Effect of bombarding energy on ion beam assisted deposited DLC film on UHMWPE

1.IntroductionItiswellknownthatultra-highmolecularweightpolyethylene(~E)isafirstchoicepolarerforuseinfabricationoftotalhipandkneeprostheses.However,overthelastfewyearsithasbecomeincreasinglyapparelltthatveryfewprosthesesimplantedinthebodyweretrulylonglifetime.Muchoftheorthopedicconunuhitynowbelievethatthelong-termfailureoftoealhipandkneeprosthesesisdireCtlyorindireCtlyduetOwear,resultingintheproduCtionofpolyethylene(PE)wearparticlesatinterneebetweentheUHMWPEandmedalcomponentif].Thesepart…     

Functionally graded calcium phosphate coatings produced by ion beam sputtering/mixing deposition

Ar+ ion beam sputtering/mixing deposition was used to produce thin calcium phosphate coatings on titanium substrate from hydroxyl-poly-calcium sodium phosphate (HPPA) and HPPA + Ti targets. Three types of coatings (one type of monolayer coating and two types of functionally graded coating) were manufactured. It was found that as-sputtered coatings were amorphous. No distinct hydroxyl band was observed in the FTIR spectra, but new absorption bands were determined for CO3(2-), which resulted during the deposition process. Compositional gradients from the surface to the interior (i.e. adjacent to the substrate) were achieved for the functionally graded coatings. Post-deposition heat treatment indicated that the bonding strength between the coating and the substrate was improved by the use of functionally graded structures.     

Dissolution/reprecipitation of calcium phosphate thin films produced by ion beam sputter deposition technique

The dissolution, reprecipitation and protein adsorption properties of amorphous CaP bioceramic thin films produced with an ion beam sputter deposition technique using hydroxyapatite (HA) and fluorapatite (FA) as starting materials were studied using Fourier transform infrared spectroscopy (FTIR) with attenuated total internal reflectance (ATR). Our studies showed that these amorphous CaP coatings dissolved to a greater extent when exposed to bovine serum albumin (BSA) in saline solution when compared to a protein free saline solution. Analysis of changes in infrared spectra revealed that coatings exposed to BSA solution exhibited a higher degree of crystalline structure after dissolution/reprecipitation than those exposed to saline alone. There was the indication that the association of inorganic and organic contents was achieved on the coating surface in BSA solution. We could detect no significant difference between the coatings produced from HA and FA targets.     

Characteristics of hydroxyapatite film formed on human enamel with the powder jet deposition technique

This study aimed to create hydroxyapatite (HAp) film by powder jet deposition with manipulating the blasting nozzle above human enamel and to examine the microstructural and mechanical properties of the HAp film and the bonding strength at the interface between the HAp film and the enamel substrate. HAp particles calcinated at 1200°C with an average size of 4.7 μm were used. The HAp particles were mixed with carrier gas (N?) to form an aerosol flow and was accelerated and blasted from the nozzle onto the enamel substrate at room temperature and atmospheric pressure. To evaluate the microstructure, scanning electron microscope (SEM) images of the surface and cross section of the HAp films and a three-dimensional profile of the HAp films were observed. To evaluate the mechanical properties, the micro-Vickers hardness and the bonding strength of the HAp films to the enamel substrate were measured. The deposition area of the HAp film was over 3 × 4 mm. The average and maximum thickness were about 30 and 40 μm, respectively. No significant difference was observed between the hardness of the HAp film and the enamel (p > 0.05). The bonding strength of the HAp film was the same as the bonding strength between composite resin and enamel. Compared with previous reports, wider and thicker HAp film was created on the enamel substrate successfully. The HAp film, which has same hardness with enamel and same bonding strength to the enamel with composite resin, would be a candidate as dental restorative materials.     

Structure, solubility and bond strength of thin calcium phosphate coatings produced by ion beam sputter deposition.

Ion beam sputter deposition was used to produce thin calcium phosphate coatings on titanium substrates. Structure, solubility and bond strength of the as-sputtered and heat treated coatings were evaluated. X-ray diffraction (XRD) analysis of the heat treated coatings revealed a hydroxyapatite-type structure. The heat treated coatings were found to have significantly lower solubility as compared to the amorphous as-sputtered coatings. Although the crystalline coatings exhibited the lowest solubility, in general, the bond strengths were lower for the heat treated coatings.     

