Elimination of methicillin‑resistant Staphylococcus aureus biofilms on titanium implants via photothermally‑triggered nitric oxide and immunotherapy for enhanced osseointegration

Background:Treatment of methicillin-resistant Staphylococcus aureus(MRSA)biofilm infections in implant placement surgery is limited by the lack of antimicrobial activity of titanium(Ti)implants.There is a need to explore more effective approaches for the treatment of MRSA biofilm infections.Methods:Herein,an interfacial functionalization strategy is proposed by the integration of mesoporous polydopamine nanoparticles(PDA),nitric oxide(NO)release donor sodium nitroprusside(SNP)and osteogenic growth peptide(OGP)onto Ti implants,denoted as Ti-PDA@SNP-OGP.The physical and chemical properties of Ti-PDA@SNP-OGP were assessed by scanning electron microscopy,X-ray photoelectron spectroscope,water contact angle,photothermal property and NO release behavior.The synergistic antibacterial effect and elimination of the MRSA biofilms were evaluated by 2′,7′-dichlorofluorescein diacetate probe,1-N-phenylnaphthylamine assay,adenosine triphosphate intensity,O-nitrophenyl-β-D-galactopyranoside hydrolysis activity,bicinchoninic acid leakage.Fluorescence staining,assays for alkaline phosphatase activity,collagen secretion and extracellular matrix mineralization,quantitative real‑time reverse transcription‑polymerase chain reaction,and enzyme-linked immunosorbent assay(ELISA)were used to evaluate the inflammatory response and osteogenic ability in bone marrow stromal cells(MSCs),RAW264.7 cells and their co-culture system.Giemsa staining,ELISA,micro-CT,hematoxylin and eosin,Masson's trichrome and immunohistochemistry staining were used to evaluate the eradication of MRSA biofilms,inhibition of inflammatory response,and promotion of osseointegration of Ti-PDA@SNP-OGP in vivo.Results:Ti-PDA@SNP-OGP displayed a synergistic photothermal and NO-dependent antibacterial effect against MRSA following near-infrared light(NIR)irradiation,and effectively eliminated the formed MRSA biofilms by inducing reactive oxygen species(ROS)-mediated oxidative stress,destroying bacterial membrane integrity and causing leakage of intracellular components(P<0.01).In vitro experiments revealed that Ti-PDA@SNP-OGP not only facilitated osteogenic differentiation of MSCs,but also promoted the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2-phenotype(P<0.05 or P<0.01).The favorable osteo-immune microenvironment further facilitated osteogenesis of MSCs and the anti-inflammation of RAW264.7 cells via multiple paracrine signaling pathways(P<0.01).In vivo evaluation confirmed the aforementioned results and revealed that Ti-PDA@SNP-OGP induced ameliorative osseointegration in an MRSA-infected femoral defect implantation model(P<0.01).Conclusions:Ti-PDA@SNP-OGP is a promising multi-functional material for the high-efficient treatment of MRSA infections in implant replacement surgeries.

Sensitivity of Total-Dose Radiation Hardness of SIMOX Buried Oxides to Doses of Nitrogen Implantation into Buried Oxides

In order to improve the total-dose radiation har dness of the buried oxides(BOX) in the structure of separation-by-implanted-oxygen(SIMOX) silicon-on-insulator(SOI),nitrogen ions are implanted into the buried oxides with two different doses,2×10 15 and 3×10 15 cm -2 ,respectively.The experimental results show that the radiation hardness of the buried oxides is very sensitive to the doses of nitrogen implantation for a lower dose of irradiation with a Co-60 source.Despite the small difference between the doses of nitrogen implantation,the nitrogen-implanted 2×10 15 cm -2 BOX has a much higher hardness than the control sample (i.e.the buried oxide without receiving nitrogen implantation) for a total-dose irradiation of 5×104rad(Si),whereas the nitrogen-implanted 3×10 15 cm -2 BOX has a lower hardness than uhe control sample.However,this sensitivity of radiation hardness to the doses of nitrogen implantation reduces with the increasing total-dose of irradiation (from 5×104 to 5×105rad (Si)).The radiation hardness of BOX is characterized by MOS high-frequency (HF) capacitance-voltage (C-V) technique after the top silicon layers are removed.In addition,the abnormal HF C-V curve of the metal-silicon-BOX-silicon(MSOS) structure is observed and explained.

