We have shown that silver ion implantation or argon ion assisted surface deposition of silver inhibits cell growth on Glassy Polymeric Carbon (GPC), a desirable improvement of current cardiac implants. In vitro biocompatibility tests have been carried out with model cell lines to demonstrate that near surface implantation of silver in GPC can completely inhibit cell attachment on implanted areas while leaving adjacent areas vulnerable to strong cell adhesion. After cleaning and sterilization and more than one year in physiologic solution, the silver implanted GPC persists in inhibiting cell attachment.

Depending on the coating method utilized and subsequent heat treatments (such as through the use of plasma-spray deposition), inter-diffusion of atomic species across titanium (Ti) and hydroxyapatite (HA) coatings may result. These events may lead to structural and compositional changes that consequently cause unexpected HA phase transformations which may clearly influence the performance of an orthopedic implant. Thus, the objective of the present in vitro study was to compare the cytocompatibility properties of chemistries that may form at the Ti:HA interface, specifically HA, tricalcium phosphate (TCP), Ti doped HA, and those containing calcium titanate (CaTiO3). In doing so, results of this in vitro study showed that osteoblast adhesion increased with greater CaTiO3 substitutions in either HA or TCP. Specifically, osteoblast adhesion on HA and TCP composites with CaTiO3 was almost 4.5 times higher than over pure HA. Material characterization studies revealed that enhanced osteoblast adhesion on these compacts may be due to increasing shrinkage in the unit lattice parameters and consequent decrease in grain size. Although all CaTiO3 composites exhibited excellent osteoblast adhesion results, Ca9HPO4(PO4)5OH phase formation into TCP/CaTiO3 increased osteoblast adhesion the most; due to these reasons, these materials should be further studied for orthopedic applications.

Amino groups were functionalized directly on the diamond surface after treating oxidation and fluorination for detection of DNAs, respectively. For simple process, immobilization of probe DNAs was carried out directly on the partially aminated diamond without linker molecules. After fabricating micropatterned diamond, specific hybridization with Cy-5 labeled target DNA at a concentration of 100 nM could be clearly detected on H-terminated, partially O-terminated, and partially F-terminated diamonds, respectively. The hybridization intensities determined by epifluorescence microscopy were compared and analyzed.

The behavior of cells at the material surface is of critical importance in the design of biomaterials. To understand and control cell responses to surfaces, different surface chemistries are commonly compared. In this study we exploit the chemical diversity of the 20 naturally occurring amino acids to make 20 surfaces with different chemical properties. The biological response of osteoblasts to these surfaces was examined. The osteoblast response to the surfaces was found to be dependant on the wettability of the surface with polar amino acid surfaces (Cys<Ser<Thr<Gln<Asn) promoting osteoblast spreading more than hydrophobic aromatic amino acid surfaces (Phe <Tyr <Trp), aliphatic amino acid surfaces (Leu<Ile<Val<Ala<Met<Gly), and Pro. The surface charge also affected the cellular response with positively charged amino acid surfaces (His<Arg<Lys) producing a higher percentage of spreading cells compared to the negatively charged surfaces (Asp<Glu). Amino acid surfaces provide a range of well defined chemical functionalities that are useful in studying the interactions of cells with material surfaces.

This work studies cell viability and cell adhesion on as grown dense films of vertically aligned carbon nanotubes (MWCNT). The MWCNTs were produced by a microwave plasma chemical vapor deposition (2,45GHz) on silicon (Si) and titanium (Ti) surfaces, using a nickel and iron catalyst, respectively. The citotoxicity tests (MTT assay and cellular adhesion) were evaluated by various incubations times with Fibroblast L929 mouse cells. The results show very high cell viability and many layers of cells adhered on the surface formed by the nanotubes tips at films grown on Si surfaces. The MWCNT grown on Ti surfaces presented lower cell viability and a reduced number of cells on the surface formed by the nanotubes tips. The different behavior is most probably related to excess iron contamination present in the case of titanium substrate, while nickel catalyst is probably enclosed by the nanotubes.

