Pulsed Laser Evaporation Research Articles

Coating of Flexible PDMS Substrates through Matrix-Assisted Pulsed Laser Evaporation (MAPLE) with a New-Concept Biocompatible Graphenic Material.

In this study, matrix-assisted pulsed laser evaporation (MAPLE) was used to deposit graphene-like materials (GL), a new class of biocompatible graphene-related materials (GRMs) obtained from a controlled top-down demolition of a carbon black, on silicone slices to test their potential use as functional coating on invasive medical devices as indwelling urinary catheters. Results indicate that the relevant chemical-physical features of the deposit (controlled by FTIR and AFM) were maintained after MAPLE deposition. After deposition, GL films underwent a biological survey toward target cellular lines (murine fibroblast NIH3T3, human keratinocytes HaCAT and the human cervical adenocarcinoma epithelial-like HeLa). Results indicate that the GL films did not lead to any perturbations in the different biological parameters evaluated. The presented results and the possibility to further functionalize the GL or combine them with other functional materials in a hybrid fashion to assure a tighter adhesion onto the substrate for use in harsh conditions open the door to practical applications of these new-concept medical devices (drug delivery, next generation flexible devices, multifunctional coatings) paving the way to the prevention of nosocomial infections driven by catheterization through antibiotics-free approaches.

Composite Coatings for Osteoblast Growth Attachment Fabricated by Matrix-Assisted Pulsed Laser Evaporation.

The bioactive and biocompatible properties of hydroxyapatite (HAp) promote the osseointegration process. HAp is widely used in biomedical applications, especially in orthopedics, as well as a coating material for metallic implants. We obtained composite coatings based on HAp, chitosan (CS), and FGF2 by a matrix-assisted pulsed laser evaporation (MAPLE) technique. The coatings were physico-chemically investigated by means of X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Infrared Microscopy (IRM), and Scanning Electron Microscopy (SEM). Further, biological investigations were performed. The MAPLE-composite coatings were tested in vitro on the MC3T3-E1 cell line in order to endorse cell attachment and growth without toxic effects and to promote pre-osteoblast differentiation towards the osteogenic lineage. These coatings can be considered suitable for bone tissue engineering applications that lack toxicity and promotes cell adhesion and proliferation while also sustaining the differentiation of pre-osteoblasts towards mature bone cells.

Innovative Technologies to Improve the Corrosion Resistance of Stainless Steels

Oxidation is one of the main degradation mechanisms that affects most industrial components. Stainless steels are used in components and equipment in the chemical and petrochemical industries (e.g., valves, plates, columns, capacitors and desalination units). Generally, the steels used in these applications have physical, mechanical and chemical properties that give them corrosion resistance. However, contaminants existing in the processed fluids are the main factor causing the increase in corrosion rate, leading to significant financial losses, which requires the development of innovative technologies to protect the metal from the action of aggressive environment. The paper presents two innovative surface protection techniques used to improve the corrosion resistance of stainless steels. Thus, Matrix-Assisted Pulsed Laser Evaporation (MAPLE) and Pulsed Laser Deposition (PLD) techniques are used to obtain deposition of hybrid nanostructures of binary oxides and porphyrins on W1.4034 martensitic stainless steel, according to EN 10083-3.

Implant Surfaces Containing Bioglasses and Ciprofloxacin as Platforms for Bone Repair and Improved Resistance to Microbial Colonization.

Coatings are an attractive and challenging selection for improving the bioperformance of metallic devices. Composite materials based on bioglass/antibiotic/polymer are herein proposed as multifunctional thin films for hard tissue implants. We deposited a thin layer of the polymeric material by matrix-assisted pulsed laser evaporation—MAPLE onto Ti substrates. A second layer consisting of bioglass + antibiotic was applied by MAPLE onto the initial thin film. The antimicrobial activity of MAPLE-deposited thin films was evaluated on Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa standard strains. The biocompatibility of obtained thin films was assessed on mouse osteoblast-like cells. The results of our study revealed that the laser-deposited coatings are biocompatible and resistant to microbial colonization and biofilm formation. Accordingly, they can be considered viable candidates for biomedical devices and contact surfaces that would otherwise be amenable to contact transmission.

