Deoxyribonucleic acid (DNA) immobilization on nanoscale architectures is critical for developing bio-compatible devices and clinical diagnoses. In this study, silicon nanowires (SiNWs) were combined with gold nanoparticles encapsulated in graphitic shells (GNPs). The resulting SiNWs-GNPs heterostructures were plasma oxidized to create carboxylic (-COOH) functionality on the surface of the graphitic carbon shell. These heterostructures and their surface chemistries were studied using electron microscopy, Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The –COOH terminated graphitic shells in heterostructures were covalently linked with DNA. The DNA molecules on these heterostructures were detected by linking with fluorescent streptavidin and observed under a fluorescence microscope. Such inorganic heterostructure-biomolecule assemblies can be very useful in the development of biomolecule analysis and detection devices.

Implantable electronic biomedical devices are used clinically to diagnose and treat an increasing number of medical conditions. Such devices typically employ hermetic packages that often incorporate electrical feedthroughs made with conventional ceramic-to-metal bonding technologies. This sealing technology is well established and provides robust hermetic seals, but is limited in both the number and spacing of electrical leads. Emerging devices for interfacing with the human nervous system, however, will require a large number of external electrical leads implemented in a miniaturized packaging configuration. Commercially available feedthrough technologies are currently incapable of providing external electrical contacts with spacings as small as 200 to 400 microns, and thus are neither compatible with integrated circuit I/O (input/output) pad spacings nor with miniature implantable packages. We report the development of a hermetic high-density feedthrough (HDF) technology that allows for conductive path densities as high as 1,000 per cm2, and that is capable of supporting neural interface devices. The fabrication process utilizes multilayer high temperature co-fired ceramic (HTCC) technology in conjunction with platinum leads. Before co-firing, green alumina substrates are interleaved with linear, parallel Pt trace arrays in either wire or thin foils to form the electrical feedthroughs. Layered stacks of spatially isolated traces are first compacted into a composite, and then fired to achieve densification. After firing, the densified multilayered composite compacts are sliced perpendicular to the Pt traces and lapped to produce multiple feedthrough arrays with a high density of leads (conductors). Both hermeticity and biocompatibility of such implantable feedthroughs are important, as both moisture and positive mobile ion contamination from the saline environment of the human body can lead to compromised performance or catastrophic failure. HDFs fabricated using this process with 100 conductors and lead-to-lead spacings as low as 400 microns have been helium leak tested repeatedly and found to exceed industry-accepted standards with helium leak rates in the range of 10–11 mbar-l/s. The spacing of the current prototype matches industry standard neural interface technology, and can be scaled to higher densities with lead-to-lead spacings as small as 200 microns. The reported HDF process has several distinct advantages over prior approaches, including the provision of a large number of conductive feedthrough leads suitable for flip-chip bonding with sub-mm lead-to-lead spacings (pitch), and the incorporation of materials (alumina and platinum) that are already used in medical implants. The implementation of such an HDF technology allows for significant package miniaturization, allowing greater flexibility in surgical placement as well as less invasive procedures for implantable electronic biomedical devices.

Here we present new materials obtained using, either fungal or isolated tobacco cells in association with different percentages of carbon nanotubes (CNTs). As a proof of concept, we used either Candida albicans or a non-green Tobacco BY-2 cell line combined with multi-walled CNTs. The electrical, mechanical, and conductivity vs temperature properties for some of these materials have been determined. C. albicans-based tissues have high conductivity and are stable at elevated temperatures. By lowering the CNTs content, we obtained a stable, electrically conductive optical transparent film, though with a relatively high sheet resistance. Further, we produced, using tobacco cells, a material that exhibits good electrical as well as mechanical properties.

Bacterial photosynthetic reaction centers (RCs) are promising materials for solar energy harvesting, due to their high internal quantum efficiency. However, applications of RCs in bio-photovoltaic devices so far show relatively low external power conversion efficiency, mainly due to low efficiency of the charge transfer to the electrode. Preferential orientation of RCs on an electrode’s surface can enhance the charge transfer rate to some extent. Yet, the results of direct coupling of RCs to an Au electrode, through cysteine residues from the H-subunit, revealed that direct electron transfer is not efficient. This work focuses on a different approach to achieve high charge transfer rate between an Au electrode and RC protein complexes by employing cytochrome c (Cyt c)\carboxylic acid-terminated linker molecules. This approach preferentially orients RCs with the primary donor site to the electrode. Furthermore, Cyt c can be considered as a conductive linker, while the charge transfer mechanism through carboxylic acid-terminated linker molecules is dominated by tunneling. The photochronoamperometric results for a two electrode cell setup indicated a 156 nA.cm-2 cathodic photocurrent density; the photocurrent was measured in an electrochemical cell with ubiquinone-10 (Q2) in the electrolyte. Negligible photocurrents were observed in the case of coupled RCs to the Au via cysteine residues on H-subunit, with only Cyt c in the electrolyte. These findings contribute to the design of highly efficient bio-photovoltaic devices.

There are many biological macro-molecules such as nucleic acids, lipids, carbohydrates and proteins. While each of them plays a vital (and interesting) part in life but there is something special about the proteins. Proteins are the key link between the processes of information and replication that take place on a genetic level and the infrastructure of living features. Understanding the properties of proteins is the key to understanding the spark of the life. In this paper we describe our study of various electrical properties of protein when performing measurements at the nanoscale. To achieve this goal we designed and fabricated a nanoelectronic probe. This nano structure consists of four thin film layers. There are two conductive layers and an insulative layer in between. There is also a protective oxide layer as the top most layer. This layer is to prevent the exposure of conductive electrodes to the solution. Underneath the bottom electrode, there is another oxide layer, which can be a thermally grown oxide. This layer insulates the first electrode from the substrate. In this study, while we use non-specific detection of streptavidin protein as a proof of concept, we emphasize that the findings of this study can be extended to specific detection of target proteins, where in this case a specific probe molecule would also be immobilized on the sensor surface.

Clozapine remains the most effective antipsychotic for management of schizophrenia, one of the most challenging mental disorders. Yet, this medication is underutilized due to the frequent blood draws associated with monitoring adverse side effects and maintaining effective drug levels in the body. Lab-on-a-chip (LOC)-based diagnostics at the point-of-care could decrease the burden on patients and doctors, enable personalized medicine, and improve treatment outcomes. Towards that goal, we present the development of an electrochemically active biomaterial probe to facilitate monitoring of clozapine as part of patient’s treatment regimen. The probe consists of the naturally derived polymer chitosan modified with catechol to provide a redox capacitor system, allowing for significant amplification. We demonstrate a 3- fold increase of the electrochemical signal generated by clozapine with the catechol-modified chitosan system over bare gold electrodes. The improved signal-to-noise ratio and overall performance of the bio-amplifier yield a detection limit below 1 μM, thus sufficient for the clinically relevant range of 1–3 μM. We further characterize the robustness of the biomaterial system with respect to re-use and storage, and demonstrate retention of its amplification characteristics when implemented on an electrochemical microchip. Our results align well with the clinical requirements and represent a critical first step in developing a point-of-care device for improved and personalized schizophrenia treatment.