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The 2011-2012 spring and summer semester summary in the group

2013-11-01

Another intense and busy semester has gone as time flies. According to the customs, our group held the review meeting of this semester. This time we chose the so-called “cool world”- Mogan Mountain instead of the campus as the meeting place, which was different from the former years. At 8:30 am on 30 July, we set out to the destination and two-hour’s journey slipped away with our happy laughters and cheerful voices. On entering the Mogan Mountain, we felt cool and refreshed immediately. In the afternoon, the meeting was held on schedule in the meeting room of the holiday village. Each of the teachers and students in our group made a summary report on the research work and group management work, which was followed by a discussion in depth on these work. There is no doubt that the communication and discussion between teachers and students not only enhanced the group cohesion, but also improved our relationship. We believe that with the joint efforts of us all, our group will become more and more excellent. For the rest of time, we toured a series of scenic spots of Mogan Mountain: the beautiful Reed Flower Field Park, the quiet Wuling Village, the soul-stirring Sword Pool and Flying Waterfall, the historical Baiyunshan Pavilion, and so on. Following the introduction of the tour guide, we enjoyed ourselves in the lovely scenery and were busy with taking photos. Time went by quickly. The two-day tour came to an end with our nostalgia. Having appreciated the beautiful sight of Mogan Mountain, enjoyed the quietness absent in cities and tasted various delicious farm food, we really feel it a worthwhile trip!

Drug Reservoirs in Materials and Biosciences given by professor Helmuth Möhwald

2013-09-26

On Sept. 23rd, we were very pleasure to invite professor Helmuth Möhwald to our department for an academic lecture- Drug Reservoirs in Materials and Biosciences. Professor Helmuth Möhwald is a member of the European academy of sciences, holding a leading position on colloid and interface. This precious lecture gave us a better understanding of his research and forefront achievements in this domain. Briefly, presentation of professor mainly concerned Fabrication of Capsules, Complex Capsules, Applications and Surface Treatment by Ultrasound. What impressed us deeply is professor’s prominent work and fascinating delivering. Afterwards, a heated discussion enhanced better communication. By this great chance, we get a better understanding of bionic system and interface dynamics. Wish our team higher achievements in scientific research!

Scitific Visit to CIC biomaGUNE in Spain

2013-09-17

Dr. candidate Bo Li in our lab was sent to CIC biomaGUNE in Spain to conduct cooperative research in June 2013. Under the supervision of Dr. Sergio E. Moya, Bo Li cooperating with Joseba Irigoyen Otamendi participated in one project, which focused on the assembly of polyelectrolyte onto SiO2 nano particles. This exchange was supported by Marie Curie Actions-International Research Staff Exchange Scheme. 10 students have been sent from our lab during the past 2 years to visit CIC biomaGUNE in Spain, Universität Leipzig in Germany or other institutions in Europe. In the next 3 years, 6-8 students will be sent to those institutions to do cooperative research. These exchange projects between Europe and China have created platforms for the young scientists to immerse themselves in a different culture and environment.

Congratulations to Shupeng She, Dahai Yu, Bo Li and Xing Liu on their successful defense of the doctoral dissertations

