The paper presents the recent results of the spreading and traction of human osteosarcoma cells on soft polydimethylsiloxane (PDMS) microgrooved surfaces. The results show that the cell tractions resulted in significant deformation of the microgrooves. The tractions were calculated, and found to be in good agreement with the results from other studies. The results suggest that the cell spreading-induced soft substrate deformation needs to be considered in the design of implantable bioMEMS structures.

The objective of this in vitro present study was to create a biosensor which can monitor in situ orthopedic tissue growth juxtaposed to a newly implanted orthopedic material. This biosensor has unique properties including the ability to sense, detect, and control bone regrowth. Such a biosensor is useful not only in regenerating tissue necessary for orthopedic implant success, but also to aid in informing an orthopedic surgeon whether sufficient new bone growth occurred. If the sensor determines that insufficient new bone growth occurred, the sensor can also act in an intelligent manner to release bone growth factors to increase bone formation. The primary biomaterial in this biosensor is anodized Ti, developed by chemical etching and passivation treatments. Carbon nanotubes (CNTs), because of their electrical and mechanical properties, are essential to consider when designing such biosensors since they will be used to apply and measure conductivity changes as new bone grows next to the implant. For this, parallel multiwall CNTs were grown from the pores of the anodized Ti by a chemical vapor deposition process. Lastly, these sensors will be composed of a conductive, biodegradable, polymer layer that degrades when bone grows and, consequently, undergoes a change in conductivity that can be measured by the CNTs grown out of the anodized Ti. This conductive, biodegradable polymer consists of polypyrrole (which is conductive) and poly-lactic-co-glycolic acid (which is biodegradable). Preliminary in vitro results suggest that osteoblast functions (specifically alkaline phosphatase activity and calcium deposition) on CNTs grown on anodized Ti are significantly enhanced when compared to anodized Ti and currently-used Ti; thus, it is anticipated that bone growth could be enhanced on these novel biomaterial sensors.

Contrary to crystalline titanium oxide (TiO2), electrochemically deposited amorphous thin TiO2 films are found significantly more sensitive towards electron beam (e-beam) exposure. E-beam irradiation experiments were performed under scanning electron microscope conditions at 20 keV with well controlled beam current (IP), current density and exposure dose. As shown by atomic force microscopy and Micro-Raman spectroscopy, even moderate e-beam exposure immediately leads to oxide reduction due to electron stimulated oxygen desorption, while exposure with IP>1 micro-A and J>1 A/cm2 triggers localized crystallization into anatase phase already after seconds of irradiation. The mechanisms for oxide reduction and beam heating induced crystallization are discussed, and a temperature estimation in the beam center indicates that crystallization occurs at less than 150 °C. The well-defined volume loss upon oxygen desorption is shown to be attractive for precise topographical surface patterning, while the triggering local structural changes within a semi-conductive amorphous matrix opens interesting possibilities for tailoring of its local electrical or catalytic properties.

We report here a procedure for the functioalization of SiO2-coated, SiONx waveguides for biological assays. Surface functionalization occurs by self-assembly of an amine-terminated silane monolayer on the waveguide, followed by partial chemical modification with functionalized polyethylene glycol (PEG) groups. Functionalized surfaces were characterized by atomic force microscopy and contact angle measurements. When combined with a BSA blocking step, these functional PEG surfaces significantly reduced non-specific binding and allowed for specific binding to occur. An antibody sandwich assay for detection of Bacillus anthracis protective antigen was used to validate these surfaces for sensing applications.

Plant and animals convert absorbed nutrients into the most readily available form of biochemical energy in cells - Adenosine triphosphate (ATP). Ion transporter proteins in the cell membranes hydrolyze ATP and use the energy from the reaction for ion transport across cell membranes. The BioCell is an energy conversion device inspired by ion transport through cell membranes that uses a proton-sucrose cotransporter (SUT4) to convert the chemical energy in ATP into electrical energy. Experiments on a single cell demonstrated that the BioCell behaves like a constant current power source with 10 - 22 kΩ internal resistance. The single cell developed a peak power of 0.7 μW per cm2 of bilayer lipid membrane (BLM) area reconstituted with 1 mg of SUT4 and 1 μl of ATP-ase at 10 kΩ load in the external circuit. The actual peak power output from the cell was 160 nW for a BLM area of 0.079 cm2 carrying 0.2 mg of SUT4 and 15 μl of ATP-ase. The 160 nW of electrical power that could be sourced from the cell with a 10 kΩ load (41 mV and 4 μA) is not sufficient to run a low power electronic device and needs to be scaled up to few microwatts. This article discusses our experimental results from stacking a BioCell in series and parallel to develop higher stack voltage and current. We observe that the cell voltage adds linearly by connecting the BioCells in series and a 10-cell stack developed a peak power of 750 nW (500 mV @ 2.5 μA observed at 265 kΩ. The peak power from the stack by connecting the cells in parallel was 1.4 μW (125 mV and 11.2 μA) at 1kΩ. The experimental results demonstrate that the power from a single cell can be scaled by connecting them in series and in parallel without appreciable losses. A survey of electronic devices indicated that a minimum of 20 μW will be required to run a demonstration application from a stack and also gives us the direction to scale the power output from a single cell.