Ceramic/polymer nanocomposites simulate bone much closer in terms of its nanostructure and associated properties, thus, offering a promising opportunity for bone regeneration in a natural way. Previous studies demonstrated improved osteoblast (bone-forming cell) adhesion and long-term functions (such as alkaline phosphatase activity and calcium-containing mineral deposition) on nanometer scale surface roughness provided by well-dispersed titania nanoparticles in poly-lactide-co-glycolide (PLGA). For example, the nanocomposites with the closest surface roughness to natural bone at the nano-scale promoted the most bone cell adhesion and calcium deposition. The current studies focus on further mimicking bone by building three-dimensional structures from titania/PLGA nanocomposites using a novel aerosol based 3D printing technique (one type of rapid prototyping technique, because, similarly, natural bone assembles its three-dimensional hierarchical architecture from nanostructured building blocks). Using this technique, bone fracture data acquired by computed tomography (CT) can be transferred into CAD models and used to direct the fabrication of versatile bone substitutes. Field emission scanning electron microscopy (FESEM) was used to characterize the structure and surface features of these 3D scaffolds. The results demonstrated that 3D printed nano-scaffolds had a well-controlled, repeatable inner structure and, moreover, possessed uniformly dispersed titania nanoparticles which provided for nano-scale surface features throughout the PLGA matrix. Osteoblast adhesion tests were conducted on the 3D titania/PLGA nanocomposite scaffolds created by this technique and the results demonstrated that these 3D scaffolds further promoted osteoblast infiltration into porous structures compared to previous nanostructured surfaces. In conclusion, results of this study have evaluated a promising new orthopedic nanocomposite and a means of fabricating a hierarchical macro-structure from such nanomaterials that can mimic properties of natural bone, thus, providing a new material and approach for more effective orthopedic applications.

Continuing the effort of our group for biocompatible, photoresist-based lithographic processes, high contrast near UV photoresists are presented along with a novel multi-step lithographic scheme. The proposed lithographic scheme is based on successive lithographic steps (exposure at 310 nm) on the same substrate for the patterning of different proteins. The photoresists are based on (meth)acrylate tetrapolymers and a near UV sensitive sulfonium salt as photoacid generator and can be processed under mild baking and development conditions allowing patterning of proteins without denaturation and loss of their molecular recognition capability. Protein patterning in successive lithographic steps down to 2μm has been achieved. Sub-1μm patterning structures have been also obtained. Lithographic results were evaluated with SEM and fluorescence microscopy, after the recognition of the patterned biomolecules by their fluorescently labeled counterparts.

There have been increasing research interests in the development of novel nano or micro-patterning techniques to create arrays of functional biomolecules for miniaturized assays, which could be used in various biomedical applications such as biosensors, proteomic, immunoassays or drug screening. Several techniques have been demonstrated capable of writing or printing biomolecules with very high degree of spatial control including dip-pen lithography, nanopipet, inkjet printing, photolithography, micro contact printing etc. The serial writing techniques provide the individual addressability whereas the parallel printing processes offer easy and fast protein patterning. However, it remains difficult to create complex patterns, such as functional multicomponent protein arrays, in parallel with individual addressability. Here we describe a novel approach to fabricate functional multicomponent protein and cell arrays where the electrowetting effect was employed to convert a water-repellent superhydrophobic surface into a wettable one allowing fast and high density addressable protein and cell deposition on the otherwise protein- and cell-resistant superhydrophobic surface. It has been shown that each element on the switchable superhydrophobic microarray could be addressed individually and different types of functional biomolecules could be selectively deposited on the microarray. Such protein patterning technique offers several advantages over other techniques including parallel protein deposition with individual addressability, possibility for large-scale patterning and easy integration with microfluidic system. The facts that the superhydrophobic surfaces can be fabricated from many hydrophobic materials and the electrowetting works for most dielectric materials allow great flexibility in the selection of the surface materials for protein deposition.

Microarrays have become one of the most convenient tools for high throughput screening and have catalyzed major advances in genomics and proteomics. Other important applications can be found in medical diagnostics, detection of biothreats, drug discovery, etc. Integration of microarrays with microfluidic devices can be highly advantageous in terms of portability, shorter analysis time and lower consumption of expensive biological analytes. Since fabrication of microfluidic devices using traditional materials such as glass is rather expensive, there is a high interest in employing polymeric materials as a low cost alternative suitable for mass production. We present proof-of-concept DNA arrays on a plastic platform for the detection of four important respiratory pathogens: Influenza A virus, respiratory syncytial virus, human enterovirus, and human metapneumovirus.

