Laser-assisted surface texturing of Ti/Zr multilayers for mesenchymal stem cell response

The formation of an ordered surface texture with micro and nanometer features on Ti/Zr multilayers is studied for better understanding and improvement of cell integration. Nanocomposite in form 30×(Ti/Zr)/Si thin films was deposited by ion sputtering on Si substrate for biocompatibility investigation. Surface texturing by femtosecond laser processing made it possible to form the laser-induced periodic surface structure (LIPSS) in each laser-written line. At fluence slightly above the ablation threshold, beside the formation of low spatial frequency-LIPSS (LSFL) oriented perpendicular to the direction of the laser polarization, the laser-induced surface oxidation was achieved on the irradiated area. Intermixing between the Ti and Zr layers with the formation of alloy in the sub-surface region was attained during the laser processing. The surface of the Ti/Zr multilayer system with changed composition and topography was used to observe the effect of topography on the survival, adhesion and proliferation of the murine mesenchymal stem cells (MSCs). Confocal and SEM microscopy images showed that cell adhesion and their growth improve on these modified surfaces, with tendency of the cell orientation along of LIPSS in laser-written lines. © 2019 by the authors

The use of lasers in dental materials: A review

Lasers have been well integrated in clinical dentistry for the last two decades, providing clinical alternatives in the management of both soft and hard tissues with an expanding use in the field of dental materials. One of their main advantages is that they can deliver very low to very high concentrated power at an exact point on any substrate by all possible means. The aim of this review is to thoroughly analyze the use of lasers in the processing of dental materials and to enlighten the new trends in laser technology focused on dental material management. New approaches for the elaboration of dental materials that require high energy levels and delicate processing, such as metals, ceramics, and resins are provided, while time consuming laboratory procedures, such as cutting restorative materials, welding, and sintering are facilitated. In addition, surface characteristics of titanium alloys and high strength ceramics can be altered. Finally, the potential of lasers to increase the adhesion of zirconia ceramics to different substrates has been tested for all laser devices, including a new ultrafast generation of lasers. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Influence of the repetition rate on the formation of laser-induced periodic surface structures

USTS 2017, Salamanca, November 22nd to 24th, 2017. -- https://www.ultrafast.es/USTS2017Peer Reviewe

Tuning the Wettability of Steel by Femtosecond Laser Structuring

CLEO: Applications and Technology 2017 San Jose, California United States 14–19 May 2017We present a strategy to control the wetting properties of steel using high-repetition rate femtosecond laser-written parallel lines and grids with variable spacing. This approach also allows generating lateral anisotropy of the wetting angle.Peer Reviewe

On the formation and features of the supra-wavelength grooves generated during femtosecond laser surface structuring of silicon

We have investigated the formation process of supra-wavelength quasi-periodic surface structures, commonly termed as grooves, produced during femtosecond laser surface structuring of a silicon target, in air. The experiments have been carried out at two wavelengths, namely 513 nm and 1026 nm, and in multi-pulse irradiation conditions. Both static, i.e., irradiating the same target location, and dynamic, namely scanning the beam along a line, configurations have been explored. We have also carried out simulations of the process by using a multiscale numerical model, based on the two-temperature model coupled to a fluid dynamics approach. The comparison of experimental and numerical results has allowed us to clearly establish the role of hydrothermal waves in the grooves formation process

Smart polymersomes and hydrogels from polypeptide-based polymer systems through α-amino acid N-carboxyanhydride ring-opening polymerization. From chemistry to biomedical applications