In recent years, considerable effort has been devoted to the design and controlled fabrication of structured materials with functional properties. The layer by layer buildup of polyelectrolyte multilayer films (PEM films) from oppositely charged polyelectrolytes1 offers new opportunities for the preparation of functionalized biomaterial coatings. This technique allows the preparation of supramolecular nano-architectures exhibiting specific properties in terms of control of cell activation and may also play a role in the development of local drug delivery systems. Peptides, proteins or DNA, chemically bound to polyelectrolytes, adsorbed or embedded in PEM films, have been shown to retain their biological activities. Recently, tissue engineering has merged with stem cell technology with interest to develop new sources of transplantable material for injury or disease treatment. Eminently interesting, are bone and joint injuries disorders because of the low self-regenerating capacity of the matrix secreting cells. We present here for the first time that embedded BMP-2 and TGFβ1 in a multilayered polyelectrolyte film can drive embryonic stem cells to the cartilage or bone differentiation depending on supplementary co-factors. We selected a model system made from layer by layer poly-ℓ-glutamic acid (PℓGA) and poly-ℓ-lysine succinylated (PℓLs) films into which BMP-2 and TGFβ1 have been embedded. Our results demonstrate clearly that we are able to induce osteogenesis in embryonic stem cells mediated by growth factors embedded in a polyelectrolyte multilayer film.

We report preliminary results of using nanoparticles to control cell attachment and growth. We present the way to create titanium surfaces with different roughness in a rage between 2 nm and 117 nm by using nanoparticles as a superficial layer and varying the evaporation parameters. We examined cell proliferation on titanium substrates with increased surface roughness compared to smooth titanium surface. We used nanoparticles to create a micrometer-sized lateral layout onto substrates preliminary structured by microcontact printing. We demonstrate controlled cell growth on substrates laterally structured with nanoparticles.

Upon the discovery of the first conducting polymer in 1976, the replacement of metal-based semiconductors in many applications with conducting polymers was inevitable. Perhaps more surprisingly these materials showed promise in many biomedical applications. The finding that electrical fields and charges modulate shape, size, and proliferation of a number of cell types including nerve and bone, has prompted biomedical engineers to focus on the development of conducting polymer scaffolds for tissue regeneration and neural probes. A number of polymers have been studied for these applications, including polypyrrole (PPy), polythiophene, and polyaniline. One serious limitation to the use of conducting polymers in biological systems is their inability to degrade. Therefore, it has been proposed to design and synthesize a biocompatible, biodegradable, semiconducting polymer, which could broaden the scope of applications for conducting polymers. For instance, these unique polymers could potentially be implemented in temporary tissue and neural scaffolds, drug delivery, short-term electrodes, and tethers between nanotubes. Therefore, the goal of this investigation is to synthesize a polymer that is degradable, while maintaining conductivity. Initially, the incorporation of pyrrole oligomers into a biodegradable polymer was attempted; however, to overcome difficulties associated with the instability of these oligopyrroles, a novel polymer design has been proposed which incorporates thiophene oligomers. Oligothiophenes (OTs) are apt to be more conductive than oligopyrroles due to a smaller band gap between the valence and conductance bands. Additionally, OTs share many of the advantageous properties of oligopyrroles, including cell compatibility, but are more stable. The proposed novel co-polymer consists of quaterthiophene oligomers tethered together by aliphatic ester linkages, which would potentially render the co-polymer conductive by means of inter and intra chain oligo overlap and degradable via cleavage of the ester bond by esterases in the body. The synthesis of the novel copolymer, poly-dialcohol dimethyl quaterthiophene-co-adipic acid (PAMQAA) has been completed successfully and corroborated by NMR and MALDI. Initial characterization indicates PAMQAA has the following properties: Mw = 11,240-64,080 g/mol, PI = 1.2-1.4, degradation temperature = ∼160°C. Currently PAMQAA is being characterized to assess its Tg, Tm, conductivity, degradability, and biocompatability. Polymer modifications could allow further optimization of properties, such as the rate of degradation and conductivity, to target better the application of interest.