Effects of lanthanum ion-implantation on microstructure of oxide film formed on Co-Cr alloy

Isothermal and cyclic oxidizing behavior of Co-40Cr alloy and its lanthanum ion-implanted samples were studied at 1000 ℃ in the air by thermal-gravimetric analysis （TGA）. Scanning electronic microscopy （SEM） and transmission electronic microscopy （TEM） were used to examine the morphology and structure of oxide film after oxidation. Secondary ion mass spectrum （SIMS） method was used to examine the binding energy change of chromium caused by La-doping and its influence on the formation of Cr2O3 film. laser Raman spectrum was used to examine the stress changes within the oxide film. It was found that lanthanum implantation remarkably reduced isothermal oxidizing rate of Co-40Cr and improved anti-cracking and anti-spalling properties of Cr2O3 oxide film. The reasons for the improvement were mainly that the implanted lanthanum reduced the grain size and internal stress of Cr2O3 oxide and increased high temperature plasticity of the oxide film. Lanthanum mainly existed on the outer surface of Cr2O3 oxide film in the form of fine La2O3 and LaCrO3 spinel particles.

Development of Niobium Oxide Coatings on Sand-Blasted Titanium Alloy Dental Implants

The purpose of this study was to use scanning electron microscopy (SEM) evaluation to determine the optimal anodizetion conditions needed to generate niobium oxide coatings on titanium alloy dental implant screws. Sand-blasted titanium alloy dental implants were anodized in dilute hydrofluoric acid (HF(aq)) solution using a Sorensen DLM 300-2 power supply. The HF concentration and anodization time were varied and the resulting implant surfaces were evaluated using a Jeol JSM-5310LV Scanning Electron Microscope to determine the ideal anodization conditions. While HF is necessary to facilitate oxide growth, increasing concentrations resulted in proportionate increases in coating delamination. In a similar manner, a minimum anodization time of 1 hour was necessary for oxide growth but longer times produced more delamination especially at higher HF(aq) concentrations. SEM imaging showed that implants anodized for 1 hour in a 0.1% HF(aq) aqueous solution had the best results. Anodization can be used to generate niobium oxide coatings on sand-blasted Ti alloy dental implants by balancing the competing factors of oxide growth and coating delamination. It is believed that these oxide coatings have the potential to improve osseointegration relative to untreated dental implants when evaluated in an in vivo study.

Influence of Yttrium Ion-Implantation on the Growth Kinetics and Micro-Structure of NiO Oxide Film

Isothermal and cyclic oxidation behaviours of pure and yttrium-implanted nickel were studied at 1000℃ in air. Scanning electronic microscopy （SEM） and transmission electronic microscopy （TEM） were used to examine the micro-morphology and structure of oxide scales formed on the nickel substrate. It was found that Y-implantation significantly improved the anti- oxidation ability of nickel in both isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation of nickel was that Y- implantation greatly reduced the growing speed and grain size of NiO. This fine-grained NiO oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained a ridge character and a relatively low internal stress level. Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scale formed on the nickel substrate.

Work Function Enhancement of Indium Tin Oxide via Oxygen Plasma Immersion Ion Implantation

Indium tin oxide （ITO） transparent conducting film was treated with oxygen plasma immersion ion implantation （PIII）. X-ray photoelectron spectroscopy （XPS） was employed to characterize the effect. The results suggested that the oxygen content in the surface was increased and maintained for more than 50 h compared with traditional plasma-treated samples. Meanwhile, the work function of ITO estimated by comparing the peak shift in the XPS diagram suggested a corresponding increase by more than 1 eV.

Impact of STI indium implantation on reliability of gate oxide

The impacts of shallow trench isolation(STI)indium implantation on gate oxide and device characteristics are studied in this work.The stress modulation effect is confirmed in this research work.An enhanced gate oxide oxidation rate is observed due to the enhanced tensile stress,and the thickness gap is around 5%.Wafers with and without STI indium implantation are manufactured using the 150-nm silicon on insulator(SOI)process.The ramped voltage stress and time to breakdown capability of the gate oxide are researched.No early failure is observed for both wafers the first time the voltage is ramped up.However,a time dependent dielectric breakdown(TDDB)test shows more obvious evidence that the gate oxide quality is weakened by the STI indium implantation.Meanwhile,the device characteristics are compared,and the difference between two devices is consistent with the equivalent oxide thickness(EOT)gap.