New Poly(N-isopropylacrylamide-butylacrylate) Copolymer Biointerfaces and Their Characteristic Influence on Cell Behavior In Vitro.

Designing and obtaining new synthetic smart biointerfaces with specific and controlled characteristics relevant for applications in biomedical and bioengineering domains represents one of the main challenges in these fields. In this work, Matrix-Assisted Pulsed Laser Evaporation (MAPLE) is used to obtain synthetic biointerfaces of poly(N-isopropyl acrylamide-butyl acrylate) p(NIPAM-BA) copolymer with different characteristics (i.e., roughness, porosity, wettability), and their effect on normal HEK 293 T and murine melanoma B16-F1 cells is studied. For this, the influence of various solvents (chloroform, dimethylsulfoxide, water) and fluence variation (250–450 mJ/cm2) on the morphological, roughness, wettability, and physico–chemical characteristics of the coatings are evaluated by atomic force microscopy, scanning electron microscopy, contact angle measurements, Fourier-transform-IR spectroscopy, and X-ray photoelectron spectroscopy. Coatings obtained by the spin coating method are used for reference. No significant alteration in the chemistry of the surfaces is observed for the coatings obtained by both methods. All p(NIPAM-BA) coatings show hydrophilic character, with the exception of those obtained with chloroform at 250 mJ/cm2. The surface morphology is shown to depend on both solvent type and laser fluence and it ranges from smooth surfaces to rough and porous ones. Physico–chemical and biological analysis reveal that the MAPLE deposition method with fluences of 350–450 mJ/cm2 when using DMSO solvent is more appropriate for bioengineering applications due to the surface characteristics (i.e., pore presence) and to the good compatibility with normal cells and cytotoxicity against melanoma cells.

Nitrites Detection with Sensors Processed via Matrix-Assisted Pulsed Laser Evaporation

This work is focused on the application of a laser-based technique, i.e., matrix-assisted pulsed laser evaporation (MAPLE) for the development of electrochemical sensors aimed at the detection of nitrites in water. Commercial carbon-based screen-printed electrodes were modified by MAPLE via the application of a newly developed composite coating with different concentrations of carbon nanotubes (CNTs), chitosan, and iron (II) phthalocyanine (C32H16FeN8). The performance of the newly fabricated composite coatings was evaluated both by investigating the morphology and surface chemistry of the coating, and by determining the electro-catalytic oxidation properties of nitrite with bare and modified commercial carbon-based screen-printed electrode. It was found that the combined effect of CNTs with chitosan and C32H16FeN8 significantly improves the electrochemical response towards the oxidation of nitrite. In addition, the MAPLE modified screen-printed electrodes have a limit of detection of 0.12 µM, which make them extremely useful for the detection of nitrite traces.

Efficient Decrease in Corrosion of Steel in 0.1 M HCl Medium Realized by a Coating with Thin Layers of MnTa2O6 and Porphyrins Using Suitable Laser-Type Approaches.

The purpose of this research is to meet current technical and ecological challenges by developing novel steel coating systems specifically designed for mechanical equipment used in aggressive acid conditions. Homogeneous sandwich-type layered films on the surface of steel electrodes were realized using a pseudo-binary oxide, MnTa2O6, and two different substituted porphyrin derivatives, namely: 5-(4-carboxy-phenyl)-10,15,20-tris (4-methyl-phenyl)-porphyrin and 5-(4-methyl-benzoate)-10,15,20-tris (4-methyl-phenyl)-porphyrin, which are novel investigated compound pairs. Two suitable laser strategies, pulsed laser deposition (PLD) and matrix-assisted pulsed laser evaporation (MAPLE), were applied in order to prevent porphyrin decomposition and to create smooth layers with low porosity that are extremely adherent to the surface of steel. The electrochemical measurements of corrosion-resistant coating performance revealed that in all cases in which the steel electrodes were protected, a significant value of corrosion inhibition efficiency was found, ranging from 65.6 to 83.7%, depending on the nature of the porphyrin and its position in the sandwich layer. The highest value (83.7%) was obtained for the MAPLE/PLD laser deposition of 5-(4-carboxy-phenyl)-10,15,20-tris (4-methyl-phenyl)-porphyrin/MnTa2O6(h), meaning that the inhibitors adsorbed and blocked the access of the acid to the active sites of the steel electrodes.

