A multifunctional osteogenic system of ultrasonically spray deposited bone-active coatings on plasma-activated magnesium

Biomimetic bone-active coatings composed of inorganic nano-hydroxyapatite(i.e.,nHA)and organic silk fibroin(i.e.,SF)are layer-by-layer deposited on Mg-Zn-Ca alloy by a controllable ultrasonic spray method.Meanwhile,plasma activation is developed as a promising strategy to pretreat magnesium surfaces,which facilitates the direct adhesion of coatings with enhanced bonding interfaces.In this work,we engineer the nHA/SF composite coatings with excellent mechanical properties and adhesion force.The optimized parameters of ultrasonic spray bring significant influence on the surface morphologies of coatings.Assisted by hybrid plasma of oxygen and nitrogen(i.e.,O_(2)/N_(2) plasma),the activated Mg-Zn-Ca surfaces are uniformly covered by a robust and compact nHA/SF composite coating,establishing a multifunctional system with superior corrosion resistance and biological performance.Interestingly,secondary oxygen plasma treatment of nHA/SF coatings(A-nHA/SF)promotes the hydrophilicity,leading to a rapid self-repair effect from surface damage.The improvement of anti-corrosion and self-repair provides a dependable platform for better cell adhesion,proliferation,spreading and differentiation.These favorable factors contribute to the preferable in vivo biocompatibility and the promotion of newly formed bones for the A-nHA/SF-coated Mg implants.This study lays important foundations for coating strategy on biomedical magnesium alloy as multifunctional osteogenic system in bioactive implantable applications.

Exploration of the enhanced performances for silk fibroin/sodium alginate composite coatings on biodegradable Mg-Zn-Ca alloy

To expand the future clinic applications of biodegradable magnesium alloy,polymer coatings with excellent biocompatibility are the keys to solve the local alkalinity and rapid hydrogen release.Natural-organic silk fibroin provides an approach to fabricate a protective coating on biomedical Mg-Zn-Ca alloy,however,the adhesion force and mechanical properties of the coating on substrates are ought to be further improved without any chemical conversion/intermediate layer.Hereby,based on VUV/O;surface activation,a hybrid of silk fibroin and sodium alginate is proposed to enhance the adhesion force and mechanical properties of the composite coatings on hydrophilic Mg-Zn-Ca alloy surfaces.Various mass ratios of sodium alginate addition were investigated to achieve the optimum coating strategy.The nanoscratch test and nanoindentation test confirmed that the adhesion force was tripled and mechanical properties index was significantly improved when the mass ratio of silk fibroin/sodium alginate was 70/30 compared to pure silk fibroin or sodium alginate coatings.Meanwhile,the corrosion rate of the coated Mg-Zn-Ca alloy was significantly delayed with the addition of sodium alginate,resulting in a reaction layer during corrosion process.Furthermore,the mechanisms for both adhesion and corrosion processes were discussed in detail.Our findings offer more possibilities for the controllable surface performance of degradable metals.

Recycled low-temperature direct bonding of Si/glass and glass/glass chips for detachable micro/nanofluidic devices

Silicon and glass are two of the most ideal materials for micro/nanofluidic devices,which have been widely used for research in multidisciplinary fields.However,many micro/nanofluidic devices enable only single use due to the irreversible bonding between Si/glass or glass/glass chips.If the silicon-and glass-based devices are fabricated to be detachable,the substrates can be reused and bonded again without repeating expensive micro/nanofabrication processes.Herein,we present a recycled direct bonding method for Si/glass and glass/glass chips based on oxygen plasma activation and low-temperature annealing processes.Strong bonding strength and void-free bonding interface are obtained after annealing at 150℃.The surfaces and the bonding interfaces are characterized to elucidate the bonding mechanisms.Moreover,immersion tests are carried out to investigate the interfacial corrosion resistance in various chemical and biological solutions as well as explore a detachable method.The bonding strengths are controlled to meet the demand for micro/nanofluidic devices and the bonding interfaces can be separated in ethanol.As a result,we succeed in the experiment of bonding and detaching of glass substrates without fracturing,which is repeated for three times.

One-step PDA coating strategy on pure Zn for blood-contacting engineering

The mechanical performance degradation caused by pitting corrosion and the insufficient biocompatibility induced with ion release inhibit the application of Zn as the new biodegradable metallic materials for blood-contacting intervention therapy.This work successfully coats a uniform polydopamine(PDA)layer on pure Zn via a one-step deposition process without introducing heavy metal elements or detrimental additives.Enhanced corrosion resistance and uniform corrosion have been performed on PDA coated Zn with corrosion products and pits reduced significantly than pure Zn during in vitro degradation.Thrombosis could be prohibited by anticoagulation performance with prothrombin time and activated partial thromboplastin time prolonged after co-incubation,and an almost 40%decrease of platelets adhesion,indicating the improved blood compatibility of coated Zn.Additionally,the poly(lactic-co-glycolic acid)(PLGA)is filmed on PDA coated Zn to realize a smooth double-coated structure with superior mechanical performance under stress loading to stably serve the multifunctional application,such as drug loading.Our strategy not only represents a facile and biological friendly method for Zn surface modification but also puts forward new ideas on preparing PDA-based coatings on active biodegradable alloys,which are beneficial for better blood-contacting engineering.

Fabrication of Ag@Ag_(2)O-MnO_(x) composite nanowires for high-efficient room-temperature removal of formaldehyde

Efficient removal of pollutant formaldehyde(HCHO) at room temperature using transition-metal oxides remains a huge challenge to date. Manganese oxide can oxidize formaldehyde, however, how to control the valence states of manganese is the key to further improve the removal efficiency. We have successfully prepared porous manganese oxide nanowires(Mn OxNWs) with large surface area and multiple valence states of manganese using simple electrospinning followed by thermal calcination and potassium permanganate solution post-treatment(C/S process). The contents of trivalent and tetravalent manganese increased significantly after C/S process. Moreover, the composition of silver oxide coated silver nanowires(Ag@Ag_(2) O NWs) is realized by assistance with oxygen plasma, which further enhanced high valence manganese. The formaldehyde removal efficiency by Ag@Ag_(2) O–Mn Oxcomposite nanowires can reach 93.7%. The high-efficient catalytic activity is confirmed to attribute to the higher surface area of composite nanowires, the high-valence manganese and the silver oxide for oxidation of formaldehyde.