Surface functionalization of titanium with zinc/strontium-doped titanium dioxide microporous coating via microarc oxidation.

Deficient osseointegration and implant-related infections are pivotal issues for the long-term clinical success of titanium (Ti) implants. Zinc (Zn) and strontium (Sr) serve dual functions by promoting osteogenesis and inhibiting bone destruction, and Zn has good antibacterial activity. As such, this study examined the preparation of a Zn/Sr-doped titanium dioxide microporous coating (MT-Zn/Sr) on a Ti surface using microarc oxidation (MAO), with Zn and Sr evenly distributed throughout the coating. In vitro, the coating could promote the adhesion, proliferation, differentiation and mineralization of osteoblasts, showing good biological activity. Antibacterial testing demonstrated the good antibacterial activity of the coating, as it inhibited the proliferation of Staphylococcus. In vivo, MT-Zn/Sr promoted early osseointegration between the Ti substrate and the bone tissue. This work is expected to provide a new method for improving the biological activity of Ti implants and thus has important theoretical significance and great clinical prospects.

An Adaptable Phospholipid Membrane Mimetic System for Solution NMR Studies of Membrane Proteins.

Based on the saposin-A (SapA) scaffold protein, we demonstrate the suitability of a size-adaptable phospholipid membrane-mimetic system for solution NMR studies of membrane proteins (MPs) under close-to-native conditions. The Salipro nanoparticle size can be tuned over a wide pH range by adjusting the saposin-to-lipid stoichiometry, enabling maintenance of sufficiently high amounts of phospholipid in the Salipro nanoparticle to mimic a realistic membrane environment while controlling the overall size to enable solution NMR for a range of MPs. Three representative MPs, including one G-protein-coupled receptor, were successfully incorporated into SapA-dimyristoylphosphatidylcholine nanoparticles and studied by solution NMR spectroscopy.

Design of 2,5-furandicarboxylic based polyesters degraded in different environmental conditions: Comprehensive experimental and theoretical study.

Nowadays, the promotion and application of aliphatic-aromatic copolyesters, such as poly (butylene adipate-co-terephthalate) (PBAT), are growing into a general trend. Although the structures of diacids exerted substantial impacts on degradation behavior, the underlying mechanisms have rarely been studied. In this work, 2,5-Furandicarboxylic acid was combined with succinic acid (PBSF), adipic acid (PBAF) and diglycolic acid (PBDF) to prepare three kinds of copolyesters. They showed unique degradation behaviors in buffer, enzyme environment and artificial seawater. These characteristics are closely related to the structural compositions of diacids. PBAFs displayed impressive biodegradability when catalyzed by Candida antarctica lipase B (CALB), while the more hydrophilic PBDFs exhibited faster hydrolysis in both buffer and artificial seawater. PBSFs, with hydrophobic and short segments, obtained a relatively slower rate of hydrolysis and enzymatic degradation. The reactivity sites and hydrolytic pathway were revealed by the combination of DFT calculation and Fukui function analysis. MD simulations, QM/MM optimizations and theozyme calculations showed that PBAF-CALB was prone to form a pre-reaction state, leading to the reduced energy barrier in the acylation process. This work revealed the effects of different structural features of diacids on polymer degradation and paved a way to design target biodegradable polymers in different degradation conditions.

Acid-triggered, degradable and high strength-toughness copolyesters: Comprehensive experimental and theoretical study.

The popularization and widespread use of degradable polymers is hindered by their poor mechanical properties. It is of great importance to find a balance between degradation and mechanical properties. Herein, poly(butylene terephthalate) (PBT) modified by SPG diol from 10% to 40 mol% were synthesized through a two-step polycondensation reaction. Chemical structures, thermal properties, mechanical properties, viscoelastic behavior and degradation of poly(butylene terephthalate-co-spirocyclic terephthalate) (PBST) were investigated. The SPG could toughen the copolyesters and the elongation at break of PBST20 was up to 260%. Moreover, the introduction of SPG enables to provide an acid-triggered degradable unit in the main chain. PBSTs copolymers maintain stable structures in a neutral environment, and the degradation under acid conditions will be unlocked. As tailoring the content of SPG, the degradation rate of the chain scission in response to acid stimuli will be adjusted. The acid degradation was proved to be occurred at the SPG units in the amorphous phase by DSC, XRD, GPC and 1H NMR tests. After the acid degradation, the hydrolysis rate will also be accelerated, adapting to the requirements of different degradation schedules. The plausible hydrolytic pathways and mechanisms were proposed based on Fukui function analysis and density functional theory (DFT) calculation.

[Study on the pharmacokinetics of tashinone II(A) -loaded polylactic acid nanoparticles in rabbit].

