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Thin films have emerged as an ideal surface treatment to the permanent implant materials to enhance properties such as biodegradation resistance, better mechanical strengths and biocompatibility. A perfect implant ought to have the ability of resistance to degradation, stimulate osseointegration, prevent bacterial adhesion, and decrease prosthetic infection. The clinical success of implants depends on the interaction of cells with material surfaces, which is an essential factor. Recent development in biomaterials has brought a variety of coatings on biomaterial to overcome these issues. The coatings impart biocompatibility, better mechanical property, and bioactivity to the biomaterial. In this review, the recent trends in surface modification by thin films of implants have been discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: TiN/TiAlN multilayers of 2μm thickness were successfully prepared by reactive DC magnetron sputtering method. XRD pattern showed the (111) preferential orientation for both TiN and TiAlN layers. XPS characterization showed the presence of different phases like TiN, TiO2, TiON, AlN and Al2O3. Cross sectional TEM indicated the columnar growth of the coatings. The average RMS roughness value of 4.8nm was observed from AFM analysis. TiN/TiAlN coating showed lower friction coefficient and lower wear rate than single layer coatings. The results of electrochemical experiments indicated that a TiN/TiAlN multilayer coating has superior corrosion resistance in 3.5% NaCl solution. [Copyright &y& Elsevier]

Abstract: Ti/TiN multilayered coatings of 200 layers with the thickness of 1.5μm were deposited by a reactive DC magnetron sputtering technique using a mixture of Ar and N2 gas. XRD technique was employed to elucidate the structural parameters. The presence of different phases like TiN, TiO x N y and TiO2 were confirmed by XPS analyses. The observation of longitudinal optic (LO) phonon modes in the Raman spectra confirmed the highly crystalline nature of the deposited films. A microhardness value of 25.5GPa was observed for Ti/TiN multilayers. The observed lower friction coefficient value for the Ti/TiN multilayers on mild steel (MS) indicated that the stack layers have better wear resistance property. Results from the electrochemical polarization and impedance studies showed the favorable behavior of the Ti/TiN multilayers, which have improved the corrosion resistance property of MS in 3.5% NaCl solution. The results of this study demonstrate that these multilayers can improve the corrosion resistance of mild steel substrates. [Copyright &y& Elsevier]

Titanium nitride (TiN) coatings were deposited on mild steel (MS) by direct current reactive magnetron sputtering. With the aim of improving the corrosion resistance of TiN, an additional nickel interlayer was brush plated on the steel substrates before TiN film formation. The phases have been identified with X-ray diffraction analysis. The hardness values of TiN layers were found to increase with the increase in thickness of the Ni interlayer. The wear track investigations of TiN layers showed that the TiN/MS system was worn out by abrasive wear mechanism while on the film with Ni interlayer is by adhesive wear. It was found that the TiN/Ni/MS stack had a weaker tendency towards corrosion and higher corrosion resistance in 3·5%NaCl than the bare MS substrate, Ni/MS and TiN/MS specimen. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) coatings of about 2 μm thick were deposited on mild steel (MS) by means of direct current (DC) reactive magnetron sputtering. AlN coatings were prepared in an Ar + N2 gas mixture and their crystal structure, microstructure, and topography were analyzed by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. XRD revealed that the films are polycrystalline in nature and have a hexagonal wurtzite structure with a predominant peak observed along the (002) plane. SEM and AFM images showed the presence of continuously covered pebble like spherical grains on the surface. These coatings showed lower coefficient of friction and excellent wear resistance compared to the bare MS substrate. The potentiodynamic polarization studies showed lower corrosion current density and higher polarization resistance for the AlN/MS structure than the uncoated MS substrate. [ABSTRACT FROM AUTHOR]

Highly transparent tin oxide thin films (SnO2) have been prepared using the sol–gel spin coating technique, optimising process parameters such as the solute concentration, spin rate and time of the turn table, film thickness (number of coatings) and heat treatment temperature. The X-ray diffraction (XRD) studies point to the polycrystalline structure of the developed films. The films deposited under optimum conditions are highly transparent in the visible region with a transmittance of 94% at 550 nm and have a resistivity of 3 × 10-2 Ωcm. The films have been obtained at a relatively low process temperature of 400°C. [ABSTRACT FROM AUTHOR]

Abstract: Porous silicon (PSi) structure was formed at different current densities in the range of 5–60mA/cm2 by the electrochemical anodization of PSi wafers etching in HF for 30min. The PSi was characterized by X-ray diffraction studies. The PSi samples prepared at current densities above and below 30mA/cm2 show PL spectra with asymmetric and overlapped peaks. On the top surface as well as inside the pores of this PSi structures the precursor sol–gel was incorporated by the spin coating technique and SnO2 was formed by heating at 400°C in air. Peaks pertaining to PSi along with those corresponding to SnO2 were observed, which confirmed SnO2 formation as thin film on the PSi surface. The PL spectra of SnO2/PSi structure aged for two months indicated a reduction in PL intensity but remained constant afterwards. SnO2 not only modifies the nature of silicon nanopores but also is expected to influence the interface states in SnO2/PSi junction. [ABSTRACT FROM AUTHOR]

