charged dye. In comparison to the traditional polymer micelles, the hydrophilic micelles may find broader applications in aqueous solutions.   

Why did you choose Polymer Chemistry to publish your work? )

Polymer Chemistry is a leading journal in the fields of polymer science and polymer materials. We believe that publishing our paper in this journal can help the paper to be read by a broad scope of readers. Another reason is the rapid review process.

In which upcoming conferences may our readers meet you?

I will probably attend the Fall 2014 ACS meeting.

How do you spend your spare time?

In my spare time, I usually play badminton with my students. I enjoy reading history books.

Which profession would you choose if you were not a scientist?

I love science. I guess, if I were not a scientist, I would be a teacher in a middle-school, or a doctor in a hospital.


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Polymer Chemistry: rapidly published, rapidly cited

Did you know that on average it takes fewer than 8 weeks from submission to publication* of a Polymer Chemistry article?

And it doesn’t take long before those articles are cited either: Polymer Chemistry has the highest immediacy indexǂ of all primary research journals in polymer science.

submit nowSo why delay sending your next article to Polymer Chemistry?

Polymer Chemistry

* Publication refers to online publication of the full edited version of the manuscript.
ǂ Immediacy index = 1.305 (2012 Journal Citation Reports ®, (Thomson Reuters, 2013)). The immediacy index is the average number of times an article is cited in the year it is published, and is an indication of how topical and urgent the work is.

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Paper of the week: Scope and limitations of the nitroxide-mediated radical ring-opening polymerization of cyclic ketene acetals

The ring-opening polymerization of cyclic ketene acetals (CKAs) by controlled radical mechanisms represents an alternative route for the synthesis of aliphatic polyesters. For the first time, 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) and 2-methylene-4-phenyl-1,3-dioxolane (MPDL) were homopolymerized by nitroxide mediated polymerization (NMP), from the commercially available SG1-based BlocBuilder MA alkoxyamine. Various experimental conditions (i.e., reaction temperature, nature of solvent, and nature of the alkyl initiating radical) were varied to determine the optimized conditions in terms of polymerization kinetics and living character of the final polymer. Chain-end extensions from either PS-SG1 or PBMDO-SG1 were also performed in order to furnish PS-b-PBMDO and PBMDO-b-PS, respectively, thus demonstrating the synthesis of block copolymers comprising a CKA block. In order to have a better insight into the polymerization mechanism, the occurrence of side reactions was analyzed by 31P NMR spectroscopy and ESI-MS. It was supposed that the ketal-based macroradical could be irreversibly trapped by nitroxide and thus the corresponding macroalkoxyamine decomposed by CO–N bond dissociation. DFT calculations as well as PREDICI modeling were also undertaken in order to support this hypothesis.

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Author of the Week: Prof. Andrew Whittaker

Prof. Andrew Whittaker is the leader of the Polymer Chemistry group within the Australian Institute for Bioengineering and Nanotechnology, and the Centre for Advanced Imaging at the University of Queensland. He received his PhD from the University of Queensland in 1986, and subsequently held positions as a postdoctoral research fellow at the Université des Sciences & Techniques de Languedoc (with Patrick Bernier) and at the Max-Planck-Institut für Polymerforschung (with Hans Spiess). He was a research chemist in Ken Packer’s labs at BP Research Sunbury for three years before returning to Australia to take up a position at the Centre for Magnetic Resonance at the University of Queensland in 1991. He was promoted to full professor in 2004 and was an inaugural Group Leader within the AIBN (2005). His research interests span many aspects of polymer physical chemistry, but currently are focused on the science and application of transport properties in swollen polymers and the structure of heterogeneous polymers. The target application areas are polymeric biomaterials (imaging agents, drug delivery, functional surfaces) and polymers for photolithography (polymer resists, block copolymer graphoepitaxy). He collaborates with scientists in the USA, UK, Germany, Japan and China.

Research website: http://www.uq.edu.au/polymer-chemistry

What was your inspiration in becoming a chemist?

My interest in chemistry is driven by natural curiosity – as a child I loved to conduct “chemical reactions” with anything at hand around the house or farm – to the bemusement of my grandparents and their livestock! I have always wanted to understand how things, in particular matter, are made and how they work – what are the building blocks of the beautiful objects around us? As a child living in the country I devoured information on chemistry – my mother bought the Encyclopaedia Britannica when I was 8 years old and I read every article within the 26 volumes related to chemistry. The authors were world-renowned – I didn’t know it then – Flory wrote the article on Polymers, for example. This natural interest led to success in the field at school and naturally onto university. An important moment for me as an undergraduate student was seeing a well-known professor of polymer physical chemistry speak of his research – his presentation was distinguished and profound and provided a firm role model for a budding scientist.

What was the motivation to write your Polymer Chemistry article?  (DOI: 10.1039/C3PY00654A)

Our group has a very active program in development of new medical imaging agents. We are in the fortunate situation of having world-class chemistry labs immediately adjacent to a powerful suite of imaging systems (MRI, PET, CT, fluorescence and all combinations) at the Centre for Advanced Imaging. We have developed an integrated program in the field of imaging agents from polymer chemistry, through in-vitro and in-vivo analysis and ultimately human imaging with our clinical partners in hospitals in Brisbane.

Why did you choose Polymer Chemistry to publish your work?

Polymer Chemistry is a high-quality journal with a record of publishing work which spans scientific disciplines. The editorial and production teams are extremely well-organised and turn-around time is short.

In which upcoming conferences may our readers meet you?

EP’2013 Xiamen; ICBNI 2013 Beijing; 62nd SPSJ Symposium on Macromolecules Kanazawa; IPST 2013 Yogyakarta; PPC13 Taiwan; ICFPAM 2013 Auckland

How do you spend your spare time?

We have a 2 year old daughter so spare time does not exist. My (dormant) hobbies include history, bush walking/camping, gardening, brewing beer and cooking.

Which profession would you choose if you were not a scientist?

I cannot imagine a career outside of science. If not chemistry then I would be a botanist.

Cyrille Boyer is a guest web-writer for Polymer Chemistry. He is currently associate professor and an ARC-Future Fellow at the Australian Centre for NanoMedicine and Center for Advanced Macromolecular Design (School of Chemical Engineering, University of New South Wales (Australia)).

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