[Research progress of electrospinning polyurethane fiber in the field of biomedical tissue engineering].

Polyurethane materials have good biocompatibility, blood compatibility, mechanical properties, fatigue resistance and processability, and have always been highly valued as medical materials. Polyurethane fibers prepared by electrostatic spinning technology can better mimic the structure of natural extracellular matrices (ECMs), and seed cells can adhere and proliferate better to meet the requirements of tissue repair and reconstruction. The purpose of this review is to present the research progress of electrostatically spun polyurethane fibers in bone tissue engineering, skin tissue engineering, neural tissue engineering, vascular tissue engineering and cardiac tissue engineering, so that researchers can understand the practical applications of electrostatically spun polyurethane fibers in tissue engineering and regenerative medicine.

Application of Geopolymer in Stabilization/Solidification of Hazardous Pollutants: A Review.

Geopolymers, as a kind of inorganic polymer, possess excellent properties and have been broadly studied for the stabilization/solidification (S/S) of hazardous pollutants. Even though many reviews about geopolymers have been published, the summary of geopolymer-based S/S for various contaminants has not been well conducted. Therefore, the S/S of hazardous pollutants using geopolymers are comprehensively summarized in this review. Geopolymer-based S/S of typical cations, including Pb, Zn, Cd, Cs, Cu, Sr, Ni, etc., were involved and elucidated. The S/S mechanisms for cationic heavy metals were concluded, mainly including physical encapsulation, sorption, precipitation, and bonding with a silicate structure. In addition, compared to cationic ions, geopolymers have a poor immobilization ability on anions due to the repulsive effect between them, presenting a high leaching percentage. However, some anions, such as Se or As oxyanions, have been proved to exist in geopolymers through electrostatic interaction, which provides a direction to enhance the geopolymer-based S/S for anions. Besides, few reports about geopolymer-based S/S of organic pollutants have been published. Furthermore, the adsorbents of geopolymer-based composites designed and studied for the removal of hazardous pollutants from aqueous conditions are also briefly discussed. On the whole, this review will offer insights into geopolymer-based S/S technology. Furthermore, the challenges to geopolymer-based S/S technology outlined in this work are expected to be of direct relevance to the focus of future research.

Influence of bovine serum albumin on corrosion behaviour of pure Zn in phosphate buffered saline.

Zinc (Zn) and its alloys have received increasing attention as new alternative biodegradable metals. However, consensus has not been reached on the corrosion behaviour of Zn. As cardiovascular artery stent material, Zn is supposed to contact with plasma that contains inorganic salts and organic components. Protein is one of the most important constitute in the plasma and could adsorb on the material surface. In this paper, bovine serum albumin (BSA) was used as a typical protein. Influences of BSA on pure Zn corrosion in phosphate buffered saline is investigated as a function of BSA concentrations and immersion durations by electrochemical techniques and surface analysis. Results showed that pure Zn corrosion was progressively accelerated with BSA concentrations (ranging from 0.05 to 5 g L-1) at 0.5 h. With time evolves, formation of phosphates as corrosion product was delayed by BSA adsorption, especially at concentration of 2 g L-1. Within 48 h, the corrosion of pure Zn was alleviated by BSA at concentration of 0.1 g L-1, whereas the corrosion was enhanced after 168 h. Addition of 2 g L-1 BSA has opposite influence on the pure Zn corrosion. Furthermore, schematic corrosion behaviour at protein/Zn interfaces was proposed. This work encourages us to think more about the influence of protein on the material corrosion and helps us to better understand the corrosion behaviour of pure Zn.

Ultrasound controlled paclitaxel releasing system-A novel method for improving the availability of coronary artery drug coated balloon.

