Surface bioactivation of Polyetheretherketone (PEEK) by magnesium chondroitin sulfate (MgCS) as orthopedic implants for reconstruction of skeletal defects.

Polyether-ether-ketone (PEEK) is clinically used as a bio-implant for the healing of skeletal defects. However, the osseointegration of clinical-sized bone grafts remains limited. In this study, surface-porous PEEK was created by using a sulfonation method and a metal-polysaccharide complex MgCS was introduced on the surface of sulfonated PEEK to form MgCS@SPEEK. The as-prepared MgCS@SPEEK was found to have a porous surface with good hydrophilicity and bioactivity. This was followed by an investigation into whether MgCS loaded onto sulfonated PEEK surfaces could promote osseointegration and angiogenesis. The in vitro results showed that MgCS@SPEEK had a positive effect on reducing the expression levels of inflammatory genes and promoting osteogenesis and angiogenesis-related genes expression levels. Furthermore, porous MgCS@SPEEK was implanted in critical-sized rat tibial defects for in vivo evaluation of osseointegration. The micro-computed tomography evaluation results revealed substantial bone formation at 4 and 8 weeks. Collectively, these findings indicate that MgCS@SPEEK could provide improved osseointegration and an attractive strategy for orthopaedic applications.

Effects of alginate/chondroitin sulfate-based hydrogels on bone defects healing.

Repairing bone defects remains challenging in orthopedics. Here, strontium (Sr) alginate hydrogels containing chondroitin sulfate (CS) were fabricated for enhancing bone defects repair. The effects of CS incorporation ratio on the morphology, structure, thermal stability, water uptake and mechanical performance of Sr-CS/alginate hydrogels were also evaluated. Increasing CS incorporation ratio, Sr-CS/alginate hydrogels exhibit decreasing mechanical properties and lower water retention capacity. In vitro results suggest that Sr-CS/alginate hydrogels with higher CS ratio facilitate the proliferation of osteoblasts. Additionally, the osteogenic genes expressions were investigated by real-time quantitative polymerase chain reaction (RT-qPCR). The results reveal that Sr-CS/alginate hydrogels should have positive effects on modulating the osteogenic factors. Moreover, by employing repair femoral cylindrical defects rabbit model, the efficiency of as-fabricated Sr-CS/alginate hydrogels in bone regeneration was evaluated. The animal study suggests that Sr-CS/alginate hydrogel could significantly facilitate bone defects repair and therefore should potentially be useful for osteochondral tissue engineering.

Fabrication of strontium Eucommia ulmoides polysaccharides and in vitro evaluation of their osteoimmunomodulatory property.

The osteoimmune environment plays indispensable roles in bone regeneration because it determines subsequent osteogenesis and osseointegration. Eucommia ulmoides polysaccharide (EUP) was proved to be an effective biomaterial that has immunomodulatory effects for improving the biomechanical quality of bone. Strontium is a trace element that inhibits inflammation and promotes bone growth. To develop a novel EUP-based osteoimmunomodulatory biomaterial with potentially enhanced bone regeneration, we synthesized strontium Eucommia ulmoides polysaccharides (EUP-Sr) and evaluated its morphology, structure and thermal stability. The materials characterization results confirmed that strontium was successfully introduced into the EUP and formed a new complex with thermal-stable property. The cytocompatibility evaluation of different concentrations of EUP-Sr by CCK8 assay suggested that EUP-Sr is beneficial to the macrophages proliferation. We further evaluated the gene expressions of RAW 264.7 cells treated with EUP-Sr. It was found that EUP-Sr could suppress inflammatory factors and osteoclastogenesis, and enhance the expressions of osteogenic factors of RAW 264.7 cells. Therefore, EUP-Sr should be a promising bioactive compound with the capability to create a positive pro-regenerative environment for skeleton tissue engineering.

Elastic modulus and migration capability of drug treated leukemia cells K562.

Leukemia is a commonly seen disease caused by abnormal differentiation of hematopoietic stem cells and blasting in bone marrow. Despite drugs are used to treat the disease clinically, the influence of these drugs on leukemia cells' biomechanical properties, which are closely related to complications like leukostasis or infiltration, is still unclear. Due to non-adherent and viscoelastic nature of leukemia cells, accurate measurement of their elastic modulus is still a challenging issue. In this study, we adopted rate-jump method together with optical tweezers indentation to accurately measure elastic modulus of leukemia cells K562 after phorbol 12-myristate 13-acetate (PMA), all-trans retinoic acid (ATRA), Cytoxan (CTX), and Dexamethasone (DEX) treatment, respectively. We found that compared to control sample, K562 cells treated by PMA showed nearly a threefold increase in elastic modulus. Transwell experiment results suggested that the K562 cells treated with PMA have the lowest migration capability. Besides, it was shown that the cytoskeleton protein gene α-tubulin and vimentin have a significant increase in expression after PMA treatment by qPCR. The results indicate that PMA has a significant influence on protein expression, stiffness, and migration ability of the leukemia cell K562, and may also play an important role in the leukostasis in leukemia.

Vibrational and electrical properties of Cu2-xTe films: experimental data and first principle calculations.

Vibrational and electrical properties of sputtered films of the copper telluride system are presented. Despite of its technological importance in photovoltaics, the fundamental properties of copper tellurides are poorly understood. Films were deposited at 200 °C by rf sputtering from targets containing mixtures of copper and tellurium powders at nominal concentrations of Cu1.25Te, Cu1.5Te, Cu1.75Te and Cu2Te. Remarkably for the copper telluride system, it was possible to obtain single-phase vulcanite (CuTe) from the Cu1.25Te target. Two-phase mixtures of rickardite (Cu7Te5) and weissite (Cu2-xTe) were achieved for other cases. Raman spectra were obtained using two laser lines: 633 and 488 nm. Density functional theory was employed to calculate the phonon dispersion curves and density of states for vulcanite. The Raman bands were in good correspondence with the calculated frequencies. In general, the Raman spectra consisted of high-intensity totally symmetric modes superimposed on monotonically decaying signals. These were explained in terms of three contributing phenomena: convolution of vibrational normal modes, phonon-coupled charge density fluctuations and time-varying local-field contributions to the electric susceptibility. Studies on the conductivity, mobility and carrier concentration were carried out by the Van der Pauw method. Micro/nano scale surface potential studies were performed through Kelvin probe force microscopy mapping.