纳曲酮植入剂不同动物体内的组织相容性和生物可降解性

目的 考察植入动物的种类和不同部位对植入剂组织相容性和生物可解降性的影响。方法 将纳曲酮植入剂植入到小鼠、大鼠、白兔和狗等不同动物以及白兔的不同部位 ,通过组织切片观察实验动物的组织相容性 ,采用凝胶色谱法测定植入剂中聚乳酸的相对分子质量 ,并比较聚乳酸的重量来考察其生物可降解性。结果 纳曲酮植入剂在 4种动物体内组织相容性良好 ,组织反应的程度略有差异。控释基质聚乳酸在体内外条件下均能降解 ,但体内降解比体外快 ,大动物的体内降解比小动物略快。结论 纳曲酮植入剂在不同动物具有良好的组织相容性和体内可降解性 。

Microstructure, mechanical and bio-corrosion properties of as-extruded Mg-Sn-Ca alloys

The as-extruded Mg？Sn？Ca alloys were prepared and investigated for orthopedic applications via using optical microscopy, scanning electron microscopy, X-ray diffraction, as well as tensile, immersion and electrochemical tests. The results showed that, with the addition of 1% Sn and the Ca content of 0.2%？0.5%, the microstructure of the as-extruded Mg？Sn？Ca alloys became homogenous, which led to increased mechanical properties and improved corrosion resistance. Further increase of Ca content up to 1.5% improved the strength, but deteriorated the ductility and corrosion resistance. For the alloy containing 0.5% Ca, when the Sn content increased from 1% to 3%, the ultimate tensile strength increased with a decreased corrosion resistance, and the lowest yield strength and ductility appeared with the Sn content of 2%. These behaviors were determined by Sn/Ca mass ratio. The analyses showed that as-extruded Mg？1Sn？0.5Ca alloy was promising as a biodegradable orthopedic implant.

Biocorrosion property and cytocompatibility of calcium phosphate coated Mg alloy

Calcium phosphate coated Mg alloy was prepared. The phase constitute and surface morphology were identified and observed by X-ray diffractometer （XRD） and SEM. The results show that the coating is composed of flake-like CaHPO4-2H2O crystals. The corrosion resistance of the coated Mg alloy was measured by electrochemical polarization and immersion test in comparison with uncoated Mg alloy. Cytocompatibility was designed by observing the attachment, growth and proliferation of L929 cell on both coated and uncoated Mg alloy samples. The results display that the corrosion resistance of the coated Mg alloy is better than that of uncoated one. The immersion test also shows that the calcium phosphate coating can mitigate the corrosion of Mg alloy substrate, and tends to transform into hydroxyapatite （HA）. Compared with uncoated Mg alloy, L929 cells exhibit good adherence, growth and proliferation characteristics on the coated Mg alloy, indicating that the cytocompatibility is significantly improved with the calcium phosphate coating.

Effect of heat treatment on microstructure, mechanical properties and in vitro degradation behavior of as-extruded Mg-2.7Nd-0.2Zn-0.4Zr alloy

Mg-2.7Nd-0.2Zn-0.4Zr （mass fraction, %） alloy was designed for degradable biomedical material. The ingots of the alloy were solution treated and then hot extruded. The extruded rods were heat treated with aging treatment, solution treatment and solution＋aging treatment, respectively. Microstructures of the alloy were observed by optical microscopy （OM） and scanning electron microscopy （SEM）. Mechanical properties at room temperature were tested. In vitro degradation behavior of the alloy immersed in simulated body fluid was measured by hydrogen evolution and mass loss tests. The degradation morphologies of the alloy with and without degradation products were observed by SEM. The results show that the grains grow apparently after solution treatment. Solution treatment improves the elongation of as-extruded alloy significantly and decreases the strength, while aging treatment improves the strength and reduces the elongation of the alloy. The yield ratio is reduced by heat treatment. The in vitro degradation results of the alloy show that solution treatment on the as-extruded alloy results in a little higher degradation rate and aging treatment on the alloy can reduce degradation rate slightly.

