Search

Diamond-like carbon (DLC) films were deposited by electron cyclotron resonance plasma-chemical vapor deposition (ECR-CVD) at different substrate bias potential (Us = −200 and −800 V). The mechanical properties and microstructure uniformity of the DLC films deposited at different positions (the distance between substrate and ECR plasma source, Decr-s) were studied. The results showed that the ionization of acetylene (C2H2) at different positions decreased with the increase of Decr-s at substrate bias potential Us = −200 V. The plasma distribution was non-uniform, so the mechanical properties and structure of the DLC films varied a lot with the change of deposition position. At substrate bias potential Us = −800 V, an additional self-sustained discharge around the substrate could be generated during ECR plasma discharge, then the ionization of C2H2 and the plasma distribution uniformity at different positions were found to be improved. The uniformity of mechanical properties and structure of DLC films could be improved due to enhanced ionization of C2H2 in front of the substrate at high values of the negative substrate bias (Us = −800 V).

Titanium oxide (Ti-O) films with different thicknesses were deposited on 316 L stainless steel and bare metal stents with the filtered cathodic vacuum arc technique. The adhesion of the Ti-O films with different thicknesses on the 316 L stainless steel sheets was studied by the tension test. The adhesion, corrosion resistance, and fatigue behavior of the Ti-O film-modified stents were then evaluated. The results show that a 25-nm-thick Ti-O film on stainless steel is tightly adhered on the stainless steel after 40% relative elongation of the steel substrate. The 25-nm-thick Ti-O film-modified bare metal stent has sufficient mechanical stability, good corrosion resistance, and can withstand 380 million cycles of pulsatile fatigue testing without film destruction and delamination. A clinical trial of the bilayer drug eluting stent (DES) with a titanium oxide base layer and an anti-proliferative sirolimus top layer shows that our DES tends to reduce the incidence of late thrombosis.

The tribochemical reaction between metal ions and proteins can result in the formation of a carbonaceous tribo-layer on the surface of metal-on-metal (MOM) artificial joints. This carbonaceous film can lubricate the tribo-pair and reduce the corrosion of the metal. The purpose of this work is to investigate the catalysis efficiency of Cu and Co ions in the formation of carbonaceous films at the contact regions. A ball-on-disc (Al2O3-on-Cu and Al2O3-on-Co alloy) friction mode in bovine serum albumin (BSA) solution was chosen for the wear test experiments. After the wear test, the tribo-layer formed on the wear spot (on Al2O3 ball) and wear track (metal disc) were collected and characterized. The results show that the Cu ions released upon friction promoted the adsorption of BSA on the wear track of Cu to give a protein film which was further transformed into a carbonaceous tribo-layer under the shear force between the Al2O3-Cu tribo-pair. When the Al2O3 ball and Co alloy were chosen as the tribo-pair, however, a carbonaceous tribo-layer was not observed on the Co alloy after the wear testing. This means that the catalysis efficiency of the Cu ion for the formation of a carbonaceous tribo-layer is stronger than that of the Co ion.

TiO2 films with thicknesses of 100 and 50 nm were deposited on NiTi shape memory alloys (SMA-NiTi) using high-power impulse magnetron sputtering. Uniaxial tensile loading, unloading, and water-bath heating experiments were conducted. X-ray diffractometry, scanning electron microscopy, and profilometry were used to characterize the phase structures of the NiTi substrates and surface morphologies of the films before and after stretching and after stretching with water-bath heating. Under uniaxial tension, the NiTi substrate experienced a B2 → B19′ martensitic phase transformation. Surface relief appeared on the film and residual deformation persisted in the NiTi after stress-relief. After heating, the NiTi substrate underwent a reverse B19′ → B2 martensitic phase transformation where the surface relief on the film disappeared and the residual deformation was eliminated. Neither cracking nor spalling was observed on the 50-nm film after tensile deformation at a maximum strain of 10%, and the shape was recovered via heating. The 100-nm film withstood a tensile deformation at a maximum strain of 10%, but slight cracking and spalling occurred during shape recovery. This is the first report on the dynamic changes in the surface morphology of inorganic films deposited on SMA-NiTi alloys. The results provide a theoretical and experimental basis for analyzing the reliability of film-modified NiTi alloy devices.

In this study, Mg ions incorporated phytic acid (PA) and zoledronic acid (ZA) of metal-organic complex coating was built on Mg substrate. This coating aims to fulfill the corrosion controlling and differential regulation on osteoblast vs. osteoclast responses simultaneously. PA and ZA molecules were co-immobilized on the alkaline pretreated Mg by a facile one-step dip-coating method. Such immobilization process was executed by the chelation reaction between PA/ZA molecules and in-situ released Mg ions. This coating showed a homogeneous structure with metal-organic like framework. The electrochemical corrosion resistance and long-term degradation behavior of coated samples were remarkably improved. Consequently, the well-controlled Mg ion release, as well as the osteo-compatible PA molecule, promoted the proliferation of pre-osteoblast cells (MC3T3-E1). Moreover, this coating significantly suppressed both the proliferation and differentiation of osteoclast cells owing to the nature of ZA. This metal-organic complex coating offers a promising modifying strategy for Mg-based orthopedic implants for osteoporotic fracture healing.

The tribological behavior of hydrogenated and hydrogen free diamond like carbon (DLC) coatings sliding against Al 2 O 3 in air and pure water was investigated by ball-on-disc reciprocation wear test, and the effect of hydrogen was discussed. The results showed that in air environment, the Al 2 O 3 slide against DLC under solid lubrication condition, and the wear of DLC coatings was mainly affected by coating mechanical properties. The hydrogen lowered the coating hardness and brought more DLC wear in air environment. In water environment, the solid lubrication effect is weak, the hydrogen began to play an important role in DLC wear. The hydrogenated DLC coating with saturated ‐CH bonds showed better wear resistance even though its hardness is lower. The hydrogenated DLC coating with unsaturated ‐CH bonds was easy to graphitize and generate massive wear no matter in water or in air environment.

Adsorption and competitive adsorption behavior of bovine serum albumin (BSA), human γ-globulin (HGG), and hyaluronic acid (HA) molecules on a diamond-like carbon (DLC) film surface were investigated by the means of a quartz crystal microbalance with dissipation (QCM-D), and antigen-antibody reactions. The results showed that a BSA monolayer could be formed on the DLC film surface with side-on orientation and that an HGG monolayer could be formed on the DLC film surface with end-on orientation by using pure BSA or HGG solutions, respectively. HA molecules were hardly adsorbed onto the surface of DLC film or HGG or BSA biomolecular layer. The results of competitive adsorption showed that HGG molecules could displace BSA molecules and that HGG was the dominantly adsorbed molecule on the DLC film surface in a mixture of BSA, HGG, and HA. The frictional behavior of a DLC film sliding against Al 2 O 3 in a mixture of BSA, HGG, and HA, was investigated by means of the friction coefficient and an open circuit potential, which suggested that the HGG molecule was the main component that formed the lubricating film.

