Archive for June, 2014

Ben Zhong Tang interviewed in Chemistry World

Polymer Chemistry Associate Editor Ben Zhong Tang was interviewed for Chemistry World about his work on alkyne polymers and aggregation induced emission.

Here are some of the highlights:

Your research on aggregation induced emission (AIE) received a lot of attention. Can you tell us more about it?

There are a lot of light emitting materials. This type of material, if you dissolve it to make a dilute solution, gives a very strong emission. However, for many of these kinds of dyes, if their concentration becomes high, their emission becomes weaker. This phenomenon has often been referred to as aggregation-caused quenching or ACQ for short. This is a problem in things like mobile phone displays, where the light emitting material is used as thin solid film. In the solid state, you know, concentration is the highest.

We have developed a family of luminogenic materials that behave in exactly the opposite way. When they are in solution, there is no emission, but when they aggregate, they emit very efficiently. It’s unusual and intriguing: previously, people have tried to solve the problem of ACQ by trying to separate the light emitting molecules. But now we have a system where the more it aggregates, the better

You’ve used these systems recently to make biosensors.

Yes, one very good application for these systems is in biology. One of the reasons for this is that light emitting species are aromatic rings, which are hydrophobic. In the body, we don’t have organic solvents: we only have water. Water is hydrophilic, so it isn’t compatible with the aromatic molecules. Traditional ACQ systems are not very good for biological applications due to the aggregate formation, but our systems work well in water, also owing to the formation of aggregates!

What current problem would you like to see polymer chemistry provide a solution to?

There are so many problems! In China, pollution is a big issue and this includes plastics. If we can come up with an economic way to recycle polymers back to monomers, then make them into new polymers in an economic way, we could reduce environmental pollution. Energy, of course, is another issue. One day we may have a very good polymer-based solar cell.

Read the full interview on the Chemistry World website: Ben Zhong Tang: Polymers for a bright future

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Paper of the week: Macroporous antibacterial hydrogels with tunable pore structures

‘Porous hydrogels with well-defined pore structure have attracted considerable attention due to their multifarious applications such as scaffolds for tissue engineering, vehicles for drug delivery and self-healing materials. CO2-in-water (C/W) high internal phase emulsions (HIPEs) and oil-in-water (O/W) HIPEs are considered as very effective templates to produce such kinds of high porosity hydrogels… In most cases, the O/W HIPEs are stabilized by large amounts of surfactants at high concentrations of 5–50 vol%, where the enormous quantity of surfactants presents economic and potential environmental problems. Therefore, much attention has been focused on the Pickering-HIPEs, which are stabilized by colloidal particles instead of traditional surfactants.’

Graphical abstract: Macroporous antibacterial hydrogels with tunable pore structures fabricated by using Pickering high internal phase emulsions as templates

In this work, Deng, Wang and co-workers prepared Artemisia argyi oil (AAO)-loaded macroporous antibacterial hydrogels by polymerization of oil-in-water Pickering HIPEs. The HIPEs were stabilized by the synergy of hydrophilic silica nanoparticles (N20) and surfactant Tween 80. The void interconnectivity and pore size of the hydrogels can be readily tailored by varying the concentrations of N20 nanoparticles and Tween 80. The in vitro release of the AAO-loaded hydrogels with different inner morphologies was evaluated and showed controlled release activity. The antibacterial activity of the AAO-loaded hydrogel was evaluated against Staphylococcus aureus and Escherichia coli. This kind of hydrogel exhibited excellent and long-term antibacterial activity indicating its potential use in biomedical and infection prevention applications.

