Osteoblast interaction with DLC-coated Si substrates

Effect of Target Power on Microstructure, Tribological Performance and Biocompatibility of Magnetron Sputtered Amorphous Carbon Coatings

The tribological properties and preosteoblast behavior of an RF magnetron-sputtered amorphous carbon coating on a Si (100) substrate were evaluated. The graphite target power was varied from 200 to 500 W to obtain various coating structures. The amorphous nature of the coatings was confirmed via Raman analysis. The contact angle also increased from 58º to 103º, which confirmed the transformation of the a-C surface from a hydrophilic to hydrophobic nature with an increasing graphite target power. A minimum wear rate of about 4.73 × 10-8 mm3/N*mm was obtained for an a-C coating deposited at a 300 W target power. The 300 W and 400 W target power coatings possessed good tribological properties, and the 500 W coating possessed better cell viability and adhesion on the substrate. The results suggest that the microstructure, wettability, tribological behavior and biocompatibility of the a-C coating were highly dependent on the target power of the graphite. A Finite Element Analysis (FEA) showed a considerable increase in the Von Mises stress as the mesh size decreased. Considering both the cell viability and tribological properties, the 400 W target power coating was identified to have the best tribological property as well as biocompatibility.

UV Sterilization Effects and Osteoblast Proliferation on Amorphous Carbon Films Classified Based on Optical Constants

Optical classification methods that distinguish amorphous carbon films into six types based on refractive index and extinction coefficient have garnered increasing attention. In this study, five types of amorphous carbon films were prepared on Si substrates using different plasma processes, including physical and chemical vapor deposition. The refractive index and extinction coefficient of the amorphous carbon films were measured using spectroscopic ellipsometry, and the samples were classified into five amorphous carbon types—amorphous, hydrogenated amorphous, tetrahedral amorphous, polymer-like, and graphite-like carbon—based on optical constants. Each amorphous carbon type was irradiated with 253.7 nm UV treatment; the structure and surface properties of each were investigated before and after UV treatment. No significant changes were observed in film structure nor surface oxidation after UV sterilization progressed at approximately the same level for all amorphous carbon types. Osteoblast proliferation associated with amorphous carbon types was evaluated in vitro. Graphite-like carbon, which has relatively high surface oxidation levels, was associated with higher osteoblast proliferation levels than the other carbon types. Our findings inform the selection of suitable amorphous carbon types based on optical constants for use in specific medical devices related to osteoblasts, such as artificial joints and dental implants.

Correlation of Cell Proliferation with Surface Properties of Polymer-like Carbon Films of Different Thicknesses Prepared by a Radio-Frequency Plasma CVD Process

In this study, correlation of cell proliferation with surface properties of the polymer-like carbon (PLC) films of different thicknesses prepared by radio-frequency plasma CVD are investigated. Four PLC samples were prepared via radio frequency plasma chemical vapor deposition on Si substrates. Each PLC film was analyzed using spectroscopic ellipsometry to determine its thickness, refractive index (n), and extinction coefficient (k); the thickness ranged from 29.0 to 356.5 nm. Based on their n−k plots, all the samples were classified as PLC-type films. The biological response of the PLC films was evaluated in vitro using a cell culture. The samples with relatively thick PLC films (>300 nm) exhibited stronger cell proliferation properties than those with thinner films. Moreover, the results of the surface analysis showed no significant differences in the surface composition of those PLC samples, as analyzed using X-ray photoelectron spectroscopy, but that as the PLC films became thicker, their surfaces became rougher on the nanoscale and their wettability improved. Overall, this study showed that careful control of the film growth of PLC films, which affects their surface properties, is essential for their use in bio-interface applications.

Argon and oxygen plasma treatment increases hydrophilicity and reduces adhesion of silicon-incorporated diamond-like coatings