2013-09-15

It was September 10, 2013, which was a special day- the Teacher’s Day of China. The doctoral dissertation defenses of four students of our group -Shupeng She, Dahai Yu, Xing Liu and Bo Li were conducted successfully at the conference room of Polymer Building. Professor Zhikang Xu of Department of Polymer Science and Engineering was invited as chairman of the dissertation committee and the chief of the fourth Chemical Science Section of NSFC Jianhua Dong, Professor Youqing Shen of Department of Chemical Engineering, Professor Jinfu Wang of College of Life Sciences and Professor Lie Ma of Department of Polymer Science and Engineering as the committee members. At the beginning, Professor Changyou Gao on behalf of our group expressed our best wishes for a happy Teacher’s Day to all the teachers present. Soon afterwards, the four doctoral students introduced their work of the doctorate study period in turn. Shupeng She mainly researched the shape change of polyelectrolyte multilayer microcapsules in response to external fields. Firstly, he investigated the deformation and recovery behaviors of spherical multilayer microcapsules squeezed through microchannel. After the basic deformation-recovery properties of spherical capsules were obtained, the RBC-like capsules were fabricated, which possessed excellent deformation-recovery properties under constricted microcapillary. Finally, the shrinkage of PAH/PSS capsules in alkaline solution containing Ca2+ was investigated, the shrinking mechanism was deduced and confirmed. Dahai Yu mainly researched the interactions between PLGA colloidal particles and cells. He prepared PLGA particles coated with PEI and BSA and investigated the influence of surface charge on the internalization processes and intracellular fate of the particles and their influences on cells. Further, redox-responsive and pH-responsive PLGA particles systems were established respectively and the responsiveness of these particles inside cells were researched carefully. Xing Liu combined siRNA technology with regenerative biological materials. Aiming at interfering TGF-β1 signal pathway, directing cell fates and ultimately inhibiting scarring, he fabricated a new kind of collagen-chitosan/silicone membrane bilayer dermal equivalent loaded with siRNA( RNAi-BDE). Then the evaluation of RNAi-BDE was conducted in vitro and in vivo. And in order to optimize RNAi-functionalized scaffolding matrix, he also researched the vital influence of the cellular microenvironment on the efficiency of siRNA transfection. Bo Li optimized systematically the structure and performance of PLGA/fibrin gel system for cartilage repair. He constructed the PLGA/fibrin gel/MSCs/TGF-β1 system, the PLGA/fibrin gel/MSCs/(PEO-b-PLL/pDNA-TGF-b1) system and the PLGA/fibrin gel/MSCs/( lipofectamine/pDNA-TGF-b1) system to research the influence of PLGA molecular weight, optimize the active factor and to research the influence of composition of the scaffold respectively. The four students presented content-rich and well-organized dissertation defenses. They were praised by the defense committee for their excellent presentation and performance when answering the questions. All the experts present made many suggestions and comments for their doctoral dissertations and had a lively discussion. After discussion, the dissertation committee agreed unanimously that the four students all successfully defended their dissertations and be conferred the doctor's degree. Congratulate the four doctoral students on their completing studies smoothly and hope the other students progress together to create more successful results in the further work and life!

Molecular interactions of diﬀerent size AuNP–COOH nanoparticles with human ﬁbrinogen

2013-09-11

Protein adsorption influences greatly the performance of materials used in biotechnology and biomedicine. The binding of fibrinogen (Fg) to nanoparticles (NPs) can result in protein unfolding and exposure of cryptic epitopes that subsequently interact with cell surface receptors. The response and its degree are dependent on the size, charge, and concentration of the NPs. In this study the binding kinetics of human Fg to negatively charged 11-mercaptoundecanoic acid-functionalized gold nanoparticles (AuNPs–COOH) ranging from 5.6 to 64.5 nm were examined. The larger NPs bound Fg with a larger number of proteins per square unit and a higher dissociation rate (Kd′), but with decreased affinity. By contrast, the 5.6 nm AuNPs–COOH behaved in a cooperative manner for Fg adsorption. In the presence of excess Fg, only the 64.5 nm AuNPs–COOH showed severe aggregation, whose degree was alleviated in a dilute Fg solution. The Fg is adsorbed through a side-on configuration and both side-on and end-on configurations on the smaller (5.6 and 14.2 nm) and 31.5 nm AuNPs–COOH, respectively. It also retains the native conformation. By contrast, on the 64.5 nm AuNPs–COOH the Fg adopts the end-on configuration and loses most of the secondary structure. Jun Deng,a Mingcong Sun,a Jiyu Zhua and Changyou Gao*a. Molecular interactions of different size AuNP–COOH nanoparticles with human fibrinogen Nanoscale, 2013,5, 8130-8137 DOI: 10.1039/C3NR02327C