We have synthesized rare-earth doped sub-10 nm diameter upconverting yttrium oxide based nanophosphors by flame spray pyrolysis. We have investigated the emitted visible fluorescence of the sub-10nm nanophosphors under both infrared excitation and electron excitation, and observed comparable narrow band emission spectra. The viability of the nanoparticles for biological imaging was confirmed by imaging the digestive system of the nematode worm C. elegans in the upconversion mode. We have surface functionalized the nanophosphors making them suitable for bio labeling.

Extensive interactions of inflammatory cells (such as macrophages) with biomaterials at the host-implant interface are often blamed for failure of implanted biomedical devices [1]. While previous studies have shown increased in vitro and in vivo bone cell (osteoblast) responses on nanophase ceramics [2], few (if any) studies have been conducted to elucidate inflammatory cell responses on such novel materials. In this study, we reported that macrophage adhesion and proliferation on nanophase (97.7 nm grain size) alumina (Al2O3) was significantly less than conventional (187.4 nm grain size) alumina, respectively, after 4, 12, 24 h. The present study provides evidence of the ability of nanophase alumina to down-regulate macrophage adhesion and proliferation, which is imperative for the future consideration of nanophase materials for orthopedic and dental applications.

A hydrogel has been developed into a promising scaffold for cell encapsulation or drug delivery useful in various biorelated research areas. DNA, with its outstanding specificity and flexibility and intrinsic biocompatibility, has been utilized as a new building block in the construction of this new three dimensional material-a DNA based hydrogel. Here, we report the synthesis, properties and applications of a DNA based hydrogel system. The DNA hydrogels are entirely constructed from branched DNA building blocks such as X-shaped DNA (X-DNA), Y-shaped DNA (Y-DNA), and T-shaped DNA (T-DNA) through an enzyme-catalyzed reaction. These DNA hydrogels can be easily patterned into different sizes with millimeter or micrometer scale and different shapes including cylindrical, rectangular, cross, star, and even the “CORNELL” logo. By adjusting the initial concentrations and original shapes of the different building blocks, the external and internal morphology and chemical/physical properties of the DNA hydrogel were easily tuned: The X-DNA based hydrogel (X-DNA gel) showed both the most swelling degree and mechanical strength as well as the higher resistance to chemical and biological degradation. Inspired by these characteristics of the DNA hydrogels, we have developed them into a drug delivery system, an artificial extracellular matrix, and even a cell-free protein producing template.

Two-photon polymerization (2PP) is a novel technology for the fabrication of complex three-dimensional (3D) microstructures. The number of applications employing this technology is rapidly increasing, and includes the fabrication of three-dimensional photonic crystals [1-4], medical devices, and scaffolds for tissue engineering [5, 6]. We have used 2PP to fabricate microneedle arrays with various geometries. These devices provide a unique approach for transdermal delivery of nucleic acid- and protein-based pharmacologic agents. Many of issues associated with conventional intravenous drug administration, including pain to the patient, trauma at the injection site, and difficulty in providing sustained release of a pharmacological agent, may be eliminated by applying the microneedles. The effect of microneedle geometry (e.g., tip sharpness and aspect ratio) on skin penetration was examined. Our results indicate that microneedles created using 2PP technique are suitable for in vivo use, and integration with next generation MEMS- and NEMS-based drug delivery devices.

Device engineering for ion channel proteins requires developing systems that incorporate mechanically stable, long-lived lipid bilayer membranes. Building on our previous work, we have further increased lipid bilayer longevity through covalent conjugation of lipid molecules in the bilayer to an encapsulating hydrogel. This is accomplished by polymerizing the hydrogel in situ around a gigaohm-seal membrane containing vinyl-modified lipid head groups, forming a conjugated hydrogel encapsulated membrane (cgHEM). Membranes formed in this manner show remarkable stability, maintaining gigaohm-level resistance for over 270 hours, better than an order-of-magnitude improvement over the previous state of the art. They also demonstrate the capacity to support the incorporation and measurement of ion channel proteins at the single-molecule level.

Crystalline silicon carbide (SiC) has the potential to become an important biomaterial and a versatile interface between the electronic and biological world. In this work, single crystal SiC biocompatibility is investigated by culturing mammalian cells directly on SiC substrates. The cell morphology and the quality of the cell adhesion have been studied using fluorescence microscopy, while MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assays have been performed to quantify cell viability and number. Standard culture-wells and silicon (Si) substrates were used as controls in the final assessment of crystalline SiC biocompatibility.