Biocompatibility and drug release behavior of spontaneously formed phospholipid polymer hydrogels

Hydrogels containing 2-methacryloyloxyethyl phosphorylcholine (MPC) moieties were formed from aqueous solutions with water-soluble MPC polymers with carboxylic acid and alkyl groups because of hydrogen bonding formation. To investigate the biocompatibility and drug release behavior of the hydrogels, we used random- and block-type carboxylic acid MPC polymers, such as poly [MPC-co-methacrylic acid (MA)] (rPMA), poly[MPC-co-4-(2-methacryloyloxyethyl) trimellitic acid (MET)] (rPMT), poly (MA-block-MPC-block-MA) (bPMA) and poly(MET-block-MPC-block-MET) (bPMT), and alkyl MPC polymers, such as poly[MPC-co-n-butyl methacrylate] (PMB) and poly(MPC-co-benzyl methacrylate) (PMBz). We investigated the biocompatibility of the spontaneously formed MPC polymer hydrogels by a hemolysis test and an in vivo injection test. The random MPC polymers having carboxylic acid groups expressed more hemolytic activity compared to the block polymers. The results of the in vivo injection test also indicated low biocompatibility of the carboxylic acid polymers especially at high concentration. The alkyl MPC polymers, the PMB and PMBz showed excellent biocompatibility in both hemolysis and in vivo injection test. However, the hydrogels, the rPMA/PMB hydrogel (rABgel) and the rPMT/PMBz hydrogel (rTZgel) lowered the hemolytic activity of elemental polymers, the rPMA and rPMT. Thus, suppression of the ionization of the carboxylic acid groups is necessary for biocompatibility. We also investigated the drug release behavior with attention to the interaction between the polymer and the drugs. The release behavior of a relatively low-molecular-weight hydrophilic drug, 5-fluorouracil, did not depend on the structure of the polymers. The higher-molecular-weight drugs, ketoprofen and indomethacin, were released faster from the block polymer hydrogel than the random polymer hydrogel, the rABgel, while the highest-molecular-weight drug, doxorubicin, was released faster from the random polymer hydrogel. A probable reason for this is the difference in the molecular structure; that is, the separated hydrophilic and hydrophobic sections in the block polymers constructed pathways where a drug can diffuse. In addition, the rTZgel suppressed the release of a drug with a large number of aromatic rings probably because of the stacking effect. The results of the compression test also suggested the existence of the stacking effect between the rTZgel and the drugs. Based on these results, control of drug release is possible by selecting a reservoir with an appropriate chemical structure to interact with the drug. For example, release of a relatively linear-structured drug with less aromatic rings can be suppressed in the rABgel rather than in the rTZgel. Thus, it can be concluded that if the ionization is suppressed, these MPC polymer hydrogels can be used as a material for a drug reservoir that can be selected according to the drug.     

The characterization of ion channels formed by Pasteurella multocida dermonecrotic toxin

The influence of the dermonecrotic lethal toxin (∼120 kDa) produced by Pasteurella multocida serovarian D on planar phospholipid bilayers was studied. It was found that the toxin is able to increase the conductance of the bilayers by formation of low-conductive and cation-selective ion channels [27 pS at 4.0 M KCl, pH 7.5; zero current potential equals to -14.5±0.5 mV at threefold transmembrane gradient KCl (120 mM/40 mM)]. In biionic conditions the channels displayed weak selectivity between Na, K and Ca ions. The shapes of current-voltage characteristics (which were measured at different pH and salt concentrations) indicate that an energetic barrier for passing ions is situated near the center of the water pore of the ion channels. The effective diameter of the ion channel's water pore was established to be equal to 2.1±0.3 nm.     

Combination of ion beam stabilisation,plasma etching and plasma deposition for the development of tissue engineering micropatterned supports

The performance of biomedical assays at both molecular and cellular level depends greatly on the ability to design new polymer surfaces. Patterns can be created by using materials with contrasted surface properties. In this work we describe in detail the preparation of micropatterned surfaces to be used as tissue engineering supports. Poly(ethylene glycol) (PEG) was used as the 'anti-fouling' polymer in opposition to functional regions covered by acrylic acid (AAc). Since spin-casted PEG films are unstable, ion beam stabilization (IBS) treatment was applied in order to render it insoluble. On the other hand, AAc films were deposited by low-power plasma chemical vapour deposition. Chemical properties of both polymers were monitored by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy while topographic features were followed by atomic force microscopy. Finally, a micropattern was produced by using a mask, which isolated the IBS-PEG from the AAc-deposited regions. Endothelial cells cultured on the surface were observed to follow the micropatterns. In fact, for a certain surface density it was observed that the cells present tensile or compressive stresses when forced to remain in the anti-fouling or the functionalised regions, respectively.     

