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Due to its biofunctions similar to NO, the CO gas signaling molecule has gradually shown great potential in cardiovascular biomaterials for regulating the in vivo performances after the implantation and has received increasing attention. To construct a bioactive surface with CO-releasing properties on the surface of magnesium-based alloy to augment the anticorrosion and biocompatibility, graphene oxide (GO) was firstly modified using carboxymethyl chitosan (CS), and then CO-releasing molecules (CORM401) were introduced to synthesize a novel biocompatible nanomaterial (GOCS-CO) that can release CO in the physiological environments. The GOCS-CO was further immobilized on the magnesium alloy surface modified by polydopamine coating with Zn2+ (PDA/Zn) to create a bioactive surface capable of releasing CO in the physiological environment. The outcomes showed that the CO-releasing coating can not only significantly enhance the anticorrosion and abate the corrosion degradation rate of the magnesium alloy in a simulated physiological environment, but also endow it with good hydrophilicity and a certain ability to adsorb albumin selectively. Owing to the significant enhancement of anticorrosion and hydrophilicity, coupled with the bioactivity of GOCS, the modified sample not only showed excellent ability to prevent platelet adhesion and activation and reduce hemolysis rate but also can promote endothelial cell (EC) adhesion, proliferation as well as the expression of nitric oxide (NO) and vascular endothelial growth factor (VEGF). In the case of CO release, the hemocompatibility and EC growth behaviors were further significantly improved, suggesting that CO molecules released from the surface can significantly improve the hemocompatibility and EC growth. Consequently, the present study provides a novel surface modification method that can simultaneously augment the anticorrosion and biocompatibility of magnesium-based alloys, which will strongly promote the research and application of CO-releasing bioactive coatings for surface functionalization of cardiovascular biomaterials and devices. [ABSTRACT FROM AUTHOR]

Highlights • The Cu/Ti film with regulating the various responses of ECs and SMCs has been prepared. • The hemocompatibility could be adjusted via the ratio of Cu/Ti. • The volume and velocity of copper ion released from film was designed via the preparation processing. Abstract A facile approach to fabricate an inorganic coating with favorable blood compatibility and accelerating endothelialization is reported. The inorganic coating with various ratios of Cu and Ti atom are prepared on 316 L stainless steel by physical vapor deposition method. The phase composition and structure as well as the element concentration of the coating are investigated by X-ray diffraction and X-photoelectron energy spectrum. The hemolysis ratio, clotting time and platelet adhesion are utilized to characterize the materials’ hemocompatibility, the copper ion releasing was also investigated via immersing test. The result indicates that copper-titanium coating show good compatibility; however, as the ratio of Cu to Ti increases, the hemolysis ratio also increases. The endothelialization degree was accelerated owing to maintain less than 7.0 μg/ml of Cu2+ concentrate, and endothelial cells proliferate more readily than smooth muscle cells. The results demonstrate that this degradable copper-containing coating is suitable as a new surface modification for vascular stents. [ABSTRACT FROM AUTHOR]

Bioceramic coatings have been widely applied to biomaterials owing to their good biocompalibility and bioinert in clinic, however, their friability and limited mechanical properties on some medical devices restrict the applications. In this work, a copper-titanium metal coating as potential medical materials was prepared by physical vapor deposition (PVD) method, the ratio of copper-titanium atom was regulated by changing the different targets current. The phase structure, dimensions distribution and element content of the copper-titanium coating were determined by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and energy dispersive spectrometer(EDS), respectively. The adherence strength between substrate and coating was characterized via nano-scratch test, and cell proliferation was employed to evaluate the biocompatibility. The results showed that the coating with various ratios of copper-titanium atom was obtained successfully. The copper distribution was uniform in the coating. The proliferation of endothelial cell was enhanced at low copper concentrate and the increase of the copper content may improve cell toxicity. The adherence strength between the coating and substrate is favorable. The results of the present study indicated that the copper-titanium coating is suitable for surface modification of biomedical devices and may be a potential biomedical material. [ABSTRACT FROM PUBLISHER]

