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Dynamic regulation of cell-extracellular matrix (ECM)-material interactions is crucial for various biomedical applications. In this study, a light-activated molecular switch for the modulation of cell attachment/detachment behaviors was established on monolayer graphene (Gr)/n-type Silicon substrates (Gr/Si). Initiated by light illumination at the Gr/Si interface, pre-adsorbed proteins (bovine serum albumin, ECM proteins collagen-1, and fibronectin) underwent protonation to achieve negative charge transfer to Gr films (n-doping) through π-π interactions. This n-doping process stimulated the conformational switches of ECM proteins. The structural alterations in these ECM interactors significantly reduced the specificity of the cell surface receptor-ligand interaction (e.g., integrin recognition), leading to dynamic regulation of cell adhesion and eventual cell detachment. RNA-sequencing results revealed that the detached bone marrow mesenchymal stromal cell sheets from the Gr/Si system manifested regulated immunoregulatory properties and enhanced osteogenic differentiation, implying their potential application in bone tissue regeneration. This work not only provides a fast and feasible method for controllable cells/cell sheets harvesting but also gives new insights into the understanding of cell-ECM-material communications.

In this work, hydrothermal treatment and ultraviolet illumination (254 nm) were utilized to regulate the surface hydroxyls of titanium dioxide (TiO2) nanodots films. The effects on light-induced cell detachment behaviors were also investigated and discussed. Scanning electron microscopy, Raman, X-ray photoelectron spectroscopy and Circular dichroism were used to characterize the surface morphology, crystalline phase, surface composition and adsorption conformation of protein molecules. It was found that a combined process of ultraviolet illumination followed by hydrothermal treatment not only promoted cells adhesion but also showed the highest efficiency in light induced cell detachment. The reason is ascribed to that such process promotes the formation of terminal hydroxyl groups in TiO2 surface, and subsequently affect the adsorption conformation of protein molecules. This study indicated that such treatment could effectively modulate the contents of surface hydroxyl groups in different states. That shows much potential in optimizing the biological performance of TiO2 based biomaterials.

This study presents a convenient and versatile way to prepare functionalized composite polydopamine/titanium dioxide (PDA/TiO2) film on polystyrene (PS). First, polystyrene substrate was immersed in dopamine chloride solution, and then collosol containing TiO2 and water was spun on it, to produce uniform, continuous PDA/TiO2 composite films. The thickness of film was controllable by adjustment of the spin speed. It was found that the films were strongly adhered on the PS substrate, with peel strength and shear strength of 2.78 MPa and 37.78 MPa, respectively. After 20 min of ultraviolet (365 nm) illumination, over 90% of fibroblasts and 77% of osteoblasts detached from the PDA/TiO2 composite film. Additionally, the detached cells showed good viability, allowing further culture and applications. This preparation method could be widely applied for cell and cell sheet harvesting directly from PS-based culture wares.

Graphene (Gr)/poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) composite films were annealed by the photothermal effect that produced between near-infrared laser and graphene. Raman spectra, X-ray Diffraction (XRD), Fourier-Transformed Infrared Spectroscopy (FTIR), Differential scanning calorimetry (DSC) are used to characterize the crystalline state of Gr/P(VDF-TrFE) films. Further, piezoelectric coefficient d33 were to test polarization performance. Finally, the Bovine serum albumin (BSA) adsorption shows that annealing and polarization of Gr/P(VDF-TrFE) films are important for protein adsorption.

Surface potential of biomaterials can dramatically influence cellular osteogenic differentiation. In this work, a wide range of surface potential on ferroelectric polyvinylidene fluoride trifluoroethylene (P(VDF-TrFE)) films was designed to get insight into the interfacial interaction of cell-charged surface. The P(VDF-TrFE) films poled by contact electric poling at various electric fields obtained well stabilized surface potential, with wide range from −3 to 915 mV. The osteogenic differentiation level of cells cultured on the films was strongly dependent on surface potential and reached the optimum at 391 mV in this system. Binding specificity assay indicated that surface potential could effectively govern the binding state of the adsorbed fibronectin (FN) with integrin. Molecular dynamic (MD) simulation further revealed that surface potential brought a significant difference in the relative distance between RGD and synergy PHSRN sites of adsorbed FN, resulting in a distinct integrin-FN binding state. These results suggest that the full binding of integrin α5β1 with both RGD and PHSRN sites of FN possesses a strong ability to activate osteogenic signaling pathway. This work sheds light on the underlying mechanism of osteogenic differentiation behavior on charged material surfaces, and also provides a guidance for designing a reasonable charged surface to enhance osteogenic differentiation. Statement of Significance The ferroelectric P(VDF-TrFE) films with steady and a wide range of surface potential were designed to understand underlying mechanism of cell-charged surface interaction. The results showed that the charged surface well favored upregulation of osteogenic differentiation of MC3T3-E1 cells, and more importantly, a highest level occurred on the film with a moderate surface potential. Experiments and molecular dynamics simulation demonstrated that the surface potential could govern fibronectin conformation and then the integrin-fibronectin binding. We propose that a full binding state of integrin α5β1 with fibronectin induces effective activation of integrin-mediated FAK/ERK signaling pathway to upregulate cellular osteogenic differentiation. This work provides a guidance for designing a reasonable charged surface to enhance osteogenic differentiation.

