Directed Irradiation Synthesis as an Advanced Plasma Technology for Surface Modification to Activate Porous and “as-received” Titanium Surfaces

For the design of smart titanium implants, it is essential to balance the surface properties without any detrimental effect on the bulk properties of the material. Therefore, in this study, an irradiation-driven surface modification called directed irradiation synthesis (DIS) has been developed to nanopattern porousand“as-received”c.p. Tisur faces with the aim of improving cellular viability. Nano features were developed using singly-charged argon ions at 0.5 and 1.0 keV energies, incident angles from 0◦ to 75◦ degrees, and fluences up to 5.0×1017 cm−2. Irradiated surfaces were evaluated by scanning electron microscopy, atomic force microscopy and contact angle, observing an increased hydrophilicity (a contact angle reduction of 73.4% and 49.3%) and a higher roughness on both surfaces except for higher incident angles, which showed the smoothest surface. In-vitro studies demonstrated the biocompatibility of directed irradiation synthesis (DIS) reaching 84% and 87% cell viability levels at 1 and 7 days respectively, and a lower percentage of damaged DNA in tail compared to the control c.p. Ti. All these results confirm the potential of the DIS technique to modify complex surfaces at the nanoscale level promoting their biological performance.Department of Defense (Spain) contract W81XWH-11-2-0067Ministry of Economy and Competitiveness of Spain grant MAT2015-71284-

Bending and positioning of nanoparticles with light

Die Wechselwirkung von Nanopartikeln mit Licht ist seit Jahrzehnten ein intensives Forschungsgebiet im Bereich der Nanowissenschaften. Dabei rücken insbesondere Methoden die es erlauben einzelne Nanopartikel mit Licht zu verändern und präzise zu positionieren immer mehr in den Fokus des wissenschaftlichen Interesses. Eine der größten Herausforderungen in diesem Zusammenhang ist es, neue und zuverlässige Wege zu finden, um einzelne Nanopartikel mit hoher Kontrolle zeitlich und räumlich exakt zu manipulieren. Zwei Beispiele, nämlich die Möglichkeit der kontrollierten Deformation einzelner Gold-Nanostäbchen mit Licht und die Verwendung plasmonischer Nanoantennenfelder für das optische Einfangen von Nanoobjekten mit hoher lateraler Präzession werden im Rahmen dieser Arbeit präsentiert. Zunächst wurde untersucht, wie einzelne Gold-Nanostäbchen in Lösung mit Licht durch eine Kombination aus plasmonischem Heizen und der Wechselwirkung von optischen und hydrodynamischen Kräften in eine V-Form gebogen werden können. Dabei kann der Biegewinkel in Abhängigkeit der verwendeten Laserintensität kontrolliert werden. Derartige V-förmige Nanoantennen aus Gold haben ein großes Anwendungspotential bei der Herstellung von Metamaterialien. Die Möglichkeit einzelne, V-förmige Nanostäbchen mit Licht zu positionieren und auf einem Substrat zu orientieren ist eine Grundvorausetzung zur Verwirklichung derartiger Oberflächen und wurde in dieser Arbeit näher untersucht. Im zweiten Teil dieser Arbeit wird die Eigenschaft von plasmonisch gekoppelten Nanoantennen, Licht in ein kleines Volumen zu bündeln ausgenutzt, um das optische Einfangen von Nanoobjekten auf plasmonischen Oberflächen zu ermöglichen. Mikro-nanostrukturierte Anordnungen von Gold-Nanodreiecken wurden durch eine Kombination aus kolloidaler Lithographie und Plasmabehandlung hergestellt. Die Anwendbarkeit dieser Nanoantennenstrukturen für das optische Einfangen von Siliziumdioxid-Partikeln wurde erforscht und die Abhängigkeit der Partikelgröße von der Nanoantennengeometrie genau untersucht. Als Erweiterung dieses Verfahrens wurde eine Kombination aus optischer Nah- und Fernfeldfalle angewendet, um einzelne Nanoobjekte wie Goldnanopartikel und Nanodiamanten präzise an einzelnen plasmonischen „Hot -Spots“ mit einer Genauigkeit von wenigen Nanometern exakt zu positionieren.Exploiting the interaction of nanoparticles with light has been a vivid area of research in nanoscience for decades. Recently, the possibility of transforming and precisely positioning nano-objects with light has increasingly come into focus. One of the biggest challenges in this regard is finding new and robust ways of manipulating single nanoparticles with high spatio-temporal control. Two methods of addressing this demanding task - namely controlling the melting and shape transformations of individual gold nanorods, and the use of plasmonic nanoantenna arrays for the enhanced optical trapping of nano-sized objects - are the subject of this thesis. First, individual gold nanorods in a solution can be bent into a V-shaped geometry upon laser irradiation through a combination of plasmonic heating, optical forces, and hydrodynamic interactions. The bending angle can be controlled within small margins by adjusting the laser intensity. Such V-shaped antennas hold great application potential for the design of metasurfaces if the precise alignment of individual antennas on a flat surface is achieved. To work toward this application, a method for optically printing and orienting bent nanorods on a surface with respect to the laser power density and polarization is presented. Second, the ability of plasmonically coupled nanostructures or nanoantennas to concentrate light into a small volume is employed for the enhanced near-field trapping of nanosized objects at plasmonic interfaces. Micro-nanopatterned arrays of plasmonic nanoantennas were synthesized via plasma-enhanced colloidal lithography. The applicability of these nanoantenna arrays for the near-field trapping of silica beads with respect to the antenna geometry and the irradiation intensities was investigated. In an extension of this general approach, a combination of optical far-field and near-field trapping was used to actively deliver individual nano-objects, such as gold nanoparticles or nanodiamonds, precisely to individual plasmonic “hot spots” with the accuracy of a few nanometers