In recent years, magnesium alloys are attracting more and more attention as a kind of biodegradable metallic biomaterials, however, their uncontrollable biodegradation speed in vivo and the limited surface biocompatibility hinder their clinical applications. In the present study, with the aim of improving the corrosion resistance and biocompatibility, the magnesium alloy (AZ31B) surface was modified by alkali heating treatment followed by the self-assembly of 3-aminopropyltrimethoxysilane (APTMS). Subsequently, poly (ethylene glycol) (PEG) and fibronectin or fibronectin/heparin complex were sequentially immobilized on the modified surface. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that the above molecules were successfully immobilized on the magnesium alloy surface. An excellent hydrophilic surface was obtained after the alkali heating treatment while the hydrophilicity decreased to some degree after the self-assembly of APTMS, the surface hydrophilicity was gradually improved again after the immobilization of PEG, fibronectin or fibronectin/heparin complex. The corrosion resistance of the control magnesium alloy was significantly improved by the alkali heating treatment. The self-assembly of APTMS and the following immobilization of PEG further enhanced the corrosion resistance of the substrates, however, the grafting of fibronectin or fibronectin/heparin complex slightly lowered the corrosion resistance. As compared to the pristine magnesium alloy, the samples modified by the immobilization of PEG and fibronectin/heparin complex presented better blood compatibility according to the results of hemolysis assay and platelet adhesion as well as the activated partial thromboplastin time (APTT). In addition, the modified substrates had better cytocompatibility to endothelial cells due to the improved anticorrosion and the introduction of fibronectin. The substrates modified by fibronectin or fibronectin/heparin complex can significantly promote endothelial cell adhesion and proliferation. Taking all these results into consideration, the method of the present study can be used for the surface modification of the magnesium alloy to simultaneously impart it better corrosion resistance, favorable blood compatibility and good cytocompatibility to endothelial cells. [ABSTRACT FROM AUTHOR]

Bio-inorganic films and drug-eluting coatings are usually used to improve the hemocompatibility and inhibit restenosis of vascular stent; however, above bio-performances couldn't combine together with single materials. In the present study, we reported a simple approach to fabricate a metal film with the aim of imparting the stent with good blood compatibility and accelerating endothelialization. The films with various ratios of Cu and Ti were prepared through the physical vapor deposition. Phase structure and element composition were investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The releasing volume of copper ion in Cu/Ti film was determined by immersing test. The hemolysis ratio, platelet adhesion and clotting time were applied to evaluate the hemocompatibility. The proliferative behaviors of endothelial cells and smooth muscle cells under certain copper concentration were investigated in vitro and in vivo. Results indicated that copper-titanium films exhibited good hemocompatibility in vitro; however, the increase of Cu/Ti ratio could lead to increasing hemolysis ratio. Endothelial cells displayed more proliferative than smooth muscle cells when the copper concentration was < 7.5 μg/ml, however both cells tended to apoptosis to some degree when the copper concentration was increased. The complete endothelialization of the film with low copper in vivo was observed at the 2nd week, indicating that the copper-titanium film with the lower copper concentration could promote endothelialization. Therefore, the inorganic copper-titanium film could be potential biomaterials to improve blood compatibility and accelerating endothelialization of vascular stents. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the noncovalent functionalization of multi-walled carbon nanotubes (MWCNTs) by an aromatic chemical, 1-pyrenebutyric acid N-hydroxysuccinimide ester (PANHS), and produced four protein- (fibrinogen, γ-globulin, hemoglobin, and fibronectin) protected gold nanoparticles (AuNPs) by a simple strategy. The formation of protein-protected AuNPs was evidenced by UV–vis spectra, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), the successful chemical modification of MWCNTs with PANHS was identified by XPS and Raman spectra, and the MWCNT–AuNP hybrids were observed by TEM. We concluded that proteins can mediate the assembly of protein-protected AuNPs on PANHS-functionalized MWCNTs. Proteins, as an intermediate that can react with both MWCNTs and AuNPs, play a significant role for mediating the formation of different hybrids based on MWCNTs. This work provides a simple and potent strategy to prepare CNT–NP hybrids by using the interaction between CNTs and biomacromolecules, and on the other hand provides a potential application of protein-protected metallic NPs for preparing novel nanomaterials. [Copyright &y& Elsevier]