In this study, the structure, adhesion, and cell viability characteristics of silicon-incorporated diamond-like carbon (Si-DLC) coatings on fused silica substrates were investigated. The effects of argon and oxygen postprocessing plasma treatments on the Si-DLC coatings were also studied. The contact angle results showed that the Si-DLC coatings were more hydrophilic than the uncoated surfaces, and postprocessing plasma treatment increased the hydrophilicity of the Si-DLC coatings. Atomic force microscopy and profilometry confirmed that postprocessing plasma treatment increased the thickness and roughness of the Si-DLC coatings. The results of microscratch testing indicated that the plasma treatments reduced the adhesion of the coatings. The x-ray photoelectron spectroscopy (XPS) showed the presence of carbon, oxygen, and silicon in the Si-DLC coatings before and after the plasma treatments. These results show that the postprocessing plasma treatment significantly reduced the atomic percentage of the carbon in the Si-DLC coatings. XPS also confirmed the presence of carbon in the form of sp³(C-C), sp²(C=C), C-O, and C=O bonds in the Si-DLC coatings; it showed that postprocessing treatments significantly increased the percentage of oxygen in the Si-DLC coatings. Fourier transform infrared spectroscopy (FTIR) analysis showed features associated with C-OH stretching, C-H bending, as well as Si-CH₂ and C-H bending in the Si-DLC coating. The XPS and FTIR results confirmed that the plasma treatment caused dissociation of the sp² and sp³ bonds and formation of C-OH bonds. The contact angle data indicated that postprocessing treatment increased the hydrophilicity of the Si-DLC coating. Similar to the uncoated substrates, L929 cells showed no change in cell viability when cultured on Si-DLC coatings. These results of the study indicate the suitability of Si-DLC coatings as inert coatings for medical and biotechnology applications.

In vitro and in vivo biocompatibility and bio-tribological properties of the calcium/amorphous-C composite films for bone tissue engineering application

Carbon-and diamond-like-carbon coated Ti alloys hold great promise for tissue engineering applications. Unfortunately, their strong intrinsic stress leads to the adhesion failure of the films. Herein, a series of a-C films with different Ca content were prepared on Ti₆Al₄V via co-sputtering deposition technology. Homogeneous spherical Ca nanoclusters, with an inner diameter of 2-6 nm, were formed in an amorphous carbon matrix. The addition of Ca induced indistinctive variation in either phase composition or topography. However, the introduction of Ca not only improved the mechanical properties of a-C film but also significantly strengthened its adhesion to osteoblasts. The bio-tribological properties of Ca/a-C films were also assessed using a tribometer in FBS solution. The Ca/a-C films exhibited a low friction coefficient of 0.083 and a low wear rate of 1.02-1.24×10^-6 mm³/Nm. The low coefficient of friction (COF) of the Ca/a-C films indicates their superior mechanical properties, making them the promising target of nanocomposite films used in bio-tribological applications. Well-stretched cells and the developed actin filaments were distinctly observed on the Ca/a-C films in the osteoblast cell adhesion experiments. In addition, the Ca/a-C films promoted cell proliferation and showed high cell viability. After being implanted for 4 weeks, the Ca/a-C implant material still adhered well to the muscle tissue, without inducing hyperergic or inflammatory reactions. Collectively, our results suggest that the Ca/a-C film is an ideal mounting material for bone tissue engineering.

Surface Characteristics and Biological Evaluation of Si-DLC Coatings Fabricated Using Magnetron Sputtering Method on Ti6Al7Nb Substrate

Diamond-like carbon (DLC) coatings are well known as protective coatings for biomedical applications. Furthermore, the incorporation of different elements, such as silicon (Si), in the carbon matrix changes the bio-functionality of the DLC coatings. This has also been proven by the results obtained in this work. The Si-DLC coatings were deposited on the Ti6Al7Nb alloy, which is commonly used in clinical practice, using the magnetron sputtering method. According to the X-ray photoelectron spectroscopy (XPS) analysis, the content of silicon in the examined coatings varied from ~2 at.% up to ~22 at.%. Since the surface characteristics are key factors influencing the cell response, the results of the cells’ proliferation and viability assays (live/dead and XTT (colorimetric assays using tetrazolium salt)) were correlated with the surface properties. The surface free energy (SFE) measurements, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the polarity and wettability of the surfaces examined increase with increasing Si concentration, and therefore the adhesion and proliferation of cells was enhanced. The results obtained revealed that the biocompatibility of Si-doped DLC coatings, regardless of the Si content, remains at a very high level (the observed viability of endothelial cells is above 70%).