The drawbacks of titanium nitride (TiN) films deposited by high power pulsed magnetron sputtering (HPPMS) are low deposition rate (compared with conventional magnetron sputtering) and high residual stress. Many methods have been used to deal with these issues. In this study, TiN films were deposited by HPPMS at different magnetic field strength Bs (40 and 115 mT) and deposition pressure Pd (0.2, 1.0, and 2.0 Pa). The effects of Bs and Pd on film deposition rate, residual stress, and mechanical properties were also investigated. The plasma in the HPPMS discharge was diagnosed by optical emission spectroscopy. Due to the stronger magnetic confinement and back-attraction around the target at higher Bs (115 mT), lower Bs (40 mT) led to a significant increase in the Ti+/Ti ratio of the substrate, by a factor of ~ 3, and a large increase in the deposition rate, especially by a factor of ~ 5.5 when the Pd was 2.0 Pa. The high Ti+/Ti ratio in front of the substrate at the lower Bs (40 mT) increased the degree of ion bombardment and resulted in a preferred and stronger (111) orientation, greater film hardness, and better adhesion strength of the TiN films. Furthermore, the increase in Pd caused more collisions and stronger scattering for metal atoms and ions, which resulted in a sharp decrease in residual stress (from 8.5 to 0.8 GPa at 40 mT Bs) and a significant increase in the adhesion strength of TiN films.

Polyetheretherketone (PEEK) is being used in various biomedical devices thanks to its bio-inertness, nontoxicity, and an elastic modulus near to that of human cortical bone. However, its oral and maxillofacial applications remain challenging owing to is hydrophobicity, lack of biocompatibility, and infectious complications. To address this problem, a biocompatible nanogranular-structured TiO2 coating assisted by a mediating layer of pre-grafted polydopamine (PDA) was deposited onto PEEK to modify its surface. The PDA-mediated TiO2 coated PEEK showed a unique surface layer of single anatase phase. The surface tended to become more hydrophilic with increased TiO2 deposition, and even turned super-hydrophilic with a sufficient amount of deposited TiO2. In vitro cell culture tests verified that such prepared PEEK improved adhesion and proliferation of both fibroblast and osteoblast cells, decreased the inflammatory reaction by suppressing TNF-α expression for macrophages, as well as enhanced the antibacterial activity against Staphylococcus aureus and Streptococcus mutans bacteria attachment when compared to only PDA coated and uncoated PEEK. Such a superior bio-performance is apparently correlated with anatase TiO2, as well as its improved physiochemical surface states, including altered surface energy. The PDA-mediated TiO2 nanostructured coating may bode well for oral and maxillofacial implants applications of PEEK.

The controllable growth of heteroepitaxial cubic SiC (3C-SiC) films and two dimensional (2D) nanosheets arrays has been successfully achieved using a 915 MHz microwave plasma enhanced chemical vapor (MPCVD) deposited technique using tetramethylsilane (TMS) and hydrogen as the resource gases. A comprehensive analysis of the surface morphology of the 3C-SiC films was performed by tuning microwave power, TMS flow rate and gas pressure. With increasing microwave power, the morphology of the SiC crystals evolves from randomly oriented nanocrystals to well-oriented pyramid shaped crystals. The rocking curve results shows that the 3C-SiC film deposited at microwave power of 9 kW and gas pressure of 50 mbar remains epitaxial feature with increasing of TMS gas flow rate. As a result, uniform heteroepitaxial 3C-SiC film was deposited on 4-in. silicon wafer at low deposition temperature (~ 860 °C). The structure of SiC film along the radial direction was measured by X-ray diffraction (XRD) results. X-ray photoelectron spectroscopy (XPS) spectra indicate the chemical information of SiC film surface and the depth profiles, which prove the uniform of elements distribution. Moreover, with increasing gas pressure, the film morphology transforms from the heteroepitaxial SiC film into 2D nanosheets, which is due to the increased ion current.

For physical surface modification of a complex workpiece, the incoming particles are difficult to arrive at the inclined surface of the complex workpiece due to self-shadowing effect. This will result in the non-uniformity distribution of structure and properties of the films on different surfaces of the complex workpiece. In order to mitigate the self-shadowing effect and improve the uniformities of film structure and properties, high power pulsed magnetron sputtering (HPPMS) was used to fabricate TiN films on 316L stainless steel substrate with different inclination angles. During deposition, the electrical characteristic of HPPMS was recorded by an oscilloscope, and the plasma component was diagnosed by optical emission spectroscopy. The structure, mechanical and corrosion properties of the TiN films deposited on substrate with different inclination angles by DC magnetron sputtering (DCMS) and HPPMS also were studied respectively. Compared with DCMS, the results showed that high ion/atom ratio and large ion flux in HPPMS led to stronger ion bombardment and adatom mobility, which caused densification of the TiN films. The uniformities of hardness and corrosion resistance of the TiN films deposited on the substrate with different inclination angles were improved by HPPMS. And for HPPMS, the longer pulses at same duty cycle could efficiently mitigate the self-shadowing effect and improve the hardness and corrosion resistance of the TiN-coated stainless steel.