Fabrication and Applications of Micro/Nanostructured Devices for Tissue Engineering

Nanotechnology allows the realization of new materials and devices with basic structural unit in the range of 1–100 nm and characterized by gaining control at the atomic, molecular, and supramolecular level. Reducing the dimensions of a material into the nanoscale range usually results in the change of its physiochemical properties such as reactivity, crystallinity, and solubility. This review treats the convergence of last research news at the interface of nanostructured biomaterials and tissue engineering for emerging biomedical technologies such as scaffolding and tissue regeneration. The present review is organized into three main sections. The introduction concerns an overview of the increasing utility of nanostructured materials in the field of tissue engineering. It elucidates how nanotechnology, by working in the submicron length scale, assures the realization of a biocompatible interface that is able to reproduce the physiological cell–matrix interaction. The second, more technical section, concerns the design and fabrication of biocompatible surface characterized by micro- and submicroscale features, using microfabrication, nanolithography, and miscellaneous nanolithographic techniques. In the last part, we review the ongoing tissue engineering application of nanostructured materials and scaffolds in different fields such as neurology, cardiology, orthopedics, and skin tissue regeneration

Advances in laser-based surface texturing for developing antifouling surfaces: A comprehensive review

Surface fouling is a major challenge faced within various engineering applications, especially in marine, aerospace, water treatment, food and beverage, and the energy generation sectors. This can be prevented or reduced in various ways by creating artificial surface textures which have fouling resistance properties. Ultrafast laser texturing provides an efficient method for the texturing of surfaces of different materials with high accuracy, precision, and repeatability. Laser texturing methods can enhance the production of well-defined surface nano- and microscale patterns. These surfaces with nano- and micro-scale patterning can be tailored to have inherent properties such as hydrophobicity, hydrophilicity, and resistance to fouling. This review gives an overview of the various types of fouling that can occur, the properties affecting a surface's fouling resistance, as well as the latest physical and chemical strategies for the generation of antifouling surfaces. Surfaces architectures which have inherent antifouling capabilities are presented. This review focuses on the utilization of the higher precision laser-based texturing offered from femtosecond laser systems for enhance fouling resistance. The process parameters to fabricate these textures and the current state of art femtosecond laser sources are presented and discussed. The challenges and future research requirements in the field of laser-based methods to fabricate antifouling surfaces are presented

Large-Area Plasmonics on Self-Organized Wrinkled Nanopatterns

The focus of my PhD project consisted in the development of self-organized, large area, industrially scalable physical methods based on wrinkling instabilities to nanopattern and functionalize tunable plasmonic polymeric polydimetilsyloxane (PDMS) and solid-state glass surfaces, both transparent, non-toxic and cheap materials, for applications of significant technological interest in photonics and bio-sensing