Combination of ion beam stabilisation, plasma etching and plasma deposition for the development of tissue engineering micropatterned supports

The performance of biomedical assays at both molecular and cellular level depends greatly on the ability to design new polymer surfaces. Patterns can be created by using materials with contrasted surface properties. In this work we describe in detail the preparation of micropatterned surfaces to be used as tissue engineering supports. Poly(ethylene glycol) (PEG) was used as the 'anti-fouling' polymer in opposition to functional regions covered by acrylic acid (AAc). Since spin-casted PEG films are unstable, ion beam stabilization (IBS) treatment was applied in order to render it insoluble. On the other hand, AAc films were deposited by low-power plasma chemical vapour deposition. Chemical properties of both polymers were monitored by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy while topographic features were followed by atomic force microscopy. Finally, a micropattern was produced by using a mask, which isolated the IBS-PEG from the AAc-deposited regions. Endothelial cells cultured on the surface were observed to follow the micropatterns. In fact, for a certain surface density it was observed that the cells present tensile or compressive stresses when forced to remain in the anti-fouling or the functionalised regions, respectively.     

Dynamics of tear film deposition and draining.

This paper investigates the deposition of the tear film on the cornea of the human eye. The tear film is laid down by the motion of the upper eyelid and then subsequently flows and thins. Of particular interest is the stability of the tear layer and the development of dry patches on the cornea. While there has been significant research on the behaviour of tear films between blinks, this paper focuses on understanding the mechanisms which control the shape and thickness of the deposited film and how this affects the subsequent film behaviour. Numerical and analytical methods are applied to a lubrication model which includes the effects of surface tension, viscosity, gravity and evaporation. The model reveals the importance of the eyelid velocity, motion of the surface lipid layer and the storage of tear film between blinks.     

Investigation of cell-substrate interactions by focused ion beam preparation and scanning electron microscopy

Cell-substrate interactions, which are an important issue in tissue engineering, have been studied using focused ion beam (FIB) milling and scanning electron microscopy (SEM). Sample cross-sections were generated at predefined positions (target preparation) to investigate the interdependency of growing cells and the substrate material. The experiments focus on two cell culturing systems, hepatocytes (HepG2) on nanoporous aluminum oxide (alumina) membranes and mouse fibroblasts (L929) and primary nerve cells on silicon chips comprised of microneedles. Cross-sections of these soft/hard hybrid systems cannot be prepared by conventional techniques like microtomy. Morphological investigations of hepatocytes growing on nanoporous alumina membranes demonstrate that there is in-growth of microvilli from the cell surface into porous membranes having pore diameters larger than 200 nm. Furthermore, for various cell cultures on microneedle arrays contact between the cells and the microneedles can be observed at high resolution. Based on FIB milled cross-sections and SEM micrographs cells which are only in contact with microneedles and cells which are penetrated by microneedles can be clearly distinguished. Target preparation of biological samples by the FIB technique especially offers the possibility of preparing not only soft materials but also hybrid samples (soft/hard materials). Followed by high resolution imaging by SEM, new insights into cell surface interactions can be obtained.     

Processing and in vitro behavior of hydroxyapatite coatings prepared by electrostatic spray assisted vapor deposition method

Hydroxyapatite (HA) bioactive coatings are often used to improve bone attachment and reduce corrosion of metal prosthesis implants. This paper reports the preparation of HA coatings onto titanium substrates using a novel electrostatic spray assisted vapor deposition (ESAVD)-based method. The deposited coatings are characterized using a combination of Fourier transform infrared spectrometer, X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and scratch test. The results confirm that well-crystallized HA coatings can be produced directly via the single-step ESAVD process, without further heat-treatment. The in vitro behavior of the as-deposited HA coating in simulated body fluid (SBF) is also presented. After 14-day immersion in SBF, the adhesion of the HA coating to the substrate increases significantly.     

Fabrication of a protein film by electrospray deposition method and investigation of photochemical properties by persistent spectral hole burning

Transparent protein film of iron-free cytochrome c (Cyt. c) was successfully manufactured by electrospray deposition (ES) method and the properties of the protein film were investigated. Excursion temperature dependence of spectral hole profiles in the photochemical hole burning for the iron-free Cyt. c in protein film and in glassy solution was investigated and compared with that of iron-free porphyrin embedded in a synthetic polymer film to clarify photochemical properties of electrospray deposited protein film. The spectral holes of iron-free porphyrin were thermally more stable in Cyt. c than in polymer, indicating compact packing of the chromophore in the protein. The ES-deposited iron-free Cyt. c in protein film showed less stable spectral hole than that in glassy solution. This difference is attributable to the electrospray deposition process of the protein involving ionization and to subsequent cross-linking of protein molecules.     