OBJECTIVES: The aim of this study is to improve local-drug delivery efficiency and tissue absorption using the ultrasound (US)-responsible drug coating based on a newly developed US-controlled paclitaxel release balloon. BACKGROUND: Low availability of the drug coating remains a major concern of the current drug coated balloon (DCB). The goal of this study is to develop a method to use an US-responsible paclitaxel-loaded microcapsules (PM) as the main content of balloon drug coating to enhance bioavailability of DCB. METHODS: An US-controlled paclitaxel release balloon is designed and fabricated based on the US-responsible paclitaxel-loaded poly (lactic-co-glycolic acid) (PLGA) microcapsules. Rapid exchange percutaneous transluminal coronary angioplasty (PTCA) balloon catheters were coated with the PM. The deployment processes of the paclitaxel-loaded microcapsules coated balloons (PMCB) under US, PMCB without US and a homogenous matrix of paclitaxel and iopromide coated balloon (PICB) were then placed in healthy and stent implanted porcine coronary arteries. RESULTS: In vitro release assay demonstrated an ability of US (1 MHz, 1.22 W/cm2 , 1 minute) to affect the release kinetics of paclitaxel from PM by inducing a 76 ± 5.4% increase in the rate of release. The paclitaxel content in target vessels are 203 ± 37 µg/g for PMCB under US, 85 ± 23 µg/g for PMCB without US, and 107 ± 31 µg/g for PICB 1-hr post-surgery. The availability of the drug for the PMCB reaches 27% under US. CONCLUSIONS: The US-controlled paclitaxel release balloon significantly improved the drug content of the target vessels in the porcine model.

Release and Transformation of BTBPE During the Thermal Treatment of Flame Retardant ABS Plastics.

Thermal scenarios inevitably occur during the lifecycle of engineering plastics laden with brominated flame retardants (BFRs). However, little information on the fate of embedded BFRs during the thermal processes is available. In this study, we measured the release and transformation of a typical BFR, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), during the thermal treatment of acrylonitrile butadiene styrene (ABS) plastics. The possible thermal scenarios were simulated by varying the heating temperature and atmosphere. The maximum release rate of BTBPE was observed at 350 °C. A release kinetic model was developed to explore the mechanism of BTBPE release while heating ABS. Material-phase diffusion was found to be the rate-determining step during release. According to the developed release model, it was estimated that 0.04-0.17% of embedded BTBPE could be released to air during the industrial processing of ABS plastics. When the heating temperature was ≥350 °C, approximately 15-56% of embedded BTBPE decomposed to bromophenols (BPs) and 1,3,5-tribromo-2-(vinyloxy) benzene (TBVOB), and the decomposition followed a first-order kinetics at 350 °C. Polybrominated dibenzo- p-dioxins and dibenzofurans (PBDD/Fs) were also significantly formed at ≥350 °C from BPs and TBVOB via a precursor mechanism. A higher temperature (≥450 °C) was favorable for the formation of PBDFs.

[Progress in Research Drug Eluting Stents Drug-looding and Drug Release Kinetics].

Drug eluting stents are one of the main devices of coronary intervention, which play a therapeutic role through the combination of medical devices. Drug is an important part of the drug eluting stents. The loading method, the type of carrier, drug and carrier interaction and the preparation process of the drug directly affect the drugs release kinetics characteristics of the device and the final treatment. According to the characteristics of the drug coating, drug coated stents can be divided into non-degradable polymers drug coated stents, biodegradable polymers drug coated stents and polymer-free drug eluting stents. This article discussed the stent coating process and drug release kinetics of the three types of drug eluting stent.

Release and Gas-Particle Partitioning Behaviors of Short-Chain Chlorinated Paraffins (SCCPs) During the Thermal Treatment of Polyvinyl Chloride Flooring.

Chlorinated paraffin (CP) mixture is a common additive in polyvinyl chloride (PVC) products as a plasticizer and flame retardant. During the PVC plastic life cycle, intentional or incidental thermal processes inevitably cause an abrupt release of short-chain CPs (SCCPs). In this study, the thermal processing of PVC plastics was simulated by heating PVC flooring at 100-200 °C in a chamber. The 1 h thermal treatment caused the release of 1.9-10.7% of the embedded SCCPs. A developed emission model indicated that SCCP release was mainly controlled by material-gas partitioning at 100 °C. However, release control tended to be subjected to material-phase diffusion above 150 °C, especially for SCCP congeners with shorter carbon-chain lengths. A cascade impactor (NanoMoudi) was used to collect particles of different sizes and gas-phase SCCPs. The elevated temperature resulted in a higher partition of SCCPs from the gas-phase to particle-phase. SCCPs were not strongly inclined to form aerosol particles by nucleation, and less present in the Aitken mode particles. Junge-Pankow adsorption model well fitted the partitioning of SCCPs between the gas-phase and accumulation mode particles. Inhalation exposure estimation indicated that PVC processing and recycling workers could face a considerably high risk for exposure to SCCPs.

Solely abluminal drug release from coronary stents could possibly improve reendothelialization.