[Display omitted] • A multifunctional coating was successfully prepared on the magnesium alloy surface. • The modified magnesium alloy has excellent hydrophilicity and corrosion resistance. • The multifunctional coating can appreciably enhance hemocompatibility and cytocompatibility of the magnesium alloy. • The modified magnesium alloy displayed better antibacterial activities due to the existence of Zn2+ and chitosan. Magnesium alloy represents one of the most potential biodegradable vascular stent materials due to its good biodegradability, biocompatibility and suitable mechanical properties, whereas the rapid degradation in physiological environment and the limited biocompatibility remain the challenges. In this study, graphene oxide (GO) was firstly functionalized by chitosan (GOCS), followed by loading zinc ions and propranolol to obtain GOCS@Zn/Pro complex, which was finally covalently immobilized on the self-assembled modified magnesium alloy surface to enhance the corrosion resistance and biocompatibility. The multi-functional coating can significantly improve the corrosion resistance and reduce the degradation rate of the magnesium alloy. Furthermore, the coating can significantly inhibit platelet adhesion and activation, reduce hemolysis rate, prolong activated partial thromboplastin time (APTT), and thus improve the blood compatibility of the magnesium alloy. In addition, the modified magnesium alloy can not only significantly promote the endothelial cell adhesion and proliferation, up-regulate the expression of vascular endothelial growth factor (VEGF) and nitric oxide (NO), but also endow the materials with good antibacterial properties. Therefore, the method of the present study can be used to modify magnesium alloy stent materials to simultaneously enhance corrosion resistance and blood compatibility, promote endothelialilization, and inhibit infections. [ABSTRACT FROM AUTHOR]

• The complex of chitosan and zinc ions (CS/Zn) was coated on TiO 2 nanotubes. • The CS/Zn coating can enhance osteoblast growth and up-regulate alkaline phosphatase and osteocalcin expression. • The coating can significantly improve the osteogenesis and osteointegration of the titanium surface. In this study, the regular nanotube array was firstly prepared on the titanium surface by anodization, and then the complex of chitosan and zinc ions (CS/Zn) was immobilized on the surface to improve the biocompatibility. The nanotubes had excellent hydrophilicity; however, the hydrophilicity was reduced after the preparation of CS/Zn coating. The CS/Zn coating can not only significantly promote the adhesion and proliferation of osteoblasts, but also up-regulate the alkaline phosphatase (ALP) and osteocalcin (OCN) expression of the osteoblasts. Therefore, the method of this study can be used to improve the osteogenesis and osteointegration of titanium surface. [ABSTRACT FROM AUTHOR]

Osteogenic and antibacterial activities are two basic requirements for orthopedic implants. The present study mainly focused on the investigation of the osteoblast behaviors and antibacterial activities of Sr/Ag-incorporated titanium dioxide (TiO 2) nanotube array (TNT) on the titanium surface. To this end, the Sr-incorporated TNT was firstly fabricated on the titanium surface by electrochemical anodization and hydrothermal treatment, and then Ag nanoparticles (AgNPs) were incorporated onto the nanotubes by reduction of the adsorbed Ag+ through ultraviolet (UV) irradiation. The TiO 2 nanotubes had excellent hydrophilicity and Sr incorporation can further enhance the hydrophilicity; however, the AgNPs loading could slightly increase water contact angle. The release of Sr2+ can not only promote osteoblast adhesion, proliferation and mineralization, but also up-regulate the alkaline phosphatase (ALP) and osteocalcin (OCN) expression. The introduction of AgNPs on Sr-incorporated nanotubes did not significantly influence the osteoblast cell behaviors; however, it can effectively inhibit the adhesion and growth of Escherichia coli. Therefore, the method of the present study is expected to be suitable for surface modification of titanium surface to simultaneously enhance the osteo-bonding ability and antibacterial activities for bone repair. Unlabelled Image • The Sr ions and Ag nanoparticles were incorporated into titanium oxide nanotubes. • The Sr/Ag-incorporated nanotubes displayed excellent hydrophilicity. • The released Sr2+ from nanotubes can significantly enhance osteoblast growth. • The Ag+ from nanotubes endow the nanotubes with better antibacterial activity. [ABSTRACT FROM AUTHOR]