OBJECTIVE: To establish a HPLC method for measuring tashinone II(A) concentration in rabbit plasma and study the pharmacokinetics of tashinone II(A) -loaded polylactic acid nanoparticles and tashinone II(A) injection in rabbits. METHODS: A single dose of TS-PLA-NP and TS II(A) injection was administered to 8 healthy rabbits via the ear-edge vein, at the set time withdrew the blood and prepared. The concentrations of tashinone II(A) in plasma were measured by HPLC with gemfibrozil as the internal standard. The pharmacokinetic parameters of TS-PLA-NP and tashinone II(A) injection were calculated by program DAS2.0. RESULTS: The average retention times of gemfibrozil and tashinone II(A) were 10.5 and 14.5 min, respectively. The half-life was prolonged from 2. 573 h of free tashinone II(A) to 4. 117 h and MRT(0-infinity) from 2.585 h to 6.033 h. The max concentration of tashinone II(A) was reduced from 0.21 to 0.134 mg/L. CONCLUSION: The method for the pharmacokinetic research of tshinone II A in rabbit plasma is accuracy, rapid and sensitive. TS-PLA-NP shows significant characteristic of delayed-release.

Cu-Co Co-Doped Microporous Coating on Titanium with Osteogenic and Antibacterial Properties.

Titanium (Ti) and its alloys are widely used in bone surgery by virtue of their excellent mechanical properties and good biocompatibility; however, complications such as loosening and sinking have been reported post-implantation. Herein we deposited a copper-cobalt (Cu-Co) co-doped titanium dioxide (TUO) coating on the surface of Ti implants by microarc oxidation. The osteogenic and antimicrobial properties of the coating were evaluated by in vitro experiments, and we also assessed ß-catenin expression levels on different sample surfaces. Our results revealed that the coating promoted the adhesion, proliferation, and differentiation of MG63 osteoblasts, and TUO coating promoted ß-catenin expression; moreover, the proliferation of Staphylococcus aureus was inhibited. To summarize, we report that Cu-Co co-doping can enhance the osteogenic and antibacterial activities of orthopedic Ti implants, leading to potentially improved clinical performance.

Phosphine polymerization by nitric oxide: experimental characterization and theoretical predictions of mechanism.

A yellow solid material [P(x)H(y)] has been obtained in the reaction of phosphine (PH(3)) and nitric oxide (NO) at room temperature and characterized by thermogravimetric analysis mass spectrometry (TGA-MS) and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. In this work using complete basis set (CBS-QB3) methods a plausible mechanism has been investigated for phosphine polymerization in the presence of nitric oxide (NO). Theoretical explorations with the ab initio method suggest (a) instead of the monomer the nitric oxide dimer acts as an initial oxidant, (b) the resulting phosphine oxides (H(3)P=O <--> H(3)P(+)O(-)) in the gas phase draw each other via strong dipolar interactions between the P-O groups, and (c) consequently an autocatalyzed polymerization occurs among the phosphine oxides, forming P-P chemical bonds and losing water. The possible structures of polyhydride phosphorus polymer were discussed. In the calculations a series of cluster models was computed to simulate polymerization.

Osteogenic activity and antibacterial ability on titanium surfaces modified with magnesium-doped titanium dioxide coating.

Aim: To improve the bioactivity and antibacterial activity of titanium (Ti) implants. Materials & methods: Magnesium (Mg)-doped titanium dioxide microporous coatings (Mg-TiO2) were prepared on the surface of Ti implants by plasma electrolytic oxidation. Results: Ti surfaces were covered with porous Mg-TiO2, and Mg was evenly distributed throughout the coating. Mg-TiO2 could not only promote osteoblast adhesion, proliferation and differentiation but also inhibit the colonization and growth of Staphylococcus. In addition, Mg-TiO2 may promote osteogenesis through the ERK/c-Fos signaling pathway as well as the early osseointegration of Ti implants. Conclusion: Mg-TiO2 has both osteogenic and antibacterial effects and thus presents important theoretical significance and clinical potential.

Antibacterial and osteogenic activity of a multifunctional microporous coating codoped with Mg, Cu and F on titanium.

As preferred materials for bone tissue repair and replacement, titanium (Ti) and its alloys have been widely applied in clinical practice. However, since these materials are bioinert, synostosis cannot occur between these materials and natural bone. Therefore, modifying the surface of Ti with bioactive elements has been the subject of intense research. In the present study, a magnesium-copper-fluorine (Mg-Cu-F) codoped titanium dioxide microporous coating (MCFMT) was prepared on the surface of Ti by micro-arc oxidation (MAO). The coating had a micro/nanoporous structure and was uniformly doped with Mg, Cu and F. In vitro, the MCFMT could promote the adhesion, proliferation, differentiation, mineralization and apoptosis of MC3T3-E1 osteoblasts. In addition, MCFMT could inhibit the growth of Staphylococcus, providing a good antibacterial effect. Further studies showed that MCFMT promoted MAPK expression and might promote osteogenesis through ERK1/2 signaling. Therefore, establishing an MCFMT coating on the Ti surface is a feasible and effective way to improve the biological activity of Ti. This study provides a new concept and method for improving the biological activity of Ti and thus has important theoretical significance and potential applications.