Due to the large degree of ionization of the sputtered flux and high quality film fabrication, high power pulsed magnetron sputtering (HPPMS) is widely used. However, compared with DC sputtering, low deposition rate is probably the drawback of the HPPMS technique and restricts its application. In order to increase the deposition rate of HPPMS, different combinations of frequency and pulse width at a constant duty cycle were used to modulate the deposition rate of the Ti film. The results showed that wider pulse width would be more effective than increasing frequency on improving titanium deposition rate for a constant duty cycle. The pulse width also would affect the power utilization ratio. Especially for a high duty cycle of 4.8% and 5.6%, a wider pulse was favorable to make full use of power on film deposition, resulting in a higher normalized static deposition rate. Meanwhile, with increase in pulse width for a constant duty cycle, adatom mobility and the deposition rate increased, contributing to growth of crystallite size and higher surface roughness of Ti thin films.

article i nfo Article history: Received 2 December 2014 Accepted in revised form 28 March 2015 Available online xxxx Smooth and dense TiO2 films with different thickness (45 nm and 300 nm respectively) were deposited on a flat CoCrMo substrate by high power impulse magnetron sputtering (HiPIMS). A cantilever resonance method was developed to load cyclic stress on the sheet samples to investigate the fatigue durability of the TiO2 films. The evolution of pre-cracks, which were introduced intentionally in the TiO2 films, was studied at the same time. Aftercyclicdeformation,thecorrosionresistanceoftheTiO2 filmcoatedCoCrMoalloywasinvestigatedbypoten- tiodynamicpolarizationtests.Theresultsshowedthattherewerenopeelings,cracksordelaminationofboth film types after 1.08 × 10 7 loading cycles with the maximum stress of 200 MPa. For the evolution of the pre-cracks in the thicker TiO2 films (300 nm), new cracks emerged near the pre-cracks in the films, while for the pre- cracks in the thinner TiO2 films (45 nm) not any new cracks were observed. The thinner films seemed to show betterfatiguedurabilitythanthicker films.Thepotentiodynamicpolarizationtestsrevealedthatthecorrosionre- sistance of the thinner TiO2 films (45 nm) was not degraded even after 1.08 × 10 7 loading cycles with the max

Stainless steel, CoCrMo alloy and titanium alloy are the most commonly used metal materials for artificial joint. But the generation of wear debris and metal ions limits the use of the metal, especially for the metal-on-metal type artificial joint. Diamond like carbon (DLC) coating can reduce the wear and corrosion of these metal alloys. But the service behavior of the DLC coating on different metal substrates may be different. This paper studied the difference of the structure, adhesion, wear and corrosion properties of the DLC coating on different substrates (stainless steel, CoCrMo or titanium alloy). The results show that the structure of the DLC coating on these substrates is similar. The DLC coating on titanium alloy shows the best adhesion than that on stainless steel and CoCrMo alloy, because the chemical bond energy holding Ti atom (of titanium alloy surface) and C atom (of DLC) together is the strongest. The failure mode of DLC coatings on 316L stainless steel and CoCrMo alloy in the friction test is coating delamination. The DLC coating on Ti6Al4V alloy shows the best wear resistance due to its good adhesion. Immersion and electrochemical tests show that the DLC coating on Ti6Al4V substrate has better stability than that on 316L stainless steel and CoCrMo alloy because the Ti6Al4V substrate can prevent the corrosion more efficiently than 316L stainless steel and CoCrMo alloy. In the case of no interlayer, Ti6Al4V alloy is the most feasible metal joint material for DLC modification with good adhesion, wear and corrosion resistance compared with 316L stainless steel and CoCrMo alloy.

In the present study, Cu-doped (1, 2, 5 and 10 wt.%) TiO 2 thin films were prepared on silicon wafers via sol–gel method and dip coating process. The prepared thin films were thermally treated at 450 °C for 1 h with a heating rate of 2 °C/min. The microstructures of synthesized thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), water contact angle measurement (WCA), and X-ray photoelectron spectroscopy (XPS). XRD results showed that the as-prepared thin films were mainly in anatase phase. XPS analysis indicated that Cu 2 O transformed into CuO with increasing content of copper. Such doped surfaces showed the ability of catalytic decomposition of exogenous donor S-nitroso-N-acetyl-penicillamine (SNAP) to generate nitric oxide (NO). Based on SEM and fluorescence analysis results, such films had the ability to inhibit platelet adhesion and activation with SNAP in vitro . This study suggested that the films were capable of generating physiological levels of NO in the presence of endogenous donor S-nitrosothiols (RSNO) when in contact with blood. So the films may be useful to improve the hemocompatibility of blood contact devices.

A series of amorphous Si–C–N hard films were prepared by an electron cyclotron resonance chemical vapor deposition method. Microstructure characterization revealed that amorphous Si–C–N hard films contained various bonding states. Among them, Si N and Si C bonds played a leading role in determining the microstructure of amorphous Si–C–N hard films. Mechanical measurements showed that the hardness of these films varied between 17 GPa and 28 GPa as a function of the tetramethylsilane flow rate. A close relation between various bonding states and hardness was found. The variation of hardness was dominated by the bond fraction that corresponded to various bonding states. Macroscopic mechanical properties of a material were illustrated from the perspective of microscopic structural characterization.

Hydrogenated amorphous carbon (a-C:H) films and unhydrogenated amorphous carbon (a-C) films are promising as artificial joint coatings due to their excellent wear resistance. In this paper, the cytocompatibility of a-C:H film and a-C film was evaluated to determine the more appropriate type for prosthesis modification. The a-C:H film was deposited by electron convolute resonance plasma enhanced chemical vapor deposition (ECR-PECVD) and a-C film was fabricated by magnetic filtered cathodic vacuum arc (MFCVA). The microstructure and physical characteristics of the films were investigated by Raman spectroscopy, contact angle measurement, atom force microscopy (AFM), electrokinetic analysis, electrical resistivity measurement and Hall effect measurement. Bovine serum albumin (BSA) and serum protein adsorption on a-C and a-C:H films was determined by micro BCA assay. RAW264.7 macrophages were cultured on the a-C:H and a-C films for 24 h to evaluate the cell death, cell activation and inflammatory cytokine release. Primary mouse osteoblasts were cultured on the a-C:H and a-C films for 2 h, 1 day, 3 days and 6 days with biological tests performed to evaluate the cell adhesion, cell viability and cell morphology. The results show that a-C film is N type semiconductor with unpaired electrons. Protein adsorption assay shows that the a-C film can covalently bind more serum proteins than a-C:H film. The unpaired electrons of a-C film contribute to its better ability to covalently bind bioactive proteins than a-C:H film, and the superior adsorption and bioactivity of the adhesion proteins on a-C film further induce the better biological performance of a-C film. In a word, a-C film induces lower inflammatory reaction and higher ostoblasts viability than a-C:H film.

In order to explore the potential application on cardiovascular stent, titanium oxide films were fabricated on CoCrMo alloy substrate by high power pulsed magnetron sputtering (HPPMS). The effect of Ti interlayer and thickness of Ti–O film on the film adhesion was investigated by the scratch test and tension test. After different tensile strain, the corrosion behavior of Ti–O coated CoCrMo alloy and bare CoCrMo alloy was also investigated by polarization tests. The results showed that the deposition of Ti interlayer can obviously improve the film adhesion and the film adhesion decreased with film thickness increase. In addition, the 30 nm Ti–O film with 10 nm Ti interlayer had excellent adhesion and it could withstand 30% relative elongation without obvious delamination. The corrosion resistance of Ti–O coated CoCrMo alloy was superior to bare CoCrMo alloy after different tensile strain. Due to its good adhesion and corrosion resistance after different tensile strain, the HPPMS Ti–O film had a potential application on CoCrMo alloy cardiovascular stent surface modification.