In this work, permeability of polymersomes was quantified by fluorescence enhancement. The polymersomes were prepared from poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL), and an acid-sensitive hydrophobic dye borondipyrromethene (BODIPY) was encapsulated into the membrane of polymersomes. H + from trifluoroacetic acid (TFA) would diffuse into the membrane of polymersomes to enhance the fluorescence of BODIPY. Intensity of the enhanced fluorescence could be used for quantifying the H + permeability of polymersomes. In addition, poly(ε-caprolactone) (PCL) was used to control the permeability ability of the membrane. Such quantitative information on the molecular diffusion of polymersomes is of fundamental importance to many of their potential applications, e.g., nanoreactors and drug delivery. [ABSTRACT FROM AUTHOR]

Owing to its excellent mechanical properties and biodegradability, magnesium-based alloys have become the research focus of biodegradable cardiovascular materials. However, the in vivo rapid degradation and poor surface endothelial regeneration and repair ability still restrict their clinical applications in the field of vascular stent materials. Nitric oxide (NO), as an endogenous gas signaling molecule, has multiple effects such as anticoagulation, promoting endothelialization, and anti-restenosis, showing a great potential for improving the performances of the cardiovascular materials and devices. In the present study, based on six-arm polyethylene glycol (PEG), a novel anticoagulant polymer (PEG-Hep-SeCA) with the catalytic release of NO was synthesized by successively introducing heparin and selenocystamine, followed by the immobilization of the as-synthesized polymer on the Zn2+-loaded polydopamine coating modified magnesium alloy surface to enhance the anti-corrosion and biocompatibility. The results demonstrated that the PEG-Hep-SeCA polymer coating was uniform and dense, which could not only obviously enhance the anticorrosion and the hydrophilicity of the magnesium alloy, but also selectively promote the bovine serum albumin (BSA) adsorption, thereby significantly improving the endothelial cells (ECs) growth and hemocompatibility. Additionally, the as-prepared polymer coating could effectively catalyze the release of NO from endogenous NO donors, which can further ameliorate the hemocompatibility and ECs growth, as well as enhance the expression of vascular endothelial cell growth factor (VEGF) and NO of the ECs. Therefore, this study opens a new way to construct the multifunctional coating with the ability of catalytic releasing NO on the surfaces of the magnesium-based alloys to simultaneously reduce the corrosion speed, improve the hemocompatibility, and accelerate the reendothelialization. [Display omitted] • A novel polymer with the catalytic release of NO was synthesized and immobilization on Mg alloy. • Corrosion resistance and blood compatibility of Mg alloy was enhanced by the coating. • The coating can up-regulate the expression of VEGF and NO in the endothelial cells. • The coating improved endothelial cells growth and adhesion on Mg alloy. [ABSTRACT FROM AUTHOR]

Titanium and its alloys are widely used in blood-contacting implantable and interventional medical devices; however, their biocompatibility is still facing great challenges. In the present study, in order to improve the biocompatibility and antibacterial activities of titanium, TiO2 nanotubes were firstly in situ prepared on the titanium surface by anodization, followed by the introduction of polyacrylic acid (PAA) and gentamicin (GS) on the nanotube surface by layer-by-layer assembly, and finally, zinc ions were loaded on the surface to further improve the bioactivities. The nanotubes displayed excellent hydrophilicity and special nanotube-like structure, which can selectively promote the albumin adsorption, enhance the blood compatibility, and promote the growth of endothelial cells to some degree. After the introduction of PAA and GS, although the superhydrophilicity cannot be achieved, the results of platelet adhesion, cyclic guanosine monophosphate (cGMP) activity, hemolysis rate, and activated partial thromboplastin time (APTT) showed that the blood compatibility was improved, and the blood compatibility was further enhanced after zinc ion loading. On the other hand, the modified surface showed good cytocompatibility to endothelial cells. The introduction of PAA and zinc ions not only promoted the adhesion and proliferation of endothelial cells but also upregulated expression of vascular endothelial growth factor (VEGF) and nitric oxide (NO). The slow and continuous release of GS and Zn2+ over 14 days can significantly improve the antibacterial properties. Therefore, the present study provides an effective method for the surface modification of titanium-based blood-contacting materials to simultaneously endow with good blood compatibility, endothelial growth behaviors, and antibacterial properties. [ABSTRACT FROM AUTHOR]