Mammalian cell viability on hydrophobic and superhydrophobic fabrics

Surface properties like hydrophobicity and morphology of the substrate are essential for cell proliferation affecting its growth, survival and also for its communication with other cells on fabrics. The combination of low surface energy and a specific surface morphology (micro/nano-roughness) leads to significantly less wettable surfaces, known as superhydrophobic characterized by high contact angle above 150° and a very small hysteresis. Such high water repellent coatings feature small area available to be exploited in many applications where interactions with aqueous environment are strongly to be avoided. In this work, the authors have investigated the influence of coating polyester fabric at different degree of hydrophobicity by mixed organic-inorganic coating with moderated to highly water repellence. Depending on the coating composition and structure, the hydrophobicity of the fabric can be finely modulated by an easy-to-prepare method applicable to commercial, low cost fabric substrates providing advanced performance. In vitro experiments have been performed in order to establish the influence of surface modification on adhesion of representative model mammalian cell lines such as 3T3 fibroblasts, HaCaT keratinocytes and HeLa epithelial carcinoma cells. The obtained results suggested that, in addition to the chemistry and morphology of the coating, the characteristics of the substrate are important parameters on the final cell viabilities.

Highly durable and biocompatible periodical Si/DLC nanocomposite coatings

Functional nanocomposite coatings comprised of periodically stacked nanolayers of diamond-like carbon (DLC) and amorphous silicon were developed for biomedical applications. The periodical nanocomposite structure provided high surface durability while silicon aided in reducing the residual stress. The structural, mechanical, tribological, and biomedical properties of the Si/DLC coatings deposited by magnetron sputtering were investigated systematically. The effect of the negative substrate bias on the structure and properties of the coatings was also assessed. The coatings demonstrated high durability and high biocompatibility. The bias voltage and bias mode affected both the hardness and residual stress of the Si/DLC coatings. Particularly, application of 60 V negative bias during the DLC layer deposition resulted in the lowest wear rate. FEM simulations showed that the wear resistance of the coatings was dictated by the hardness as well as the adhesion between the coatings and a chromium sub-layer. The periodical alternation of Si and DLC nanolayers led to a significant improvement of MC3T3 cell adhesion compared to the previously published data for Si-DLC composites.

Analyses of Biofilm on Implant Abutment Surfaces Coating with Diamond-Like Carbon and Biocompatibility

The aim of this study was to evaluate the surface free energy (SFE), wetting and surface properties as well as antimicrobial, adhesion and biocompatibility properties of diamond-like carbon (DLC)-coated surfaces. In addition, the leakage of Escherichia coli through the abutment-dental implant interface was also calculated. SFE was calculated from contact angle values; R a was measured before and after DLC coating. Antimicrobial and adhesion properties against E. coli and cytotoxicity of DLC with human keratinocytes (HaCaT) were evaluated. Further, the ability of DLC-coated surfaces to prevent the migration of E. coli into the external hexagonal implant interface was also evaluated. A sterile technique was used for the semi-quantitative polymerase chain reaction (semi-quantitative PCR). The surfaces showed slight decreases in cell viability (p<0.05), while the SFE, R a, bacterial adhesion, antimicrobial, and bacterial infiltration tests showed no statistically significant differences (p>0.05). It was concluded that DLC was shown to be a biocompatible material with mild cytotoxicity that did not show changes in R a, SFE, bacterial adhesion or antimicrobial properties and did not inhibit the infiltration of E. coli into the abutment-dental implant interface.

Investigation of silicon carbon nitride nanocomposite films as a wear resistant layer in vitro and in vivo for joint replacement applications

Silicon-contained CN_x nanocomposite films were prepared using the ion beam assisted magnetron sputtering under different nitrogen gas pressure. With increase of the nitrogen pressure, silicon and nitrogen content of the CN_x films drastically increase, and is saturated as the P_N2 reach about 40%. Surface roughness and the contact angle are increase, while the friction coefficient decreased. The CN_x film with 5.7at.% Si content possess the lowest friction coefficient of only 0.07, and exhibited the best tribological properties. The impact of CN_x films with different silicon content on the growth and the activation of osteoblasts were compared to that of Ti6Al4V. The incorporation of silicon in the CN_x film also showed an increase cell adhesion. Bonding structure and surface energy were determined to be the factors contributing to the improved biocompatibility. Macrophages attached to 5.7at.% Si contained CN_x films down regulated their production of cytokines and chemokines. Moreover, employed with Si contained CN_x coated joint replacements, which were implanted subcutaneously into Sprague-Dawley mice for up to 36days, the tissue reaction and capsule formation was significantly decreased compared to that of Ti6Al4V. A mouse implantation study demonstrated the excellent in vivo biocompatibility and functional reliability of wear resist layer for joint replacements with a Si doped a-CN_x coating for 36days.