OBJECTIVES: To compare a new stent with an asymmetric coating, eluting the drug to the abluminal surface, to a stent with a conventional coating eluting the drug both to the luminal and the abluminal side. BACKGROUND: Stents with asymmetric coating, eluting the drug to the vessel wall (BPSES-A), could potentially give faster reendothelialization after percutaneous coronary interventions (PCI) and decrease in in-stent thrombosis and late restenosis. METHODS: BPSES-A, conventional coated stents (BPSES-C), biodegradable polymer stents without drug (BPS, for control), and bare metal stents (BMS, for control) were implanted into the coronary arteries of 38 pigs (75 stents). Pigs were sacrificed after 4, 12, and 24 weeks. Quantitative coronary angiography was used to compare in-stent late lumen loss (LLL) and electron microscopy was used to reveal levels of reendothelialization. RESULTS: The stents were all successfully implanted. LLL of BPSES-A, BPSES-C, BMS, and BPS were 0.56 ± 0.51, 0.60 ± 0.58, 0.89 ± 0.43, and 1.68 ± 0.30 mm, respectively, after 4 weeks. LLL of BPSES-A and BPSES-C were 0.63 ± 0.53 and 0.69 ± 0.24 mm, respectively, after 12 weeks. LLL of BPSES-A, BPSES-C, and BMS were 0.42 ± 0.15 m, 0.56 ± 0.28 mm, and 0.99 ± 0.13 mm, respectively, after 24 weeks. The scaling of reendothelialization was as follows: after 4 weeks BMS > = BPS > BPSES-A > BPSES-C, after 12 weeks BPSES-A > BPSES-C, and after 24 weeks BMS > BPSES-A > BPSES-C. Reendothelialization was better in BPSES-A than BPSES-C (P < 0.05). There was no correlation between LLL and reendothelialization (P = 0.42). CONCLUSION: Asymmetric coating of coronary stents might be helpful to improve reendothelialization. © 2016 Wiley Periodicals, Inc.

Preparation and catalytic activity of poly(N-vinyl-2-pyrrolidone)-protected Au nanoparticles for the aerobic oxidation of glucose.

PVP-protected Au nanoparticles (NPs) for the aerobic oxidation of glucose were prepared by using NaBH4 reduction method. The effects of processing parameters such as Au3+ ion concentration, reaction temperature, ratio of NaBH4 or PVP to Au3+, and solvent composition on their particle sizes and catalytic activities were studied in detail and the synthesis conditions optimized. As-prepared Au NPs possessed a FCC structure, with an average size varying from about 100 to 2.6 nm depending on their preparation conditions. The size changes affected their catalytic activities in the aerobic oxidation of glucose. The Au NPs with the average size of 2.6 nm prepared under the optimal conditions showed a high instantaneous catalytic activity as well as a high long-time stability. Based on the kinetic study on the glucose oxidation over the PVP-protected Au NPs, the corresponding apparent activation energy was determined as 82 kJ mol(-1).

A nation-wide study for the occurrence of PPD antioxidants and 6PPD-quinone in road dusts of China.

N,N'-substituted p-phenylenediamines (PPDs) are widely used antioxidants in rubber tires, which could be released and accumulated in road dusts with rubber tires wear. As ozonation product of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), 6PPD-quinone (6PPD-Q) exhibited higher toxicity to coho salmon. However, studies on their environmental behaviors are still limited. Road dust is the major medium PPDs exist, which significantly affects the levels of PPDs in other mediums, especially surface water and particulate matter. In this study, road dust samples were collected in 55 major cities of China to explore the distribution characteristics of PPDs and 6PPD-Q. The concentrations of total PPDs (ΣPPDs) and 6PPD-Q in urban trunk road dust samples were in the ranges of 7.90-727 and 3.00-349 ng/g, with median concentrations of 68 and 49 ng/g, respectively. 6PPD and 6PPD-Q are the dominant components in most road dusts. The functional region-dependent pollution characteristics of PPDs and 6PPD-Q give the first finding that urban tunnel road was the highly polluted region, followed by urban trunk roads. Suburban road dusts had a lower pollution level. Moreover, the estimated daily intake (EDI) of PPDs and 6PPD-Q for children was much higher than adults.

Melatonin promotes water-stress tolerance, lateral root formation, and seed germination in cucumber (Cucumis sativus L.).