Titanium and tantalum have been widely used for orthopedic and dental implant applications. However, how their inherent surface features regulate cellular osteogeneses still remains elusive. In this study, we engineered two distinct TiO2 and Ta2O5 nanorod films as the two model oxidized surfaces to investigate their intrinsic osteogenic behaviors. The results indicated that the distinctive gradient on zeta potential against pH, corresponding to the deprotonation rate, but not the hydroxyl amount or hydroxylation polarity played a critical role on the cellular osteogenic performance. TiO2 nanorod film with a higher deprotonation rate significantly upregulated the expression of osteogeneses-related gene and protein, comparing to that of Ta2O5 nanorod film. These results might be attributed to that surface with higher deprotonation rateprovided more Bronsted acid-base surface sites to react with protein residues, leading to a mild change in conformation of the absorbed proteins, and subsequently facilitating to trigger the integrin-focal adhesion cytoskeleton actin transduction pathway. This study, therefore, provides a new insight into the understanding the role of material surface hydroxylation on cellular osteogenic responses.

Mechanical stimuli at the bone-implant interface are considered to activate the mechanotransduction pathway of the cell to improve the initial osseointegration establishment and to guarantee clinical success of the implant. However, control of the mechanical stimuli at the bone–implant interface still remains a challenge. In this study, we have designed a strategy of a magnetically responsive coating on which the mechanical stimuli is controlled because of coating deformation under static magnetic field (SMF). The iron oxide nanoparticle/mineralized collagen (IOP-MC) coatings were electrochemically codeposited on titanium substrates in different quantities of IOPs and distributions; the resulting coatings were verified to possess swelling behavior with flexibility same as that of hydrogel. The relative quantity of IOP to collagen and the IOP distribution in the coatings were demonstrated to play a critical role in mediating cell behavior. The cells present on the outer layer of the distributed IOP-MC (O-IOP-MC) coating with a mass ratio of 0.67 revealed the most distinct osteogenic differentiation activity being promoted, which could be attributed to the maximized mechanical stimuli with exposure to SMF. Furthermore, the enhanced osteogenic differentiation of the stimulated MC3T3-E1 cells originated from magnetically actuated mechanotransduction signaling pathway, embodying the upregulated expression of osteogenic-related and mechanotransduction-related genes. This work therefore provides a promising strategy for implementing mechanical stimuli to activate mechanotransduction on the bone–implant interface and thus to promote osseointegration. Statement of Significance The magnetically actuated coating is designed to produce mechanical stimuli to cells for promoting osteogenic differentiation based on the coating deformation. Iron oxide nanoparticles (IOPs) were incorporated into the mineralized collagen coatings (MC) forming the composite coatings (IOP-MC) with spatially distributed IOPs, and the IOP-MC coatings with outer distributed IOPs (O-IOPs-MC) shows the maximized mechanical stimuli to cells with enhanced osteogenic differentiation under static magnetic field. The upregulated expression of the associated genes reveals that the enabled mechanotransduction signaling pathway is responsible for the promoted cellular osteogenic differentiation. This work therefore provides a promising strategy for implementing mechanical stimuli to activate mechanotransduction on the bone–implant interface to promote osseointegration.

Light-induced surface potential have been demonstrated as an effective bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation regulator. However, traditional bone repair implants almost were weak or no light-responsive. Fortunately, surface modification was a feasible strategy to realize its light functionalization for bone implants. Herein, a graphene oxide (GO)/titanium dioxide (TiO2) nanodots composite coating on the surface of titanium (Ti) implant was constructed, and GO was reduced to reduced graphene oxide (rGO) with the method of UV-assisted photocatalytic reduction. After rGO deposited on the surface of TiO2, a heterojunction formed at the interface of rGO and TiO2. With visible light illumination, positive charges accumulated on the surface of rGO/TiO2 film, and performed as a positive surface potential change. The light-induced surface potential which was generated under proper light intensity is harmless to the cell adhesion and proliferation behavior, but presented a good BMSCs osteogenic differentiation promoting effect, and the activation of the voltage-gated calcium channels through surface potential and the promotion of the adsorption of osteogenic growth factors could be the reason. This work given a new insight of the modification for Ti implant with a light-induced surface potential, and shows potential application for bone regeneration on the clinical practice through light stimulation.

A series of Ni1-xCux/Sm-doped ceria (Ni1-xCux/SDC) anodes have been prepared through introducing a soluble pore former with the co-pressing and co-sintering process. Uniform hierarchical porous microstructures are formed in Ni0.9Cu0.1/SDC anode with interconnected large pores of 2–5 μm and 100–300 nm small pores on the wall. The solid oxide fuel cell (SOFC) based on such anode exhibits exceptional electrochemical catalytic activity for dry CH4 oxidation and a maximum power density of 379 mW cm−2 is acquired at 600 °C. Durability test results show only 2.4% power density drop is observed after 72 h operation under a constant cell voltage of 0.5 V. The results have demonstrated that the optimization of anode microstructures is an effective way to improve the performance and long-term stability of Ni1-xCux alloy-based anode-supported SOFC.

In the process of biomaterials mediated bone regeneration, rhBMP-2 delivery at efficient dose in sustained kinetics is crucial for promoting cell osteogenic differentiation. Meanwhile, surface morphology of the biomaterials could regulate cellular responses as well as strengthen the rhBMP-2 interaction with cells for better bone induction. Herein, TiO2 nanorod films with varied mesoporous bioactive glass (MBG) incorporation amount were designed to strengthen the efficacy of rhBMP-2, basing on optimized loading/release behaviors and surface nanostructure cooperatively. The MBG incorporation improved rhBMP-2 loading amount and regulated its release behavior. Consequently, the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) on the incorporated films was extremely enhanced, and the incorporated nanorod film with 200nm MBG thickness exhibited the best osteoinduction effect. However, MBG film and the incorporated nanorod film had the same loading amount of rhBMP-2, the latter showed a much higher expression of 7-day osteogenic differentiation index than the former, which could be attributed to the synergistic effect of optimized rhBMP-2 release behavior and surface morphology. The MBG incorporated TiO2 nanorod films here presents a promising strategy for enhancing osteoinduction through optimized rhBMP-2 release behavior.