This was accomplished by amplifying the genetic material from the viruses and simultaneously labeling the amplicons with a fluorescent dye (Cy3) via a highly sensitive multiplex Reverse Transcription Polymerase Chain Reaction (RT-PCR). The resultant RT-PCR product was hybridized, without further purification, with an array of specific oligonucleotide probes (20 mers) that had been covalently bound to a plastic substrate. Results indicate a high signal to background ratio that is comparable to commercially available microarray glass slides. In addition, 5 minute hybridization on this plastic substrate has been demonstrated using a centrifugal microfluidic platform, paving the way to a rapid medical diagnostic device for point-of-care use that is based on a low-cost portable Micro-Total-Analysis-System (μ-TAS).

Understanding how biomineralization occurs in the extracellular matrix (ECM) of bone cells is crucial to the development of a successfully engineered bone tissue scaffold, and to date there has not been a well-established method for the quantitative examination of bone mineralization in situ. We investigated the mechanical properties of MC3T3-E1 osteoblast-like cells and the crystalline properties of their biomineralized ECM in vitro using shear modulation force microscopy (SMFM), confocal laser scanning microscopy (CLSM), synchrotron X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The elastic modulus of the mineralizing cells increased at time points corresponding to mineral production, whereas that of the non-mineralizing cells did not vary significantly over time. CLSM showed a restructuring of the F-actin fiber network of mineralizing cells with time, which indicates remodeling activities in the cytoskeleton and was not seen in the non-mineralizing cells. Both XRD and FTIR showed that the mineralizing subclone produced hydroxyapatite in situ and that the non-mineralizing subclone was in fact weakly biomineralizing.

Synthetic adhesives have largely displaced natural adhesives in the automotive, aerospace, biomedical, electronic, and marine equipment industries over the past century. We have demonstrated the thin film deposition of biological adhesives using piezoelectric inkjet technology. A MEMS based piezoelectric actuator was controlled to jet uniform fluid flow of the adhesive solution through the ink jet nozzles. Microscopic deposition of adhesives enables improved bonding for a range of advanced electronic and biomedical applications. By printing such small and spatially aligned drops, bond lines between materials are reduced, ultimately resulting in increased bond strength and structural integrity. Piezoelectric ink jet deposition of biological adhesives may greatly improve wound repair in next generation eye repair, fracture fixation, organ fixation, and wound closure.

Hydrogenated diamond-like-carbon (a-C:H) and hydrogen-free amorphous carbon (a-C) coatings are known to be biocompatible and have good chemical inertness. For this reason, both of these materials are strong candidates to be used as a matrix that embeds metallic elements with antimicrobial effect. In this comparative study, we have incorporated silver into standard diamond-like carbon (DLC) coatings by plasma ion implantation and deposition (PIII&D) using methane (CH4) plasma and simultaneously depositing Ag from a pulsed cathodic arc source. In addition, we have grown amorphous carbon – silver composite coatings using a dual-cathode pulsed filtered cathodic-arc (FCA) source. The silver atomic content of the deposited samples was analyzed using glow discharge optical spectroscopy (GDOES). In both cases, the arc pulse frequency of the silver cathode was adjusted in order to obtain samples with approximately 5 at.% of Ag. Surface hardness of the deposited films was analyzed using the nanoindentation technique. Cell viability for both a-C:H/Ag and a-C:/Ag samples deposited on 24-well tissue culture plates has been evaluated.

Micro- or nano-particles encapsulating hydrophobic quantum dots were prepared by the emulsion technique. Films containing quantum dots were also prepared by film casting methods. Quantum dots without hydrophilic coating were directly mixed with polymer solution to prepared extremely stable films or particles that do not phase-separate with time. The surface of the particles or films could be modified to have different hydrophilicity and/or functional groups. Particles with 1.5 ± 0.16 μm and 320 ± 26 nm in diameters and films of 300 μm in thickness were prepared. NIH 3T3 and EMT-6 were culture on the films containing quantum dots for 8 – 20 h. Compared to the control, quantum dot were delivered directly and efficiently into the cells without toxicity. When implanted near tumor cells in Balb/C mice, quantum dots migrated from the films into the tumor cells for at least 3 days. Considering that the quantum dot dispersion in aqueous media is relatively unstable and difficult to handle, our stable particles or films containing hydrophobic quantum dots can become versatile probes for biological applications.

Hydrophilic and hydrophobic groups were selectively incorporated on the poly(methyl methacrylate) [PMMA] surface using a Xe2 excimer lamp and ArF excimer laser. With this new technique, a protein adsorption on the PMMA surface can be controlled.