Adhesion and differentiation of Saos-2 osteoblast-like cells on chromium-doped diamond-like carbon coatings

Diamond-like carbon (DLC) thin films are promising for use in coating orthopaedic, dental and cardiovascular implants. The problem of DLC layers lies in their weak layer adhesion to metal implants. Chromium is used as a dopant for improving the adhesion of DLC films. Cr-DLC layers were prepared by a hybrid technology, using a combination of pulsed laser deposition (PLD) from a graphite target and magnetron sputtering. Depending on the deposition conditions, the concentration of Cr in the DLC layers moved from zero to 10.0 at.%. The effect of DLC layers with 0.0, 0.9, 1.8, 7.3, 7.7 and 10.0 at.% Cr content on the adhesion and osteogenic differentiation of human osteoblast-like Saos-2 cells was assessed in vitro. The DLC samples that contained 7.7 and 10.0 at.% of Cr supported cell spreading on day 1 after seeding. On day three after seeding, the most apparent vinculin-containing focal adhesion plaques were also found on samples with higher concentrations of chromium. On the other hand, the expression of type I collagen and alkaline phosphatase at the mRNA and protein level was the highest on Cr-DLC samples with a lower concentration of Cr (0-1.8 at.%). We can conclude that higher concentrations of chromium supported cell adhesion; however DLC and DLC doped with a lower concentration of chromium supported osteogenic cell differentiation.

Endothelialization of TiO2 Nanorods Coated with Ultrathin Amorphous Carbon Films

Carbon plasma nanocoatings with controlled fraction of sp(3)-C bonding were deposited on TiO2 nanorod arrays (TNAs) by DC magnetic-filtered cathodic vacuum arc deposition (FCVAD). The cytocompatibility of TNA/carbon nanocomposites was systematically investigated. Human umbilical vein endothelial cells (HUVECs) were cultured on the nanocomposites for 4, 24, and 72 h in vitro. It was found that plasma-treated TNAs exhibited excellent cell viability as compared to the untreated. Importantly, our results show that cellular responses positively correlate with the sp(3)-C content. The cells cultured on high sp(3)-C-contented substrates exhibit better attachment, shape configuration, and proliferation. These findings indicate that the nanocomposites with high sp(3)-C content possessed superior cytocompatibility. Notably, the nanocomposites drastically reduced platelet adhesion and activation in our previous studies. Taken together, these findings suggest the TNA/carbon scaffold may serve as a guide for the design of multi-functionality devices that promotes endothelialization and improves hemocompatibility.

Effect of nonthermal plasma treatment on surface chemistry of commercially-pure titanium and shear bond strength to autopolymerizing acrylic resin

The effect of nonthermal plasma on the surface characteristics of commercially pure titanium (cp-Ti), and on the shear bond strength between an autopolymerizing acrylic resin and cp-Ti was investigated. A total of 96 discs of cp-Ti were distributed into four groups (n=24): Po (no surface treatment), SB (sandblasting), Po+NTP and SB+NTP (methane plasma). Surface characterization was performed through surface energy, surface roughness, scanning microscopy, energy dispersive spectroscopy, and X-ray diffraction tests. Shear bond strength test was conducted immediately and after thermocycling. Surface treatment affected the surface energy and roughness of cp-Ti discs (P<.001). SEM-EDS showed the presence of the carbide thin film. XRD spectra revealed no crystalline phase changes. The SB+NTP group showed the highest bond strength values (6.76±0.70 MPa). Thermocycling reduced the bond strength of the acrylic resin/cp-Ti interface (P<.05), except for Po group. NTP is an effective treatment option for improving the shear bond strength between both materials.

Controlling conductivity of carbon film for L-929 cell biocompatibility using magnetron sputtering plasmas

The effectiveness of conductive carbon films for cell adhesion and growth was demonstrated.

Addition of nanoscaled bioinspired surface features: A revolution for bone related implants and scaffolds?