Cardiovascular implants find wide clinical applications, making a great contribution to the treatment of cardiovascular diseases. Such devices, endovascular stents, artificial vascular grafts, prosthetic heart valves to name a few typical examples, have been the mainstay of cardiovascular surgery. However, failure cases of the implants still exist, which urge us to understand what has happened at the blood-contacting interface and how the tissues have responded during the post-implantation period. Aiming to eliminate these pathological events, various approaches of surface modification of the cardiovascular devices have been used in order to improve hemocompatibility and cytocompatibility. In this review, the blood–biomaterial interfacial events and the evolution of the surface modification strategies are discussed, together with the recent developments on the surface modification of cardiovascular materials like biomimetic extracellular matrix and accelerated endothelialization. These novel surface modification strategies open a new chapter on designing ideal blood-friendly implantable materials.

Mechanical and chemical durability is of equal importance as bio-functionality for surface-modifying films on biomedical devices. This is in particular true for those serving on combined conditions of loading and a corrosive ambient. In this work, we investigated the deformation and corrosion behaviors of Ti–O films coated onto 316L stainless steel aimed for cardiovascular stent applications. The Ti–O films were synthesized by plasma immersion ion implantation and deposition (PIII&D), and the investigation conditions were as required for cardiovascular stents concerning plastic deformation and corrosion. Tensile and three point bending tests showed that no peeling and delaminating occurred on the Ti–O film which had undergone relatively high plastic deformation (4% to16% elongation). Electrochemical corrosion tests showed that the deformed PIII&D Ti–O film coated 316L SS suffered more severe corrosion in simulated body fluid (SBF) than the non-deformed, but remained comparable to uncoated 316L SS, which is clinically acceptable for stents. Due to the good mechanical and chemical durability as well as biomedical functionalities, the PIII&D Ti–O films appear promising as surface-modification of cardiovascular stents in real applications.

The influence on the tribological properties in a modified metal‐on‐polymer (CoCrMo/UHMWPE) articulation should be tested with DLC coated or N + ion implanted into artificial hip joint heads. For this a diamond like carbon (DLC) film was deposited on a CoCrMo artificial hip joint head by filtered cathodic vacuum arc technique (FCVA) with a thickness of approximately 600 nm. Alternatively nitrogen ions were implanted into the CoCrMo artificial hip joint head by plasma immersion ion implantation (PIII) technology. Before wear tests, the surface morphology and topography of unmodified, DLC coated and N + implanted CoCrMo heads were investigated by optical microscopy (OM) and stylus profilometry. Then a MTS hip joint simulator was used to characterize the tribological properties of the artificial hip joint implants. The wear loss of UHMWPE cup and wear morphology of both the CoCrMo head and UHMWPE cup were investigated after hip joint simulator wear tests. The results showed that the DLC film deposited on the CoCrMo joint head by FCVA method had excellent tribological properties and didn't fail during two million wear cycles while the N + implanted layer formed on the CoCrMo head was damaged during the wear test. Compared with sliding against unmodified CoCrMo head, the UHMWPE cup had a higher wear rate when sliding against DLC coated or N + implanted CoCrMo head. In our opinion, only applying the surface modification (DLC film or N + implantation) on the CoCrMo head could not improve the wear resistance of metal‐on‐polymer (CoCrMo/UHMWPE) articulation for artificial hip joint implant.

Hydrogenated amorphous carbon (a-C:H) film is deposited on CoCrMo alloy by plasma immersion ion implantation and deposition (PIII-D) at different flow ratios of acetylene to argon (C 2 H 2 /Ar). The results show that Ar fraction in the C 2 H 2 –Ar gas mixture has an important effect on the structure and the adhesion of the a-C:H films. When Ar fraction in the C 2 H 2 –Ar gas mixture is less than 50%, the fabricated a-C:H film composition transfer from graphite-like to diamond-like which contains higher sp 3 binding thanks to Ar ion bombardment, and the adhesion strength decreased with the increment of Ar fraction. But when Ar fraction in the C 2 H 2 –Ar gas mixture is beyond 50%, the fabricated film contains more sp 2 bonding for thermally driven and exhibits higher adhesion strength with the increment of the Ar fraction.

The titanium oxide film has been deposited on Si wafers (110) by unbalance reactive magnetron sputtering and modified by phosphorus ion implantation and succeeding vacuum annealing. The structural, states of surface chemistry and surface morphology of the films have been investigated by X-ray diffraction (XRD), X-ray photoelectric spectroscopy (XPS), atomic force microscope (AFM) and Scanning Electron Microscope (SEM), respectively. The results of XRD show rutile structure of as-deposited film, which is not changed by phosphorus implantation and vacuum annealing. However, a slightly shift of the peaks position to higher degree and the half width increases after ion implanted and vacuum annealing represent that the variety of the structure film caused by these treatments. The surface roughness is inclined to increase with the rising of annealing temperature for both undoped and P doped titanium oxide films. The surface chemistry presents significant difference between undoped and phosphorus doped films after a vacuum annealing, it may be attributed to the different evolvement of the surface defects existing in the film, which may be considered as an important influencing factor in the blood compatibility of the titanium oxide film.

Surface modification with a high power glow discharge is an emerging technology that can be used to improve the surface characteristics. Titanium oxide films are prepared using a high-power impulse magnetron sputtering (HPPS-M) glow discharge with a current density of 2 A/cm 2 and a power density of 1 kW/cm 2 . Observing optical emission spectrum confirms that singly-ionized titanium ions are produced in the plasma. Ions are extracted from the HIPIMS glow plasma by a substrate placed near the plasma source. It is found that the substrate is immersed in the HPPS-M glow plasma. The film is deposited by a HPPS-M, and the results are compared to those of magnetron sputtering operated by a stationary dc power source. The deposition rate is lower by HPPS-M than that by DC-MS. The main structure of the films is rutile, however an anatase structure is also observed. The mixed structure is obtained at an oxygen rate as low as 5%. Anatase structure is not significantly observed in HPPS-M compared to that in DC-MS. The intensity of the XRD profiles becomes weaker with increasing the substrate position due to the collisions of metal species with the plasma species and the background gas particles. The deposition rate of the prepared titanium oxide film is significantly influenced by the production rate of titanium ions, distance of the substrate, and the gas mixture ratio. With regard to the effect of the gas ratio, the difference in the deposition rate is probably based on the argon ion density available to sputter titanium atoms that would eventually contribute to the titanium oxide film deposition.