A comprehensive investigation was carried out to determine the changes that occurred in water-stressed cucumber (Cucumis sativus L.) in response to melatonin treatment. We examined the potential roles of melatonin during seed germination and root generation and measured its effect on reactive oxygen species (ROS) levels, antioxidant enzyme activities, and photosynthesis. Melatonin alleviated polyethylene glycol induced inhibition of seed germination, with 100 µm melatonin-treated seeds showing the greatest germination rate. Melatonin stimulated root generation and vitality and increased the root:shoot ratio; therefore, melatonin may have an effect on strengthening cucumber roots. Melatonin treatment significantly reduced chlorophyll degradation. Seedlings treated with 100 µm melatonin clearly showed a higher photosynthetic rate, thus reversing the effect of water stress. Furthermore, the ultrastructure of chloroplasts in water-stressed cucumber leaves was maintained after melatonin treatment. The antioxidant levels and activities of the ROS scavenging enzymes, i.e., superoxide dismutase, peroxidase, and catalase, were also increased by melatonin. These results suggest that the adverse effects of water stress can be minimized by the application of melatonin.

Crown jewel-structured Au/Pd nanoclusters as novel catalysts for aerobic glucose oxidation.

Low-coordination Au sites have been proved to play a key role in defining the catalytic activity of Au nanoclusters (NCs). At the present time, it is still of great interest and challenge to design and synthesize catalysts containing the desired amount of low-coordinated Au atoms by a simple, easy, and large-scale method. In this study, PVP-protected 'crown jewel'-structured Au/Pd (CJ-Au/Pd) catalyst containing an abundance of top Au atoms were prepared by redox replacement reaction between Pd NCs and Au3+ ions. The catalytic activity of the CJ-Au/Pd NCs for aerobic glucose oxidation is about 3 times higher than that of the Au/Pd alloy NCs prepared by alcohol reduction method, although all of these NCs possess almost the same particle size.

Co-release of hexabromocyclododecane (HBCD) and Nano- and microparticles from thermal cutting of polystyrene foams.

Polystyrene foam is a very important insulation material, and hexabromocyclododecane (HBCD) is frequently used as its flame retardant. HBCD is persistent, bioaccumulative, and toxic, and therefore workplace exposure and environmental emission should be avoided. In this study, we investigated the co-release of HBCD and aerosol particles during the thermal cutting of expanded polystyrene foam (EPS) and extruded polystyrene foam (XPS). The generated particles were simultaneously measured by a fast mobility particle sizer (FMPS) and collected by a cascade impactor (NanoMoudi). In the breathing zone of a cutting worker, the number concentration of aerosol particles was above 1 × 10(12) particles m(-3), and the air concentration of HBCD was more than 50 µg m(-3). Most of the released HBCD was partitioned into particles with an aerodynamic diameter at the nanometer scale. The average concentrations of HBCD in these submicrometer particles generated from the thermal cutting of EPS and XPS were 13 times and 15 times higher than the concentrations in raw foams, respectively. An occupational exposure assessment indicated that more than 60% of HBCD and 70% of particles deposited in the lung of cutting worker would be allocated to the alveolar region. The potential subchronic (or chronic) toxicity jointly caused by the particles and HBCD calls for future studies.

Human adipose-derived mesenchymal stem cells-derived exosomes encapsulated in pluronic F127 hydrogel promote wound healing and regeneration.

BACKGROUND: Large area skin trauma has always been a great challenge for both patients and clinicians. Exosomes originating from human adipose-derived mesenchymal stem cells (hADSCs) have been a novel promising cell-free treatment in cutaneous damage repair. Nevertheless, the low retention rate of exosomes post-transplantation in vivo remains a significant challenge in clinical applications. Herein, we purposed to explore the potential clinical application roles of hADSCs-Exos encapsulated in functional PF-127 hydrogel in wound healing. METHODS: hADSCs-Exos were isolated from human hADSCs by ultracentrifugation. An injectable, biocompatible, and thermo-sensitive hydrogel Pluronic F-127 hydrogel was employed to encapsulate allogeneic hADSCs-Exos, and this complex was topically applied to a full-thickness cutaneous wound in mice. On different days post-transplantation, the mice were sacrificed, and the skin tissue was excised for histological and immunohistochemical analysis. RESULTS: Compared with hADSCs-Exos or PF-127 only, PF-127/hADSCs-Exos complexes enhanced skin wound healing, promoted re-epithelialization, increased expression of Ki67, α-SMA, and CD31, facilitated collagen synthesis (Collagen I, Collagen III), up-regulated expression of skin barrier proteins (KRT1, AQP3), and reduced inflammation (IL-6, TNF-α, CD68, CD206). By using PF-127/hADSCs-Exos complexes, hADSCs-Exos can be administrated at lower doses frequency while maintaining the same therapeutic effects. CONCLUSION: Administration of hADSCs-Exos in PF-127 improves the efficiency of exosome delivery, maintains the bioactivity of hADSCs-Exos, and optimizes the performance of hADSCs-Exos. Thus, this biomaterial-based exosome will be a promising treatment approach for the cutaneous rejuvenation of skin wounds.