Our expanding ability to handle the "literally invisible" building blocks of our world has started to provoke a seismic shift on the technology, environment and health sectors of our society. During the last two decades, it has become increasingly evident that the "nano-sized" subunits composing many materials—living, natural and synthetic—are becoming more and more accessible for predefined manipulations at the nanosize scale. The use of equally nanoscale sized or functionalised tools may, therefore, grant us unprecedented prospects to achieve many therapeutic aims. In the past decade it became clear that nano-scale surface topography significantly influences cell behaviour and may, potentially, be utilised as a powerful tool to enhance the bioactivity and/ or integration of implanted devices. In this review, we briefly outline the state of the art and some of the current approaches and concepts for the future utilisation of nanotechnology to create biomimetic implantable medical devices and scaffolds for in vivo and in vitro tissue engineering,with a focus on bone. Based on current knowledge it must be concluded that not the materials and surfaces themselves but the systematic biological evaluation of these new material concepts represent the bottleneck for new biomedical product development based on nanotechnological principles.

Variations to the nanotube surface for bone regeneration

The complex mechanisms of the bone cell-surface interactions are yet to be completely understood, and researchers continue to strive to uncover the fully optimized implant material for perfect osseointegration. A particularly fascinating area of research involves the study of nanostructured surfaces, which are believed to enhance osteogenic behavior, possibly due to the mimicry of components of the extracellular matrix of bone. There is a growing body of data that emphasizes the promise of the titanium oxide (TiO₂) nanotube architecture as an advanced orthopedic implant material. The review herein highlights findings regarding TiO₂ nanotube surfaces for bone regeneration and the osteogenic effects of minute changes to the surface such as tube size and surface chemistry.

Structural and biocompatible characterization of TiC/a:C nanocomposite thin films

In this work, sputtered TiC/amorphous C thin films have been developed in order to be applied as potential barrier coating for interfering of Ti ions from pure Ti or Ti alloy implants. Our experiments were based on magnetron sputtering method, because the vacuum deposition provides great flexibility for manipulating material chemistry and structure, leading to films and coatings with special properties. The films have been deposited on silicon (001) substrates with 300 nm thick oxidized silicon sublayer at 200 °C deposition temperature as model substrate. Transmission electron microscopy has been used for structural investigations. Thin films consisted of ~20 nm TiC columnar crystals embedded by 5 nm thin amorphous carbon matrix. MG63 osteoblast cells have been applied for in vitro study of TiC nanocomposites. The cell culture tests give strong evidence of thin films biocompatibility.

Evaluation of trabecular bone formation in a canine model surrounding a dental implant fixture immobilized with an antimicrobial peptide derived from histatin

JH8194 induces osteoblast differentiation, although it was originally designed to improve antifungal activity. This suggests that JH8194 is useful for implant treatment. Therefore, the aim of this study was to evaluate the osseointegration capacity of JH8194-modified titanium dental implant fixtures (JH8194-Fi). The implants were randomly implanted into the edentulous ridge of dog mandibles. Healing abutments were inserted immediately after implant placement. Three weeks later, peri-implant bone levels, the first bone-to-implant contact points, and trabecular bone formation surrounding the implants were assessed by histological and digital image analyses based on microcomputed tomography (microCT). The histological analysis revealed an enhancement of mature trabecular bone around the JH8194-Fi compared with untreated fixtures (control-Fi). Similarly, microCT combined with analysis by Zed View™ also showed increased trabecular bone formation surrounding the JH8194-Fi compared with the control-Fi (Student's t-test, P < 0.05). JH8194 may offer an alternative biological modification of titanium surfaces to enhance trabecular bone formation around dental implants, which may contribute to the transient acquirement of osseointegration and the long-term success of implant therapy.

Investigation of cell-substrate interactions by focused ion beam preparation and scanning electron microscopy

Cell-substrate interactions, which are an important issue in tissue engineering, have been studied using focused ion beam (FIB) milling and scanning electron microscopy (SEM). Sample cross-sections were generated at predefined positions (target preparation) to investigate the interdependency of growing cells and the substrate material. The experiments focus on two cell culturing systems, hepatocytes (HepG2) on nanoporous aluminum oxide (alumina) membranes and mouse fibroblasts (L929) and primary nerve cells on silicon chips comprised of microneedles. Cross-sections of these soft/hard hybrid systems cannot be prepared by conventional techniques like microtomy. Morphological investigations of hepatocytes growing on nanoporous alumina membranes demonstrate that there is in-growth of microvilli from the cell surface into porous membranes having pore diameters larger than 200 nm. Furthermore, for various cell cultures on microneedle arrays contact between the cells and the microneedles can be observed at high resolution. Based on FIB milled cross-sections and SEM micrographs cells which are only in contact with microneedles and cells which are penetrated by microneedles can be clearly distinguished. Target preparation of biological samples by the FIB technique especially offers the possibility of preparing not only soft materials but also hybrid samples (soft/hard materials). Followed by high resolution imaging by SEM, new insights into cell surface interactions can be obtained.