Traditional plasma ion immersion implantation (PIII) can effectively improve material mechanical property and corrosion resistance. But the modified layer by PIII is too thin for many industrial applications. High frequency and low voltage plasma immersion ion implantation (HLPIII) has advantages of PIII and nitriding. Comparing with traditional ion nitriding, HLPIII can obtain higher implantation energy and create a thick modified surface layer. In the present paper nitriding layers were synthesized on industrial pure iron using high frequency and low voltage plasma immersion ion implantation with different RF power (400 W, 600 W, and 800 W). The microstructure of the nitriding layers was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties such as microhardness and wear resistance were analyzed using HXD1000 microhardness and CSEM pin-on-disk wear testing machine. The anodic polarization characteristics were measured in a 0.9% NaCl solution at room temperature to examine the corrosion resistance of the nitriding layer. The results reveal that Fe 2 N, Fe 3 N and Fe 4 N coexist in the nitriding layer. The nitriding layer is a corrosion protective coating on industrial pure iron in 0.9% NaCl solution. The hardness, wear resistance and corrosion resistance of the nitrided layers on industrial pure iron increase with RF power.

The hydrogenated amorphous carbon films (a-C:H, so-called diamond-like carbon, DLC) have exceptional physical and mechanical properties and have wide applications. In the present study, amorphous hydrogenated carbon films (a-C:H) have been deposited on a Si (100) substrate at different hydrogen flow using electron cyclotron resonance chemical vapor deposition (ECR-CVD). The flow of hydrogen changed from 10 sccm to 40 sccm and the flow of acetylene was fixed at 10 sccm. The microstructure and properties of the a-C:H were measured using visible Raman spectra, Fourier transform infrared (FTIR) spectroscopy, UV–VIS spectrometer,surface profilometer and nano-indentation. The results showed that the sp3 content and sp3–CH2 structure in the amorphous hydrogenated carbon films increased with the hydrogen flow. The deposition rate decreased with the hydrogen flow. The residual stress and the nano-hardness of the amorphous hydrogenated carbon films increased with the hydrogen flow. Consequently, the a-C:H film become more diamond-like with the increase of hydrogen flow.

Ti–O film was deposited on cobalt-chromium alloy (L-605) coronary stents by metal vacuum arc source deposition. The corrosion resistance of the Ti–O film modified and bare L-605 stents was investigated by cyclic potentiodynamic polarization tests in phosphate buffered solution (PBS, 37 ± 1 °C). The optical microscopy and scanning electron microscopy (SEM) images of the modified stents indicated that the surface of all stent cells was very smooth and uniform, and the thickness of Ti–O film was about 10 nm. There were not any cracks and delamination on stent surface after dilation by angioplasty. The polarization results showed that the natural corrosion potential of the Ti–O film modified and bare stents was similar. But the corrosion current density of Ti–O film modified stent was lower than that of the bare stent at all scanned potential range. Compared with Ti–O film modified stent, the bare stent was more susceptible to corrosion. After cyclic potentiodynamic polarization test, the slight localized corrosion was found on the surface of bare stents. But no film flakes or localized pitting can be observed on Ti–O film modified stent. All these results showed that Ti–O film modified stent had the better corrosion resistance, compared with the bare L605 stent.

In this work, ultrahigh molecular weight polyethylene (UHMWPE) was modified with oxygen plasma generated by microwave electron cyclotron resonance (ECR). Surface microstructure and properties of UHMWPE were studied by means of water contact angle measurement, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy, scratch test and wear test. The results showed that O 2 plasma treatment could effectively improve the wettability, anti-scratch and tribological properties of UHMWPE. Many oxygen-based functional groups generated on the surface of the O 2 plasma modified UHMWPE, which resulted in the improvement of wettability. The plasma treatment process increased the crosslinking of UHMWPE molecular chains, which further enhanced the action force between the molecular chains and finally increased the surface hardness, anti-scratch capacity and tribological properties of UHMWPE.

A duplex treatment of plasma nitriding followed by deposition of a Ti/TiN multilayer coating was performed on commercial pure iron. Plasma nitriding was carried out using high frequency low bias voltage plasma immersion ion implantation (HLPIII), and the Ti/TiN multilayer films were deposited using unbalanced magnetron sputtering on the nitrided iron surface. The plasma nitriding layer was 4 μm thick, consisting of mainly e-Fe3N and γ-Fe4N. The microhardness of the iron with Ti/TiN multilayer coating + plasma nitriding duplex treatment was over 18 GPa, somewhat harder than that of iron with a Ti/TiN multilayer film but without plasma nitriding, and almost 5 times that of the (only) nitrided iron. The film-cohesion for Ti/TiN multilayer film on the nitrided substrate was much better than that on the substrate without nitriding treatment. Comparing with the Ti/TiN film on bare iron, the samples with Ti/TiN multilayer coating + plasma nitriding duplex treatment have better corrosion resistance.

Wettability of amorphous carbon films can be adjusted by doping with other elements, including F, Si, Ti, O and N. In this study, nitrogen-doped hydrogenated amorphous carbon (a-C:H:N) films were deposited on silicon wafers (100) by plasma immersion ion implantation–deposition (PIII-D) using C2H2 + N2 gas mixtures. Film composition and bonding structure were analyzed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Surface morphology of the films was characterized using an extended multimode nanoscope atomic force microscope (AFM). Wettability examination was performed using the sessile drop method. Bloodcompatibility of the films was assessed by in vitro platelet adhesion test. The results suggest that a-C:N:H film synthesized at the highest N2/C2H2 flux ratio of 2/1 presents better anti-thrombotic property than the low temperature isotropic pyrolytic carbon (LTIC) and this improvement of bloodcompatibility can owe to the increase of hydrophilicity of the film caused by N incorporation in the carbon network and additional increase of surface roughness.