the Rewards of 2012-2013 Spring and Summer Semester

2013-09-09

In order to motivate students’ working enthusiasm, continuously improve the overall level of research work and encourage students to involve in daily management of the group actively, it is the students who made a great progress in research work, who worked hard or who contributed greatly to management of group’s instruments during this 2012-2013 spring and summer semester that are awarded according to the group’s rules fairly, justly and outright. On the basis of group’s rules, PhD candidates-Deng Jun, Xing Dongming, Jiang Pengfei, Zhang Wenbo and postgraduates-Zhang Yuanhong, Song Xiaoxue, Hu Bin, Liu Xiaofan, Li Luyan, the nine students get the Outstanding Postgraduate Award; PhD candidates-Li Bo, Yu Dahai, She Shupeng and Liu Xing, the four students get the Special Contribution Award; all the PhD candidates are awarded for their hard work; all the students obtain nutrition allowance; instrument management fee is given out accordingly. Totally the graduate student award amounts to ￥55 500 in this semester. In this semester, 8 undergraduates such as Li Chengling, Cui Xiaojing have done their graduation projects, 13 undergraduates such as Li Huanbin, Chen Yuming have done SRTP projects, many of them achieved excellent results in examination. 17 undergraduates have achieved allowance and bonus, totaling up to ￥9187.50. Hope the schoolmates make more progress!

Professor Guoping Chen at the National Institute for Materials Science in Japan was invited to make academic report

2013-08-22

Professor Guoping Chen at the National Institute for Materials Science in Japan was invited to make a report themed: Challenges in Biomaterials and Tissue Engineering Research at Polymer Building on August 13, 2013. The report included the following four aspects: 1. Stepwise tissue development-mimicking matrices; 2. Cultured cell-derived matrix scaffolds; 3. Funnel-like porous scaffolds with open surface pores; 4. Hybrid porous scaffolds. After the report, students had a warm response and actively asked questions, and Professor Chen answered these questions patiently.

Modulating the nanorods protrusion from poly(allylamine hydrochloride)-g-pyrene microcapsules by 1-pyrenesulfonic acid so

2013-07-15

It was found previously that the Schiff base bonds in poly(allylamine hydrochloride)-g-pyrene (PAH-Py) microcapsules (MCs) are hydrolyzed at pH 2 within 1 h, leading to disassembly of the MCs and protrusion of pyrene aldehyde (Py) nanorods (NRs) on the capsule surface. Herein, we found a new way to modulate the protrusion of NRs by addition of 1-pyrenesulfonic acid sodium salt (PySO3Na). Along with the increase in PySO3Na to Py molar ratio in the MCs solution, the protrusion of NRs was progressively blocked and even inhibited at a ratio of 2.3, and at this condition, the microcapsules were stable under pH 2 for 24 h. After the composite microcapsules with excess PySO3Na were washed with a pH 10 solution and then incubated in a pH 2 solution, the NRs could be protruded from the MCs again. The fluorescence peak position of the PAH-Py/PySO3Na MCs gradually red-shifted with a decrease in pH value, and a sharp transition occurred at pH 3.6, demonstrating the formation of pyrene excimers between the PySO3Na small molecules and the pendant Py groups on the PAH chain. The formed excimers take the role of blocking the self-assembly of cleaved Py molecules instead of inhibiting the hydrolysis of the Schiff base, whereas the MCs were stabilized by the charge interaction between PySO3Na and PAH backbone and the hydrophobic interaction between the pyrene rings. Schematic illustration showing the formation of PAH-Py microcapsules (a–c) and protrusion (c–e) and non-protrusion (c–d′ and e) of NRs without (d) and with (d′) the presence of PySO3Na, respectively. Erjia Guan, Tianxiang Wang, Zhipeng Wang, Changyou Gao* Journal of Colloid and Interface Science http://www.sciencedirect.com/science/article/pii/S0021979713004827

Control over the gradient differentiation of rat BMSCs on a PCL membrane with surface-immobilized alendronate gradient

2012-12-17

Gradient biomaterials can offer progressively changed signals to specific tissue interface, and thereby modulate the conjunction between different tissues. A linear density gradient of alendronate (Aln), a molecule that is capable of promoting osteogenic differentiation of bone mesenchymal stem cells (BMSCs), was created on the aminolyzed poly(ε-caprolactone) (PCL) membrane. X-ray photoelectron spectroscopy and quartz crystal microbalance with dissipation revealed the linear increase of Aln amount as a function of position on the PCL membrane. By contrast, the surface wettability and energy were kept unchanged. The surface-grafted Aln showed a stronger ability to induce the osteogenic differentiation of rat BMSCs than its counterpart in culture medium of the same amount, and the osteo-inductive culture medium. On the Aln-grafted gradient surface the BMSCs showed gradient osteogenic differentiation as a function of membrane position in terms of cell morphology, alkaline phosphatase activity, calcium deposition, and the expression of osteogenic proteins including collagen type I, Runt-related transcription factor 2 (Runx2) and osteocalcin (OCN).