Macroporous antibacterial hydrogels with tunable pore structures fabricated by using Pickering high internal phase emulsions as templates by Shengwen Zou, Zengjiang Wei, Yang Hu, Yonghong Deng, Zhen Tonga and Chaoyang Wang, Polym. Chem. 2014, 5, 4227-4234.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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Paper of the week: Bio-based covering materials for surface design

‘Innovative approaches for the syntheses of polymeric structures bearing polypeptides have received enormous interest in the fields of biomedicine, drug delivery, biomineralization, nanoscale self-assembly, and tissue engineering. The conjugation of synthetic polymers with polypeptides can result in novel biomaterials that possess the following characteristics: biorecognition-like properties similar to antibody/antigen interactions, biodegradability properties, biocatalyst activity, and compatibility with blood and/or tissue.’

Graphical abstract: Electrochemical deposition of polypeptides: bio-based covering materials for surface design

In this article, Endo, Timur, Yagci and co-workers reported on a simple and efficient approach for the electrochemical deposition of polypeptides as bio-based covering materials for surface design. The method involves N-carboxyanhydride (NCA) ring-opening polymerization from its precursor to form a thiophene-functionalized polypeptide macromonomer (T-Pala), followed by electropolymerization. The obtained conducting polymer, namely polythiophene-g-polyalanine (PT-Pala), was characterized and utilized as a matrix for biomolecule attachment. The biosensing applicability of PT-Pala was also investigated by using glucose oxidase (GOx) as a model enzyme to detect glucose. Finally, the antimicrobial activities of newly synthesized T-Pala and PT-Pala were also evaluated. Interestingly, this technique is experimentally facile and can be applied to various types of polypeptides.

Electrochemical deposition of polypeptides: bio-based covering materials for surface design by Huseyin Akbulut, Murat Yavuz, Emine Guler, Dilek Odaci Demirkol, Takeshi Endo, Shuhei Yamada, Suna Timur and Yusuf Yagci, Polym. Chem. 2014, 5, 3929-3936.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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Author of the Week: Zhenkun Zhang

zhenkunzhangZhenkun Zhang obtained his B.S. and M.S. degree in Chemistry from Nankai University in China in 1999 and 2002, respectively. He obtained his Ph.D. degree in 2007 from University of Twente in the Netherlands by working in Prof. Jan. K. Dhont’s group in Forschungszentrum Jülich, Germany. After that, he spent one year in postdoctoral training at the Centre de Recherche Paul Pascal of the CNRS in France with Dr. Eric Grelet. From Sept. 2008 to Mar. 2011, he conducted postdoctoral research with Prof. Jan Vermant and Prof. Dr. Christian Clasen at the Catholic University of Leuven in Belgium. In June of 2011, he joined the Institute of Polymer Chemistry (IPC) at Nankai University and then was promoted to associate professor in the same year. In his previous research, he mainly focused on applying chemical modifications to rodlike viruses to create well-defined models for the fundamental research of soft matter such as chiral nematic liquid crystals, hydrogels, etc. Together with his collaborators, he also made some progress in the preparation of polymeric ellipsoidal colloids and succeeded in the large-scale directed self-assembly of such particles at a fluid-fluid interface. His current research interests are the preparation and controlled assembly of virus/polymer hybrids, understanding and application of the chiral nematic liquid crystal phase of rodlike viruses, self-assembly of anisotropic particles at fluid-fluid interfaces.

Group web-link: http://polymer.nankai.edu.cn/zhang/

What was your inspiration in becoming a chemist?

It is a destiny. I was indeed good in most of the subjects I had to learn at school, except for sports. When I was at the junior school we started to learn chemistry. I could get a very high score in each examination and then was promoted to the assistant to the chemistry teacher to help him with collecting the homework and examination papers. At that time, I was surprised by the fact that gas bubbles appeared when I poured on vinegar to remove water scale, and I tried to plug two iron sticks to a potato with the hope of producing some electricity to power a tiny bulb. I continued to make high scores in each chemistry test and worked as the assistant to the chemistry teacher through my days in high school. When it was time to pick a major for my university study, I put chemistry as the top choice and went to the college of chemistry at Nankai University in China, which was then claimed to have the best chemistry in China. Since then, I have never stayed away from chemistry.