Kaolinite Thin Films Grown by Pulsed Laser Deposition and Matrix Assisted Pulsed Laser Evaporation.

In this work, thin films of lamellar clays were deposited by laser techniques (matrix assisted pulsed laser evaporation (MAPLE) and pulsed laser deposition (PLD)). The focus of this paper is the optimization of deposition parameters for the production of highly oriented crystalline films. The films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Contact angle measurements were employed to identify the wetting properties of the deposited thin films. Hydrophobic to superhydrophilic films can be prepared by using different deposition techniques and deposition parameters. MAPLE led to superhydrophilic films with contact angles in the range 4°–8°, depending on the microstructure and surface roughness at micro and nano scale. The 1064 nm PLD had a high deposition rate and produced a textured film while at λ = 193 nm an extremely thin and amorphous layer was depicted. Oriented kaolinite films were obtained by MAPLE even at 5 wt.% kaolinite in the target.

Epitaxially crystallized polyethylene exhibiting near‐equilibrium melting temperatures*

AbstractThe morphology and orientation of polymer crystals are important factors which determine the performance of thin‐film, polymer‐based technologies such as organic electronic devices and gas separation membranes. Here, we utilize polymer‐substrate epitaxy to achieve a highly oriented crystalline morphology during thin‐film processing. To accomplish this, we employ matrix‐assisted pulsed laser evaporation (MAPLE), a slow physical vapor deposition process, to deposit linear polyethylene epitaxially atop a graphene substrate. Via MAPLE, we demonstrate the ability to achieve a film morphology comprised of well‐aligned, edge‐on crystalline lamellae. Furthermore, we show that MAPLE can be exploited to grow crystalline lamellae composed entirely of extended polymer chains which exhibit a near‐equilibrium melting temperature. Our study demonstrates that MAPLE, as a bottom‐up approach, can deposit polymer thin films with improved control over crystalline morphology.

PEG-Functionalized Magnetite Nanoparticles for Modulation of Microbial Biofilms on Voice Prosthesis.

This study reports the fabrication of nanostructured coatings based on magnetite, polyethyleneglycol, and biologically active molecule (polymyxin B-PM) for producing biofilm-resistant surfaces (voice prosthesis). Magnetite nanoparticles (MNPs) have been synthesized and functionalized using a co-precipitation method and were further deposited into thin coatings using the matrix-assisted pulsed laser evaporation (MAPLE) technique. The obtained nanoparticles and coatings were characterized by X-ray diffraction (XRD), thermogravimetric analysis with differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM), transmission electron microscopy with selected area electron diffraction (TEM-SAED), Fourier-transform infrared spectroscopy (FT-IR), and infrared microscopy (IRM). Their antibiofilm activity was tested against relevant Staphylococcus aureus and Pseudomonas aeruginosa bacterial strains. The Fe3O4@PEG/PM surface of modified voice prosthesis sections reduced the number of CFU/mL up to four orders of magnitude in the case of S. aureus biofilm. A more significant inhibitory effect is noticed in the case of P. aeruginosa up to five folds. These results highlight the importance of new Fe3O4@PEG/PM in the biomedical field.