Phenomenon and Mechanism of Capsule Shrinking in Alkaline Solution Containing Calcium Ions

2012-12-17

Shrinking phenomenon of poly(allylamine hydrochloride) (PAH)/poly(styrene sulfonate, sodium salt)(PSS) multilayer microcapsules was observed when they were incubated in alkaline solutions containing Ca2+. The shrinking was universal to those polyelectrolyte multilayer capsules regardless of the wall thickness and wall compositions suppose the conditions were proper. The shrinking extent increased along with the increase of solution pH and Ca2+ concentration, and reached to a maximum value of 70% (from 7.4 to 2.3 μm). The shrunk capsules with a hollow structure and thick wall could well maintain their spherical shape in a dry state. During the capsule shrinking partial loss of the polyelectrolytes especially PSS took place, and the loss amount increased along with the increase of solution pH although the alteration patterns were different at lower Ca2+ concentration. The complexation of PSS with Ca2+, which is believed one of the major reasons governing the capsule shrinking, was demonstrated by X-ray photoelectron spectroscopy and turbidity experiment. The mechanism is proposed, which relies on the synergistic effects of deprotonation of PAH and screening of PSS by Ca2+ leading to the thermodynamically favored-capsule shrinking.

RNAi functionalized collagen-chitosan/silicone membrane bilayer dermal equivalent for full-thickness skin regeneration wi

2012-12-17

Scar inhibition of dermal equivalent is one of the key issues for treatment of full thickness skin defects. To yield a bioactive RNAi functionalized matrix for skin regeneration with inhibited scarring, collagen-chitosan/silicone membrane bilayer dermal equivalent (BDE) was combined with trimetylchitosan (TMC)/siRNA complexes which could induce suppression of transforming growth factor-b1 (TGF-b1) pathway. The RNAi-BDE functioned as a reservoir for the incorporated TMC/siRNA complexes, enabling a prolonged siRNA release. The seeded fibroblasts in the RNAi-BDE showed good viability, internalized the TMC/siRNA complexes effectively and suppressed TGF-b1 expression constantly within 14 d. Application of the RNAi-BDE on the full-thickness skin defects of pig backs confirmed the in vivo inhibition of TGF-b1 expression by immunohistochemistry, real-time quantitative PCR and western blotting during 30 d post surgery. The levels of other scar-related factors such as collagen type I, collagen type III and α-smooth muscle actin (a-SMA) were also down-regulated. In combination with the ultra-thin skin graft transplantation for 73 d, the regenerated skin by RNAi-BDE had an extremely similar structure to that of the normal one. Our study reflects the latest paradigm of tissue engineering by incorporating the emerging biomolecule siRNA. The 3-D scaffolding materials for siRNA delivery may have general implications in generation of bioactive matrix as well.

FW: Polymer Chemist Position at Nanyang Technological University (Singapore)

2012-10-22

Antimicrobial polymers are now urgently needed to combat bacteria and fungi. Antimicrobial polymers are superior to antimicrobial peptides as they are can be designed to be non-toxic and biocompatible. We have developed various antimicrobial polymers and peptides that are highly effective and our findings are published in top journals like Biomacromolecules, Biomaterials, Adv. Materials, and Nature Materials. Requirement: i) one PHD student (to study at NTU under Professor Mary Chan) ii) one Postdoctoral fellow (PHD degree in Polymer Chemistry or related field is necessary) Remuneration: The pay is competitive and the position offers opportunity for technology, innovation and commercialization. How to Apply: Please send email to Professor Mary Chan at School of Chemical and Biomedical Engineering at NTU. Email: mbechan@ntu.edu.sg Website: http://www3.ntu.edu.sg/home/mbechan/ Biography Professor Mary Chan-Park is currently a full professor at the School of Chemical and Biomedical Engineering at the Nanyang Technological University Singapore (NTU Singapore). Her main research interests are in polymers in nanoscience and biotechnology. She has developed a new series of antimicrobial polymers leading to patents that have been licensed to companies. She has published extensively, with more than 170 papers in top-tier journals such as Nature Materials, Advanced Materials, Advanced Functional Materials, Small, J. Biomed. Materials Research Part A, Biomaterials, etc. Dr Chan-Park obtained her B.Eng (Chem) and PH.D from the National University of Singapore and MIT in 1986 and 1993 respectively. Professor Mary Chan joined the academia in 2001, bringing with her extensive experience from the chemical industry. She was formerly a senior technical manager in Sipix Imaging (CA, USA) working on e-paper and deputy director at the Singapore Institute of Standards and Industrial Research before joining NTU.