Carbon Nanotube Polymer Scaffolds as a Conductive Alternative for the Construction of Retinal Sheet Tissue.

With the great success of graphene in the biomedical field, carbon nanotubes have attracted increasing attention for different applications in ophthalmology. Here, we report a novel retinal sheet composed of carbon nanotubes (CNTs) and poly(lactic-co-glycolic acid) (PLGA) that can enhance retinal cell therapy. By tuning our CNTs to regulate the mechanical characteristics of retina sheets, we were able to improve the in vitro viability of retinal ganglion cells derived from human-induced pluripotent stem cells incorporated into CNTs. Engrafted retinal ganglion cells displayed signs of regenerating processes along the optic nerve. Compared with PLGA scaffolds, CNT-PLGA retinal sheet tissue has excellent electrical conductivity, biocompatibility, and biodegradation. This new biomaterial offers new insight into retinal injury, repair, and regeneration.

Spraying polyacrylamide solution to improve the removal of particle-phase dioxins by bag filter in a full-scale municipal solid waste incineration system.

A field experiment was conducted in a modern municipal solid waste (MSW) incineration power plant to explore the feasibility of using chemical agglomeration agent anionic polyacrylamide (PAM) to reduce the atmospheric emission of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Spraying PAM solution into the cooling tower caused an obvious decrease in the volume fraction of ultrafine and fine particles with diameter of 0.3-30 µm in BF fly ash, and a significant reduction in dust content in stack gas. The increased agglomeration of particles promoted the removal of particle-phase PCDD/Fs by BF, and thus resulted in a lower atmospheric emission of PCDD/Fs. The calculated removal efficiency of PCDD/Fs by BF was almost positively proportional to the concentration of PAM solution, while inversely proportional to the average content of dusk in stack gas. Compared with the control treatment, the spraying of 0.1 g/L PAM solution enhanced the removal efficiency of total tetra-to octa-CDD/Fs (∑PCDD/Fs) from 93.8% to 97.8% by BF, and resulted in a decrease of 47.0% in the concentration of international toxicity equivalent (I-TEQ) in stack gas. During the experiment of 2 d, the spraying of PAM solution did not induce a significant change in the differential pressure of BF, and did not essentially affect the partitioning behaviors of PCDD/F homologues between flue gas and BF fly ash. In view of technical safety and low cost, PAM application is recommended for reducing the atmospheric emission of PCDD/Fs from MSW incineration system.

GSH-Sensitive Nanoscale Mn3+-Sealed Coordination Particles as Activatable Drug Delivery Systems for Synergistic Photodynamic-Chemo Therapy.

Activatable nanoscale drug delivery systems (NDDSs) are promising in maximizing cancer specificity and anticancer efficacy, and a multifunctional metal-organic nanomaterial is one of the new star NDDSs which requires further exploration. Herein, a novel DOX@MnCPs/PEG NDDSs were constructed by first synthesizing Mn3+-sealed coordination particles (MnCPs), modified with a targeted PEGylated polymer, and then loading anticancer drug doxorubicin (DOX). MnCPs were prepared from the assembly of Mn3+ ions and hematoporphyrin monomethyl ether (HMME) molecules. Furthermore, MnCPs had an average size of ∼100 nm and a large surface area (∼52.6 m2 g-1) and porosity (∼3.6 nm). After the loading of DOX, DOX@MnCPs/PEG exhibited a high DOX-loading efficacy of 27.2%, and they reacted with glutathione (GSH) to confer structural collapse, leading to the production of Mn2+ ions for enhanced magnetic resonance imaging (MRI), free HMME for augmented photodynamic effect, and free DOX for chemotherapy. As a consequence, these DOX@MnCPs/PEG NDDSs after intravenous injection showed efficient tumor homing and then exerted an obvious suppression for tumor growth rate by synergistic photodynamic-chemo therapy in vivo. Importantly, most of the DOX@MnCPs/PEG NDDSs could be gradually cleared through the renal pathway, and the remaining part could slowly be metabolized via the feces, enabling high biosafety. Therefore, this work provides a type of GSH-sensitive NDDS with biosafety, caner specificity, and multifunctionality for high synergistic treatment efficacy.

