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Chitosan-gelatin (Cs-Gel) scaffolds are modified with poly (DL-lactic acid) (PDLLA) dichloromethane solution of different concentrations (0.1, 0.5, and 1.0%) and immersed in water after the evaporation of the solvent. The swollen scaffolds are freeze dried. The concentration of PDLLA has significant effects on both the physicomechanical properties and the cytocompatibility. Data reveal that only the 0.1% concentration could increase the tensile strength fourfold in comparison with the pristine Cs--Gel scaffold, while maintaining the human fibroblast adhesion, migration, and proliferation just like the Cs--Gel scaffold. [ABSTRACT FROM AUTHOR]

The article presents research report on high-strength and fibrous capsule–resistant zwitterionic elastomers. Topics include mechanical strength and long-term resistance to the fibrous capsule formation are two major challenges for implantable materials; and demonstrates a class of durable and fibrous capsule–resistant materials but also provides design principles for zwitterionic elastomeric hydrogels.

Prediction of the diffusion coefficient of solute, especially bioactive molecules, in hydrogel is significant in the biomedical field. Considering the randomness of solute movement in a hydrogel network, a physical diffusion RMP-1 model based on obstruction theory was established in this study. The physical properties of the solute and the polymer chain and their interactions were introduced into this model. Furthermore, models RMP-2 and RMP-3 were established to understand and predict the diffusion behaviors of proteins in hydrogel. In addition, zwitterionic poly(sulfobetaine methacrylate) (PSBMA) hydrogels with wide range and fine adjustable mesh sizes were prepared and used as efficient experimental platforms for model validation. The Flory characteristic ratios, Flory-Huggins parameter, mesh size, and polymer chain radii of PSBMA hydrogels were determined. The diffusion coefficients of the proteins (bovine serum albumin, immunoglobulin G, and lysozyme) in PSBMA hydrogels were studied by the fluorescence recovery after photobleaching technique. The measured diffusion coefficients were compared with the predictions of obstruction models, and it was found that our model presented an excellent predictive ability. Furthermore, the assessment of our model revealed that protein diffusion in PSBMA hydrogel would be affected by the physical properties of the protein and the PSBMA network. It was also confirmed that the diffusion behaviors of protein in zwitterionic hydrogels can be adjusted by changing the cross-linking density of the hydrogel and the ionic strength of the swelling medium. Our model is expected to possess accurate predictive ability for the diffusion coefficient of solute in hydrogel, which will be widely used in the biomedical field. [ABSTRACT FROM AUTHOR]

Natural polysaccharides play an important role in the formation of nanohydroxyapatite (nHA) crystals in biological systems. In this study, we synthesized nHA crystals in the presence of four polysaccharides, i.e., pectin, carrageenan, chitosan, and amylose, referred as PeHA, CaHA, CsHA, and AmHA, respectively. X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscope, and thermogravimetric analysis were used to investigate the formation of nHA crystals. The shape of prepared nHA crystals is needle/rod-like in all cases, whereas the size increases in the order of PeHA, CaHA, CsHA, and AmHA. The presence of polysaccharides induces the heterogeneous nucleation of nHA and further modulates the crystal growth. Our data suggest that the interaction intensity between nHA and polysaccharides is in the decreasing order of PeHA, CaHA, CsHA, and AmHA, resulting in the smallest nHA crystals with pectin. It is also demonstrated that a high polysaccharide concentration and short reaction time are adverse to nHA crystals, especially for the polysaccharides with carboxyl groups. This study can provide insight into the effects of polysaccharides with different chemical functional groups (−COOH, −OSO3H, −NH2, −OH) on the formation of nHA crystals. [ABSTRACT FROM AUTHOR]

Thesteady-state multiplicity in azeotropic distillation processeshas been theoretically predicted and verified experimentally for decades.However, it is a tough task to detect all the steady-state solutions.The purpose of this article is 2-fold: first, it provides a systematicalstudy on the multiplicity in homogeneous azeotropic distillation withintermediate entrainer and a novel strategy is proposed to find allthe steady-state solutions using “Design Specs/Vary”in Aspen Plus. Operating on the unstable steady-state branch benefitsboth energy saving and reducing capital investment with the productquality specified. Because of the great benefits that operating onthe unstable steady-state branch offers, the second purpose is topresent suitable control schemes to stabilize the operating pointon the unstable steady-state branch to achieve robust control. [ABSTRACT FROM AUTHOR]

Abstract: A well-timed delivery of bioactive macromolecules from the porous scaffolds is very important in tissue engineering. Tetrandrine (Ted) is one of a large number of known plant derived bisbenzylisoquinoline alkaloids and is obtained from the roots of Stephania tetrandria. Ted can be used as a modifier to poly(l-lactic acid) scaffolds to promote chondrocyte differentiation and secrete type II collagen. But the effect of Ted on chondrocyte''s behavior strongly depends on the concentration of Ted in the culture media. Here amphiphilic diblock copolymer (PLAE) composed of l-lactide and methoxy poly(ethylene glycol) (MePEG) was prepared and the Ted loaded copolymeric nanospheres were obtained by self-emulsification and then solvent evaporation. The mean sizes of core/shell type PLAE nanospheres and Ted-loaded nanospheres are about 60 and 100nm, respectively. Chitosan–gelatin (Cs–Gel) porous scaffolds loaded with PLAE–Ted nanospheres were fabricated through freeze drying. Ted release behaviors from PLAE–Ted nanospheres and porous scaffolds were investigated. The result shows that the Ted-loaded nanospheres could be embedded within Cs–Gel scaffolds and no initial burst release could be observed in the release patterns. Here a room can be provided for the scaffolds to sustained release bioactive component in tissue engineering. [Copyright &y& Elsevier]

A novel tri-block co-polymer, HO2C-PLA-PEG-PLA-CO2H (co-polymer II), with polybasic carboxylic acids as the end-groups was synthesized and characterized by IR and 1H-NMR. Based on the successful synthesis of co-polymer II, water-soluble sodium salicylate and oil-soluble tetrandrine, used as model drugs, were loaded in the co-polymer microparticles prepared through a modified multiple emulsion method. The encapsulation efficiency and drug-releasing behaviour were also investigated. It is found that the microparticles of about 10 μm in size are porous and can be produced from co-polymer II in better encapsulation efficiency (up to 86.65% and 55.94%) compared to those made from PLA/PEG/PLA (co-polymer I) (77.50% and 44.01%). The drug-release behaviour of co-polymer II exhibits an extended continuous release behaviour and the initial burst was reduced obviously. The results show that such functionalised PLA/PEG/PLA carrier provides higher drug encapsulation efficiency and better profiles. [ABSTRACT FROM AUTHOR]