Influences of surface chemistry and swelling of salt-treated polyelectrolyte multilayers on migration of smooth muscle ce

2012-10-12

Cell migration is controlled by surface chemistry and swelling of substrates.The cell migration plays a crucial role in a variety of physiological and pathological processes such as wound healing and tumor metastasis. C. Gao and co-workers at Zhejiang University, Hangzhou, China, have shown that both the surface chemistry and swelling of the salt-etched polyelectrolyte multilayers, rather than the surface roughness and wettability, play primary roles in controlling cell migration. The negatively charged and highly hydrated surface can effectively promote the mobility of smooth muscle cells. These basic principles provide new guidelines for design of advanced biomaterials in regenerative medicine. Lulu Han, Zhengwei Mao, Jindan Wu, Yuying Zhang and Changyou Gao*. Influences of surface chemistry and swelling of salt-treated polyelectrolyte multilayers on migration of smooth muscle cells. Journal of Royal Society Interface, doi: 10.1098/rsif.2012.0546.

Influence of Surface Coating of PLGA Particles on the Internalization and Functions of Human Endothelial Cells

2012-10-11

This study is focused on the uptake of PLGA particles with different coatings and its influences on the functions and toxicity of human endothelial cells. The PLGA particles coated with polyethyleneimine (PEI) or bovine serum albumin (BSA) were prepared via a one-step emulsion method, which had a similar diameter of ~420nm in water and ~170nm in a dry state but oppositely charged surfaces. Both types of the particles were readily internalized into ells within a short time regardless of their surface chemistry. Uptake of the positively charged particles caused apparently decrease of cell viability, but did not significantly influence mitochondrial membrane potential. The cell adhesion and migration were significantly affected, especially after uptake of the PLGA-PEI particles. Quantitative RT-PCR results indicated down-regulation of the mRNA expression of adhesion relevant genes, i.e. fibronectin, laminin and focal adhesion kinase (FAK) after particles internalization. The secretion levels of von Willebrand factor (vWF) and 6-k-PGF1α were not significantly influenced regardless of the surface coating. Dahai Yu †, Yuying Zhang †, Xiangyan Zhou , Zhengwei Mao *, and Changyou Gao *. Influence of Surface Coating of PLGA Particles on the Internalization and Functions of Human Endothelial Cells. Biomacromolecules, 2012, 13 (10), pp 3272–3282. DOI: 10.1021/bm3010484

News

The 2011-2012 spring and summer semester summary in the group

Drug Reservoirs in Materials and Biosciences given by professor Helmuth Möhwald

Scitific Visit to CIC biomaGUNE in Spain

Congratulations to Shupeng She, Dahai Yu, Bo Li and Xing Liu on their successful defense of the doctoral dissertations

Molecular interactions of diﬀerent size AuNP–COOH nanoparticles with human ﬁbrinogen

the Rewards of 2012-2013 Spring and Summer Semester

Professor Guoping Chen at the National Institute for Materials Science in Japan was invited to make academic report

Modulating the nanorods protrusion from poly(allylamine hydrochloride)-g-pyrene microcapsules by 1-pyrenesulfonic acid so

Control over the gradient differentiation of rat BMSCs on a PCL membrane with surface-immobilized alendronate gradient

Phenomenon and Mechanism of Capsule Shrinking in Alkaline Solution Containing Calcium Ions

RNAi functionalized collagen-chitosan/silicone membrane bilayer dermal equivalent for full-thickness skin regeneration wi

FW: Polymer Chemist Position at Nanyang Technological University (Singapore)

Influences of surface chemistry and swelling of salt-treated polyelectrolyte multilayers on migration of smooth muscle ce

Influence of Surface Coating of PLGA Particles on the Internalization and Functions of Human Endothelial Cells

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