Due to its surface properties, especially the presence of abundant amine groups, pulsed-plasma polymerized allylamine (PPAa) is used to manufacture biosensor and modify surface of metallic biomaterials. In the present study, PPAa films on 316L medical stainless steel are prepared by pulsed radio frequency (RF) plasma polymerization using allylamine as a precursor under different duty cycles. The effect of the pulsed duty cycles on the composition, structure, surface morphology, wettability and mechanical properties of PPAa films are investigated by Fourier transform infrared (FTIR) spectroscopy, laser Raman spectra, X-ray photoelectron spectroscope (XPS), atom force microscope (AFM), contact angle measurement, nanoscratch test and substrate straining method. All results of FTIR, XPS and Raman indicate that there are more amine groups from allylamine monomer on the 20/80 film fabricated by 20% duty cycle. The wettability of the 20/80 film is higher than that of 20/30 film prepared using 40% duty cycle. AFM micrographs demonstrate no remarkable differences in the morphological characteristics, but grain size of 20/30 film is larger than that of 20/80 film. The critical force of 20/80 film is about 71.86 mN, higher than that of 20/30 film and has a better scratch resistance. It is estimated that the mechanical properties of the plasma polymerization are different.

The paper presents the investigation of the effect of the process parameters on the structure of hydrogenated amorphous carbon (a-C:H) films deposited on Si(100) substrate by electron cyclotron resonance microwave plasma chemical vapor deposition method (ECR-PCVD). The investigation is based on an orthogonal experimental design and analysis method. Both the carbon sp3/sp2 bonding ratio and hydrogen content are evaluated from the visible Raman spectra deconvolution. The statistical results indicate that the sp3/sp2 bonding ratio is mainly affected by microwave power, and it decreases as the microwave power increases. The hydrogen content in a-C:H films is mainly affected by the substrate bias voltage, and it decreases with increasing the bias voltage. The effect of other parameters on the structure of a-C:H films is relatively not significant, but is also discussed in the paper.

Pure iron is a potential material for coronary artery stents based on its biocorrodible and nontoxic properties. However, the iron stents could lose their mechanical stability prematurely due to their corrodible degradation. In this study, Fe–O thin films were prepared on the pure iron by plasma immersion ion implantation and deposition (PIII&D) to improve its corrosion resistance and biocompatibility. The X-ray photoelectron spectroscopy (XPS) and glancing angle X-ray diffraction (GAXRD) results showed the phase structure of the films transformed from FeO to Fe3O4 with the increase of the oxygen flux. The Fe–O film fabricated under the low oxygen flux (3.4 sccm) effectively improved the corrosion resistance of pure iron and had much better adhesion than under the high oxygen flux. The systematic evaluation of hemocompatibility, including in vitro platelets adhesion, prothrombin time (PT), thrombin time (TT), indicated that the number of platelet adhesion, platelet activation on the surface of FeO film were remarkably decreased compared with pure iron, the PT and TT were almost the same as the original plasma. The results of human umbilical vein endothelial cells (HUVECs) culture showed HUVECs had good adhesion and proliferation behavior on the FeO film. It was indicated that, after depositing FeO thin film by PIII&D under the low oxygen flux, the corrosion resistance and biocompatibility of pure iron were effectively improved.

Oxygen plasma immersion ion implantation (PIII) was conducted in magnesium with oxygen doses in the range of 2.5 × 1015 ions cm− 2 up to 2.0 × 1016 ions cm− 2, and the corrosion properties were investigated in neutral phosphate buffer solution (PBS, pH 7.4) and chloride ion enriched PBS (145 mM Cl−, pH 6.4) (PBS(Cl−)). Significantly enhanced corrosion resistance against PBS was achieved on Mg treated with high oxygen doses above 1 × 1016 ions cm− 2. The corrosion current density Icorr of treated Mg was almost five orders less than that of untreated Mg; no intermediate values are obtained for samples with intermediate doses. However, all samples we prepared in this case could not withstand the more aggressive PBS(Cl−). No improvement of corrosion resistance in such solution has been observed even for surfaces implanted at 2.0 × 1016 ions cm− 2. The enhanced corrosion resistance against neutral PBS is ascribed to increased Mg–O bonding states formed on the surface layer of magnesium by the PIII process, as discerned by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) measurements. Further the more homogenous surface morphology, due to the ion bombardment effect, as observed by atomic force microscopy (AFM) may contribute. The Mg–O bondings can be dissolved easily in Cl− enriched and more acidic ambience, as shown with PBS(Cl−).

The prevention of medical device related infection remains an important concern because of the high risk of complications. Efforts to prevent bacterial colonization of biomaterials have focused on surface modification. This paper investigates the antibacterial behavior of polyethylene terephthalate (PET) surfaces modified by ion implantation with silver ions (Ag + ). PET films were modified by silver ion implantation at a dose of 1 × 10 16 ions/cm 2 . X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface structure and composition. The results indicate that silver was successfully implanted into the surface of the PET. The static contact angle of water decreased from an original value of 83.5° to 67.6° following Ag + implantation, which suggests that the hydrophilic property of the modified PET is improved. The quantity of Staphylococcus epidermis (SE) adhered onto the different PET films was quantitatively determined using colony forming units (CFU) plate counting in vitro . The results indicate that the quantity of SE adhered onto PET films implanted with Ag + is 5.3 × 10 6 CFU/ml, but the quantity of SE adhered onto virgin PET films is 2.23 × 10 7 CFU/ml. The releasing concentration of silver ions from the implanted PET is 0.22 mg/ml over 2 h. The release of antibacterial silver ions may be an important reason for less SE adhered to the PET surface modified by Ag + implantation. The free energy of adhesion (D F Adh ) of SE on the PET surfaces modified by Ag + implantation is positive, which means that this adhesion is energetically unfavorable.

Surface modification has become an important way to develop new antithrombotic biomaterials. In the past ten years Ti–O films have been engaging much research attention because of their excellent antithrombotic properties. In order to understand the thromboresistance mechanisms involved, we focus our attention in this work on the influence of phosphorus doping on the structure, properties and thromboresistance behavior of these films. The results show that the electrical resistance of the film decreases with increasing annealing temperature, and that phosphorus is redistributed within the film after annealing. The films exhibit different wettability after annealing at various temperatures. P-doped Ti–O thin films show significant improvement of thromboresistance after annealing at higher temperatures. It is suggested that the thromboresistance of Ti–O thin films is related to their semiconductor nature.

