A multi-functional MgF_(2)/polydopamine/hyaluronan-astaxanthin coating on the biodegradable ZE21B alloy with better corrosion resistance and biocompatibility for cardiovascular application

The cardiovascular diseases(CVD)continue to be the major threat to global public health over the years,while one of the effective methods to treat CVD is stent intervention.Biomedical magnesium(Mg)alloys have great potential applications in cardiovascular stents benefit from their excellent biodegradability and absorbability.However,excessive degradation rate and the delayed surface endothelialization still limit their further application.In this study,we modified a Mg-Zn-Y-Nd alloy(ZE21B)by preparing MgF_(2) as the corrosion resistance layer,the dopamine polymer film(PDA)as the bonding layer,and hyaluronic acid(HA)loaded astaxanthin(ASTA)as an important layer to directing the cardiovascular cells fate.The electrochemical test results showed that the MgF_(2)/PDA/HA-ASTA coating improved the corrosion resistance of ZE21B.The cytocompatibility experiments also demonstrated that this novel composite coating also selectively promoted endothelial cells proliferation,inhibited hyperproliferation of smooth muscle cells and adhesion of macrophages.Compared with the HAloaded rapamycin(RAPA)coating,our MgF_(2)/PDA/HA-ASTA coating showed better blood compatibility and cytocompatibility,indicating stronger multi-functions for the ZE21B alloy on cardiovascular application.

Preparation of functional coating on magnesium alloy with hydrophilic polymers and bioactive peptides for improved corrosion resistance and biocompatibility

Biodegradable magnesium alloy stents(MAS)have great potential in the treatment of cardiovascular diseases.However,too fast degradation and the poor biocompatibility are still two key problems for the clinical utility of MAS.In the present work,a functional coating composed of hydrophilic polymers and bioactive peptides was constructed on magnesium alloy to improve its corrosion resistance and biocompatibility in vitro and in vivo.Mg-Zn-Y-Nd(ZE21B)alloy modified with the functional coating exhibited moderate surface hydrophilicity and enhanced corrosion resistance.The favourable hemocompatibility of ZE21B alloy with the functional coating was confirmed by the in vitro blood experiments.Moreover,the modified ZE21B alloy could selectively promote the adhesion,proliferation,and migration of endothelial cells(ECs),but suppress these behaviors of smooth muscle cells(SMCs).Furthermore,the modified ZE21B alloy wires could alleviate intimal hyperplasia,enhance corrosion resistance and re-endothelialization in vivo transplantation experiment.These results collectively demonstrated that the functional coating improved the corrosion resistance and biocompatibility of ZE21B alloy.This functional coating provides new insight into the design and development of novel biodegradable stents for biomedical engineering.

Mg alloy cardio-/cerebrovascular scaffolds: Developments and prospects

Vascular scaffolds are one of the important application fields of biodegradable Mg alloys, and related research has been carried out for more than 20 years. In recent years, the application expansion of Mg alloy vascular scaffolds has brought new challenges to the research of related fields. This review focuses on the relevant advances in the field of Mg alloys for both cardio-/cerebrovascular scaffolds. The frequently investigated alloy series for vascular scaffolds were reviewed. The bottleneck of processing of Mg alloy minitubes was elucidated.The idea of functionalized surface modification was also pointed out in this review, and the authors put forward guidelines based on research experience in terms of scaffold structural design and degradation behavior evaluation. Finally, suggestions for further research directions of Mg alloy vascular scaffolds were provided.

Recent advances in cardiovascular stent for treatment of in-stent restenosis:Mechanisms and strategies