Optimization of Glycyrrhiza polysaccharide liposome by response surface methodology and its immune activities.

Glycyrrhiza polysaccharide liposome (GPSL) was prepared by reverse-phase evaporation method and optimized with response surface methodology. As a result, the optimum preparation conditions were as follows: the ratio of soybean phosphatide to Glycyrrhiza polysaccharide (GPS) of 24:1, temperature of drug incubation of 46°C, the ultrasound time of 16min. Confirmation experiments and transmission electron micrograph (SEM) exhibited the entrapment efficiency of liposome as 78.33±0.25%, with spherical shape and uniform sizes. Furthermore, proliferation assay, allogeneic mixed lymphocyte reaction and supernatant cytokines of chBM-DCs were performed by MTT and ELISA methods to investigate the immune-modulating effects of GPSL and GPS. The results showed that GPSL could significantly promote the proliferation of immature chBM-DCs, enhance the ability of mature chBM-DCs to induce T-cell proliferation and modulate the mature chBM-DCs to secret cytokines such as IL-2, IFN-γ and IL-10. These evidences indicated that the immune-modulating activity of GPS was significantly improved after encapsulated with liposome.

[Study on the mechanism of the interaction of methylene blue and sulfation pachymaran].

In order to understand the mechanism of the interaction of sulfate polysaccharides and small molecules at molecular level, the structure of pachymaran was decorated by Wolfrom, and sulfation pachymaran (SP) was prepared. The maximum binding number (N = 54) and the binding equilibrium constant (K = 1.563 x 10(6)) of the sulfation pachymaran and methylene blue (MB) were obtained by the exoterica model. The influence of the molar ratio of MB/SP, ethanol, hydroxypropyl-beta-cyclodextrin, Triton X-100 and NaCl on the spectra of MB-SP complex was investigated. The mechanism of the color changes of methylene blue and sulfation pachymaran reaction system has been discussed. The authors draw the conclusion that the color changes result mainly from the hydrophobic interaction between methylene blue molecules binding on sulfation pachymaran on the base of the electrostatic interaction of methylene blue and sulfation pachymaran.

[Bowel preparation before colorectal surgery: from intestinal mucosal barrier].

The routine bowel preparation before colorectal surgery usually includes mechanical and medicine preparations, with the original purpose of reducing complications such as anastomosis leakage, wound, and abdominal infections. Many domestic hospitals are still employing the methods of three-day bowel preparation, while in the West, the way of this preparation has dramatically changed. In last decade, one-day preparation has been widely accepted internationally, with two major medications of sodium phosphate and polyethylene glycol frequently used in the clinic. It has also been indicated that excessive mechanical and medicinal bowel preparations exert harmful effects on the combined intestinal barrier, and may result in various complications. A few reports have suggested to omit the mechanical bowel preparation before surgery, which is still under controversy, however, well-designed clinical trials are needed to readjust and regulate the duration and intensity of bowel preparation before colorectal surgery in China.

Effects of microbubble size on ultrasound-mediated gene transfection in auditory cells.

Gene therapy for sensorineural hearing loss has recently been used to insert genes encoding functional proteins to preserve, protect, or even regenerate hair cells in the inner ear. Our previous study demonstrated a microbubble- (MB-)facilitated ultrasound (US) technique for delivering therapeutic medication to the inner ear. The present study investigated whether MB-US techniques help to enhance the efficiency of gene transfection by means of cationic liposomes on HEI-OC1 auditory cells and whether MBs of different sizes affect such efficiency. Our results demonstrated that the size of MBs was proportional to the concentration of albumin or dextrose. At a constant US power density, using 0.66, 1.32, and 2.83 µm albumin-shelled MBs increased the transfection rate as compared to the control by 30.6%, 54.1%, and 84.7%, respectively; likewise, using 1.39, 2.12, and 3.47 µm albumin-dextrose-shelled MBs increased the transfection rates by 15.9%, 34.3%, and 82.7%, respectively. The results indicate that MB-US is an effective technique to facilitate gene transfer on auditory cells in vitro. Such size-dependent MB oscillation behavior in the presence of US plays a role in enhancing gene transfer, and by manipulating the concentration of albumin or dextrose, MBs of different sizes can be produced.