Impact of Molecular Asymmetry of Block Copolymers on the Stability of Defects in Aligned Lamellae

2021 ◽  
Vol 54 (17) ◽  
pp. 8024-8032
Author(s):  
Tianyi Hu ◽  
Yongzhi Ren ◽  
Weihua Li
Keyword(s):  
Block Copolymers ◽  
Molecular Asymmetry ◽  
The Stability

pH-responsive microspheres encapsulated with iron oxide nanoaggregates for gastrointestinal delivery

2012 ◽  
Vol 27 (1) ◽  
pp. 54-66 ◽  
Author(s):  
Young Ju Son ◽  
Hyuk Sang Yoo
Keyword(s):  
Iron Oxide ◽  
Block Copolymer ◽  
Block Copolymers ◽  
Diblock Copolymer ◽  
Ph Responsive ◽  
Polymeric Microspheres ◽  
Intestinal Delivery ◽  
Poly Ethylene ◽  
The Stability

Block copolymer-stabilized iron oxide nanoaggregates were fabricated into pH-responsive polymeric microspheres for intestinal delivery of the magnetic nanoaggregates. A diblock copolymer consisted of methoxy poly(ethylene glycol) (mPEG) and poly(e-caprolactone) (PCL) was synthesized by ring-opening polymerization. Microspheres, consisted of Eudragit L100-55 encapsulate and stabilized magnetic nanoaggregates, were prepared by an oil-in-oil emulsification technique. The magnetization of the microspheres decreased, and the stability of the magnetic nanoaggregates in aqueous solutions increased as the amount of block copolymers in the microspheres increased. The encapsulated magnetic nanoaggregates were visualized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The encapsulation efficiency of nanoaggregates of the microspheres increased as the amount of diblock copolymer in the nanoaggregates was increased. The in vitro experiments confirmed the pH-dependent release of the nanoaggregates from the microspheres. The microspheres were administered to the animals by oral gavages, and the nanoaggregates in small intestines were visualized by histological examination of intestinal inner walls. Higher amounts of the block copolymer in the nanoaggregates increased the uptake efficiency in the intestinal tissues. Thus, the incorporation of the block copolymers in the magnetic nanoaggregates increased the intestinal absorption of the aggregates and Eudragit microspheres and effectively protected the nanoaggregates at low pH conditions of the stomach area.

Effect of Substrate and Molecular Weight on the Stability of Thin Films of Semicrystalline Block Copolymers

Langmuir ◽  
2007 ◽  
Vol 23 (7) ◽  
pp. 3673-3679 ◽  
Author(s):  
Guo-Dong Liang ◽  
Jun-Ting Xu ◽  
Zhi-Qiang Fan ◽  
Shao-Min Mai ◽  
Anthony J. Ryan
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Block Copolymers ◽  
The Stability

scholarly journals Cellulose Nanocrystal-Enhanced Thermal-Sensitive Hydrogels of Block Copolymers for 3D Bioprinting

2021 ◽  
Vol 7 (4) ◽  
pp. 397
Author(s):  
Yuecheng Cui ◽  
Ronghua Jin ◽  
Yifan Zhang ◽  
Meirong Yu ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Block Copolymers ◽  
3D Printing ◽  
Three Dimensional ◽  
Enhancement Effect ◽  
3D Bioprinting ◽  
Forming Mechanism ◽  
Molecular Weights ◽  
Good Biocompatibility ◽  
The Stability

 The hydrogel formed by polyethylene glycol-aliphatic polyester block copolymers is an ideal bioink and biomaterial ink for three-dimensional (3D) bioprinting because of its unique temperature sensitivity, mild gelation process, good biocompatibility, and biodegradability. However, the gel forming mechanism based only on hydrophilic-hydrophobic interaction renders the stability and mechanical strength of the formed hydrogels insufficient, and cannot meet the requirements of extrusion 3D printing. In this study, cellulose nanocrystals (CNC), which is a kind of rigid, hydrophilic, and biocompatible nanomaterial, were introduced to enhance the hydrogels so as to meet the requirements of extrusion 3D printing. First, a series of poly(ε-caprolactone/lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone/ lactide) (PCLA-PEG-PCLA) triblock copolymers with different molecular weights were prepared. The thermodynamic and rheological properties of CNC-enhanced hydrogels were investigated. The results showed that the addition of CNC significantly improved the thermal stability and mechanical properties of the hydrogels, and within a certain range, the enhancement effect was directly proportional to the concentration of CNC. More importantly, the PCLA-PEG-PCLA hydrogels enhanced by CNC could be extruded and printed through temperature regulation. The printed objects had high resolution and fidelity with effectively maintained structure. Moreover, the hydrogels have good biocompatibility with a high cell viability. Therefore, this is a simple and effective strategy. The addition of the hydrophilic rigid nanoparticles such as CNC improves the mechanical properties of the soft hydrogels which made it able to meet the requirements of 3D bioprinting.

scholarly journals Durable vesicles for reconstitution of membrane proteins in biotechnology

2017 ◽  
Vol 45 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Paul A. Beales ◽  
Sanobar Khan ◽  
Stephen P. Muench ◽  
Lars J.C. Jeuken
Keyword(s):  
Block Copolymers ◽  
Membrane Proteins ◽  
Protein Function ◽  
Physical Stability ◽  
Great Promise ◽  
Working Environments ◽  
Improved Stability ◽  
The Stability ◽  
In Vitro Performance

The application of membrane proteins in biotechnology requires robust, durable reconstitution systems that enhance their stability and support their functionality in a range of working environments. Vesicular architectures are highly desirable to provide the compartmentalisation to utilise the functional transmembrane transport and signalling properties of membrane proteins. Proteoliposomes provide a native-like membrane environment to support membrane protein function, but can lack the required chemical and physical stability. Amphiphilic block copolymers can also self-assemble into polymersomes: tough vesicles with improved stability compared with liposomes. This review discusses the reconstitution of membrane proteins into polymersomes and the more recent development of hybrid vesicles, which blend the robust nature of block copolymers with the biofunctionality of lipids. These novel synthetic vesicles hold great promise for enabling membrane proteins within biotechnologies by supporting their enhanced in vitro performance and could also contribute to fundamental biochemical and biophysical research by improving the stability of membrane proteins that are challenging to work with.

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