In this work, mineralized collagen coatings with different loading quantity of bovine serum albumin (BSA) were prepared via in situ electrochemical deposition on titanium substrate. The microstructure and BSA loading quantity of the coatings could be controlled by the electrochemical deposition parameters, such as deposition potential, BSA concentration and its adding sequence in the electrolyte. The BSA loading quantity in the coatings was obtained in the range of 0.0170-0.173mg/cm(2), enhancing the cell adhesion and proliferation of the coatings with the simultaneous release. The distinct release behaviors of BSA were attributed to their gradient distribution with different mineralization degrees, which could be adjusted by the deposition process. These results suggest that in situ electrochemical deposition is a promising way to incorporate functional molecules into the mineralized collagen coatings and the mineralized BSA/collagen coatings are highly promising for improving the rhBMP-2 loading capability (1.8-fold).

High performance of biomaterial surfaces provides a sound basis to mediate cellular growth behavior. In this work, we attempted to incorporate both positive and negative magnetostriction particles of CoFe2O4 (CFO) and TbxDy1−xFe2 alloy (TD) into piezoelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) for forming high magnetoelectric effect films, on which osteogenic differentiation could be dynamically mediated by a magnetic-field-induced surface potential (φME).The negatively poled film with TD/CFO volume ratio of 1:4 (1T4C) showed a highest magnetoelectric effect with φME of −171 mV at 2800 Oe. Compared with CFO/P(VDF-TrFE) and TD/P(VDF-TrFE) films, the φME increased about 213% and 173%, respectively. This could result from that P(VDF-TrFE) dipole domains receive a larger off-axial stress caused by the distribution characteristic of CFO and TD in P(VDF-TrFE), consequently to facilitate P(VDF-TrFE) dipole domain rearrangement. When MSCs were cultured on 1T4C film for 7 or 14 days, the magnetic actuation was setup to begin at the 4th or 8th day after the culture. The 7-day osteogenic differentiation was hardly affected for magnetic actuation at 4th day, moreover, the 14-day differentiation was significantly enhanced for magnetic actuation at 8th day. The enhancement appears just at a relatively late period of the cell growth, probably because the cells need a steady change in cell membrane potential to disassociate pairs of β-catenin and E-cadherin and activate osteogenic-related signaling pathway. This work could provide an alternative way to promote performance for magnetoelectric materials, and get insight into understanding of interactions of surface potential with cells.

Anatase TiO2 nanodot films have been found to be able to release cells under light illumination with excellent efficiency and safety. In the present study, we investigated the effects of rutile contents in TiO2 nanodot films on such light induced cell detachment behavior. The results showed that TiO2 nanodot films with different contents of rutile phase have been prepared successfully. The content of rutile phase increased with the increase in calcination temperature. All films possessed good cell adhesion but there was a decrease in cell proliferation with the increasing content of rutile phase. Single cell detachment assay showed that the films with high rutile contents (calcined at 900 °C and 1100 °C) showed better cell detachment performance. That was ascribed to the changes of the secondary structure of extracellular proteins adsorbed on the nanodot surface after ultraviolet (365 nm, UV365) illumination. In addition, cell sheets detached through UV365 illumination maintained high activity and could be further used in tissue engineering. The present work showed that the existence of rutile phase is helpful in cell detachment behavior and it could be utilized to optimize light-induced cell detachment behavior. Statement of Significance This work discovers that the presence of rutile phase in TiO2 nanodot films could improve the light-induced cell detachment behavior, although rutile phase is inferior to anatase phase on light induced superhydrophilicity. That strongly supported that the behaviors of adsorbed proteins are crucial in acquiring cell sheet with light illumination. In fact, the state and behavior of adsorbed protein greatly affect the interaction between biomaterials and living cells. Therefore, we consider this work is not only important in harvesting cells or cell sheets through light illumination, but also helpful in further understanding of interaction between biomaterials and cells.

For orthopedic implant coatings, excellent biological performance and anti-infective property have been both increasingly required for implantation surgery. In this work, TiO 2 nanorod films with good cellular responses and mesoporous bioactive glass (MBG) with good drug loading and release ability were adopted, and MBG-incorporated TiO 2 nanorod films were prepared by the sol–gel technique. The effects of TiO 2 nanorod density and MBG composition on the formation of the incorporated films were investigated. The results show that T-MBG (SiO 2 /CaO/P 2 O 5 /TiO 2 = 80/5/5/10) tightly cohered to TiO 2 nanorods in the films, and the degree of T-MBG incorporation ranged from about 100 nm to 300 nm of exposed TiO 2 nanorods in height. T-MBG incorporation had a positive role in the cytocompatibility of the films. Importantly, T-MBG incorporation improved greatly the drug release behavior of the TiO 2 nanorod films. The present work provides an approach to build organized nanostructure films on implant surfaces with satisfactory biological performance and essential anti-infective ability.

Europium (Eu) doped TiO 2 nanodot films were prepared through a phase-separation-induced self-assembly method. Eu was doped to impart the nanodots with luminescence property so that the protein adsorption could be in situ characterized quantitatively. Bovine serum albumin (BSA) was adsorbed on the surface of Eu-doped titanium nanodot films. It was found that the photo luminescence intensity at 616 nm decreased with the increase of BSA adsorption time. Also, Eu-doped TiO 2 nanodot films showed good biocompatibility. These results suggested that Eu-doped TiO 2 nanodot films could provide a feasible in situ way to evaluate protein adsorption if prepared on the surface of bioimplants.