Incorporation of Nano-Zinc Oxide in Lamellar Zirconium Phosphate: Synthesis and Characterization

In order to provide ultraviolet barrier, antifungal and antibacterial properties, nano-zinc oxide (ZnO) was added to lamellar zirconium phosphate (ZrP). The phosphate was synthesized via reaction of zirconium oxychloride octahydrate and phosphoric acid following its chemical modification with Jeffamine and nano-ZnO. Diffractometric, morphological, thermal, structural and relaxometric evaluations were conducted. Fourier transform infrared spectroscopy (FTIR) revealed increase of the area between 4000 - 3000 cm-1 due to the formation of ionic specie PO? +NH3-[C-(H)(CH3)-CH2-O-(C-(H)(CH3)-CH2-O)8-(CH2-CH2-O-CH3)] and nano-ZnO particles. Wide-angle X-ray diffraction indicated that intercalation of Jeffamine was successful. Thermogravimetry confirmed that nano-ZnO particle forced the expulsion of Jeffamine outside ZrP galleries. Scanning electron microscopy evidenced the Jeffamine intercalation and sample heterogeneity. Hydrogen molecular relaxation indicated the increase of molecular rigidity owing to the formation of ionic specie and the addition of nano-ZnO particles. It was postulated that a multifunctional and miscellaneous material constituted by as prepared ZrP, some delaminated ZrP platelets and nano-ZnO particles was achieved. The material has potential for usage as filler in polymeric composites.

Effects of Al and N plasma immersion ion implantation on surface microhardness,oxidation resistance and antibacterial characteristics of Cu

A1 and N were introduced into copper substrate using plasma immersion ion implantation （PIII） in order to enhance its hardness and oxidation resistance. The dosage of N ion is 5 × 1016 cm-2, and range of dosage of A1 ion is 5× 1016-2× 1017 cm-2. The oxidation tests indicate that the copper samples after undergoing PIII possess higher oxidation resistance. The degree of oxidation resistance is found to vary with implantation dosage of AI ion. The antibacterial tests also reveal that the plasma implanted copper specimens have excellent antibacterial resistance against Staphylococcus aureus, which are similar to pure copper.

Effect of Ce^+ Ion Implantation upon Oxidation Resistance of Superalloy K38G

The oxidation behavior (isothermal and cyclic oxidation) of cast superalloy K38G and the effect of Ce^+ ion implantation with dose of 1×10^(17) ions/cm^2 upon its oxidation resistance at 900 and 1000 ℃ in air were investigated. Meanwhile, the influence of Ce^+ implantation on oxidation behavior of K38G with pre-oxide scale at 1000 ℃ in air was compared. The pre-oxidation was performed at 1000 ℃ in static air for 0.25 and 1.5 h, respectively. It is shown that the homogeneous external mixture oxide of rutile TiO_2+Cr_2O_3 and non-continuous internal oxide of Al_2O_3 are formed during the oxidation procedure in all the cases. The isothermal oxidation resistance and the cracking or spallation resistance of superalloy K38G implanted with Ce^+ by both of the two different implantation ways are not improved notably. This may be attributed to the mixed oxide composition characteristics and the blocking effect differences of Ce^+ segregation along the oxide grain boundaries on the transport process for different diffusing ions.

Effect of thermal oxidation on the surface characteristics and corrosion behavior of a Ta-implanted Ti-50.6Ni shape memory alloy

A NiTi shape memory alloy （SMA） modified by Ta ion implantation was subjected to oxidation treatment in air at 723 and 873 K. Atomic force microscopy （AFM）, Auger electron spectroscopy （AES）, and grazing incidence X-ray diffraction （GIXRD） measurements were conducted to investigate the surface characteristics, including surface topography, elemental depth profiles, and surface phase structures. The surface roughness of the Ta-implanted NiTi increases after oxidation, and the higher the oxidation temperature is, the larger the value is. The surface of the Ta-implanted NiTi oxidized at 723 K is a nanolayer mainly composed of TiO2/Ta2O5 and TiO with depressed Ni content. The Ta-implanted NiTi oxidized at 873 K is mainly covered by rutile TiO2 in several micrometers of thickness. Potentiodynamic polarization tests indicated that the corrosion resistance of the Ta-implanted NiTi was improved after thermal oxidation at 723 K, but a negative impact was found for the Ta-implanted NiTi oxidized at 873 K.