The bioactivity of magnetron sputtered thin film metallic glasses (TFMGs) of Zr 48 Cu 36 Al 8 Ag 8 (at.%) on titanium substrates was tested for bio implant applications. The structural and elemental compositions of TFMGs were analyzed by XRD, XPS and EDAX. X-ray diffraction analysis displayed a broad hump around the incident angle of 30–50°, suggesting that the coatings possess a glassy structure. An in situ crystal growth of hydroxyapatite was observed by soaking the sputtered specimen in simulated body fluid (SBF). The nucleation and growth of a calcium phosphate (Ca–P) bone-like hydroxyapatite on Zr 48 Cu 36 Al 8 Ag 8 (at.%) TFMG from SBF was investigated by using XRD, AFM and SEM. The presence of calcium and phosphorus elements was confirmed by EDAX and XPS. In vitro electrochemical corrosion studies indicated that the Zr-based TFMG coating sustain in the stimulated body-fluid (SBF), exhibiting superior corrosion resistance with a lower corrosion penetration rate and electrochemical stability than the bare crystalline titanium substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • B- or Si-containing TiO 2 -based coatings decorated with Cu or Fe nanoparticles. • Coatings have optimal porosity and desired content of bioactive elements. • Doping with B or Si improves proliferation and differentiation of osteoblastic cell. • Coatings exhibit good mineralization ability when exposed to simulated body fluid. • B-doped TiO 2 coating have a pronounced biocidal effect. • Cu/TiO 2 coatings are effective against multidrug-resistant pathogenes and prevent biofilm formation. Fabrication of bactericidal yet bioactive and biocompatable coatings is still a challenge. Here we report on novel bioactive, bactericidal, antifouling, and cytocompatible TiO 2 -based multi-element coatings that are effective against multidrug-resistant pathogenes. Bioactive elements (Ca, P, Si, and B) were added from electrolytes during plasma electrolytic oxidation (PEO), after which the coatings were subjected to ion implantation with Fe and Cu ions. Careful selection and optimization of PEO modes allowed obtaining optimal porosity and desired content of bioactive elements. Doping with B or Si improved the proliferation and differentiation of MC3T3-E1 osteoblastic cell. In addition, these materials exhibited good mineralization ability when exposed to simulated body fluid. B- and Si-containing PEO coatings, decorated with Cu nanoparticles, showed good cytocompatibility, strong antibacterial activity against Escherichia coli and Staphylococcus aureus multidrug-resistant strains and completely prevented S. aureus biofilm formation. The B-doped PEO coating also had a pronounced biocidal effect, which may be associated with the boron dissolution and the formation of boron oxide. [ABSTRACT FROM AUTHOR]

• TiO 2 -based coatings produced by plasma electrolytic oxidation and ion implantation. • Coatings show high Ca and P ion release and fast mineralization in simulated body fluid. • Coatings generate high amount of reactive oxygen species after UV and sunlight irradiation. • Osteoblastic cells well adhere and proliferate on the surface of TiO 2 -based coatings. • Ag/TiO 2 coating exhibits a strong bactericidal effect against E. coli and S. aureus strains. Plasma electrolytic oxidation (PEO) of Ti alloys was carried out in three different electrolytes based on Ca and P compounds. For the first time, the PEO TiO 2 -based coatings were subjected to ion implantation with Ag and Pt ions to form Ag(Pt) nanoparticles (NPs) on their surface. The PEO coatings released a high amount of Ca and P ions resulting in fast mineralization during their exposure in simulated body fluid. The TiO 2 , Ag/TiO 2 , and Pt/TiO 2 samples generated reactive oxygen species (ROS) after being exposed to various irradiation conditions (UV, visible light, and storage in the dark). The Ag-doped TiO 2 coating exhibited a strong bactericidal effect against E. coli U20 (antibiotic-sensitive), E. coli K261 (antibiotic-resistant), S. aureus 839, and S. aureus 224/228 (methicillin-resistant) strains and inhibited the early stage of their biofilm formation. The Pt/TiO 2 sample was effective toward E. coli U20 and antiadhesive for S. aureus 224/228 strains. The surface of TiO 2 -based coatings was adhesive for osteoblastic cells and able to maintain a high level of MC3T3-E1 cell proliferation. Cytocompatibility of the TiO 2 , Ag/TiO 2 , and Pt/TiO 2 coatings was also confirmed by MTT assay. Good in vitro mineralization ability and high antibacterial efficiency of the Ag/TiO 2 coatings were achieved with only short-term reduction in the osteoblastic cell proliferation and ALP activity. [ABSTRACT FROM AUTHOR]