Light-induced cell detachment on the substrate of TiO 2 nanodots has been proved to be a safe and attractive method for cell harvesting in tissue engineering. In order to improve the cell release efficiency, bioinert platinum with excellent charge transport loading in biocompatible graphite was prepared. 20 wt.% Pt/C powder showing excellent electrical, chemical and bioactive properties was incorporated to a TiO 2 system. We investigated the biocompatibility of Pt/C–TiO 2 composite films with different amounts of Pt/C with C/tetrabutyl titanate molar ratio varying from 0 to 0.42. The adhesion and proliferation rates of pre-osteoblastic MC3T3-E1 cells (mouse calvaria-derived) on the films prepared with the highest C/TiO 2 molar ratio are higher than that of the pure TiO 2 and other films, indicating a Pt/C dose-dependent effect. It is shown that the detachment efficiency of MC3T3-E1 cells depends on Pt/C amount and UV illumination time. Moreover, films prepared with C/tetrabutyl titanate molar ratio of 0.42 showed 93% cell detachment ratio within 5 min of UV illumination, while bare TiO 2 films only reached 75%, indicating an improved cell release efficiency by the incorporation of Pt/C. However, an interesting phenomenon was found that longer illumination time showed lower detachment ratios to some extent, which is contrary to our previous work. It is believed that this work presents the improved cell detachment efficiency by the incorporation of Pt/C.

BaTiO 3 /Ni 0.5 Zn 0.47 Fe 2 O 4 ceramic composites with various compositions were sintered at different temperatures. It is found both the formation and electromagnetic properties of the composite ceramics are strongly dependent on the percolation transition of NZFO. As NZFO content x is low ( x =0.1 and 0.2), the density increases with increasing the sintering temperature T from 1220 °C to 1300 °C, while it decreases as x is high ( x =0.65, 0.75 and 0.85). It is ascribed to the mismatch between the densification of BTO and NZFO. Both the permeability and low-frequency permittivity of the composites exhibit typical percolation behaviors, which are appropriate to the Kirkpatrick׳s effective medium model with the percolation threshold f c ranging from 0.35 to 0.5. As x f c , the permeability varies little and the low-frequency permittivity decreases with increasing T , owing to the dominant control of nonmagnetic BTO and the decrease in the defects in BTO, respectively. In comparison, as x > f c , both the permeability and permittivity increase considerably with increasing T . By analyzing the magnetic and dielectric dispersion spectra, it is revealed they are attributed respectively to the enhancement of domain-wall motion and the increase in the grain conductivity of NZFO.

In this study, we investigated the differences between amorphous and anatase TiO2 at the biomolecular level which could explain differences in the osteoblast response on these surfaces. The number of surface hydroxyl groups in the TiOHT form on amorphous and anatase TiO2 was found to be the most important factor, resulting in adsorption of bovine serum albumin as a monolayer on amorphous TiO2 nanodots but as a multilayer on anatase TiO2 nanodots. The reason for this is that the presence of more TiOHT groups on amorphous TiO2 nanodots attracts more –NH3+ groups on BSA molecules, causing the conformation of surface-bound BSA molecules to differ from those adsorbed on anatase TiO2 nanodots. Fibronectin which is subsequently adsorbed on anatase TiO2 nanodots then retains a more active conformation for osteoblast adhesion and mineralization.

Controlling the formation of conductive particles to be nano-scale is important for achieving percolation effect in metal dispersed thin film composite to contribute extraordinary dielectric properties required for miniaturization of electronic devices. In this paper, lactic acid (LA) and citric acid (CA) were used as dual complexing agents to prepare a typical Ag nanoparticle dispersed PbTiO 3 (PTO) composite thin film by using a sol-gel method. The phase structure of the thin film and the coordination effect between complexing agent and metallic ions were investigated. It revealed that LA coordinated with Ti 4 + and Pb 2 + and CA coordinated with Ag + . Lead was fixed inside the gel network by LA and restricted to evaporate during heat treatment thus the pyrochlore phase was prevented from forming in the thin film. Ag + was coordinated by CA and the diffusion and thus aggregation of silver during gelation and annealing process were weakened. Silver nanoparticles dispersed in the PTO matrix formed with dual complexing agents of LA and CA introduced during the preparation process. The composite thin film of perfect perovskite phase with silver nanoparticles embedded was obtained at the molar ratio of LA/lead = 0.5 and CA/lead = 0.5. The dielectric constant of the thin film with silver nanoparticles is 5 times higher than that without silver nanoparticles.

Pb 0.4 Sr 0.6 (Ti 0.97 Mg 0.03 )O 2.97 (PST) thin films were deposited on ITO/glass substrates with (1 0 0)/(0 0 1) oriented Tb-doped-PbTiO 3 (Tb-PT) layer inserted by magnetron sputtering method at room temperature. And the PST thin film is well-crystallized in (1 0 0) direction at annealing temperature of 600 °C for 30 min. The oriented Tb-PT layer promotes a (1 0 0) orientation, restrains structural distortion and improves phase quality of PST thin film. The (1 0 0) oriented PST thin film has higher permittivity and lower dielectric loss compared with the randomly oriented one. The tunability of the PST thin film is dramatically improved by 90% compared to that of randomly oriented PST without Tb-PT inserting layer, from 33% for randomly oriented PST without the inserting layer to 62.66% for the oriented one with the inserting layer. It is attractable to be used in high quality dielectric tunable devices.

