Laminin Adsorption and Adhesion of Neurons and Glial Cells on Carbon Implanted Titania Nanotube Scaffolds for Neural Implant Applications

Interfacing neurons persistently to conductive matter constitutes one of the key challenges when designing brain-machine interfaces such as neuroelectrodes or retinal implants. Novel materials approaches that prevent occurrence of loss of long-term adhesion, rejection reactions, and glial scarring are highly desirable. Ion doped titania nanotube scaffolds are a promising material to fulfill all these requirements while revealing sufficient electrical conductivity, and are scrutinized in the present study regarding their neuron–material interface. Adsorption of laminin, an essential extracellular matrix protein of the brain, is comprehensively analyzed. The implantation-dependent decline in laminin adsorption is revealed by employing surface characteristics such as nanotube diameter, (Formula presented.) -potential, and surface free energy. Moreover, the viability of U87-MG glial cells and SH-SY5Y neurons after one and four days are investigated, as well as the material’s cytotoxicity. The higher conductivity related to carbon implantation does not affect the viability of neurons, although it impedes glial cell proliferation. This gives rise to novel titania nanotube based implant materials with long-term stability, and could reduce undesirable glial scarring

Compositional Patterning in Carbon Implanted Titania Nanotubes

Ranging from novel solar cells to smart biosensors, titania nanotube arrays constitute a highly functional material for various applications. A promising route to modify material characteristics while preserving the amorphous nanotube structure is present when applying low-energy ion implantation. In this study, the interplay of phenomenological effects observed upon implantation of low fluences in the unique 3D structure is reported: sputtering versus readsorption and plastic flow, amorphization versus crystallization and compositional patterning. Patterning within the oxygen and carbon subsystem is revealed using transmission electron microscopy. By applying a Cahn–Hilliard approach within the framework of driven alloys, characteristic length scales are derived and it is demonstrated that compositional patterning is expected on free enthalpy grounds, as predicted by density functional theory based ab initio calculations. Hence, an attractive material with increased conductivity for advanced devices is provided. © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH Gmb

Conductive Tracks in Carbon Implanted Titania Nanotubes: Atomic-Scale Insights from Experimentally Based Ab Initio Molecular Dynamics Modeling

Ion implantation of titania nanotubes is a highly versatile approach for tailoring structural and electrical properties. While recently self-organized nanoscale compositional patterning has been reported, the atomistic foundations and impact on electronic structure are not established at this point. To study these aspects, ab initio molecular dynamic simulations based on atomic compositions in C implanted titania nanotubes according to elastic recoil detection analysis are employed. Consistent with experimental data, carbon accumulates in chainlike precipitates, which are favorable for enhancing conductivity, as revealed by density-functional theory electronic ground states calculations are demonstrated

Fibroblast Response to Nanocolumnar TiO2 Structures Grown by Oblique Angle Sputter Deposition

Cells are established to sense and respond to the properties, including nano- and microscale morphology, of the substrate they adhere to, which opens up the possibility to tailor bioactivity. With this background, the potential of tilted TiO2 nanostructures grown by oblique angle sputtering to affect fibroblasts with particular focus on inducing anisotropy in cell behavior is explored. By depositing TiO2 at different oblique angles relative to the substrate normal, morphologies, columnar tilt angle, roughness, and distances between neighbored nanocolumns can be adjusted. To assess bioactivity of the resulting structures, L929-mouse fibroblasts are seeded in vitro on TiO2 nanostructured substrates. Angle-dependent movement and velocity distributions of the cells on differently tilted columns and a smooth reference sample are studied. Cell proliferation rates and cell areas are additional factors which provide information about viability and the well-being of cells. It could be shown that the local topography of the surface has an influence on the directed movement of the cells. © 2021 The Authors. Advanced Materials Interfaces published by Wiley-VCH Gmb

Tailoring morphology in titania nanotube arrays by implantation: experiments and modelling on designed pore size—and beyond

Titania nanotube arrays are an exceptionally adaptable material for various applications ranging from energy conversion to biomedicine. Besides electronic properties, structural morphology on nanometre scale is essential. It is demonstrated that ion implantation constitutes a versatile method for the synthesis of tailored nanotube morphologies. Experimental-phenomenological observations reveal a successive closing behaviour of nanotubes upon ion implantation. Employing molecular dynamics calculations in combination with analytical continuum models, the physical origins of this scenario are unravelled by identifying ion bombardment induced viscous flow driven by capillarity as its underlying mechanism besides minor contributions from sputtering and redeposition. These findings enable the tailoring of nanotube arrays suitable for manifold applications

Conductive Tracks in Carbon Implanted Titania Nanotubes: Atomic-Scale Insights from Experimentally Based Ab Initio Molecular Dynamics Modeling

Ion implantation of titania nanotubes is a highly versatile approach for tailoring structural and electrical properties. While recently self-organized nanoscale compositional patterning has been reported, the atomistic foundations and impact on electronic structure are not established at this point. To study these aspects, ab initio molecular dynamic simulations based on atomic compositions in C implanted titania nanotubes according to elastic recoil detection analysis are employed. Consistent with experimental data, carbon accumulates in chainlike precipitates, which are favorable for enhancing conductivity, as revealed by density-functional theory electronic ground states calculations are demonstrated

Carbon and Neon Ion Bombardment Induced Smoothing and Surface Relaxation of Titania Nanotubes

Titania nanotube arrays with their enormous surface area are the subject of much attention in diverse fields of research. In the present work, we show that not only 60 keV and 150 keV ion bombardment of amorphous titania nanotube arrays yields defect creation within the tube walls, but it also changes the surface morphology: the surface relaxes and smoothens in accordance with a curvature-driven surface material’s transport mechanism, which is mediated by radiation-induced viscous flow or radiation-enhanced surface diffusion, while the nanotubes act as additional sinks for the particle surface currents. These effects occur independently of the ion species: both carbon and neon ion bombardments result in comparable surface relaxation responses initiated by an ion energy of 60 keV at a fluence of 1 × 1016 ions/cm2. Using atomic force microscopy and contact angle measurements, we thoroughly study the relaxation effects on the surface topography and surface free energy, respectively. Moreover, surface relaxation is accompanied by further amorphization in surface-near regions and a reduction in the mass density, as demonstrated by Raman spectroscopy and X-ray reflectivity. Since ion bombardment can be performed on global and local scales, it constitutes a versatile tool to achieve well-defined and tunable topographies and distinct surface characteristics. Hence, different types of nanotube arrays can be modified for various applications

Conductive Tracks in Carbon Implanted Titania Nanotubes: Atomic-Scale Insights from Experimentally Based Ab Initio Molecular Dynamics Modeling

Ion implantation of titania nanotubes is a highly versatile approach for tailoring structural and electrical properties. While recently self-organized nanoscale compositional patterning has been reported, the atomistic foundations and impact on electronic structure are not established at this point. To study these aspects, ab initio molecular dynamic simulations based on atomic compositions in C implanted titania nanotubes according to elastic recoil detection analysis are employed. Consistent with experimental data, carbon accumulates in chainlike precipitates, which are favorable for enhancing conductivity, as revealed by density-functional theory electronic ground states calculations are demonstrated