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In this study, the effects of substrate temperature and ablation wavelength/mechanism on the structural, mechanical, and bioactivity properties of hydroxyapatite (HA) coatings were investigated. HA coatings were deposited on both Si(100) and Ti6Al4V surfaces. Substrate temperature varied from room temperature to 800 °C. Depositions were performed in Ar/H2O and vacuum environments. X-ray diffraction, scanning electron microscopy, and atomic force microscopy techniques were used to analyze structural and morphological variations. The adherence of coatings to the substrates was assessed by the pull-out method. The obtained data indicated that with the temperature increase, the coatings steadily crystallized. However, temperatures above 700 °C adversely affected protein adsorption and adhesion properties. Similar trends were confirmed via pull-out testing, protein adsorption, and cell proliferation tests. The ablation mechanism was also proven to play an important role in the deposition process. Overall, this study provides further evidence that crystallinity is a vital factor in the functionality of the coatings and depends on the deposition conditions. However, all measurements directly indicated that beyond 700 °C, the morpho-structural, mechanical, and bioactivity properties degrade. [ABSTRACT FROM AUTHOR]

This document discusses the use of hydroxyapatite (HA) coatings for orthopedic and dental implants. HA is a bioceramic material that enhances fixation and osseointegration at the implant-tissue interface. The document highlights the advantages of using biodegradable implants, such as eliminating the need for a secondary surgical intervention. It also explores the use of synthetic and biological-derived HA, with the latter showing enhanced mechanical performance and bioactivity. Various techniques for coating implants with HA are discussed, including plasma spray, pulsed laser deposition, and biomimetic coating. The document concludes by emphasizing the focus on the synthesis and characterization of HA-based coatings for applications in bone repair, tissue engineering, and dental implants. [Extracted from the article]

10.3390/coatings9050335 11 Fischer D., de la Fuente G.F., Jansen M. A new pulsed laser deposition technique: Scanning multi-component pulsed laser deposition method. In this respect, one should mention (i) scanning multicomponent pulsed laser deposition [[11]], (ii) combined PLD and magnetron sputtering [[12]], (iii) multibeam PLD [[13]], (iv) off-axis PLD [[14]], (v) combinatorial PLD [[15]], and (vi) reactive pulsed laser deposition [[17], [19]]. Various physical vapor deposition (PVD) techniques, such as molecular beam epitaxy, electron beam physical vapor deposition, pulsed laser deposition (PLD), arc discharge, magnetron sputtering and/or ion beam sputtering, are currently used for coating or growing thin films on solid substrates. One should note that the PLD process is based on the capability of laser radiation, usually in the ultraviolet range, to efficiently interact with solid-state or liquid targets, resulting in the congruent ablation of materials from the target surface and subsequent deposition on a substrate. [Extracted from the article]

Carbon thin films of 50-100 nm thickness were synthesized by Pulsed Laser Deposition in vacuum at different laser fluences from 2 to 6 J/cm2. The deposited films were characterized by Raman spectroscopy for compositional assessment, scanning electron microscopy for morphology/thickness evaluations, and X-ray reflectivity for density, thickness, and roughness determinations. The films were ~100 nm thin, smooth, droplet-free, made of a-C:H type of diamond-like carbon. The mechanical properties of synthesized films were studied by nanoindentation and adhesion tests. The films that were obtained at low laser fluences (2, 3 J/cm2) had better mechanical properties as compared to those synthesized at higher fluences. The mean values of hardness were around 20 GPa, while the friction coefficient was 0.06. The deposition conditions of carbon thin films that displayed the best mechanical properties were further used to coat commercial drills. Both uncoated and coated drills were tested on plates that were made of three types of steel: Stainless steel 304, general use AISI 572 Gr 65 steel (OL60), and AISI D3 tool steel (C120). All of the drill edges and tips were studied by optical and scanning electron microscopes. The coated samples were clearly found to be more resistant, and displayed less morphological defects than their uncoated counterparts when drilling stainless steel and OL60 plates. In the case of C120 steel, carbon coatings failed because of the high friction between drill and the metal plate resulting in tip edges blunting that occurred during processing. [ABSTRACT FROM AUTHOR]