(100) Oriented (PbxSr1−x)TiO3 (PST) thin films were prepared on indium tin oxide coated glass substrates by sol–gel technique with rapid thermal processing. The dielectric permittivity and tunability of the thin films with different dispersion degrees of orientation were investigated in detail by characterizing the full width at half maximum of their (100) peak based on rocking curves at different annealing temperatures. Influence of orientation dispersion on dielectric properties was exhibited in the tunable dielectric thin films. It shows that the dielectric constant and hence the tunability of the sol–gel derived PST thin films are improved with the decrease in the dispersion degree of orientation of the perovskite phase other than the increase in the content of crystalline phase in the thin films. The dielectric constant (capacitance) and figure of merit of the oriented thin films are 3–6 times and 1 times higher than that of randomly oriented thin film respectively.

The (1 0 0) oriented (Pb,Sr)TiO3 (PST) thin films were prepared using terbium-doped lead titanate as inducing layer. Misfit strain of the PST thin films changed gradually along direction of thickness and with different compositions. Controlled by the strain, the Curie temperature was independent of the composition of the PST and the width of the Curie peak was broadened. The as-prepared PST thin films exhibited stable high dielectric tunability which was almost independent of composition as well as applied temperature. With the composition of PST changing from PST35 (PbxSr1−xTiO3 x = 0.35) to PST50, the room temperature tunability of the PST thin films maintains a stable value of about 40%. At a high applied temperature of 200 °C, the PST thin films still show a high tunability of about 35%. The strain-assisted control of the Curie temperature and the Curie peak width is attractive in designing high stable devices with high dielectric tunability.

Titanium dioxide (TiO 2 ) nanorods and calcium phosphate (CaP) composite coatings were prepared and characterized. TiO 2 nanorod films were grown on titanium substrates via a hydrothermal method. Then, calcium phosphate was deposited into TiO 2 nanorod films electrochemically in an aqueous electrolyte containing calcium and phosphorus species. As a result, CaP/TiO 2 nanorod coatings were obtained. The amount of calcium phosphate deposited could be controlled through varying temperature, voltage and duration. It was found that both the presence of calcium phosphate and UV treatment could affect the surface wettability of the composite coatings. A bovine serum albumin adsorption test showed that the protein adsorption ability of the composite coatings was also improved with the presence of calcium phosphate and UV treatment. Moreover, the presence of calcium phosphate could promote the deposition of bone-like minerals. It is suggested that such coatings may exhibit promising initial cellular responses and thus be a good alternate for bioactive coatings.

Hydroxyapatite (HA)/ZnO-nanorod composite coatings were fabricated on Si substrates in this work. ZnO nanorods were firstly grown on the substrate through a hydrothermal method, and then CaP precursor solution was spin-coated on the surface and fired to form HA/ZnO-nanorod composite coatings. The results showed that ZnO nanorods were grown on substrates and hydroxyapatite was deposited between nanorods, leading to a composite coating. The surface wettability of such coating could be adjusted through ultraviolet treatment, from rather hydrophobic to hydrophilic. Such coatings showed different protein adsorption property from both ZnO nanorod coating and HA coating. Also, a desirable Zn ion release ability was observed. Such coatings could be potentially applied as bioactive coatings on metallic bioimplant surface.

We investigated the use of TiO2 nanorod films to construct an instructive microenvironment for regulation of biological activity. Rutile TiO2 nanorod films were fabricated via a hydrothermal method. Heat treatment was used to adjust the atomic arrangement order degree of the nanorod surfaces. The influence of changes in the nanorod surface on the films was characterized. The results show that heated nanorod films were well crystallized and the nanorod surfaces had a regular atomic arrangement. Unheated nanorod films had a higher contact angle and lower sensitivity to UV illumination, and showed good capacity for protein adsorption at an early stage, which may lead to better cytocompatibility. The results provide an insight into construction of an appropriate microenvironment for interaction between biomaterials and cells.

A range of silica nanofibers with refined mesoporous microstructures were successfully synthesized via the combination of electrospinning and the sol–gel method. It was found that the concentration of nonionic surfactant Pluronic F127 (EO 106 PO 70 EO 106 ) significantly influenced the morphology and mesoporous structure of silica nanofiber. With the reduced F127/Tetraethyl orthosilicate (TEOS) mass ratio, from 0.28 to 0.14, the diameter of silica nanofibers decreased from 453 nm to 130 nm, and more importantly, the size and the orientation of the internal mesopores were remarkably regulated. It has therefore been a critical step forward to a new hierarchical silica fiber for modern optical and biomedical applications.

The phenomenon of light-induced cell detachment is reported. Mouse calvaria-derived, pre-osteoblastic (MC3T3-E1) cells were cultured on a TiO(2) nanodot-coated quartz substrate. After 20 min of UV365 illumination, over 90% of the cells would detach from the surface. Moreover, intact cell sheets could be obtained in the same way. It was found that the as-obtained cells showed good viability, and could be used for further culture processes and other applications. Also, biocompatibility and safety characterizations indicated that the use of TiO(2) nanodots and UV365 illumination was safe for such cell detachment. It is suggested that adsorbed extracellular matrix proteins play key roles in developing cell sheets and ensuring biocompatibility. The present light-induced cell detachment method demonstrates a promising way for rapid cell/cell sheet harvesting.

