Journal of Wuhan University of Technology-Materials Science Edition最新文献

The effects of coal metakaolin on the mechanical properties of high-belite sulphoaluminate cement under compressive loading were investigated. The composition and microstructure of hydration products at different hydration times were analyzed by X-ray diffraction and scanning electronic microscopy. The hydration process of blended cement was studied via electrochemical impedance spectroscopy. In particular, replacing a part of cement with CMK (10%, 20%, and 30%) was found to promote the hydration process, to refine the pore size, and to improve the compressive strength of the composite. The best compressive strength of the cement was achieved at a CMK content of 30% after 28 days hydration, being improved by 20.13 MPa, or 1.44 times relative to that of undoped specimens. Furthermore, the compressive strength is shown to correlate with the impedance parameter R_CCP, which allows the latter to be used for nondestructive assessment of the compressive strength of blended cement materials.

Using nerve guide conduits (NGCs) to promote the regeneration of PNI is a feasible alternative to autograft. Compared with NGCs made of single material, composite NGCs have a greater development prospect. Our previous research has confirmed that poly(D, L-lactic acid)/β-tricalcium phosphate/hyaluronic acid/chitosan/nerve growth factor (PDLLA/β-TCP/HA/CHS/NGF) NGCs have excellent physical and chemical properties, which can slowly release NGF and support cell adhesion and proliferation. In this study, PDLLA/β-TCP/HA/CHS/NGF NGCs were prepared and used to bridge a 10 mm sciatic nerve defect in 200-250 g Sprague-Dawley (SD) rat to verify the performance of the NGCs in vivo. Substantial improvements in nerve regeneration were observed after using the PDLLA/β-TCP/HA/CHS/NGF NGCs based on gross post-operation observation, triceps wet weight analysis and nerve histological assessment. In vivo studies illustrate that the PDLLA/β-TCP/HA/CHS/NGF sustained-release NGCs can effectively promote peripheral nerve regeneration, and the effect is similar to that of autograft.

A new composite antibacterial material ZnO/Cu²⁺-Chitosan/Montmorillonite (ZCCM) was prepared with montmorillonite as carrier, Zn(Ac)₂•2H₂O, Cu(NO₃)₂•3H₂O and chitosan as raw materials. ZCCM was characterized by X-ray diffraction, nitrogen physical adsorption, scanning electron microscopy and energy dispersion spectrometry. The antibacterial activity of ZCCM against Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus was evaluated by minimal inhibitory concentration, minimum bactericidal concentration and the influence of growth curves. ZCCM displays excellent antibacterial activity which is higher than ZnO-Montmorillonite, Cu²⁺-Montmorillonite and ZnO/Cu²⁺-Montmorillonite. In addition, the antibacterial mechanism of ZCCM was investigated by analyzing bacterial morphology, integrity of cell membrane, lipid peroxidation and the effect of histidine on antibacterial activity of materials. It is found that cell morphologies of bacteria are damaged and bacterial cells are shrunken. With the increase of cell membrane permeability, the intracellular dissolved matters leak continuously. What's more, the reactive oxygen species are generated and biomacromolecules are oxidized.

To optimize the preparation process of chitosan microspheres and study its loading capacity, chitosan microsphere was prepared by crosslinking with glutaraldehyde, and bovine serum albumin (BSA) was absorbed onto chitosan microsphere. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FITR), TA instruments and zeta potentiometer analyzer were used to characterize the parameters with respect to size, thermal characters, morphology, and zeta potential of the microspheres. The loading capability and in vitro release tests were carried out. The results showed that chitosan microsphere with particle size less than 10 μm and positively charged (+25.97±0.56 mV) can be obtained under the aldehyde group to amino group ratio at 1:1. A loading capacity of BSA at 28.63±0.15 g/100 g with corresponding loading efficiency at 72.01±1.44% was obtained for chitosan microsphere. In vitro test revealed a burst release followed by sustained-release profile.