Over the last years, an increasing research interest was observed in the field of PLD synthesis of oxides and nitrides. When compared to other plasma-assisted deposition methods, such as plasma spraying or plasma enhanced chemical vapor deposition, the Pulsed Laser Deposition (PLD) technique stands as a simple, versatile, rapid, and cost-effective approach for the fabrication of high-quality structures from a wide range of materials [1,2]. One should note that, in the dedicated literature, there are studies on the in vivo testing of CaP-based coatings (especially HA) synthesized by numerous physical vapor deposition methods, but only few of them addressed the PLD technique. An important aspect that should be mentioned is related to the targets' preparation for PLD synthesis of iron-doped indium oxide films. [Extracted from the article]

The aim of this review is to present the state-of-the art achievements reported in the last two decades in the field of pulsed laser deposition (PLD) of biocompatible calcium phosphate (CaP)-based coatings for medical implants, with an emphasis on their in vivo biological performances. There are studies in the dedicated literature on the in vivo testing of CaP-based coatings (especially hydroxyapatite, HA) synthesized by many physical vapor deposition methods, but only a few of them addressed the PLD technique. Therefore, a brief description of the PLD technique, along with some information on the currently used substrates for the synthesis of CaP-based structures, and a short presentation of the advantages of using various animal and human implant models will be provided. For an in-depth in vivo assessment of both synthetic and biological-derived CaP-based PLD coatings, a special attention will be dedicated to the results obtained by standardized and micro-radiographies, (micro) computed tomography and histomorphometry, tomodensitometry, histology, scanning and transmission electron microscopies, and mechanical testing. One main specific result of the in vivo analyzed studies is related to the demonstrated superior osseointegration characteristics of the metallic (generally Ti) implants functionalized with CaP-based coatings when compared to simple (control) Ti ones, which are considered as the "gold standard" for implantological applications. Thus, all such important in vivo outcomes were gathered, compiled and thoroughly discussed both to clearly understand the current status of this research domain, and to be able to advance perspectives of these synthetic and biological-derived CaP coatings for future clinical applications. [ABSTRACT FROM AUTHOR]

We report on biological-derived hydroxyapatite (HA, of animal bone origin) doped with lithium carbonate (Li-C) and phosphate (Li-P) coatings synthesized by pulsed laser deposition (PLD) onto Ti6Al4V implants, fabricated by the additive manufacturing (AM) technique. After being previously validated by in vitro cytotoxicity tests, the Li-C and Li-P coatings synthesized onto 3D Ti implants were preliminarily investigated in vivo, by insertion into rabbits' femoral condyles. The in vivo experimental model for testing the extraction force of 3D metallic implants was used for this study. After four and nine weeks of implantation, all structures were mechanically removed from bones, by tensile pull-out tests, and coatings' surfaces were investigated by scanning electron microscopy. The inferred values of the extraction force corresponding to functionalized 3D implants were compared with controls. The obtained results demonstrated significant and highly significant improvement of functionalized implants' attachment to bone (p-values ≤0.05 and ≤0.00001), with respect to controls. The correct placement and a good integration of all 3D-printed Ti implants into the surrounding bone was demonstrated by performing computed tomography scans. This is the first report in the dedicated literature on the in vivo assessment of Li-C and Li-P coatings synthesized by PLD onto Ti implants fabricated by the AM technique. Their improved mechanical characteristics, along with a low fabrication cost from natural, sustainable resources, should recommend lithium-doped biological-derived materials as viable substitutes of synthetic HA for the fabrication of a new generation of metallic implant coatings. [ABSTRACT FROM AUTHOR]