3D integration of micro- and nanostructures into bio-analytical devices

This study aims to develop a process which allows 3D integration of micro and nanostructures in microchannels. A fabrication process was established for the large area integration of hierarchical micro and nanostructures in microchannels. This novel process, which is called 3D molding, takes advantage of an intermediate thin flexible stamp such as PDMS from soft lithography and a hard mold such as brass from hot embossing process. However, the use of a thin intermediate polydimethylsiloxane (PDMS) stamp inevitably causes dimensional changes in the 3D molded channel, with respect to those in the brass mold protrusion and the intermediate PDMS stamp structures. We have investigated the deformation behavior of the 3D molded poly(methyl methacrylate) (PMMA) substrate and the intermediate PDMS stamp in 3D molding through both experimentation and numerical simulation. It was found that for high aspect ratio brass mold protrusion, the maximum strain of the intermediate layer occurs in the bottom center of the 3D channels. However, with decreasing the aspect ratio of brass mold protrusion the highest elongation occurs at the bottom corners of the channel causing less elongation of the intermediate PDMS stamp and imprinted structures on the bottom surface of the 3D channel. A modified 3D molding process which is called 3D nanomolding is developed which allows nanopatterning the surface of small microfeatures. Using 3D nanomolding process and solvent assisted bonding microdevices with no side, one side, three sides and four sides patterned were fabricated. To characterize 3D flow patterns induced by the surface structures on microdevices, confocal microscopy was used as dyed water and undyed water injected from separate inlets of micromixer were mixed along the microchannel at flow rates of 10 and 40 μL/min. The standard deviation of the normalized intensity measured in the confocal image of the cross section of the channel was used for quantifying the degree of mixing and evaluating the mixing performance of all four different microdevices. Experimental and simulation results show that by patterning the surface of the micromixer, flow patterns can be manipulated, which can improve mixing through stretching and folding of fluid elements and therefore increasing the interfacial area between fluids and cutting down the diffusion length. The effect of increasing velocity on increasing standard deviation (decreasing mixing) was also found to be less for the micromixers whose surfaces are patterned compared to the plain channel

LASER SHOCK IMPRINTING OF METALLIC NANOSTRUCTURES AND SHOCK PROCESSING OF LOW-DIMENSIONAL MATERIALS

Laser shock imprinting (LSI) is proposed and developed as a novel ultrafast room-temperature top-down technique for fabricating and tuning of plasmonic nanostructures, and processing of one-dimensional semiconductor nanowires and two-dimensional crystals. The technique utilizes a shock pressure generated by laser ablation of sacrificial materials. Compared with conventional technologies, LSI features ambient condition, good scalability, low cost and high efficiency

Micropatterning of a PSF electrospun anti-biofouling membrane for water filtration via Hot Embossing

One of the most ambitious goals of the last decades is increasing drinkable water availability in poor countries. Among a number of strategies for water treatment, pressure-driven filtration using polymeric membranes is a promising approach as it is green, scalable, and cheap. However, there are some major limitations. Membrane fouling is a critical issue in water filtration as it limits the efficiency and durability of membranes; strategies against the effect of several types of fouling have been studied by many research groups so far. Biofouling is the unwanted formation and growth of a biofilm, and the prevention of this phenomenon needs to be tackled to get performant membranes; among various ways of inhibiting biofouling, bioinspired micro- and nanopatterns have been found to be really effective, so structuring the surfaces of membranes could be a non-selective method for discouraging bacteria proliferation to achieve better performances and increase their durability. Membranes, as well as antibiofouling and antibacterial surfaces, need to be tested. In the present work, the developing of a method for Water Contact Angle measuring without a goniometer, and a standard procedure for curing Poly Ethylene Glycol Diacrylate and Poly Propylene Glycol Diacrylate for antibacterial tests, were found. The developing of a procedure for molding polymers for analysis of an antibacterial bioinspired nanopattern has been initiated; the optimization of Hot Embossing (HE) processes for engraving a micro- and a nanopattern on microporous Polysulfone (PSF) mats obtained by electrospinning was carried out