Microstructure and properties of biodegradable β-TCP reinforced Mg-Zn-Zr composites

Magnesium alloys have good biocompatibility, but their mechanical properties and corrosion resistance may not be satisfied for using as degradable materials within bone due to its high corrosion rate in the physiological environment. Nano β-TCP particles were added into Mg-Zn-Zr alloy to improve its microstructure and the properties. As-extruded Mg-3Zn-0.8Zr alloy and Mg-3Zn-0.8Zr/xβ-TCP （x=0.5%, 1.0% and 1.5%） composites were respectively fabricated. The grains of Mg-Zn-Zr/β-TCP composites were significantly refined. The results of the tensile tests indicate that the ultimate tensile strength and the elongation of composites were improved with the addition of β-TCP. The electrochemical test result in simulation body fluid shows that the corrosion resistance of the composites was strongly enhanced comparing with that of the alloy. The corrosion potential of Mg-3Zn0.8-Zr/1.0β-TCP composite is 1.547 V and its corrosion current density is 1.20×10 6 A/cm 2 .

Test on Evaluation Method for Biodegradability of Lubricants

Using carbon tetrachloride （CCl4） as extraction agent, the activated sludge from Tianjin Jizhuangzi Sewage Treatment Plant as inoculum, the test study on biodegradability of lubricants was carried out. The test flasks containing the mineral medium, the test oil and the inoculum were placed in incubation together with flasks containing poisoned blanks for periods of 0 and 21 days, respectively. Flasks containing the reference materials in place of the test oil were run in parallel. At the end of the incubation period, the contents of the flasks were subjected to sonic vibration, and were acidified and extracted by using CCI4. The extracts were then analysed by infra-red （IR） spectrometer to measure the maximum absorption of the C-H stretch of CH2-CH3 band at wavelength of 2 930 cm^-1. The absorption values were used to calculate the residual oil contents of the poisoned and test flasks. Consequently the biodegradability of the test oil was calculated. The test results indicate that the differences in the biodegradability of test materials in different tests are within 5.5%, and consistent with the data described in Coordinating European Council （CEC） L-33- A-93. The biodegradability of lubricants can be evaluated by this method effectively.

Recent Advances in Colloidal Lubricant Detergents

Overbased lubricant detergents are important components in lubricating oil. Recently, a lot of papers about the synthesis mechanism, colloidal structure, acid neutralization and antifrictiorL properties of overbased detergents have been published with the development of experimental techniques, which can help us better understand the process of preparation and application of overbased detergents and propound new strategies for improving various performances of overbased detergents. In the future, the synthesis of environmentally friendly and multi-functional lubricant detergent using biodegradable vegetable oil instead of mineral oil as raw materials will be a primary objective for the colloidal lubricant detergent industry.This paper mainly presents the latest advances in the investigation of colloidal lubricant detergents.

Comprehensive Study on Degradation and Management of Baiyangdian Lake in North China

Baiyangdian lake as the kidney of north China plays a huge ecological function, bringing about environmental and economic benefits as well as aesthetics value. It takes the role of adjusting climate, slowing flood, storing water, alleviating drought, maintaining the water body＇s purifying capacity, protecting biodiversity as well as vegetating fish and reed, developing eco-tourism etc.. Now it is degenerating under the pressure from both physical and human society. This paper studied the process, condition and root causes of the lake shrinking, pollution, biodiversity losing and disasters. Adaptation and integrative management strategies are also put forward for maintaining the ecological function and sustainable development.

In Vitro Antimicrobial Activity Study of Some New Arginine-based Biodegradable Poly （Ester Urethane）s and Poly （Ester Urea）s

Bactericidal activity of some arginine based biodegradable polymers-PEURs （poly （ester urethane）s） and PEUs （poly （ester urea）s） with low cytotoxicity was studied in in vitro experiments. Various bacterial strains both Gram-positive and Gram-negative were used to explore the bactericidal activity of the cationic polymers. As the test objects, the following microorganisms were used： Bacillus subtilis, Staphylococcus aureus, Mycobacterium album, Pseudomonas fluorescens, Escherichia coli, Actinomyces griseus and Aspergillus niger. The obtained results showed that the new cationic polymers suppressed the growth of the studied microorganisms and the bactericidal activity of the tested cationic polymers strongly depending on their chemical structure.