Influence of Yttrium Implantation on Oxidation Behavior of Co-40Cr Alloy at 900℃

The oxidation behavior of Co 40Cr alloy with and without yttrium implantation was studied at 900 ℃ in the air. Scanning electron microscopy(SEM), secondary ion massive spectroscopy(SIMS), transmission electron microscopy(TEM) and high resolution electron microscopy(HREM) were used to study the forming mechanism of oxide film on the alloy. It is found that the binding energy of Cr on the alloy surface is decreased by yttrium implantation, thus the formation of protective Cr 2O 3 film on the substrate is accelerated. In the mean time, the binding energy of Cr inside the oxide scale is increased by yttrium implantation, and this would reduce the Cr 3+ cation diffusion through the film. Yttrium implantation decreases the grain size and the growing speed of oxide film. SIMS and TEM/HREM results show that some yttrium exists as small YCrO 3 particles at Cr 2O 3 grain boundary near the oxide/gas interface, and a few small Y 2O 3 particles exist near the substrate/oxide interface. Besides, yttrium may also segregate to Cr 2O 3 grain boundary as Y 3+ , reduce Cr 3+ cation diffusion and change the mechanical properties of the oxide film. The ability of anti oxidation of Co 40Cr alloy is greatly improved by yttrium implantation.

Confocal Laser Scanning Microscope Evaluation of Early Bacterial Colonization on Zirconium Oxide and Titanium Surfaces:An in vivo Study

To investigate the bacterial colonization on zirconium oxide and titanium surfaces in vivo quantitatively using a confocal laser scanning microscope （CLSM）. Ten samples of zirconium oxide ceramic and commercially pure titanium were fabricated and polished using silicon carbide abrasive paper. One sample from each group was evaluated topographic pattern under a scanning electron microscope. One sample from each group was to evaluate roughness using a profilometer. Eight volunteers were selected. The samples were cemented at the buccal surfaces of upper first molars. All samples were removed after 48 hours, immersed in SYTO-9 and propidium iodide fluorescent to stain for adherent bacteria and obseIved with CLSM. Fewer bacteria were observed in zirconia group than titanium group. However, there was no statistical difference between two groups. The experimental results demonstrate that zirconium oxide may be considered as a promising material for dental implant abutments.

Early Osseointegration of Implants with Cortex-like TiO2 Coatings Formed by Micro-arc Oxidation:A Histomorphometric Study in Rabbits

In our previous studies, a novel cortex-like Ti O2 coating was prepared on Ti surface through micro-arc oxidation（MAO） by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment were testified. This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration. A sand-blasting and acid-etching（SLA） coating that has been widely used in clinical practice served as control. Topographical and chemical characterizations were conducted by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, contact angle meter, and step profiler. Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic, whereas the SLA surface was hydrophobic. The roughness of MAO was similar to that of SLA. The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT, histological analysis, and fluorescent labeling at the bone-implant interface four weeks after surgery. The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation. Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces. It was suggested that with micro/nanostructure and superhydrophilicity, the cortex-like MAO coating causes excellent osseointegration, holding a promise of an application to implant modification.

Effect of lanthanum ion implantation on oxidation behavior of zircaloy

In order to investigate the effect of lanthanum ion implantation on theoxidation behavior of zircaloy at 500℃, Zircaloy specimens were implanted by lanthanum ions with adose range from 5xl0^(16) to 2xl0^(17) ions/cm^2 at room temperature, and then oxidized at 500℃ for100 min. The valence of the oxides in the scale was analyzed by X-ray Photoelectron Spectroscopy(XPS). The phase structures of the oxides in the scale were examined by Glancing Angle X-rayDiffraction (GAXRD). With the increase of implanted lanthanum ions dose, the phase structures in theoxide scale are transformed from monoclinic zirconia to hexagonal one and then to monoclinic oneagain. The measurement of weight gain showed that a similar change from the decreased gain toincreased one again is achieved in the oxidation behavior of lanthanum ion implanted zircaloycompared with that of as-received zircaloy.