The Ag nanoparticle dispersed percolative PbTiO 3 ceramic thin film was prepared in situ by sol–gel method with excess lead introduced into a sol precursor. The influence of excess lead and the heat treatment time on the formation of Ag nanoparticles was investigated by energy dispersive X-ray spectra, scanning electron microscopy, X-ray diffraction, and ultraviolet–visible absorption spectra. Results showed that the excess lead introduced into the sol precursor was in favor of the crystallization of the thin film and in favor of formation of the perovskite phase without the pyrochlore phase. Lead-rich Ag–Pb alloy particles first formed in the thin films and then decomposed to become large numbers of Ag nanoparticles of about 3 nm in size in the thin films when the heat treatment time was longer than 2 min. The content of the Ag nanoparticles increased with increasing the heat treatment time. The percolative behavior appears typically in the Ag nanoparticle dispersed thin films. The dielectric constant of the thin film was about 3 times of that without Ag nanoparticles.

In order to inhibit carbon deposition in Ni/Sm-doped ceria (SDC) anode in a solid oxide fuel cell, copper was incorporated through both addition of preformed Ni 0.95 Cu 0.05 alloy and impregnation of Cu nitrate solution. It was found that besides those preformed Ni-based alloy grains, some Cu, which is actually Cu-rich alloy, attached preferentially on the surface of those Ni-based alloy grains as nanoparticles. Carbon deposition in such anode decreased significantly with the increasing amount of Cu-rich alloy nanoparticles. For anode with 10 wt.% Cu impregnation and 600 °C reduction, the carbon deposition was only 12.7 wt.% when exposed to dry methane for 2 h. In comparison, that was actually less than 1/10 of Ni 0.95 Cu 0.05 /SDC anode without any Cu impregnation. It is demonstrated that the existence of Cu rich alloy nanoparticles in Ni 0.95 Cu 0.05 /SDC anode could mitigate carbon deposition owing to the suppression of carbon nucleation and decrease of growth site.

(001)/(100) oriented PbTiO3 (PT) thin film is prepared on a non single crystal Indium Tin Oxide (ITO)/glass substrate by sol–gel method. The mechanism of orientation is investigated via dopant element, dopant amount, oxygen pressure of atmosphere, different type of substrate, different thickness of substrate, different sol concentration and blocking layer. By substituting 2% Zn2 +, or 2% Fe3 +, or 2% Co2 + ions in the Ti site of PT perovskite phase and heating at the oxygen-poor atmosphere, the PT thin film grown on the ITO(260 nm)/glass substrate forms well with (001)/(100) orientation. Moreover, this orientation phenomenon only appears when the solution concentration is below 0.1 mol/L. The orientation of PT which is attributed to the hybrid influences of defect dipole from the PT and the intrinsic electrostatic field from the ITO substrate is revealed. This work represents an important step toward controllable formation of oriented thin film on a non single crystal substrate.

We report the controlled hydrothermal growth of rutile TiO 2 nanorods on Si wafers by using an anatase TiO 2 nanodot film as an assisted growth layer. The anatase nanodot film was prepared on the wafer by phase-separation-induced self-assembly and subsequent heat-treatment at 500 °C. The nanodots on the wafer were then subjected to hydrothermal treatment to induce the growth of rutile TiO 2 nanorod films. The size and dispersion density of the resulting TiO 2 nanorods could be varied by adjusting the Ti ion concentration in the growth solution. The TiO 2 nanorods were of the rutile phase and grew in the [001] direction. The growth mechanism reveals that the growth of the rutile nanorods was wholly dependent on the existence of rutile TiO 2 seeds, which could be formed by the dissolution–reprecipitation of the anatase nanodots during hydrothermal treatment or under the high-temperature conditions of the subsequent heat-treatment of the as-prepared nanodots. In controlling the rutile nanorod growth, the anatase nanodots show more efficiency than a dense anatase film. Preliminary evaluations of the rutile nanorod films have demonstrated that the wettability changed from highly hydrophobic to superhydrophilic and that the photocatalytic activity was enhanced with increasing nanorod dispersion density.

Titanium silicide thin films and nanowires (NWs) were prepared on a glass substrate using the APCVD method. Gaseous SiH 4 and TiCl 4 were used as precursors for Si and Ti, respectively. TiSi 2 thin films were precipitated on the glass substrate first, and then single-crystal TiSi NWs were grown on the TiSi 2 thin films as-prepared by controlling the concentrations of the source gases, SiH 4 and TiCl 4 , without using any catalysts. The TiSi NWs were typically 1–2 μm long and 15–50 nm thick. The growth direction of the NWs was perpendicular to the (1 1 0) plane, in which a competition in growth rate among different crystallographic planes of the TiSi crystalline phase occurs. The oriented growth of the TiSi crystalline phases is responsible for the formation of the NWs.

Ti5Si3 thin films were coated on glass substrate by atmospheric pressure chemical vapor deposition method at different temperatures. Electrical and corrosion properties of the thin films were investigated. The results show that the electrical resistivity of the thin films decreases initially with the increase in deposition temperature. However, it increases with the further increase of the temperature. The lowest electrical resistivity of 107 μΩ⋅cm is obtained at 710 °C. The least corrosion rates of the thin films at 95 °C of 0.10 nm/min and 0.13 nm/min in 1 N and 10 N acid solution and of 0.33 nm/min and 6.55 nm/min in 1 N and 10 N alkali solution, respectively, are obtained by weight-loss measurement method. The corrosion mechanisms of the thin films were also discussed in detail.

In this work, a phase-separation-induced self-assembly (PSIA) approach was developed to prepare PbTiO 3 nanodots on substrates. Lead titanate nanodots on Si wafer were obtained through Marangoni instability induced phase separation and following heat-treatment. It was found that acetylacetone added in the precursor played important roles not only in the incorporation of Pb into the nanodots, but also in the phase separation process. The size and density of PT nanodots could be controlled through the concentrations of precursor and phase separation adjuster, i.e., tetrabutyl-titanate and polyvinylpyrrolidone. The nanodots size and density were from 10 nm to ∼100 nm and from 0.5 × 10 10 dots/cm −2 to 4.6 × 10 10 dots/cm −2 respectively. Such preparation provides a simple way to prepare titanate nanodots on substrate.

