Browsing by Author "Wang, Xinling"

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New self-assembled supramolecular polymers formed by self-complementary sextuple hydrogen bond motifs
(2012)
Cheng, Chih-Chia
;
Lin, I-Hong
;
Yen, Ying-Chieh
;
Chu, Chih-Wei
;
Ko, Fu-Hsiang
A new supramolecular material, N-(6-(3-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl) propanamido)pyridin-2-yl)undec-10-enamide (U-DPy) possesses an extremely high association constant (K-a > 10(7) M-1), which is able to dimerize through a self-complementary sextuple hydrogen-bonding array. As the end groups of an oligomer, U-DPy forms a self-assembling polymer system. These new mono- and difunctional telechelic supramolecular polymers have highly prominent properties, leading to a substantial increase in viscosity, thermal stability and unique morphology changes in the solid state. More surprisingly, they can self-organize into lamellar crystallization and a spherical structure. In addition, upon increasing the concentration in the solution state, the size of the resulting spherical structure is gradually increased. These spherical structures are constructed from supramolecular polymers with a high degree of polymerization.
Pepsin-inspired polyurethanes containing a tyrosine-fumaric acid-tyrosine segment
(2012)
Lu, Haoxiang
;
Wang, Wei
;
Zheng, Zhen
;
Sun, Peiyu
;
Wang, Xinling
Two kinds of novel peptide mimetic pepsin-inspired degradable polyurethanes were synthesized and characterized. A synthetic pseudo tripeptide acted as chain extender and provided active sites for pepsin biodegradation. In vitro degradation behavior was investigated in simulated gastric fluid containing pepsin, and assessed by H-1 NMR, mass loss and SEM. The results indicated that the pseudo peptide bonds in polyurethanes were effectively digested by the action of pepsin. Furthermore, the rate and degree of pepsin-inspired polyurethanes in simulated gastric fluid containing pepsin could be controlled by alteration of the soft segments and activity of pepsin. The influence of the polymers on human umbilical vein endothelial cells was evaluated by WST-1 assay. The results indicated that the polymers sustained much higher cell viability than the controls.
Reduction-sensitive rapid degradable poly(urethane-urea)s based on cystine
(2012-04-01)
Lu, Haoxiang
;
Sun, Peiyu
;
Zheng, Zhen
;
Yao, Xiong
;
Wang, Xinling
Two kinds of novel reduction-sensitive rapid degradable poly(urethane-urea)s were synthesized and characterized based on a cystine derivative chain extender which provided active sites for reductive degradation. In vitro degradation study was carried out under physiological conditions mediated by glutathione and dithiothreitol respectively, and was assessed by H-1 NMR, GPC and SEM. The results indicated that the disulfide bonds in poly(urethane-urea)s were effectively cleaved while the structures of urethane groups and soft segments remained almost unaffected. Still, the rate and degree of reductive degradation could be controlled by the structures of the polymers. The influence of the poly(urethane-urea)s on human umbilical vein endothelial cells was investigated by WST-1 assay. The results indicated that the polymers sustained much higher cell viability than the controls. It is possible that the poly(urethane-urea)s can be potentially applied for temporary biomaterials such as wound closure devices, cell scaffolds and sophisticated drug delivery systems. (C) 2011 Elsevier Ltd. All rights reserved.