PMMA was firstly irradiated with a Xe2 excimer lamp in the presence of perfluoropolyether [PFPE] liquid layer to incorporate CF3 groups, and secondly, the PMMA surface was irradiated by an ArF excimer laser through a patterned reticle in the presence of water to incorporate OH groups or NH2 groups in an ammonia gas ambience. The area ratio of hydrophilic and hydrophobic of the modifying sample was made to 1:3, 1:1, and 3:1. The results showed that the fibrin absorption on the sample with hydrophilic and hydrophobic micro domains depended on the area ratio of the hydrophilic and hydrophobic. The absorption coefficient of the amide band remarkably decreased with increase in water contact angle. Furthermore, it was confirmed that the absorption coefficient of fibrin decreased as the interval of CF3 and OH or NH2 groups was narrowed from 250 to 20 μm, and the fibrin sticking on the modified surface with the 20 μm hydrophilic and hydrophobic micro domains was reduced to one-twenty of that on the untreated sample.

Functional relationships between the biomaterial interface and extracellular matrix (ECM) proteins are intimately involved in cellular adhesion and function. Structural changes of ECM proteins upon adsorption to a surface alter the protein's biological activity by varying the availability of molecular binding sites. Recent work using native and organically modified sol-gel silica as a neuronal biointerface revealed that changes in surface nanotopography of bulk versus thin film materials result in dramatic differences in fibronectin structure, cell survival, and neuronal differentiation. In order to further investigate interactions between chemical functionality and surface topography, we evaluated the global conformation of human fibronectin adsorbed to seven different organically modified silica gels and thin films. Chemical functional groups were introduced into the materials either by altering the starting precursor or by doping with poly-l-lysine or polyethylenimine. Surface topography measurements by atomic force microscopy show that films have surface features less than 25 nm while bulk materials of the same precursor chemistry have features ranging from 50 – 100 nm in size. Fluorescence resonance energy transfer spectroscopy (FRET) revealed a strong interaction between surface topography and chemical functionality. Fibronectin remain globular on all bulk materials regardless of chemical modification. The same changes in precursors or dopant chemistry, however, induced changes in the conformation of fibronectin on the thin films. The differentiation of PC12 cells on the surface indicated a strong impact of the surface features and suggest a possible optimal fibronectin folding state.

In this study, we describe the selective adhesion 4 hour and proliferation 24 hour and 4 days of inflammatory cells (specifically, macrophages) on aligned carbon nanofiber/nanotube patterns on a polymer matrix. The results showed for the first time that macrophage adhesion and proliferation on aligned Carbon nanofibers (CNFs) was significantly less than on the polymer matrix. The present in vitro study thus provided evidence of the ability of CNFs to down-regulate macrophage adhesion and proliferation important to decrease harmful body reaction, which is imperative for the future consideration of CNFs for numerous implant applications.

Association of amphiphilic triblock copolymers with lipid membranes results in versatile novel materials with enormous potential in many areas of bionanotechnology. The molecular architecture and concentration of block copolymers along with environmental variables such as temperature and pH provide means to tune these structures for desired applications and also allow for designing signal-responsive materials. Understanding interaction between block copolymers and lipid bilayers is crucial for applications in nanomedicine. Monte Carlo simulations are used to explore the effect of molecular architecture on the mode of insertion of triblock copolymers into lipid bilayers. The results are compared with small angle X-ray scattering data.

Water based silk solutions were successfully inkjet printed for the first time into patterns of parallel lines onto vinyl plastic substrates. Human bone marrow stromal cells (hMSCs) were seeded on the silk printed patterns and cultured in the presence of 100 ng/ml of bone morphogenic protein (BMP-2). After one week of culture cell growth and attachment showed site specificity on the silk printed lines. Both alkaline phosphatase activity and cell morphology indicated hBMSCs differentiation into osteogenic cells along the silk printed lines. After 4 week of culture, the cellular bridging of adjacent silk printed lines took place for all interline distances lower than 1.25 mm. Therefore, commercial inkjet printing technology can produce complex viable cellular patterns with 111 ± 24 μm lateral resolution, through the deposition of bioactive materials. The results provide a first step toward cell specific control using 3D inkjet printing techniques using biocompatible gel systems to regulate cell functions.