Bioactivity of titanium following sodium plasma immersion ion implantation and deposition

Bio-activation of titanium surface by Na plasma immersion ion implantation and deposition (PIII and D) is illustrated by precipitation of calcium phosphate and cell culture. The bioactivity of the plasma-implanted titanium is compared to that of the untreated, Na beam-line implanted and NaOH-treated titanium samples. Our data show that the samples can be classified into two groups: non-bioactive (untreated titanium and beam-line Na implanted titanium) and bioactive (Na-PIII and D and NaOH-treated titanium). None of the four types of surfaces exhibited major cell toxicity as determined by lactate dehydrogenase (LDH) release. However, the LDH release was higher on the more bioactive PIII and NaOH-treated surfaces. From a morphological point of view, cell adherence on the NaOH-treated titanium is the best. On the other hand, the cell activity and protein production were higher on the non-bioactive surfaces. The high alkaline phosphatase activity per cell suggests that the active surfaces support an osteogenic differentiation of the bone marrow cells at the expense of lower proliferation. The use of Na-PIII and D provides an environmentally cleaner technology to improve the bioactivity of Ti compared to conventional wet chemical processes. The technique is also particularly useful for the uniform and conforming treatment of medical implants that typically possess an irregular shape and are difficult to treat by conventional ion beam techniques.     

Increased iron deposition in rat liver fibrosis induced by a high-dose injection of dimethylnitrosamine

Using a developed rat model of hepatic necrosis and subsequent fibrosis induced by a high-dose intraperitoneal injection of dimethylnitrosamine (DMN), we studied iron deposition and expression of transforming growth factor-beta(1) (TGF-beta(1)) during the development of persistent liver fibrosis. Rats were sacrificed at several timepoints from 6 h to 10 months post-injection and the livers were examined for iron content and distribution, and for expression of alpha-smooth muscle actin, ED-1, TGF-beta(1), and collagen (alpha(2))I. Morphologic evidence of acute submassive hemorrhagic necrosis peaked at 36 h; on day 3 the residual parenchyma contained activated hepatic stellate cells (HSCs) and necrotic areas contained numerous macrophages; and on day 5, necrotic tissues and erythrocytes had been phagocytosed and macrophages contained abundant iron deposits. From days 7 to 10, iron-laden macrophages and activated HSCs (myofibroblasts) populated the fibrous septa in parallel. From week 2 to month 10, closely arranged macrophages and myofibroblasts were found in central-to-central bridging fibrotic tissue. TGF-beta(1) was strongly detected in both macrophages and HSCs during development of liver fibrosis. Our data suggest that increased iron deposition may be involved in the initiation and perpetuation of rat liver fibrosis. Iron-laden macrophages may influence HSCs through the action of TGF-beta(1) in DMN-induced liver fibrosis.     

Electrochemically assisted deposition of thin calcium phosphate coatings at near-physiological pH and temperature

An electrochemical method for the deposition of calcium phosphate phases on titanium surfaces using the galvanostatic mode is presented. Deposition was performed in a (Ca(2+) / H(x)PO(4) ((3-x)-))-containing electrolyte near physiological conditions with regard to pH (6.4) and temperature (36 degrees C). Cathodic alkalization leads first to the formation of a thin homogeneous layer that shows a nanoscale surface topography of alternating wall-like elevations and channels. It is thought that these channels in the calcium phosphate prelayer are formed as pathways for hydroxyl ions and hydrogen. Upon this layer, spheres of amorphous calcium phosphate (ACP) are formed as indicated by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy. According to transmission electron microscopy images, these spheres consist of small clusters of calcium phosphate (approximately 30 nm) and can grow up to 300 nm in diameter. Characteristic for this ACP is a high water content as seen by FTIR. As a function of current density, the ACP is then transformed into crystalline hydroxyapatite (HAP), which was identified using FTIR and X-ray diffraction. The morphology of the HAP crystals can be described as needles with dimensions of <500-nm length and <60-nm width. By choice of different electrochemical parameters, a homogeneous coating of either ACP, HAP, or the intermediate phase can be achieved, as shown in a kinetic phase diagram, thus allowing the formation of coatings with different properties in solubility and morphology.     