Treatments of atherogenesis,one of the most common cardiovascular diseases(CVD),are continuously being made thanks to innovation and an increasingly in-depth knowledge of percutaneous transluminal coronary angioplasty(PTCA),the most revolutionary medical procedure used for vascular restoration.Combined with an expanding balloon,vascular stents used at stricture sites enable the long-time restoration of vascular permeability.However,complication after stenting,in-stent restenosis(ISR),hinders the advancement of vascular stents and are associated with high medical costs for patients for decades years.Thus,the development of a high biocompatibility stent with improved safety and efficiency is urgently needed.This review provides an overview of current advances and potential technologies for the modification of stents for better treatment and prevention of ISR.In particular,the mechanisms of in-stent restenosis are investigated and summarized with the aim to comprehensively understanding the pathogenesis of stent complications.Then,according to different therapeutic functions,the current stent modification strategies are reviewed,including polymeric drug eluting stents,biological friendly stents,prohealing stents,and gene stents.Finally,the review provides an outlook of the challenges in the design of stents with optimal properties.Therefore,this review is a valuable and practical guideline for the development of cardiovascular stents.

Investigation of Mg–Zn–Y–Nd alloy for potential application of biodegradable esophageal stent material

In recent years,due to unhealthy dietary habits and other reasons,advanced esophageal cancer patients are on the rise,threatening human health and life safety at all times.Stents implantation as an important complementary or alternative method for chemotherapy has been widely applied in clinics.However,the adhesion and proliferation of pathological cells,such as tumor cells,fibroblasts and epithelial cells,may interfere the efficacy of stents.Further multiple implantation due to restenosis may also bring pain to patients.In this contribution,we preferred a biodegradable material Mg–Zn–Y–Nd alloy for potential application of esophageal stent.The hardness testing showed that Mg–Zn–Y–Nd alloy owned less mechanical properties compared with the commercial esophageal stents material,317L stainless steel(317L SS),while Mg–Zn–Y–Nd displayed significantly better biodegradation than 317L SS.Cell apoptosis assay indicated Mg–Zn–Y–Nd inhibited adhesion and proliferation of tumor cells,fibroblasts and epithelial cells.Our research suggested potential application of Mg–Zn–Y–Nd alloy as a novel material for biodegradable esophageal stent.

The therapeutic potential of MSC-EVs as a bioactive material for wound healing

In clinical trials,cell therapy,especially mesenchymal stem cells(MSC),contributed to wound treatment options in an innovative way.While,there are some limitations of MSC during the application process,including strict maintenance requirements and unpredictable differentiation.In order to expand the scope of application and reduce the restrictions related to direct use of SMC,the mechanisms of stem cells need to be studied.The latest research found that the effect of cell therapy is achieved mainly through paracrine effects,and the major bioactive vesicles which responsible for the paracrine effects is exosome.Exosome is a kind of extracellular membrane vesicle,which secreted from various cells and contain proteins,lipids and nucleic acids,to coordinate intercellular communication.In this review,the main cells type and cytokines relevant to every healing stage has been discussed,and the research about MSC-derived exosomes that has therapeutic effects has been summarized.At last,the potential application of exosomes as a bioactive material in the treatment of wound healing and related challenges as well as its possible solutions are discussed to reveal highly effective therapeutic strategies.

Reveal crucial subtype of natural chondroitin sulfate on the functionalized coatings for cardiovascular implants

Surface functionalization is generally accepted as one of the most useful methods for endowing better biocompatibility of the cardiovascular implants. Chondroitin sulfate(CS) is a commercial drug applied for preventing cardiovascular diseases in clinics, suggesting a potential application for functionalized coatings. Our previous work demonstrated that the CS conjugated onto the poly-dopamine(PDA)/hexanediamine(HD) co-deposited 316 L stainless steel(316 L SS) could endow the surface stronger multi-functions for cardiovascular implants. However, the natural CS has two subtypes, CS A and CS C,while it is still unclear which subtype makes more contribution to the surface modification of cardiovascular implants. Thus, the present study focus on comparing CS A and CS C via preparing functionalized coatings on the cardiovascular implants. Our data suggested PDA/HD-CS C coating possessed better blood compatibility and pro-endothelialization function through controlling the phenotype and distribution of macrophages, smooth muscle cells and endothelial cells in time sequence and space sequence.