Dopant-Tunable Ultrathin Transparent Conductive Oxides for Efficient Energy Conversion Devices

Ultrathin film-based transparent conductive oxides(TCOs)with a broad work function(WF)tunability are highly demanded for e cient energy conversion devices.However,reducing the film thickness below 50 nm is limited due to rapidly increasing resistance;furthermore,introducing dopants into TCOs such as indium tin oxide(ITO)to reduce the resistance decreases the transparency due to a trade-o between the two quantities.Herein,we demonstrate dopant-tunable ultrathin(≤50 nm)TCOs fabricated via electric field-driven metal implantation(m-TCOs;m=Ni,Ag,and Cu)without com-promising their innate electrical and optical properties.The m-TCOs exhibit a broad WF variation(0.97 eV),high transmittance in the UV to visible range(89–93%at 365 nm),and low sheet resistance(30–60Ωcm-2).Experimental and theoretical analyses show that interstitial metal atoms mainly a ect the change in the WF without substantial losses in optical transparency.The m-ITOs are employed as anode or cathode electrodes for organic light-emitting diodes(LEDs),inorganic UV LEDs,and organic photovoltaics for their universal use,leading to outstanding performances,even without hole injection layer for OLED through the WF-tailored Ni-ITO.These results verify the proposed m-TCOs enable e ective carrier transport and light extraction beyond the limits of traditional TCOs.

Oxidation of pre-oxidized GH128 alloy implanted with Ce^+ at 1000℃

The influence of Ce implantation into preformed scales with a dose of 1×1017 ions/cm2 on the subsequent oxidation behavior of GH128 alloy at 1 000 ℃ in air was investigated. The pre-oxidation was carried out at 1 000 ℃ in air for 1 h and 5 h respectively. Cr2O3, NiO and NiCr2O4 formed on the surface of all specimens. Ce implantation decreased the subsequent oxidation rate of both the alloy and the 1 h pre-oxidized alloy, however, had no effect on that of the 5 h pre-oxidized alloy. The beneficial effect was most obvious in the directly implanted alloy. During the cyclic oxidation for 600 h, Ce implantation for all specimens with or without preferential oxidation played a similar beneficial effect on the oxide spallation resistance. The results indicate that Ce incorporated into the oxide scales affects the diffusion of the reaction species to some extent, the wavy interface and small grain structure make a significant contribution to improving the spallation resistance of the oxide scales.

DEFLECTION METHOD FROM TWO SIDES OXIDATION TO STUDY EFFECT OF Y ON INTERNAL STRESS OF OXIDE SCALES

Au investigation was carried ont of the effect of Y addition upon the internal stress of Al_2O_3 scale formed during oxidation of sputtering coating on Co-30Cr-6Al alloy and the growth stress of oxidized film on Fe-23Cr-5Al alloy heating up to 900℃ in air,using a specially designed deflection method from thin strip specimen with coat- ings,ion-implanted Y on one side and oxidized onto both sides.Results indicate that Y may decrease the internal stress of oxide scale on 2×10^(17) Y^+/cm^2 implanted Co- 30Cr-6Al coating,and increase one on 2×10^(16) Y^+/cm^2 implanted Fe-23Cr-5Al alloy. This seems due to whether or not Y promotes the plastic deformation of oxide scale.In addition,at initial oxidation stage,the change of growth stress of oxide scale formed on Y-implanted Co-30Cr-6Al coating may be related to the influence of Y on oxidation process of the coating.

INFLUENCE OF Ce ION IMPLANTATION ON OXIDATION BEHAVIOR OF Ni20Cr ALLOY

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Impact of Ion Implantation on Licorice(Glycyrrhiza uralensis Fisch) Growth and Antioxidant Activity Under Drought Stress

Low energy ion beams are known to have stimulation effects on plant generation and to improve plants＇ intrinsic quality. In the present study, the growth and physiological index of licorice implanted with 0, 8, 10; 12 and 14× （2.6× 10^15） ions/cm^2 were investigated under well-watered and drought-stress conditions. The results showed that a proper dose of ion implan- tation was particularly efficient in stimulating the licorice growth and improving the plant biomass significantly in both the well-watered and drought-stress conditions. The physiological results of licorice measured by leaf water potential, lipid oxidation, soluble protein and antioxidant system showed a significant correlation between ion implantation and water regime except for leaf water potential. Therefore, the study indicated that ion implantation can enhance licorice＇s drought tolerance by increasing the activity of superoxide dismutase （SOD）, eatalase （CAT） and DPPH （1,1-diphenyl-2-picrylhydrazyl） radical scavenging ability to lower oxidative damage to lipids in plants. Ion beam implantation, therefore, provides an alternative method to enhance licorice drought tolerance.