Organic Heterostructures with Indium‐Free Transparent Conductor Electrode for Optoelectronic Applications

Herein, the properties of the organic heterostructures with triple‐layer ZnO/Ag/ZnO as a replacement for ITO and mixed layer containing arylenevinylene oligomer (based on triphenylamine or carbazole) donor and nonfullerene (perylene diimide) acceptor mixed in the ratio 1:2 and the effect of a buffer layer of PEDOT‐PSS intercalated between triple layer and mixed organic layer are discussed. The UV−vis transmission and photoluminescence (PL) properties are investigated in correlation with the surface topography and reveal a good match between the absorption and emission domain, which can favor the generation of the charge carriers. The heterostructure with the mixed layer based on triphenylamine oligomer shows the widest absorption domain, and the PL spectra of the heterostructures realized with either triphenylamine or carbazole oligomer show peaks corresponding to the radiative decay of the donor and acceptor. The I−V characteristics in the dark indicate a slightly nonlinear behavior and the current is affected by the charge carriers recombination on the defects present in the thick mixed layer deposited by matrix‐assisted pulsed laser evaporation. The effect of the PEDOT‐PSS buffer layer on the electrical properties of the organic heterostructure with ZnO/Ag/ZnO electrode is also investigated.

Thin Films of Nanocrystalline Fe(pz)[Pt(CN)4] Deposited by Resonant Matrix-Assisted Pulsed Laser Evaporation.

Prior studies of the thin film deposition of the metal-organic compound of Fe(pz)Pt[CN]4 (pz = pyrazine) using the matrix-assisted pulsed laser evaporation (MAPLE) method, provided evidence for laser-induced decomposition of the molecular structure resulting in a significant downshift of the spin transition temperature. In this work we report new results obtained with a tunable pulsed laser, adjusted to water resonance absorption band with a maximum at 3080 nm, instead of 1064 nm laser, to overcome limitations related to laser–target interactions. Using this approach, we obtain uniform and functional thin films of Fe(pz)Pt[CN]4 nanoparticles with an average thickness of 135 nm on Si and/or glass substrates. X-ray diffraction measurements show the crystalline structure of the film identical to that of the reference material. The temperature-dependent Raman spectroscopy indicates the spin transition in the temperature range of 275 to 290 K with 15 ± 3 K hysteresis. This result is confirmed by UV-Vis spectroscopy revealing an absorption band shift from 492 to 550 nm related to metal-to-ligand-charge-transfer (MLCT) for high and low spin states, respectively. Spin crossover is also observed with X-ray absorption spectroscopy, but due to soft X-ray-induced excited spin state trapping (SOXIESST) the transition is not complete and shifted towards lower temperatures.

Organic Thin Films Deposited by Matrix-Assisted Pulsed Laser Evaporation (MAPLE) for Photovoltaic Cell Applications: A Review

Human society’s demand for energy has increased faster in the last few decades due to the world’s population growth and economy development. Solar power can be a part of a sustainable solution to this world’s energy need, taking into account that the cost of the renewable energy recently dropped owed to the remarkable progress achieved in the solar panels field. Thus, this inexhaustible source of energy can produce cheap and clean energy with a beneficial impact on the climate change. The considerable potential of the organic photovoltaic (OPV) cells was recently emphasized, with efficiencies exceeding 18% being achieved for OPV devices with various architectures. The challenges regarding the improvement in the OPV performance consist of the selection of the adequate raw organic compounds and manufacturing techniques, both strongly influencing the electrical parameters of the fabricated OPV devices. At the laboratory level, the solution-based techniques are used in the preparation of the active films based on polymers, while the vacuum evaporation is usually involved in the deposition of small molecule organic compounds. The major breakthrough in the OPV field was the implementation of the bulk heterojunction concept but the deposition of mixed films from the same solvent is not always possible. Therefore, this review provides a survey on the development attained in the deposition of organic layers based on small molecules compounds, oligomers and polymers using matrix-assisted pulsed laser evaporation (MAPLE)-based deposition techniques (MAPLE, RIR-MAPLE and emulsion-based RIR-MAPLE). An overview of the influence of various experimental parameters involved in these laser deposition methods on the properties of the fabricated layers is given in order to identify, in the forthcoming years, new strategies for enhancing the OPV cells performance.