Environmentally Degradation of r-PMMA/PMMA-Blend-PU/Ecoflex Sheet

Poly （methyl methacrylate） scrap was applied to prepare the impact modification of r-PMMA/PMMA-blend-PU/Ecoflex sheet by casting process. The Ecoflex and polyurethane were used as biodegradable polymer and impact modified respectively. This research was ascertained tile way to reduce the processing cost of PMMA sheet and the industrial waste by recycled PMMA scrap into the production process. The r-PMMA/PMMA-blend-PU/Ecoflex sheet was studied potential degradation by landfills for six months. After degradation the percentage of weight loss of specimens was increasing depend on amount of Ecoflex content and degradation period. While, the surface morphology of r-PMMA/PMMA-blend-PU/Ecoflex sheet after six months was damaged and demonstrated that Ecoflex had an effect on PMMA-blend-PU sheet in potential biodegradation. The mechanical and physical properties of r-PMMA/PMMA-blend-PU/Ecoflex sheet were described. Finally, the impact strength of r-PMMA/PMMA-blend-PU/Ecoflex sheet from this research, it is possible to use r-PMMA and Ecoflex in the acrylic casting sheet product.

Study on Preparation of Temperature-sensitive Injectable Hydrogel

To get a sort of new scaffold material for soft tissue reconstruction,we have prepared XLHA-PNIPAAm and XLHA-MC injectable hydrogels through blending crosslinked HA(XLHA) and two temperature-sensitive materials differed in degradation poly(N-isopropylacrylamide)(PNIPAAm) and methylcellulose(MC),respectively.We tested the injectablility,enzymatic biodegradability,temperature-sensitivity,structure cytotoxicity and hemolysis of the two injectable hydrogels.Our research has successfully obtained the preparation condition of XLHA-PNIPAAm injectable hydrogel,and verified that adding non-degradable material PNIPAAm can postpone the degradation of HA more effectively than degradable material MC.PNIPAAm prepared with 5 kGy dose radiation,MBAAm/NIPAAm(M/M)=0.015,monomer concentration=3% produced XLHA-PNIPAAm with slowest enzymatic biodegradability.DSC results showed that temperature-sensitivity of the XLHA-PNIPAAm was more stable than that of XLHA-MC.Two composite hydrogels were qualified in cytotoxicity and hemolysis tests and the biocompatibility of XLHA-PNIPAAm hydrogel showed better than XLHA-MC hydrogel.

Recent advances in flexible and stretchable electronics, sensors and power sources

There has been ongoing keen interest to mold electronic devices into desired shapes and be laid on desired configurable surfaces. In specific, the ability to design materials that can bend, twist, compress and stretch repeatedly, while still able to maintain its full capability as conductors or electrodes, has led to numerous efforts to develop flexible and stretchable (bio)devices that are both technologically challenging and environmentally friendly (e.g. biodegradable). In this review, we highlight several recent significant results that have made impacts toward the field of flexible and stretchable electronics, sensors and power sources.

Multifunctional devices based on planar microsupercapacitors:Progress and challenges

With the boom of portable,wearable,and implantable smart electronics in the last decade,the demand for multifunctional microscale electrochemical energy storage devices has increased.Owing to their excellent rate performance,high power density,long cycling lifetime,easy fabrication,and integration,multifunctional planar microsupercapacitors(PMSCs)are deemed as one of the ideal micropower sources for next-generation flexible on-chip electronics.Therefore,we offer a comprehensive overview of the recent progress regarding multifunctional devices based on PMSCs,including stretchable,self-healing,stimulus-responsive,thermosensitive,biodegradable,and temperaturetolerant microdevices.We also emphasize the unique applications of multifunctionally integrated PMSCs in the construction of self-powered and sensor-integrated systems in terms of multifunctional operation modes.Finally,the key challenges and future prospects related to these multifunctional devices are discussed to stimulate further research in this flourishing field.