Composite coatings of S-HA nanoparticles and Schiff base on ZE21B alloy for stronger corrosion resistance and biological performance

In order to prolong the service time and enhance the biocompatibility of magnesium(Mg)alloys used for cardiovascular scaffolds,the composite coatings of Schiff base(corrosion inhibitor)and sulfonated hyaluronic acid(S-HA)nanoparticles(NP@S-HA)with different sulfur content(10.02 wt%and 11.55wt%)were prepared on ZE21B alloy by means of electrostatic spraying with spraying time of 0.5 min,1.0 min and 1.5 min in this paper.Through a series of representations including corrosion experiments and biological characterization,the composite coatings with a sulfur content of 11.55wt%and a spray time of 1.0 min were finally picked due to its better comprehensive performances,which provides a new possibility for the surface modification of degradable Mg alloy cardiovascular scaffolds.

Microstructure Evolution of Primary γ′ Phase in Ni3Al-Based Superalloy

In this work,water cooling,air cooling(AC)and furnace cooling(FC)were applied to investigate the effect of cooling rate on microstructure evolution of primaryγ′in a newly designed Ni3Al-based alloy.The results showed that nucleation rate of primaryγ′increased with increasing cooling rate.In addition,higher cooling rate shortened growth period of primaryγ′,which made its morphology close to the initial precipitatedγ′.For AC and FC specimens,due to the lower cooling rate,primaryγ′possessed longer growth period and its morphology was mainly due to the evolution of lattice misfit betweenγand primaryγ′.Meanwhile,growth of primaryγ′depended on lattice misfit distribution between its corner and edge area.Moreover,primaryγ′morphologies of sphere,cube and concave cube with tip corners were illustrated by considering interaction between elemental diffusion and elastic strain energy.

Micro-patterned hydroxyapatite/silk fibroin coatings on Mg-Zn-Y-Nd-Zr alloys for better corrosion resistance and cell behavior guidance

In this study,a micro-patterned hydroxyapatite/silk fibroin(HA-SF)coating was firstly fabricated on the surface of Mg-Zn-Y-Nd-Zr alloy by template-assisted electrospraying technique coupling with spin coating technique.Two types of micro-patterns were achieved with high contour accuracy,namely HA SF(line-pattern)and HA-SF(dot-pattern).The microstructure,composition,surface wettability and corrosion behaviors of the coatings were investigated by SEM,EDS,FTIR,XRD,water contact angle and potentiodynamic polarization test.The results revealed the hydrophilic nature of coatings and two orders of magnitude reduction of corrosion density(icorr)as compared with that of the substrate.All the micro-patterned surfaces promoted the attachment of MC3T3-E1 cells with visible filopodia after 1 d incubation.In addition,coatings with line pattern exhibited the superior guidance to cell migration as compared to dot pattern,and the preference of cell attachment in the convex zone was observed.In summary,the obtained micro-patterned HA-SF coatings possessed the remarkably improvement of anticorrosion ability and good efficacy in guidance of cell attachment and alignment,which can serve as a promising strategy for cellular response modulation at the interface of magnesium-based implants and bone.

Colorectal cancer and adjacent normal mucosa differ in apoptotic and inflammatory protein expression

Colorectal cancer usually refers to the occurrence of the appendix,rectum or colon and other parts of the ma-lignant tumor in the large intestine mucosa and glands,is also one of the most common malignant tumors in human.In recent years,studies have shown that chronic inflammation is the"initiator"of cancer.Inflammation plays a causal role in the early formation of tumors by regulating the initiation and promotion of tumor genesis and development through a series of inflammatory cytokines.Inflammation plays a causal role in the early for-mation of tumors by regulating the initiation and promotion of tumor genesis and development through a series of inflammatory cytokines.The latter part of this review describes the role of several important inflammatory factors:tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),and transforming growth factor-β(TGF-β)in col-orectal cancer.In normal mucosa,inflammatory factors play an important role in the immune response of the body.However,when a large number of inflammatory factors accumulate,they will cause pathological damage to the body,trigger inflammation and even deteriorate into cancer.Serum levels of most inflammatory factors were low in healthy controls,but were elevated in colorectal cancer patients.Here,we review the relationship be-tween apoptosis,inflammation and cancer,and analyze the difference in the expression of inflammatory proteins in colorectal cancer and its adjacent mucosa.