In this paper, titanium oxide (Ti–O) thin films were fabricated by plasma immersion ion implantation and deposition (PIII-D), and subsequently hydrogen ions were implanted into the film surface by PIII to improve the biocompatibility of blood and vascular contacting biomaterials and prosthesis such as stents, etc. The films were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and atomic force microscopy (AFM). The contact angle of Ti–O films with simulated body fluid was measured. The biological behavior of cultured human umbilical vein endothelial cells (HUVECs) on Ti–O film surfaces was evaluated by an in vitro cultured HUVEC experiment. The in vitro investigation of cultured ECs on Ti–O films revealed that the biological behavior of HUVECs, such as adherence, growth and proliferation etc., were better biologically for hydrogen-containing Ti–O films than for untreated Ti–O films. The results of our study support the hypothesis that the surface morphology and biological properties such as wettability and surface tension etc. of the implanted Ti–O films are changed to a more desirable range by the high energy H plasma immersion ion implantation and by H incorporation in the films. As a result, the H-containing Ti–O films possess good biocompatibility.

Tantalum oxide (Ta–O) films have been widely used as dielectric, optoelectronics and high temperature resistance materials. But the biological response of the Ta–O films is rarely studied. In this paper, the biomedical properties of Ta–O films were studied. Tantalum oxide films were deposited on Si(100) and glass substrate at different oxygen-to-argon ratios by DC reactive unbalanced magnetron sputtering. The structure, blood compatibility, surface energy and semiconductor properties were studied. The results showed that the Ta–O films were amorphous and its optical band-gap increased from 3.65 eV to 3.95 eV with increasing oxygen pressure. The surface energy of Ta–O films were about 40–46 mJ/m2. The low surface energy, and low dispersive energy were the reasons of their better blood compatibility. There were less platelet adhered and aggregated at the Ta–O film which deposited at O2/Ar ratio 0.4, and it had better antithrombotic properties.

Silver (Ag) modified polyethylene terephthalate (PET) surface by filtered cathodic vacuum arc (FCVA) technique is performed. The structure and component of the modified surface are characterized by X-ray photoelectron spectroscopy (XPS) and the cross-section is observed by scanning electron microscope (SEM). The results show that a 4–5 μm silver layer is formed on the PET surface. The results of the colony forming units (CFU) plate counting in vitro indicate that the adhesion of Staphylococcus epidermidis (SE) to PET is suppressed by silver coating. The adhesion efficiency of SE on the modified surface is only about 25% of the untreated PET surface. The interfacial free energy of adhesion (Δ F Adh ) of SE onto the silver coating deposited on PET is + 8.6 mJ/m 2 , and this means that bacterial adhesion is energetically unfavorable. The releasing rate of silver ions from the PET modified by silver FCVA is 0.12 μg/mL during 2 h. The release of antibacterial silver ion may be another reason of less SE adhered to the PET surface modified by Ag FCVA. The release of lactate dehydrogenase (LDH) was used to evaluate the immediate toxicity of the PET modified by silver FCVA method. It is showed that this modified surface has low toxicity.

One of the important considerations of antithrombotic biomaterial improvement is to control the response of blood cells and plasma proteins to the materials. Material surface characteristics can be suggested as the important factors that influence the response of blood to materials. Thus, modifying the surface characteristics of a material becomes an important way to endue it with the antithrombotic function of preventing blood cell/plasma protein activation. This article is going to summarize results from previous studies on functional inorganic films coated with blood contacting biomaterials, including fabricating condition, characteristics and antithrombotic function. The functional inorganic films of Ti–O, a-C:N:H and Si–N synthesized using PIII-D on the surface of a biomaterial can endue it with the antithrombotic function of preventing platelet adhesion/activation. The characteristics of the films changed with alteration of the fabrication condition and influenced their antithrombotic function strongly. The in vitro test results showed that improved biomaterial surfaces with special antithrombotic function can be obtained from the optimization of the fabrication condition according to the understanding of the blood–materials interaction.

In this paper, we synthesized titanium oxide films using unbalanced magnetron sputtering and etched subsequently the surface of the Ti–O films by Ar plasma to obtain different surface morphology. The surface characteristics of the etched Ti–O films were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Atom force microscopy (AFM). The wettability of etched Ti–O film was measured by a contact angle method. The biological behavior of cultured human umbilical vein endothelial cells (HUVECs) onto Ti–O film surfaces was evaluated by the in vitro HUVECs cultured experiment. The analysis results of film surface characteristics indicated that the structure of Ti–O film was uninfluenced after being etched by Ar plasma, but the composition of films were changed from nonstoichiometric to stoichiometric due to etching process, and the surface roughness of Ti–O films was decreased after being etched. Investigation on ECs cultured on Ti–O film surfaces shows that the etched Ti–O film surface could be accepted by ECs in a survival period, and the biological behavior of ECs was significantly varied as the Ti–O film surfaces etched in different degree. The adherence, growth and proliferation of HUVECs are in good state on stoichiometric TiO 2 film surface with a certain range of roughness, and proper wettability. The work indicated that the etched Ti–O film surfaces with certain characteristics are helpful for seeding ECs. Furthermore, the biocompatibility mechanism of ECs on films based on the relationship between the Ti–O film characteristics and biological behavior of ECs is preliminarily analyzed.

TiO 2− x films were synthesized on carbon by plasma-based ion implantation and deposition (PBII-D). Electrochemical behaviors of the prepared films were investigated in phosphate buffer solution (PBS) and fibrinogen containing PBS solution (PBS(Fn)), to probe charge transfer phenomena between TiO 2− x film and fibrinogen. Electrochemical impedance spectroscopy (EIS) as well as simulated values of equivalent circuit units including reaction resistance and electric double layer has been obtained, indicating different charge transfer rate occurred across the interfaces. The shape of Mott-Schottky spectroscopy around the rest-open potential indicates that TiO 2− x films are typical n-type semiconductor. Donor density results calculated by Mott-Schottky theory show that TiO 2− x films exhibit higher donor density in PBS(Fn) than in PBS, indicating charge transfer from fibrinogen to TiO 2− x films, and the space charge layers bend lower.

Titanium oxide films synthesized by plasma immersion ion implantation and deposition (PIII&D) were micro-patterned using argon plasma etching. Wells containing organized arrays of square holes of different depths separated by gaps of 25 μm were produced on the surface of the titanium oxide by etching for 30, 60, 90, and 120 min. The surface wettability and tension of the samples were evaluated. Human umbilical vein endothelial (HUVE) cells were cultured on both smooth and patterned surfaces. The effects of surface micro-patterning on the behavior of the HUVE cells were investigated. Our results show that the titanium oxide prepared by PIII&D has good cyto-compatibility and the micro-patterns influence both the surface energy and cell behavior. Our results demonstrate the feasibility of using micro-patterned surfaces to modulate HUVE cell behavior.