This study is focused on the adhesion and differentiation of the human primary mesenchymal stem cells (hMSC) to osteoblasts lineage on biological-derived hydroxyapatite (BHA) and lithium-doped BHA (BHA:LiP) coatings synthesized by Pulsed Laser Deposition. An optimum adhesion of the cells on the surface of BHA:LiP coatings compared to control (uncoated Ti) was demonstrated using immunofluorescence labelling of actin and vinculin, two proteins involved in the initiation of the cell adhesion process. BHA:LiP coatings were also found to favor the differentiation of the hMSC towards an osteoblastic phenotype in the presence of osteoinductive medium, as revealed by the evaluation of osteoblast-specific markers, osteocalcin and alkaline phosphatase. Numerous nodules of mineralization secreted from osteoblast cells grown on the surface of BHA:LiP coatings and a 3D network-like organization of cells interconnected into the extracellular matrix were evidenced. These findings highlight the good biocompatibility of the BHA coatings and demonstrate that the use of lithium as a doping agent results in an enhanced osteointegration potential of the synthesized biomaterials, which might therefore represent viable candidates for future in vivo applications. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present the current status on animal-origin hydroxyapatite (HA) coatings synthesized by Pulsed Laser Deposition (PLD) technique for medical implant applications. PLD as a thin film synthesis method, although limited in terms of surface covered area, still gathers interest among researchers due to its advantages such as stoichiometric transfer, thickness control, film adherence, and relatively simple experimental set-up. While animal-origin HA synthesized by bacteria or extracted from animal bones, eggshells, and clams was tested in the form of thin films or scaffolds as a bioactive agent before, the reported results on PLD coatings from HA materials extracted from natural sources were not gathered and compared until the present study. Since natural apatite contains trace elements and new functional groups, such as CO32− and HPO42− in its complex molecules, physical-chemical results on the transfer of animal-origin HA by PLD are extremely interesting due to the stoichiometric transfer possibilities of this technique. The points of interest of this paper are the origin of HA from various sustainable resources, the extraction methods employed, the supplemental functional groups, and ions present in animal-origin HA targets and coatings as compared to synthetic HA, the coatings' morphology function of the type of HA, and the structure and crystalline status after deposition (where properties were superior to synthetic HA), and the influence of various dopants on these properties. The most interesting studies published in the last decade in scientific literature were compared and morphological, elemental, structural, and mechanical data were compiled and interpreted. The biological response of different types of animal-origin apatites on a variety of cell types was qualitatively assessed by comparing MTS assay data of various studies, where the testing conditions were possible. Antibacterial and antifungal activity of some doped animal-origin HA coatings was also discussed. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) films were synthesized onto Si(100) substrates by pulsed laser deposition (PLD) in vacuum or nitrogen, at 0.1, 1, 5, or 10 Pa, and substrate temperatures ranging from RT to 800 °C. The laser parameters were set at: incident laser fluence of 3–10 J/cm2 and laser pulse repetition frequency of 3, 10, or 40 Hz, respectively. The films' hardness was investigated by depth-sensing nanoindentation. The optical properties were studied by FTIR spectroscopy and UV-near IR ellipsometry. Hardness values within the range of 22–30 GPa and Young's modulus values of 230–280 GPa have been inferred. These values were determined by the AlN film structure that consisted of nanocrystallite grains, strongly dependent on the deposition parameters. The values of optical constants, superior to amorphous AlN, support the presence of crystallites in the amorphous film matrix. They were visualized by TEM and evidenced by FTIR spectroscopy. The characteristic Reststrahlen band of the h-AlN lattice with component lines arising from IR active phonon vibrational modes in AlN nanocrystallites was well detectable within the spectral range of 950–500 cm−1. Control X-ray diffraction and atomic force microscopy data were introduced and discussed. All measurements delivered congruent results and have clearly shown a correlation between the films' structure and the mechanical and optical properties dependent on the experimental conditions. [ABSTRACT FROM AUTHOR]

Simple and lithium-doped biological-origin hydroxyapatite layers were synthesized by Pulsed Laser Deposition technique on medical grade Ti substrates. Cytotoxic effects of lithium addition and the biocompatibility of obtained coatings were assessed using three cell lines of human origin (new initiated dermal fibroblasts, immortalized keratinocytes HaCaT, and MG-63 osteosarcoma). Antimicrobial properties of obtained coatings were assessed on two strains (i.e., Staphylococcus aureus and Candida albicans), belonging to species representative for the etiology of medical devices biofilm-associated infections. Our findings suggest that synthesized lithium-doped coatings exhibited low cytotoxicity on human osteosarcoma and skin cells and therefore, an excellent biocompatibility, correlated with a long-lasting anti-staphylococcal and -fungal biofilm activity. Along with low fabrication costs generated by sustainable resources, these biological-derived materials demonstrate their promising potential for future prospective solutions—viable alternatives to commercially available biomimetic HA implants—for the fabrication of a new generation of implant coatings. [ABSTRACT FROM AUTHOR]