α-tricalcium phosphate (α-TCP), biphasic α/β-tricalcium phosphate (α/β-TCP) with different two phase ratio and β-tricalcium phosphate (β-TCP) powders were prepared by calcining an amorphous calcium phosphate (ACP) precursor at a temperature ranging from 800 to 900 °C. The microstructural characterization revealed that the particles in the monophasic and the biphasic TCP powders had about 1 μm in size, and agglomerated by 500 nm ones. In comparison with monophasic TCP powders, the dissolution–reprecipitation behaviors of the biphasic TCP powders in an acetate buffer solution with pH 5 were studied. The biphasic TCPs demonstrated a different behavior from the monophasic TCPs, including changes in morphology and crystalline phase. The unique behavior can be tailored by controlling the α-TCP content in the biphasic TCP powders.

Rutile TiO2 nanorod films have been successfully prepared on titanium substrate via a hydrothermal method using Tetra-n-butyl titanate as Ti source in the presence of concentrated hydrochloric acid. The effect of Ti substrate annealing treatment and adding of additional alkali metal chlorides in hydrothermal solution on the growth of TiO2 nanorod films has been studied using scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and water contact angle measurement. The growth mechanism of the TiO2 nanorods on Ti substrate has also been discussed. It has shown that the initial rutile film transformed from anatase promotes the nucleation and epitaxial growth of rutile TiO2 nanorods. The superior wettabilities of the TiO2 nanorods resulted from treatments of vacuum and ultraviolet show great potential for applications in orthopaedic, dental implants, and possible photocatalysis.

article i nfo Available online 21 January 2011 Magnesium-containing fluoridated hydroxyapatite (MgxFHA) coatings have been developed to improve the biological performances of fluoridated hydroxyapatite (FHA) coatings. The coatings are deposited on Ti6Al4V substrates via a sol-gel process. The interface between the coating and substrate is characterized by scanning electron microscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy for coating thickness, elemental distribution and chemical states. Pull-off test is used to evaluate the adhesion strength. The results show that the interdiffusion of elements happens at the coating/substrate interface. The incorporation of Mg ions into FHA coatings enhances the pull-off adhesion strength between the coating and the substrate, but no significant difference is observed with different Mg concentrations.

Herein, we report a photoinduced transition of hydrophobicity to high hydrophilicity of TiO2 nanodot films in applications of cell sheet engineering. A phase-separation-induced self-assembly process was adopted to prepare a TiO2 nanodot gel film on a substrate. Subsequently, a hydrothermal treatment (with ethanol/water at 140 °C for 2 h) was used to convert the nanodot gel film to TiO2 nanodot solid film. The resulting TiO2 dots were amorphous with adjustable size and density. The amorphous TiO2 nanodot film showed a conversion from a good hydrophobic surface, with a water contact angle (WCA) of 67.6 ± 2.0°, to a highly hydrophilic one, with a WCA of 5.3 ± 2.0° (i.e. almost superhydrophilic) after UV irradiation. A good reversibility was also observed.

Implants with antibiotic drug loaded bioactive coatings have been increasingly applied in orthopedic operations. Here we report the drug release behavior of gentamycin loaded chitosan/calcium phosphate coatings on titanium. Chitosan/calcium phosphate coatings with different component ratios and surface topographies were prepared by electrochemical deposition method. Our results showed that the drug release from these coatings was controlled by their component ratio and surface topography, and the former ratio played a more significant role. The present coatings could provide an effective way to create both good bioactivity and antibacterial activity.

Zinc-substituted tricalcium phosphate/fluoridated hydroxyapatite (ZnTCP/FHA) biphasic composite coatings and Zinc containing fluoridated hydroxyapatite (ZnFHA) coating were prepared on Ti6Al4V substrates through a modified sol–gel method. The release of zinc ions from these coatings was characterized through a designed cycled immersion test: the coatings were soaked in the TRIS solution with pH of 7.25 at 37 °C for 96 h (one cycle). This process was repeated twice with the solution refreshed at the end of the each cycle. The Zn concentrations were measured at a 24-hour interval during the first cycle and at the end of each cycle. The results indicated that ZnTCP/FHA coatings released Zn at a rather slow and sustained rate while ZnFHA coatings released Zn at a rapid and therefore unsustained rate. This Zn release behavior difference is attributed to the different chemical states of Zn in the coatings. The current results demonstrated that the designed biphasic composite approach could potentially be a good way to tailor the release of Zn through combinations of different Zn chemical states, with the durability of the coatings not impaired.

Highly (1 0 0)-oriented Pb 0.4 Sr 0.6 TiO 3 (PST40) thin films have been prepared on the Tb doped PbTiO 3 (PTT) thin film coated ITO/glass substrate by sol–gel technique. The PTT inducing layers are (1 0 0)-oriented and can help to control the orientation of PST40 thin films. Crystallization of the PST40 thin film with the PTT inducing layer is more perfect than that without PTT layer due to less distortion in the thin film. The dielectric tunability of the PST40 thin film with PTT layer therefore reaches 65%, which is 85% higher than that without PTT layer. The dielectric loss of the PST thin film is only 0.05. These results indicate that (1 0 0)-oriented Tb doped PbTiO 3 can be used as an inducing layer for highly (1 0 0)-oriented tunable materials on ITO/glass substrate.