Comparative cell behavior on carbon-coated TiO2 nanotube surfaces for osteoblasts vs. osteo-progenitor cells

Surface engineering approaches that alter the topological chemistry of a substrate could be used as an effective tool for directing cell interactions and their subsequent function. It is well known that the physical environment of nanotopography has positive effects on cell behavior, yet direct comparisons of nanotopographic surface chemistry have not been fully explored. Here we compare TiO(2) nanotubes with carbon-coated TiO(2) nanotubes, probing osteogenic cell behavior, including osteoblast (bone cells) and mesenchymal stem cell (MSC) (osteo-progenitor cells) interactions with the different surface chemistries (TiO(2) vs. carbon). The roles played by the material surface chemistry of the nanotubes did not have an effect on the adhesion, growth or morphology, but had a major influence on the alkaline phosphatase (ALP) activity of osteoblast cells, with the original TiO(2) chemistry having higher ALP levels. In addition, the different chemistries caused different levels of osteogenic differentiation in MSCs; however, it was the carbon-coated TiO(2) nanotubes that had the greater advantage, with higher levels of osteo-differentiation. It was observed in this study that: (a) chemistry plays a role in cell functionality, such as ALP activity and osteogenic protein gene expression (PCR); (b) different cell types may have different chemical preferences for optimal function. The ability to optimize cell behavior using surface chemistry factors has a profound effect on both orthopedic and tissue engineering in general. This study aims to highlight the importance of the chemistry of the carrier material in osteogenic tissue engineering schemes.

Wettability control by DLC coated nanowire topography

Here we have developed a convenient method to fabricate wettability controllable surfaces that can be applied to various nanostructured surfaces with complex shapes for different industrial needs. Diamond-like carbon (DLC) films were synthesized on titanium substrate with a nanowire structured surface using plasma immersion ion implantation and deposition (PIII&D). The nanostructure of the DLC films was characterized by field emission scanning electron microscopy and found to grow in a rippling layer-by-layer manner. Raman spectroscopy was used to investigate the different bonding presented in the DLC films. To determine the wettability of the samples, water contact angles were measured and found to vary in the range of 50°-141°. The results indicated that it was critical to construct a proper surface topography for high hydrophobicity, while suitable I(D)/I(G) and sp²/sp³ ratios of the DLC films had a minor contribution. Superhydrophobicity could be achieved by further CF₄ implantation on suitably structured DLC films and was attributed to the existence of fluorine. In order to maintain the nanostructure during CF₄ implantation, it was favorable to pre-deposit an appropriate carbon content on the nanostructure, as a nanostructure with low carbon content would be deformed during CF₄ implantation due to local accumulation of surface charge and the following discharge resulting from the low conductivity.

Differential patterning of neuronal, glial and neural progenitor cells on phosphorus-doped and UV irradiated diamond-like carbon

Diamond-like carbon (DLC) is an attractive biomaterial for coating human implantable devices. Our particular research interest is in developing DLC as a coating material for implants and electrical devices for the nervous system. We previously reported that DLC is not toxic to N2a neuroblastoma cells or primary cortical neurons and showed that phosphorus-doped DLC (P:DLC) could be used to produce patterned neuron networks. In the present study we complement and extend these findings by exploring patterning of dorsal root ganglion (DRG) explants, human neural progenitor cells (hNPC) and U-87 astroglioma cells on P:DLC. Further P:DLC data is provided to highlight that P:DLC can be used as an effective coating material for in vitro multi-electrode arrays (MEAs) with potential for patterning groups of neurons on selected electrodes. We also introduce ultraviolet (UV) irradiation as a simple treatment to render DLC neurocompatible. We show that UV:DLC can be used to support patterned and unpatterned cortical neuron growth. These findings strongly support the use of DLC as tailorable and tuneable substrate to study neural cell biology in vitro and in vivo. We conclude that DLC is a well-suited candidate material for coating implantable devices in the human nervous system.