Vascular stent interventional therapy is the main method for clinical treatment of coronary artery diseases. However, due to the insufficient biocompatibility of cardiovascular materials, the implantation of stents often leads to serious adverse cardiac events. Surface biofunctional modification to improve the biocompatibility of vascular stents has been the focus of current research. In this study, based on the structure and function of extracellular matrix on vascular injury healing, a novel fibronectin-loaded poly-l-lysine/heparin nanoparticles was constructed for stent surface modification. In vitro blood compatibility evaluation results showed that the nanoparticles-modified surface could effectively reduce platelet adhesion and activation. In vitro cellular compatibility evaluation results indicated that the nanocoating may provide adequate efficacy in promoting the adhesion and proliferation of endothelial cells and thereby accelerate endothelialization. This study provides a new approach for the surface biological function modification of vascular stents. [ABSTRACT FROM AUTHOR]

Graphene is considered to be the core material for the next Industrial Revolution. In this work, graphene oxide (GO) was prepared using a modified Hummers method and, then, reduced to obtain graphene. NH–RGO and VC–RGO were obtained by reducing GO under the same conditions by using hydrazine hydrate and vitamin C, respectively. X-ray diffraction (XRD) spectra were employed to characterize its crystal structure. A scanning electron microscope (SEM) was used to observe the microstructure. The defect degree was determined using Raman spectra. The resistivity of the nitrogen-doped graphene was determined using a four-probe method. The results showed that the preparation time was shorter when vitamin C was used for the GO reduction; further, both the required temperature and the environmental pollution were low in this case. The characteristic peaks of XRD were more obvious than those of NH–RGO and had fewer defects. Raman spectroscopy showed that the G-peak of the prepared VC–RGO was narrower and the D-peak was weaker. Further, the Raman spectroscopy ID/IG was smaller and the structural performance was better. The sheet resistivity of VC–RGO of approximately 0.0163 Ωm was slightly smaller than that of NH–RGO (0.0171 Ωm). Therefore, the proposed method is an ideal method for replacing hydrazine hydrate to produce graphene. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Poly(ε-caprolactone) modified organic dyes was developed through the dyes initiating polymerization. • The enhanced fluorescence intensity was optimized by varying molecular weight of polymer. • The long term cellular imaging was realized by poly(ε-caprolactone) modification. Abstract Application of organic dyes is limited in biomedical fields due to the rapid self-quenching, poor stability and water solubility. In this work, polymer modified organic dyes is developed through the dyes initiating polymerization. The polymer length is studied by tuning the amount of monomer. With an optimal molecule weight of the polymer, the π–π stacking from π-conjugated organic fluorescent dyes and fluorescence quenching are inhibited, resulting in an enhancement of fluorescence intensity and photostability. Nanoparticles are further fabricated to be used for cell uptake based on the optimized organic dyes. Then, long term cellular fluorescence imaging is realized. This work highlights the potential of polymer modification to improve the performance of organic dyes and expand their applications. [ABSTRACT FROM AUTHOR]

Abstract Heparin-like membranes (CPBS) with nanofibers (approximate diameters of 100–500 nm) were prepared through electrospinning of a blended solution of carboxymethyl chitosan nanoparticle (CMCN, diameters 483 nm) and poly (vinyl alcohol) (CMCN/PVA) onto the surface of modified bacterial cellulose sulfate (BCS) membranes. SEM images confirmed that the CMCN were stretched to nanofibers during electrospinning. The presence of BCS on the collector of electrospinning machine increased the spinnability of CMCN/PVA solution. FTIR and XPS measurement revealed that there were SO 3 −, COO−, and OH groups on the surface of CPBS membrane, expressing structural similarity to heparin. CPBS membranes maintained hydrophilicity and the glutaraldehyde crosslinked CPBS membrane was stable in water. The clotting time and platelet adhesion experiments expressed the anticoagulant properties of CPBS. The APTT, TT and PT of CPBS increased up to 116.0%, 189.8%, and 50% than those of the plasma, (67.4 s, 16.2 s, and 48.4 s, respectively). No platelets adhered onto the surface of CPBS. An inflammatory response was determined according to activation of the macrophages seeded onto the membranes. Highlights • Carboxymethyl chitosan nanopowders (CMCN) were electrospun to nanofibers. • Heparin-like membranes were created from CMCN and bacterial cellulose sulfate (BCS). • Utilizing BCS as the receptor increases the electrospinning properties of CMCN/PVA blend. • Heparin-like membranes possess potent anticoagulant properties. [ABSTRACT FROM AUTHOR]