What was the motivation to write your Polymer Chemistry article? (DOI: 10.1039/C4PY00508B)

Hydrogels are normally made from polymer. In other words, polymers are the key backbone of most of hydrogels. Nowadays, there is increasing interest in the hydogels made from nanoscale fibrous particles which are the results of supramolecular self-assembly of some small molecules. This kind of hydrogel is less controllable and tunable in terms of their mechanical, rheological properties and structure. I have been working with a rodlike virus which has a slender shape with a diameter only 6.6 nm and a length of 880nm. One day, I got the idea that this virus should be the ideal backbone for a fibrous hydrogel. In addition, since I started my own group, I learned from my fellow colleagues about the intriguing properties of boronic acid containing polymers which have found many potential applications such as in glucose sensing materials for the benefit of diabetes treatment. To my surprise, there are barely any reports about binding the boronic acid containing polymers to some biological substrates like proteins to create interesting materials. We decided to design a boronic acid containing polymer with an end functional group which can bind to my favorite natural protein assembly- the rod-like virus. In this way, we created the multiple responsive virus based hydrogel.

Why did you choose Polymer Chemistry to publish your work?

During the work leading to the results presented in the current manuscript, we have read several papers from Polymer Chemistry about boronic acid containing polymers. The quality of the papers is very high and impressive. We also learned that this journal has a fast review and publication process. Our manuscript has been subjected to the assessment of three referees, who gave very objective, insightful and detailed comments. Communication with the Editors is also very pleasant.

At which upcoming conferences may our readers meet you?

I plan to attend the 4th Zing Polymer Chemistry Conference in Cancun, Mexico on 10th December 2014 – 13th December 2014.

How do you spend your spare time?

I like playing with my kid, reading and running when I have free time.

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

Once, for a while, I was obsessed with internet technology, especially website designing and programming. If I were not working in academia, I would have been a programmer.

Read Zhenkun Zhang’s lastest Polymer Chemistry article here:

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

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Paper of the week: A new platform for synthesis of functional aliphatic polyesters

‘Functional polymers open up applications with endless possibilities, where properties can be tailored, altered, and/or maintained over the complete lifetime of the material. In light of this, the focus today is on conferring function to the main chain of the polymer. One class of polymers that is inherently of great value for many applications is aliphatic polyesters; because of their ester functionality, they most often degrade within a reasonable time frame. Unfortunately, many of these monomers lack sites that allow alterations and modifications of the polymer backbone. Therefore, a major scientific focus has been on imparting different functionalities to aliphatic polyesters.’

Graphical abstract: Establishing α-bromo-γ-butyrolactone as a platform for synthesis of functional aliphatic polyesters – bridging the gap between ROP and SET-LRP

In this article, Albertsson and co-workers felt inspired to use γ-lactones as inexpensive and straightforward monomers that can bestow the desired functionality on commonly used aliphatic polyester. More specifically, they used α-bromo-γ-butyrolactone (αBrγBL) as a comonomer with ε-caprolactone (εCL) or L-lactide (LLA) to produce copolymers with active and available grafting sites, e.g., for SET-LRP, where the choice of the grafting monomers is limited only by one’s imagination. The authors believe that αBrγBL inherently holds all the prerequisites to act as a platform monomer for the synthesis of functional aliphatic polyesters, i.e., it is inexpensive, available, and able to form isolated grafting sites along the polymer chain. The incorporation of isolated αBrγBL is a feature that makes this class of copolymers unique and is considered to provide a route to the “perfect graft copolymer” with a degradable backbone.

Establishing α-bromo-γ-butyrolactone as a platform for synthesis of functional aliphatic polyesters – bridging the gap between ROP and SET-LRP by Peter Olsén, Jenny Undin, Karin Odeliusa and Ann-Christine Albertsson, Polym. Chem. 2014, 5, 3847-3854.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

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