Anti-Biofilm Coatings Based on Chitosan and Lysozyme Functionalized Magnetite Nanoparticles.

Biofilms represent a common and increasingly challenging problem in healthcare practices worldwide, producing persistent and difficult to manage infections. Researchers have started developing antibiotic-free treatment alternatives in order to decrease the risk of resistant microbial strain selection and for the efficient management of antibiotic tolerant biofilm infections. The present study reports the fabrication and characterization of magnetite-based nanostructured coatings for producing biofilm-resistant surfaces. Specifically, magnetite nanoparticles (Fe3O4) were functionalized with chitosan (CS) and were blended with lysozyme (LyZ) and were deposited using the matrix-assisted pulsed laser evaporation (MAPLE) technique. A variety of characterization techniques were employed to investigate the physicochemical properties of both nanoparticles and nanocoatings. The biological characterization of the coatings assessed through cell viability and antimicrobial tests showed biocompatibility on osteoblasts as well as antiadhesive and antibiofilm activity against both Gram-negative and Gram-positive bacterial strains and no cytotoxic effect against human-cultured diploid cells.

Biofilm-Resistant Nanocoatings Based on ZnO Nanoparticles and Linalool.

Biofilms represent an increasing challenge in the medical practice worldwide, imposing a serious threat to public health. As bacterial strains have developed antibiotic resistance, researcher’s attention has been extensively focused on developing more efficient antimicrobial strategies. In this context, the present study reports the synthesis, physicochemical characterization, ex vivo biodistribution, and in vitro evaluation of the capacity of nanostructured surfaces based on zinc oxide (ZnO) and biologically active molecules to modulate clinically relevant microbial biofilms. ZnO nanoparticles (NPs) were synthesized through a co-precipitation method without thermal treatment. The matrix-assisted pulsed laser evaporation (MAPLE) was applied for preparing nanostructured coatings based on ZnO NPs surface modified with linalool that were further characterized by X-ray diffraction (XRD), thermogravimetric analysis with differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM), transmission electron microscopy with selected area electron diffraction (TEM-SAED), Fourier-transform infrared spectroscopy (FT-IR), and infrared microscopy (IRM). Histological analyses carried out at 7 days and 14 days after the intraperitoneal administration of linalool modified ZnO NPs revealed the absence of the latter from the brain, kidney, liver, lung, myocardium, and pancreas. Through in vitro assays on prokaryotic cells, it was proven that ZnO coatings hinder microbial biofilm formation of both Gram-positive and Gram-negative bacteria strains.

Pulsed Laser Deposition of Thin-Film Coatings in an Electrostatic Field

The work is devoted to the problem of thin metal coatings deposition on dielectric substrates using the method of target material pulsed laser evaporation. The main advantage of laser ablation over other methods of coating deposition is the possibility of using practically any material as a target, while the resulting films are characterized by a high correspondence of the phase and chemical composition to the target material. The possibility of using an electrostatic field to improve the efficiency of coating deposition process is considered. Under the action of an electric field formed between the plates of high-voltage electrodes, the ablation products leave the treatment area and settle on the substrate surface. Examples of coatings deposited under various ablation conditions are shown.

Vibronic transitions and spin-orbit coupling of three-membered metallacycles formed by lanthanide-mediated dehydrogenation of dimethylamine.

Metal-mediated N-H and C-H bond activation of aliphatic amines is an effective strategy for synthesizing biologically important molecules. Ln (Ln = La and Ce) atom reactions with dimethylamine are carried out in a pulsed-laser vaporization supersonic molecular beam source. A series of dehydrogenation species are observed with time-of-flight mass spectrometry, and the dehydrogenated Ln-containing species in the formula Ln(CH2NCH3) are characterized by single-photon mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical calculations. The theoretical calculations include density functional theory for both Ln species and multiconfiguration self-consistent field and quasi-degenerate perturbation theory for the Ce species. The MATI spectrum of La(CH2NCH3) consists of a single vibronic band system, which is assigned to the ionization of the doublet ground state of N-methyl-lanthanaaziridine. The MATI spectrum of Ce(CH2NCH3) displays two vibronic band systems, which are attributed to the ionization of two-pair lowest-energy spin-orbit coupling states of N-methyl-ceraaziridine. Both metallaaziridines are three-membered metallacycles and formed by the thermodynamically and kinetically favorable concerted dehydrogenation of the amino group and one of the methyl groups.