Diphenylalanine (FF), as the smallest unit and core recognition motif of β-amyloid (Aβ), could self-assemble into nanofibers, which induces an early onset of Alzheimer's disease (AD). Green/near-infrared fluorescent BODIPY probes were designed and synthesized to detect FF-assembly, providing unique insights into the chemical and molecular mechanism of Aβ aggregation and drug development for AD. [ABSTRACT FROM AUTHOR]

Owing to its excellent mechanical properties, two-dimensional (2D) titanium dioxide (TiO 2) nanosheets allow the introduction of huge strain and complex strain fields without fracture. It is confirmed theoretically and experimentally that the strain engineering of 2D TiO 2 nanosheets can be used as a rational and effective method to tune the atomic structure, lattice vibration, and optoelectronic properties to improve the performance related to the photocatalytic field. The TiO 2 nanosheets with a high exposure ratio of (001) crystal plane have special properties such as high carrier mobility, high optoelectronic activity, excellent chemical stability and so on. In this study, DFT calculation was used to explore the effect of mechanical strain on the anisotropic photoelectric properties of the defect-free and oxygen defect induced TiO 2 nanosheet, and the differences between them are compared. The results show that strain engineering can not only change their bandgap, electronic structure, and light absorption range but also produce some novel mechanical phenomena. The systematic study of the effect of strain engineering on the anisotropy of 2D TiO 2 nanosheets will help to design and develop new TiO 2 -based photocatalysts. • Strain engineering can improve the photoelectric performance of TiO 2 nanosheets. • Strain engineering changes the bandgap, electronic structure, and light absorption range. • The defect-free and oxygen defect inducedTiO 2 nanosheets show some commonalities in mechanics. • The TiO 2 nanosheetschange from indirect to direct bandgap under strain. [ABSTRACT FROM AUTHOR]

Late thrombus and restenosis caused by delayed endothelialization and insufficient biocompatibility of polymer coating continue to be the greatest limitations of drug-eluting stents. In this study, based on the specific structure of vascular basement membrane, a novel biomimetic nano-coating was constructed by incorporating laminin into electrostatic-assembled heparin/poly- l -lysine nanoparticles. Alteration of heparin and poly- l -lysine concentration ratio in a certain range has no significantly influence nanoparticle size, uniformity and stability, but may affect the chemical property and subsequently the binding efficiency to dopamine-coated titanium surface. By use of this feature, four different nanoparticles were synthesized and immobilized on titanium surface for creating gradient nanoparticle binding density. According to in vitro biocompatibility evaluation, the nanoparticle modified surfaces were found to effectively block coagulation pathway and reduce thrombosis formation. Moreover, NP10L and NP15L modified surface with relatively low heparin exposing density (4.9 to 7.1 μg/cm2) showed beneficial effect in selective promoting EPCs and ECs proliferation, as well as stimulating cell migration and NO synthesis. [ABSTRACT FROM AUTHOR]

Based on the theory of plate and shell mechanics, single TiO 2 nanoribbon and nanotube were abstracted into a two-dimensional (2D) thin plate model and cylindrical shell model respectively. The mechanical behavior under load in the corresponding working environment was discussed, and the corresponding continuum equivalent mechanical model and mechanical behavior were established and theoretically calculated, respectively. Combined with the measured results of the atomic force microscope (AFM), the theoretical and experimental results are compared to verify the rationality of the theoretical model. Herein, the constitutive equations and solution approaches are given, and the reliability of the theoretical model is confirmed by the measured results of AFM, which could provide an important basis for the application of nanodevices or structures based on TiO 2 nanoribbons or nanotubes. • The elastic behavior of single TiO 2 nanobelt and nanotube was studied. • The experimental results verify the rationality of the theoretical model. • This work provides a basis for the applications of nano-TiO 2 in nanodevices. [ABSTRACT FROM AUTHOR]