In vitro and in vivo studies on as-extruded Mg-5.25wt.%Zn-0.6wt.%Ca alloy as biodegradable metal

Magnesium alloys have shown prospective applications as a new biodegradable metal within bone. To garantee the longterm biocompatibility, a Mg-Zn-Ca alloy,composing of essential elements for human, was prepared and its feasibility for orthopedic applications was investigated. The in vitro and in vivo corrosion of Mg-Zn-Ca alloy as well as the biocompatibility were studied. The in vitro corrosion tests in five kinds of physiological solutions showed that the corrosion rates and corrosion morphologies of the alloy were strongly influenced by the solution used. The addition of serum in Hank’s and MEM significantly slowed down the corrosion rate and improved the corrosion uniformity of the alloy. The corrosion rate decreased with increasing serum concentration.The alloy showed the slowest corrosion rate as well as homogeneous corrosion morphology in MEM＋10%FBS. Both the indirect and direct cell experiments indicated good cytocompatibility of the extruded Mg-Zn-Ca alloy. In vivo, we observed a gradual degradation process from the surface of extruded Mg-Zn-Ca alloy and only 40% in volume of implant was left after 4 weeks implantation in medullary cavities of mice. The micro-CT and histological analyses revealed its good biocompatibility with peri-implant new bone formation and increasing cortical bone thickness with increasing implantation period. This study showed that the extruded MgZn-Ca alloy provided sufficient biocompatibility for orthopedic application, though the in vivo corrosion rate should be further reduced for clinical use.

“Building-block crosslinking”micelles for enhancing cellular transfection of biocompatible polycations

Incorporating functional ligands and biodegradable bonds into biocompatible low-molecular-weight(LMW)polymers,such as 1.8 kDa poly(ethylenimine)(PEI1.8 k),is a common strategy to improve the properties of LMW polymers including biosafety and delivery efficacy.This study demonstrates the hypothesis that introducing different functional ligands and linked reductive disulfides in PEI 1.8k will achieve superior siRNA transfection efficiency.By incorporating PEI-X(X represents cholesterol(Ch),heptafluorobutyric anhydride(HFBA,F)and 4-carboxyphenylboronic acid(PBA))functional ligands into PEI 1.8k and subsequently crosslinking with each other via disulfide bond links,reductive-responsive PEI-X-SS-X-PEI copolymers were constructed to enhance the cellular transfection via the synergistic effect of the high affinity of Ch,F and PBA to cell membranes and the disulfide reduction triggered intracellular disassembly of micelles and subsequent siRNA release.Extraordinarily,ternary Ch-SS-F-SS-PBA micelles exhibited the strongest siRNA transfection efficiencies in in vitro cell experiments and in vivo animal experiments due to the coordination of enhanced serum stability,promoted cell uptake and endosomal escape,and cell targeting ability.This strategy of constructed multifunctional polymer here we called"building-block crosslinking"showed a simple and smart way to synthesize new materials.Also this strategy of constructing ligands-directed reduction-sensitive micelles improves the transfection efficiency of LMW PEI and provides a valuable insight to develop novel gene delivery systems.

In vitro and in vivo cytocompatibility evaluation of biodegradable magnesium-based stents: a review

Biodegradable magnesium（Mg）-based vascular stents have been designed as temporary scaffolds to treat angiostenotic lesions for the maintenance of normal blood flow.Numerous studies have presented in vitro and in vivo tests for the evaluation of the safety and feasibility of Mg-based vascular stents and the related materials. Therein the cytocompatibility is a basic and important parameter in the evaluation system. In this review, we summarize the applications and limitations of in vitro evaluation methods including basic characterization methods and direct and indirect cytotoxicity tests. We discuss the influencing factors on cytotoxicity, such as surface roughness, preconditioning of sample surface, cell type for the biocompatibility evaluation in direct contact as well as conditions for the formation of extracts/degradation products for indirect assays. Besides, we highlight the recent in vivo animal tests and clinical trials about Mgbased stents along with some associated results. The aim of this review is to provide a meaningful reference in the further developments and related evaluation methods of Mg-based stents.

Biodegradable polymeric nanoparticles based on amphiphilic principle:construction and application in drug delivery

The use of nanotechnology in drug-delivery systems(DDS) is attractive for advanced diagnosis and treatment of cancer diseases. Biodegradable polymeric nanoparticles, for example, have promising applications as advanced drug carriers in cancer treatment. In this review, we discuss the development of drug-delivery systems based on an amphiphilic principle mainly conducted by our group for anti-cancer drug delivery. We first briefly address the synthetic chemistry for amphiphilic biodegradable polymers. In the second part, we summarize progress in the application of self-assembled polymer micelles using amphiphilic biodegradable copolymers as anti-tumor drug carriers.