Adsorption of alkanethiols on GaAs (001) surface under low coverage conditions was studied using density functional calculations in a periodic supercell approach. The study of physisorbed precursor and transition to chemisorption revealed that hydrogen atoms stay on the surface upon S-H bond cleavage and significantly affect desorption products and energies, in agreement with available experimental data. Binding of thiols to GaAs is found to be comparable or stronger than that of thiols to noble metals surfaces. Calculated thiolate-surface binding energies are found to be higher for Ga-rich than for As-rich surfaces, and are strongly dependent on surface reconstruction, adsorption site and coverage. This dependence is explained by the violation or fulfillment of electron counting rule, rehybridization of surface atom orbitals and strain relaxation upon addition of extra electrons brought by adsorption.

This paper compared the results of osteoblast-like UMR-106 cells response to 3-D biodegradable porous with nonporous PHBV (poly (3-hydroxybutyrate-co-3-hydroxyvalerate) films. Nonporous PHBV films were prepared by solvent casting and evaporation. Porous PHBV films were prepared by solute leaching of salt/PHBV cast film. Sieved sodium chloride (∼150 μm) was used to create a matrix with high porosity and then leached out by the solvent. Thermo gravimetric analysis showed that over 99% of the salts were leached out by the solvent. Osteoblast-like UMR-106 cells were seeded onto the nonporous and porous PHBV films, respectively. After 6 and 10 days of incubation, growth rate of UMR-106 cells on porous film was higher than on nonporous film. The viable cell proliferation on the porous and nonporous PHBV film was quantified by (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) (MTS) assay. The results of this study suggest that the UMR-106 cells proliferate more on the porous PHBV matrix and porous PHBV films are a promising material for bone tissue engineering applications.

In this work, we investigate the feasibility of using a surface-tethered heptapeptide sequence as the basis for a ferroelectric-actuated component in a nanofluidic device. The fluorescently-labeled peptide sequence, (CISLLHSTC) is shown by fluorescence microscopy to selectively coat the PZT patterned channel floors. The peptide binding strength to PZT is determined over a range of flow rates in the patterned channel by imaging the fluorescence intensity of the coated channel and monitoring the output spectroscopically. The peptide is found to be stripped from the PZT at flow rates exceeding 5mL/h. Initial results demonstrating the possibility of covalently integrating the short peptide sequence to larger biological components such as antibodies are also presented.

We have demonstrated microscale patterning of biotin and streptaividin proteins using an athermal rapid prototyping process based on piezoelectric inkjet technology. A MEMS-based piezoelectric actuator was used to dispense picoliter quantities of fluid through micron-sized nozzles. Atomic force microscopy and Fourier infrared spectroscopy studies were performed on CAD/CAM deposited proteins that were prepared using several firing voltages. Our results indicate that piezoelectric inkjet deposition is a powerful non-contact, non-destructive process for developing high-throughput biological microarrays for use in biosensing, cell culturing, and tissue engineering.

The objective of the current study was to utilize a natural self-assembled organic biomaterial (helical rosette nanotubes (HRNs)) to improve bone growth necessary for orthopedic implant applications. The DNA base pair building blocks of HRNs can self-assemble through 18 H-bonds to form a supermacrocycle in water which then stack to form a nanotube 3.5 nm in diameter and several μm in length. The nanometric features and ability to place diverse amino acid side chains on HRNs make them intriguing materials for orthopedic applications. In this study, HRNs are combined with a biocompatible hydrogel matrix in order to obtain more robust scaffolds. Bone cell experiments in vitro demonstrated that the novel HRNs with hydrogels could greatly enhance osteoblast (bone-forming cell) adhesion even at a very low concentration (close to 0.001mg/ml). Morphology of the HRNs with hydrogel scaffolds was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Results showed that there were bundles of nanotubes in the HRNs with hydrogel scaffolds. Therefore, considering the good biocompatibility and nano bone-like structure of these scaffolds, the nanostructured hydrogel matrix with HRNs have the potential to serve as novel bone building agents for “on-the-site” orthopedic applications.

Enzymes are proteins that catalyze chemical reactions, participating in almost all processes in the cell to achieve significant reaction rates and serving a wide variety of functions inside living organisms. Here, we intended to control enzymatic activities by applying external radio frequency magnetic field (RFMF) through nanosized antenna. Ribonuclease A (RNase A), which is a relative small protein that cleave single-stranded RNA, was conjugated to magnetite nanoparticles (NP) by non-covalent interaction. The diameters of Fe3O4 nanoparticles are less than 10nm. External RFMF was applied, and the enzymatic activities of RNase A were tuned at different levels by varying the frequencies and incubation times. Comparison results by using water bath were also presented.