Bipolar electrochemistry is a promising technology especially in the fields of micro- and nanoscience, but it does not receive enough attention at present. In this paper, bipolar electrochemistry was successfully employed to fabricate TiO 2 nanotubes with the diameter, length and composition gradients on titanium foils (as bipolar electrodes, BPE) within an applied voltage range of 50–120 V. The formation mechanism of the nanotube gradients and the role of the interface potential difference between BPE and the electrolyte on the forming driving force were thoroughly discussed. The results showed that the TiO 2 nanotubes geometries could readily be controlled by adjusting the location on BPE and the applied voltages. The largest diameter and tube length occurred near the edge of BPE anode and then decreased with the distance away, but increased with the applied voltages. However, at certain locations, 35 mm away from the edge of BPE anode at 120 V, 30 mm at 100 V, 25 mm at 75 V and 15 mm at 50 V, massive little cylindrical oxides, rather than hollow nanotubes began to appear. The formation mechanism of the gradient nanotubes was generalized into the filed-assisted oxidation, chemical and field-assisted dissolution, and the synergy of two processes, which corresponded to three stages of the current density-time curves, the initial exponential drop, then rapid rise, and subsequent increase at different rates at 50–120 V, respectively. The average current density was also increased with an increase of the applied voltage. The interface potential difference E between the electrolyte and BPE titanium, instead of the applied voltages E total , essentially determined the driving force of anodic actions, leading to the formation of TiO 2 nanotube gradients. Since E was less than E total , the largest diameter and length of nanotubes were less than those in conventional anodization at the same applied voltages. However, at 30 V, the insufficient interface potential difference E cannot bring about hollow tubular structure on the whole BPE titanium. This study on the fabrication and formation mechanism of the gradient TiO 2 nanotubes will provide important scientific values and engineering application prospects, such as in screening the performance of catalytic, sensing and biomedical materials, or steering the molecular or macroscopic motion. [ABSTRACT FROM AUTHOR]

Highly photostable conjugated polymer based nanoprobe, poly(para-phenylene ethynylene), had been developed. Tumor targeting ligands folate modification made those nanoprobes to be easily and selectively taken up by cells. By grafting extended polyester side chain acting as the molecular insultors, the interchain energy transfer by isolation of conjugated polymer backbones was able to minimize, which led to reduction of π-π stacking, resulting in the quantum yield increased accordingly from 0.14% up to 36%. This method of polymer modification led to highly fluorescent functionalized nano-poly(para-phenylene ethynylene). Highly photostable conjugated polymer based nanoprobe, poly(para-phenylene ethynylene), had been developed. By grafting extended polyester side chain acting as the molecular insultors, the interchain energy transfer by isolation of conjugated polymer backbones was able to minimize, which led to reduction of π-π stacking. This method of polymer modification led to highly fluorescent functionalized nano-poly(para-phenylene ethynylene). [Display omitted] 1. Poly(para-phenylene ethynylene) (PPEs) was developed into highly photostable conjugated polymer nanoprobe. 2. Tumor targeting ligands folate modification made PPEs nanoprobes to be easily and selectively taken up by cells. 3. By grafting polyester side chain acting as the molecular insultors, the QY of PPEs nanoprobes increased 257 times. 4. Polymer modification could improve the fluorescent properties of dyes and improve them applied in more fields. [ABSTRACT FROM AUTHOR]

The biocompatibility of currently used coronary artery stent is still far from perfect, which closely related to insufficient endothelialization and thrombus formation. In this study, heparin, fibronectin and VEGF were immobilized on Ti surface to construct a multifunctional microenvironment with favorable properties to inhibit thrombosis formation and promote endothelialization simultaneously. The microenvironment on Ti surface was characterized in detail and demonstrated that the Hep/Fn/VEGF biofunctional coating was constructed successfully on Ti surface. The influence of surface properties such as chemical composition, roughness, hydrophilicity, and binding density of biomolecules on the performances of hemocompatibility and cytocompatibility was evaluated and discussed. Modified surface significantly enhanced the AT III binding density and prolonged the clotting time. In vitro platelet adhesion and activation assays further proved that the modified surface presented favorable anti-coagulant property. In addition, the proliferation of endothelial progenitor cells (EPCs) and endothelial cells (ECs) on the Hep/Fn/VEGF biofunctional coating was significantly promoted. In conclusion, the Hep/Fn/VEGF biofunctional coating was successfully constructed with desirable anticoagulant and endothelialization supporting properties. This work may provide a promising approach for biofunctional surface modification of coronary artery stent to acquire a desired multifunctional microenvironment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphene oxide and titanium dioxide were combined to get RGO@TiO 2 hybrid filler. • RGO@TiO 2 hybrid filler is used to enhance silk fibroin (RSF) biomaterials. • RGO@TiO 2 hybrid filler has a better reinforcing effect than the single filler. • RGO@TiO 2 endows RSF mat with good biocompability and antibacterial property. • The composite mat can be a potential candidate for tissue engineering. Reduced graphene oxide/titanium dioxide (RGO@TiO 2) hybrid nanoparticle was synthesized and used as a filler to study the synergistic effects on electrospun regenerated silk fibroin (RSF) mats. The incorporation of the hybrid filler increased the average diameter of RSF fibers, but decreased the content of β-sheet conformation. The breaking strength of RSF/RGO@TiO 2 composite mat increased by 220%. Moreover, the composite mat supported the growth and expansion of cells and had a good antibacterial property. This study may provide a new development perspective of multifunctional nanocomposite based on RGO@TiO 2 hybrid filler. [ABSTRACT FROM AUTHOR]