Improving the blood compatibility of titanium alloy artificial heart valves by TiO2/TiN duplex films was studied. In the duplex TiO2/TiN film, the titanium oxide is for improving blood compatibility and the TiN film is mainly to improve the mechanical property of the films. The mechanical properties of TiN films synthesized by plasma immersion ion implantation and deposition at different bias voltages and substrate temperatures are studied. Its structure is examined using X-ray diffractometry and TEM. The fatigue property of the artificial heart valve modified by TiO2/TiN duplex film is also investigated. The fatigue property and the wear resistance of the artificial heart valve modified by TiO2/TiN duplex film are significantly improved compared with bare titanium alloy artificial heart valve. The present investigation shows that TiO2/TiN duplex film is suitable for applications such as artificial heart valve coating.

The aim of the paper is to characterize titanium oxide films synthesized by unbalanced magnetron sputtering and metal vacuum arc deposition, as well as to test the microstructure, composition, sheet resistance and blood compatibility. With increasing oxygen inlet, the rutile TiO 2 can be synthesized in both processes. The sheet resistance of the samples increases with higher oxygen pressure and it shows a sharp increase when only rutile TiO 2 exists in the films, a similar tendency was found for pulsed vacuum arc plasma deposition and unbalanced magnetron sputtering methods. The films synthesized by the unbalanced magnetron sputtering and pulsed vacuum arc deposition sample contain the rutile phase and have a similar composition, but the microstructures like grain size and roughness are different. These will affect the semiconductivity and the surface energy, and these properties affected their blood compatibility and made their blood compatibility more different. The platelet adhesion behavior of rutile TiO 2 synthesized by unbalanced magnetron sputtering is better than the one synthesized by pulsed vacuum arc deposition.

Amorphous silicon nitride (a-SiN x ) thin films were fabricated by pulsed reactive closed-field unbalanced magnetron sputtering ultra-high purity n -type single crystal silicon in Ar–N 2 mixtures. The effect of N 2 fraction on the discharge behavior, deposition rate, composition, chemical bonding configurations, surface morphology, nano-hardness, elastic modulus and optical band gap were primarily investigated. It was found that good stability of reactive sputtering process was maintained by the adoption of the bipolar pulsed magnetron power supply with 180° out-of-phase and the pulsed substrate bias. The arc events and the disappearing anode effect in DC reactive magnetron sputtering of a-SiN x films were prevented. A higher deposition rate (>20 nm/min) for a-SiN x films was achieved. The radical transition of the sputtering mode leads to the deposition rate initially decreased dramatically and then slowly with the increase of N 2 fraction. N to Si atomic ratio (N/Si) gradually increased and N is preferentially incorporated in its NSi 3 stoichiometric ratio configuration and the Si–N network followed a tendency to tetrahedral chemical order with the increase of N 2 fraction in the inlet gases. The a-SiN x films deposited at high N 2 fraction were consistently N-rich. The film surface microstructure was transformed from coarse granular mounds surrounded by tiny micro-void regions to homogeneous, continuous, dense and slender hills, as well as a progressive densification and refinement of the film microstructure occurs as the N 2 fraction is increased. With the increase of the N/Si atomic ratio, the resistance of the a-SiN x films surface region to plastic deformation improved; hardness and elastic modulus increased, correspondingly. The as-sputtered a-SiN x films exhibit good optical transparency in visible region and the optical band gap E opt can be varied in a broad range of 1.70–3.62 eV depending on the N 2 fraction in Ar–N 2 mixtures. The increment of optical band gap E opt of the as-sputtered a-SiN x films is determined primarily by the recession of the valence band maximum.

SiNx:H films with different N/Si ratios were synthesized by plasma-enhanced chemical vapor deposition (PECVD), aimed for BioMEMS or other biomedical applications. In vitro platelet adhesion tests were conducted to evaluate the hemocompatibility of the prepared films and the results were compared to low-temperature isotropic carbon (LTI-C) which is the most commonly used materials in commercial blood contacting biomedical devices such as artificial heart valves. Our results indicate that the SiNx:H films offer acceptable hemocompatibility compared to LTI-C and possess better characteristics. The hydrophilic property in terms of surface free energy is considered to contribute to the platelet adhesion and activation behavior. The thrombogenicity of the materials is investigated from the thermodynamic and kinetic points of view. Our results indicate that the Si–N bonds play a crucial role in determining the hydrophilic property of the film and consequently affect the blood/surface reactions and hemocompatibility of the films. D 2005 Elsevier B.V. All rights reserved.

Poly(ethlene terephthalate) (PET) used in artificial heart valve sewing rings were treated by argon plasma discharge and grafted by different molecular water-soluble polymer—polyethylene glycols (PEG). The surface properties of the plasma treated and grafted films were determined by contact angle measurement, X-ray photoelectron spectroscopy (XPS), and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The contact angle of water decreased from 83.5° to 38.7° and the interfacial energy diminished from 30.7 to 6.3 mN/m. The ratio of oxygen to carbon increased from 0.15 to 0.25. All the results revealed that PEG chains were successfully grafted onto the surface of the PET films. The interaction between the surface-modified PETs and blood components was investigated to evaluate the blood compatibility of the samples. Activated partial thromboplastin time (APTT) of the PET-PEG was significantly longer than that of the untreated PET. Scanning electron microscopy (SEM) and optical microscopy indicated that adhered, aggregated and morphologically changed platelets were significantly reduced by grafting PEG chains onto the PET films. The in vitro blood compatibility tests suggested that the blood compatibility of PET grafted with PEG was related to the molecular weight of PEG. The best blood compatibility was achieved when the grafted molecular weight of PEG was 6000. The hemocompatibility improvement can be explained by the low interfacial free energy, sterically hindered effects of PEG chains, and maintaining of the normal conformation.

The present paper presents the results of surface modifications of biomaterials using plasma immersion ion implantation (PIII) in Institute of Surface Modification of Biomaterials in Southwest Jiaotong University. In the research, titanium oxide films and diamond-like carbon (DLC) films doped with different elements, as well as surface modification of polymers, are prepared using PIII. The blood compatibility of the films is investigated. Significant improvement in blood compatibility of the films compared with those untreated substrate materials is confirmed. The mechanisms of the blood compatibility of the films are discussed. The results show that the energy band structure of the material surface may be a controlling factor in the blood compatibility of the material. A film with an n-type semiconductor nature would have a better blood compatibility. Improvement in wear resistance of hip joint and modification of antibacterial property of artificial heart valve suture ring material is also presented in the paper.