Chandler-Loop surveyed blood compatibility and dynamic blood triggered degradation behavior of Zn-4Cu alloy and Zn.

Zinc (Zn) and its alloys have been considered promising absorbable metals for medical implants. However, the dynamic interaction between Zn-based materials and human blood after implantation remains unclear. In this study, a modified Chandler-Loop system was applied to assess the blood compatibility and initial degradation behavior of a Zn-4.0Cu (wt%) alloy (Zn-4Cu) and Zn with human peripheral blood under circulation conditions. In this dynamic in vitro model, the Zn-4Cu and Zn showed sufficient blood compatibility. The numbers of erythrocytes, platelets, and leukocytes were not significantly altered, and appropriate activations of the coagulation and complement system were observed. Concerning initial degradation behavior, the product layers formed on the surfaces comprise a mixture of organic and inorganic compounds while the inorganic constituents decrease toward the outer surface. Considering the corrosion morphology and electrochemical behaviors, Zn-4Cu exhibited milder and more uniform degradation than Zn. Additionally, long-term degradation tests of 28 days in human peripheral blood, human serum, and Dulbecco's phosphate-buffered saline (DPBS) demonstrated that the Zn-4Cu showed relatively uniform degradation in blood and serum. On the contrary, in DPBS, severe localized corrosion appeared along the grain boundary of the secondary phase, which was likely attributed to the acceleration of galvanic corrosion. The Zn was found with localized corrosion impeded in the blood albeit with apparently developed deep pitting holes in the serum and DPBS.

Insight into role and mechanism of Li on the key aspects of biodegradable ZnLi alloys: Microstructure evolution, mechanical properties, corrosion behavior and cytotoxicity.

ZnLi based alloys have been proved as desirable candidates for biodegradable materials accounting for its high mechanical performance and great biocompatibility. However, effects of Li on microstructure and comprehensive properties of Zn alloys are seldom investigated and need to be addressed. Herein, Zn-(0.1-1.4 wt%)Li alloys are fabricated and systematically analyzed. Lath-like Zn precipitates are observed in the primary ß-LiZn4 (ß) phase of Zn-(0.5-1.4 wt%)Li alloys, leading to the formation of dense ß/Zn lamellar structure with an inter-spacing of 0.8 µm. Mechanical tests show that the strengths of the ZnLi alloys have at least tripled due to the formation of dense ß/Zn lamellar structure. Early degradation behaviors of the ZnLi alloys in simulated body fluid (SBF) reveal a competitive releasing of Li+ and Zn2+. As the priority of Li+ releasing becomes more obvious with increasing Li content in the alloys, aqueous insoluble Li-rich corrosion products containing LiOH and Li2CO3 form a passivation film on Zn-(0.5-1.4 wt%)Li alloys. Consequently, corrosion rate decreases significantly from 45.76 µm/y of pure Zn to 14.26 µm/y of Zn-1.4Li alloy. Importantly, observations of white light interferometer microscope and transmission electron microscope demonstrate that ß phase degrades prior to Zn in the alloys, suggesting that biomedical implants made of ZnLi alloys are likely to degrade completely in human body. Cytotoxicity tests of the alloys exhibit no cytotoxicity in 10% extracts. The most tolerated Zn2+/Li+ concentrations of the alloy extracts to L-929 cells are calculated, which provides guidance for future design of Zn alloys containing Li.

Enhancement in mechanical and corrosion resistance properties of a biodegradable Zn-Fe alloy through second phase refinement.

Biodegradable Zn alloys containing Fe suffer from a common problem that FeZn13 second phase particles are coarse. This problem roots thermodynamically from the negligible solid solubility of Fe in Zn and priority of FeZn13 solidification over Zn. In this paper, bottom circulating water-cooled casting method is successfully developed to significantly refine FeZn13 particles in Zn-0.3Fe alloy, owing to its cooling speed about 8 times of that of conventional casting. The second phase refinement alleviates brittleness of the alloy, increases the ultimate tensile strength by about 62%, and decreases electrochemical corrosion rate (CR) by about 19%, but immersion CR by only about 4% due to barrier effect of corrosion products. Viability of human umbilical vein endothelial cells maintains at a high level over 95% in 25-100% extracts. A great potential is shown for improving comprehensive properties of biodegradable Zn alloys without changing its chemical compositions through such a physical method.