• Titanium dioxide nanotube arrays of different diameters were prepared by anodization. • Titanium dioxide nanotubes with smaller diameters have better biocompatibility. • The anatase has better biocompatibility than amorphous titanium dioxide. Titanium dioxide nanotube arrays (TNTAs) have attracted extensive attention in the fields of biomaterials and biomedicine due to their unique tubular structure and good biocompatibility. In this paper, TNTAs with different nanotube diameters and lengths were in situ prepared on the titanium surface by the anodic oxidation, and their crystal structures were further changed by annealing treatment. The effects of TNTAs with different diameters and crystals on the blood compatibility and endothelial cell behaviors were investigated. The results showed that TNTAs with the diameter of 30∼90 nm can be obtained by controlling the anodization voltage, and annealing treatment did not obviously change the diameters and lengths of the nanotube arrays. However, annealing treatment can transform the amorphous TNTAs into the anatase structure. The diameter and crystal structure of the nanotube arrays played a key role in the surface wettability and protein adsorption. The nanotube array with larger diameter displayed better surface hydrophilicity as compared to the pristine titanium, and annealing treatment further enhanced the hydrophilicity. As compared to the pristine titanium, the nanotube array structure had the characteristic of selective protein adsorption, and the nanotube array can promote the bovine serum albumin (BSA) adsorption and prevent the fibrinogen (FIB) adsorption, however, the increase of nanotube diameter could reduce BSA adsorption and increase FIB adsorption. Besides, the nanotube array with anatase structure can promote BSA adsorption while reduce FIB adsorption. Therefore, the TNTAs with smaller diameter and anatase crystal had good blood compatibility and cell compatibility, they can not only reduce platelet adhesion and hemolysis rate but also increase endothelial cell adhesion and proliferation. In conclusion, the nanotube arrays of the present study can be used to improve the cell compatibility and blood compatibility of the titanium implants. [ABSTRACT FROM AUTHOR]

Due to its good biodegradability and mechanical properties, magnesium alloys are considered as the ideal candidate for the cardiovascular stents. However, the rapid degradation in human physiological environment and the poor biocompatibility seriously limit its application for biomaterials. In the present study, a chitosan/heparinized graphene oxide (Chi/HGO) multilayer coating was constructed on the AZ31B magnesium alloy surface using layer-by-layer (LBL) method to improve the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectrum (RAMAN), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that a dense and compact Chi/HGO multilayer coating was fabricated on the magnesium alloy surface. The results of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), pH value changes and magnesium ion release suggested that the multilayer coating can significantly enhance the corrosion resistance of the magnesium alloy. Moreover, the Chi/HGO multilayer coating could not only significantly reduce the hemolysis rate and platelet adhesion, but also promote the adhesion and proliferation of endothelial cells. Therefore, the Chi/HGO multilayer coating can simultaneously improve the corrosion resistance and biocompatibility of the magnesium alloys. • A chitosan/heparinized graphene oxide multilayer coating is obtained by LBL. • The corrosion resistance of AZ31B is obviously improved by the coating. • The coating enhances the biocompatibility of the material surface. • This method can be used in the application of magnesium alloy in vascular stents. [ABSTRACT FROM AUTHOR]