不同比例聚乳酸羟基乙酸复合骨支架的低温沉积制造及性能

背景：研究证实,在聚乳酸羟基乙酸中加入磷酸三钙或珍珠粉可以使两者的性能互补,不仅为细胞提供良好的生长环境,而且能使细胞更快、更好地生长。 目的：通过低温层积制造技术制备以聚乳酸羟基乙酸为基体、复合珍珠粉或磷酸三钙的支架材料。 方法：采用低温层积制造技术制备聚乳酸羟基乙酸与珍珠粉或磷酸三钙质量比分别为10∶0、5∶2、7∶3和6∶4的聚乳酸羟基乙酸/珍珠粉或聚乳酸羟基乙酸/磷酸三钙复合支架,检测支架的微观结构、接触角、压缩弹性模量。将生长至基本融合的MC3T3-E1细胞以1×10⁴/cm³的密度接种至纯聚乳酸羟基乙酸无孔支架、纯聚乳酸羟基乙酸有孔支架、5∶2聚乳酸羟基乙酸/珍珠粉和5∶2聚乳酸羟基乙酸/磷酸三钙支架上,接种1,3 h,采用流式细胞仪检测细胞黏附率;接种1,4,7 d,利用Alamar Blue法检测细胞增殖。 结果与结论：纯聚乳酸羟基乙酸支架具有相互交联贯通的微孔结构,微孔大小3-15 μm;5∶2聚乳酸羟基乙酸/珍珠粉或5∶2聚乳酸羟基乙酸/磷酸三钙支架具有较好的连续微孔结构,孔径大小为10-25 μm。随着珍珠粉或磷酸三钙含量的增加,复合支架的亲水性增加。加入珍珠粉或磷酸三钙能够提高复合支架的压缩力学性能,但随着含量增加,支架力学性能呈现先增强后减弱。珍珠粉或磷酸三钙的加入,改善了聚乳酸羟基乙酸的细胞亲和力,改善了支架的生物相容性,其中以5∶2聚乳酸羟基乙酸/珍珠粉复合支架生物相容性最好。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

Biocompatibility and electrical output performance of composite piezoelectric film and osteogenic differentiation of rabbit bone marrow mesenchymal stem cells

BACKGROUND: Adjustable piezoelectric effect can promote tissue regeneration and repair. Piezoelectric materials are widely used in weight-bearing tissue engineering. OBJECTIVE: To prepare a piezoelectric film material that can promote bone regeneration, and to explore its structural characterization, electrical output performance, biocompatibility, and effect of electrical output on osteogenic differentiation of rabbit bone marrow mesenchymal stem cells. METHODS: Using poly-3-hydroxybutyrateco/4-hydroxybutyrate (P34HB) as raw material, barium calcium stannate titanate powder (Ba_0.94Ca_0.06Sn_0.08Ti_0.92O₃, BCST) was added according to mass ratios of 0%, 5%, 10%, 15%, and 20%. Dichloromethane was added to solve P34HB, and the thickness of 150-200 μm BCST/P34HB piezoelectric film was prepared by vacuum drying method. After polarization in the oil bath, the surface morphology, crystal phase composition, piezoelectric coefficient and open circuit voltage were tested. The effect of BCST/P34HB electrical output at 110 Hz and 0.25 N force on the proliferation and osteogenic differentiation of rabbit bone marrow mesenchymal stem cells was tested. RESULTS AND CONCLUSION: (1) Scanning electron microscopy, X-ray diffraction, water contact angle, piezoelectric coefficient and electrical output performance tests showed that when the mass ratio of BCST increased to 20%, the BCST/P34HB piezoelectric film had good piezoelectric properties (d₃₃=5.9 pC/N) and electrical output performance (180 mV), which was closer to the suitable range of 500 mV for electrical stimulation. (2) Live and dead staining showed that on the first day of co-culture, 15% group and 20% group showed less red fluorescence. On the 5^th day of culture, the number of green fluorescence in each group was significantly higher than that on the first day, and the red fluorescence was not observed in the 10%, 15% and 20% groups, and only a small amount of red fluorescence was observed in the 0% and 5% groups. (3) On the 1^st, 3^rd and 5^th days of co-culture with rabbit bone marrow mesenchymal stem cells, Almar blue staining exhibited that the number of cells in each group showed an increasing trend with the increase of time. On the 5^th day of culture, the number of cells in the 20% group was significantly more than that in the 0% group (P < 0.05). (4) On day 10 of osteogenic induction, alkaline phosphatase staining results showed that the positive rate of the 20% group was significantly higher than that of the 0% group (P=0.000 1). On day 21, alizarin red staining and quantitative analysis of calcium nodules showed a similar trend to alkaline phosphatase staining. Compared with the 0% group, the 15% group and 20% group showed significant differences (P < 0.01, P < 0.000 1). (5) The results showed that 20% BCST/P34HB films had good piezoelectric properties, electrical output properties, biocompatibility and the ability of promoting osteogenic differentiation of bone marrow mesenchymal stem cells. © 2024, Publishing House of Chinese Journal of Tissue Engineering Research. All rights reserved.