The synthesis of smart stimuli-responsive polymeric materials for nanomedicine applications has attracted the interest of a large number of scientists that focuses on the effective encapsulation of pharmaceutical compounds and control of their biodistribution. The development of multifunctional polymeric materials is mainly guided by the goal of achieving active compounds which selectively target the pathological sites, therefore minimizing systemic side effects. These materials are divided in two categories based on their mode of administration: the first is based on systemic administration, while the second relies on localized mode of action. Polymersomes are nanocarriers that are delivered through the blood compartment and are the best systems to carry both hydrophilic drugs in their interior hollow space or/and hydrophobic drugs encapsulated in their hydrophobic layer. Polymeric hydrogels on the other hand are systems for localized drug delivery of both kinds of pharmaceuticals, depending on their solubility. Even though a large number of polymeric materials that form either nanocarrier or hydrogel delivery systems has been investigated, a surprisingly small subset of these technologies has demonstrated potentially curative preclinical results, and fewer have progressed towards commercialization. One of the most promising classes of polymeric materials for drug delivery applications is polypeptides, which combine the properties of the conventional polymers with the 3D structure of natural proteins such as α-helices and β-sheets. In this article, the synthetic pathways followed to develop well-defined stimuli-responsive polymer delivery systems based on polypeptides that have been prepared through ring-opening polymerization (ROP) of N-carboxyanhydrides are reviewed, including a discussion of their in vivo and in vitro efficacy. This review is limited to systems presented over the last eighteen years. © 2018 Elsevier B.V

Biomimetic structures via self-organization in multiple-scan, femtosecond-laser irradiated surfaces

European Congress and Exhibition on Advanced Materials and Processes (2017), Thessaloniki, Greece, from 17 – 22 September, 2017. -- http://euromat2017.fems.eu/#Peer Reviewe

Biomimetic surface structures in steel fabricated with femtosecond laser pulses: influence of laser rescanning on morphology and wettability

11 pags., 5 figs., 1 tab. -- Open Access funded by Creative Commons Atribution Licence 4.0. -- This article is part of the Thematic Series "Biological and biomimetic surfaces: adhesion, friction and wetting phenomena".The replication of complex structures found in nature represents an enormous challenge even for advanced fabrication techniques, such as laser processing. For certain applications, not only the surface topography needs to be mimicked, but often also a specific function of the structure. An alternative approach to laser direct writing of complex structures is the generation of laser-induced periodic surface structures (LIPSS), which is based on directed self-organization of the material and allows fabrication of specific micro- and nanostructures over extended areas. In this work, we exploit this approach to fabricate complex biomimetic structures on the surface of steel 1.7131 formed upon irradiation with high repetition rate femtosecond laser pulses. In particular, the fabricated structures show similarities to the skin of certain reptiles and integument of insects. Different irradiation parameters are investigated to produce the desired structures, including laser repetition rate and laser fluence, paying special attention to the influence of the number of times the same area is rescanned with the laser. The latter parameter is identified to be crucial for controlling the morphology and size of specific structures. As an example for the functionality of the structures, we have chosen the surface wettability and studied its dependence on the laser processing parameters. Contact angle measurements of water drops placed on the surface reveal that a wide range of angles can be accessed by selecting the appropriate irradiation parameters, highlighting also here the prominent role of the number of scans.This work has been supported by the LiNaBioFluid Project (H2020-FETOPEN-2014–2015RIA, Grant No. 665337) of the European Commission as well as the research grant (TEC2014–52642-C2–1-R) from the Spanish Ministry of Economy and CompetitivenessPeer Reviewe

Partial ablation of Ti/Al nano-layer thin film by single femtosecond laser pulse

The interaction of ultra-short laser pulses with Titanium/Aluminium (Ti/Al) nano-layered thin film was investigated. The sample composed of alternating Ti and Al layers of a few nanometres thick was deposited by ion-sputtering. A single pulse irradiation experiment was conducted in an ambient air environment using focused and linearly polarized femtosecond laser pulses for the investigation of the ablation effects. The laser induced morphological changes and the composition were characterized using several microscopy techniques and energy dispersive X-ray spectroscopy. The following results were obtained: (i) at low values of pulse energy/fluence, ablation of the upper Ti layer only was observed; (ii) at higher laser fluence, a two-step ablation of Ti and Al layers takes place, followed by partial removal of the nano-layered film. The experimental observations were supported by a theoretical model accounting for the thermal response of the multiple layered structure upon irradiation with ultra-short laser pulses. Published by AIP Publishing