Isoflavonoid-Antibiotic Thin Films Fabricated by MAPLE with Improved Resistance to Microbial Colonization

Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative) bacteria represent major infectious threats in the hospital environment due to their wide distribution, opportunistic behavior, and increasing antibiotic resistance. This study reports on the deposition of polyvinylpyrrolidone/antibiotic/isoflavonoid thin films by the matrix-assisted pulsed laser evaporation (MAPLE) method as anti-adhesion barrier coatings, on biomedical surfaces for improved resistance to microbial colonization. The thin films were characterized by Fourier transform infrared spectroscopy, infrared microscopy, and scanning electron microscopy. In vitro biological assay tests were performed to evaluate the influence of the thin films on the development of biofilms formed by Gram-positive and Gram-negative bacterial strains. In vitro biocompatibility tests were assessed on human endothelial cells examined for up to five days of incubation, via qualitative and quantitative methods. The results of this study revealed that the laser-fabricated coatings are biocompatible and resistant to microbial colonization and biofilm formation, making them successful candidates for biomedical devices and contact surfaces that would otherwise be amenable to contact transmission.

Laser synthesis of NixZnyO/reduced graphene oxide/carbon nanotube electrodes for energy storage applications

Porous multicomponent surface layers consisting of bimetallic oxide nanoparticles, carbon nanomaterials reduced graphene oxide (GO) and multiwall carbon nanotubes (MWCNTs) were prepared by reactive inverse matrix assisted pulsed laser evaporation. The layers were tested as electrodes for supercapacitor devices. Bimetallic oxide nanoparticles were grown through the mixing of simple inorganic oxides and organic compounds in distilled water. A frequency quadrupled Nd:YAG laser was used for the irradiation of the target dispersions consisting of GO platelets, MWCNTs, NiO, and Zn acetate. Besides oxide nanoparticles synthesis, which were present both on the surface of GO platelets and MWCTs and were also encapsulated within the MWCNTs walls, the GO platelets used for the preparation of the target dispersion were reduced under the effect of the laser pulses. An enhancement of the electrochemical performances of the nanohybrid electrodes were obtained as a results of the formation of bimetallic oxide nanoparticles. The electrodes exhibit fast charge–discharge cycling rate and improved storage capacity as compared to compound layer counterparts containing carbon nanomaterials, reduced graphene oxide, carbon nanotubes and simple binary transition metal oxide nanoparticles, 40F/cm3 volumetric capacitance at 10 mV/s scan rate, 1.5 mW/cm3 energy density and 12 W/cm3 power density at 4 mA/cm3 current density.

Physical Vapour Deposited Biomedical Coatings

This Special Issue was devoted to developments made in Physical Vapour Deposited (PVD) biomedical coatings for various healthcare applications. The scrutinized PVD methods were Radio-Frequency Magnetron Sputtering (RF-MS), Cathodic Arc Evaporation, Pulsed Electron Deposition and its variants, Pulsed Laser Deposition, and Matrix Assisted Pulsed Laser Evaporation (MAPLE), due to their great promise especially in the dentistry and orthopaedics. These methods have yet to gain traction for industrialization and large-scale application in biomedicine. A new generation of implant coatings can be made available by the (1) incorporation of organic moieties (e.g., proteins, peptides, enzymes) into thin films by innovative methods such as combinatorial MAPLE, (2) direct coupling of therapeutic agents with bioactive glasses or ceramics within substituted or composite layers via RF-MS, or (3) by innovation in high energy deposition methods such as arc evaporation or pulsed electron beam methods.