Pb{sub 0.4}Sr{sub 0.6}TiO{sub 3} (PST) thin films doped with various concentration of Bi were prepared by a sol-gel method. The phase status, surface morphology and dielectric properties of these thin films were measured by X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance analyzer, respectively. Results showed that the thin films with the maximum dielectric constant and minimum dielectric loss were obtained for x=0.15. For x

Ferroelectric/ferrimagnetic PbTiO 3 /NiFe 2 O 4 composite thin films with nano-scale PbTiO 3 and NiFe 2 O 4 phases homogeneously dispersed in each other were synthesized by sol–gel in situ method. The phase structure and morphology of the composite thin films and their dielectric, ferroelectric and ferromagnetic properties were measured respectively in detail. Results show that the ferroelectric/ferrimagnetic composite thin film with PbTiO 3 and NiFe 2 O 4 phases is successfully synthesized at heat-treatment temperature of 850 °C. It is significantly isotropic due to the nanometer scale grain size of the constituent PbTiO 3 and NiFe 2 O 4 phases. A capacitance of 60–100 pF with a good frequency independence over the conventional applied frequency range, ferroelectric hysteresis loops with the applied electric field of 500 kV/cm, a saturation magnetization higher than 4.8 MT, and a coercive field of 5280 A/m with well suitable ferrimagnetic properties are obtained from the thin film with the composition ratio PbTiO 3 /NiFe 2 O 4 of 50/50 post heat-treated at 850 °C. The ferroelectric/ferrimagnetic composite thin film is desirable for multifunctional device application.

ZnO nanoflowers were grown on Si substrate through the adoption of a ZnO seed-layer with unique morphology and subsequent immersing in suitable growth medium. Depending on the ZnO seed-layers, ZnO nanostructures varied from nanosheets to nanoflowers. The ZnO nanoflower is composed of nanosheets with 20–30 nm in thickness. XRD results revealed a hexagonal phase of these nanostructures. The ZnO nanoflowers can exhibit strong UV and relatively weak visible luminescence at room temperature. The water wettability of the ZnO nanoflowers showed good hydrophilic property without UV illumination.

Porous NiO-Ce 0.8 Sm 0.2 O 1.9 (NiO-SDC) ceramics with homogeneous pore distribution were prepared using polystyrene (PS) spheres as pore templates. NiO-SDC powders were synthesized by a glycine-nitrate method, ultrasonically mixed with PS spheres in ethanol, dried and then pressed into green pellets. The pellets were sintered to yield porous NiO-SDC ceramics. The effects of the sintering temperature on the microstructure and mechanical strength of the ceramics were investigated. NiO-SDC ceramics sintered at 1200 and 1350°C have interconnected pore structures and high compression strength. When single cells were fabricated using porous NiO-SDC ceramics as anode-supported layers, the peak power density of the cells at 600°C was 333 and 353 mW·cm −2 for ceramics sintered at 1200 and 1350°C, respectively. The results indicated that these porous ceramic materials are promising for anode substrates for solid oxide fuel cells.

Well-defined crystalline dendritic structured lead selenide (PbSe) was prepared via a template-free, facile hydrothermal route using Pb(NO 3 ) 2 as the lead ion source, selenourea (CH 4 N 2 Se) as the selenide source at 150 °C for 24 h. The sample was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electronic microscopy (TEM). XRD patterns showed that phase-pure PbSe was produced. Novel PbSe dendritic structure is synthesized as indicated by SEM and TEM. The quality and composition of the products was determined with X-ray photoelectron spectroscopy (XPS). The influencing factors for the morphologies are discussed and the formation mechanisms are proposed. The studies on the corresponding photoluminescence (PL) properties of the dendritic structured PbSe were also carried out.

Uniformly distributed PbTiO 3 nanodots were successfully prepared by phase separation approach. A precursor sol film was first spin-coated on Si wafer and then spontaneously separated into two distinct phases owing to the Marangoni instability. PT nanodots with tailorable size and density were obtained after further heat treatment. X-ray diffraction analysis indicated that these nanodots showed a perovskite structure. An excellent room temperature field emission property of PbTiO 3 nanodots was observed: the minimum turn-on voltage was about 5.3 V/μm; while the emission current density reached about 270 μA cm −2 at an applied field of about 9.25 V/μm.

article i nfo Available online xxxx Magnesium (Mg) is a trace element in natural bone, its existence plays an important role in cell adhesion and bone formation. To improve the biological properties, Mg and fluorine (F) are simultaneously incorporated in hydroxyapatite (HA) to form MgxFHA coating on titanium alloy via sol-gel process. In vitro bioactivity of the coating is evaluated by examination of apatite precipitation on surface of the coatings during immersion in simulated body fluid. The chemical states of Mg and F in the coating are examined by X-ray photoelectron spectroscopy. Grazing incidence X-ray diffraction and scanning electron microscopy are employed for phase identification and surface morphology changes are compared after soaking in the SBF solutions for 7 to 28 days. The results show that both Mg and F ions are indeed incorporated into the HA crystal structure. The presence of F promotes Mg incorporation into the HA crystal structure. The presence of Mg makes the coatings more bioactive in promoting bone formation. However, at high Mg concentration, formation of β- TCMP (Mg substituted β-TCP) takes place.

In this work, pure Ba2Ti9O20 (B2T9) ceramics phases are prepared at 1300 °C after precursor solution combustion, powders calcination and sintering. The effects of incomplete combustion on B2T9 formation during the citrate solution combustion (CSC) process were studied. Different precursor solutions were designed and prepared to control the completeness of combustion. The results showed complete combustion product facilitates B2T9 formation; while incomplete combustion product, which is an inhomogeneous Ti-rich amorphous phase, affects the intermediate phase formation after calcining, and finally inhibits B2T9 formation.