Memristors (MRs) are considered promising devices with the enormous potential to replace complementary metal-oxide-semiconductor (CMOS) technology, which approaches the scale limit. Efforts to fabricate MRs-based hybrid materials may result in suitable operating parameters coupled to high mechanical flexibility and low cost. Metal–organic frameworks (MOFs) arise as a favorable candidate to cover such demands. The step-by-step growth of MOFs structures on functionalized surfaces, called surface-supported metal–organic frameworks (SURMOFs), opens the possibility for designing new applications in strategic fields such as electronics, optoelectronics, and energy harvesting. However, considering the MRs architecture, the typical high porosity of these hybrid materials may lead to short-circuited devices easily. In this sense, here, it is reported for the first time the integration of SURMOF films in rolled-up scalable-functional devices. A freestanding metallic nanomembrane provides a robust and self-adjusted top mechanical contact on the SURMOF layer. The electrical characterization reveals an ambipolar resistive switching mediated by the humidity level with low-power consumption. The electronic properties are investigated with density functional theory (DFT) calculations. Furthermore, the device concept is versatile, compatible with the current parallelism demands of integration, and transcends the challenge in contacting SURMOF films for scalable-functional devices.

The biopigment eumelanin, ubiquitous in flora and fauna, is made up of chemically heterogeneous macromolecules based on the 5,6‐dihydroxyindole and 5,6‐dihydroxyindole‐2‐carboxylic acid building blocks. The exciting possibility of designing eumelanin‐based technologies for bioelectronics and sustainable electronics has to be properly assessed by gaining insights on the charge transfer and charge carrier transport in the pigment, preferably in film form, easily amenable to devices. In this work, we report a study on the electrochemical behaviour of films of eumelanin and its derivatives synthesized in dimethyl sulfoxide (DMSO eumelanins) in different aqueous electrolytes, with different chemical compositions and pH. DMSO eumelanins feature an improved solubility in the solvent DMSO, of relevance for processing purposes. The voltammetric currents are higher at relatively low pH (5.5), as expected considering the well‐established proton transport properties of the biopigment. Raman spectroscopy and atomic force microscopy performed on eumelanin films were combined with thermogravimetry with the aim of advancing knowledge on the molecular and supramolecular features of synthetic commercially available eumelanin, DMSO eumelanins as well as natural eumelanin (Sepia melanin). The results collected permit unprecedented insights on the physicochemical properties of eumelanin. © 2016 Society of Chemical Industry

Important clinical concerns in orthopedics and dental implantology are associated with a significant release of titanium (Ti) metal ions and debris due to the low corrosion resistance of this material. Chemical modifications on Ti surfaces have been performed in order to minimize effects of corrosion. In this contribution, zinc oxide (ZnO) thin films were deposited onto Ti surfaces and functionalized with four different organic bifunctional molecules in order to increase the corrosion resistance. SEM and XPS indicated the formation of nanostructured ZnO thin film with hydroxyl groups available for covalent functionalization. The adhesion mechanism analyzed by XPS suggest that the attachment on ZnO occurs by carboxylic acid, silane, thiol and hydroxyl groups for 4aminophenylpropionic acid (APPA), 3-aminopropyltrimetoxysilane (APTMS), 3-mercaptopropionic acid (MPA), and polyethylene glycol (PEG) molecules. Electrochemical analysis for the functionalized ZnO specimens with APPA showed noble open circuit potentials (−0.2 V) and significant decrease in the corrosion current density (5.3 × 10 −7 A/cm 2) when compared to the values obtained for pristine Ti (−0.56 V and 2.3 × 10 −6 A/cm 2), indicating a promising material for applications in biomedical fields.

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In this study, a novel label-free electrochemical biosensor based on the zeolitic imidazole framework (ZIF-8) was developed for monitoring protein–protein interactions (PPIs). ZIF-8 was deposited on interdigitated electrodes and employed as a transducing material and simultaneously carried the thioredoxin-1 (Trx-1) protein, followed by the deposition of increased concentrations of the cytoplasmic domain of a disintegrin and metalloproteinase 17 (ADAM17cyto) known as the Trx-1 binding partner. Structural and morphological characterizations were used to validate and verify the formation of ZIF-8. The ZIF-8 crystals showed a rhombic dodecahedral structure with mainly exposed (011) facets, a mean particle size of 205 (±22) nm, and a ZIF-8 film thickness around 61 (±6) nm. The interaction between Trx-1 and ADAM17cyto proteins was analyzed through electrochemical impedance spectroscopy (EIS). The results indicate a linear and inverse relationship between the impedance responses at 0.1 Hz for ADAM17cyto concentrations from 50 nM to 8 μM, with a coefficient of variation from 1.0% to 11.4%. The proposed biosensor also displayed a significant selectivity and stability verified by using ADAM17cyto mutant and BSA as controls. As a proof-of-concept, we compared the results with a widely used type of PPI assay based on antibody recognition, the solid-phase binding assay, using the same proteins. The solid-phase binding assay was able to detect a significant binding only in ADAM17cyto concentrations above 0.5 μM, with a coefficient of variation varying from 5.4% to 27.5%. The results demonstrate that the developed biosensor was 10× more sensitive and reproducible than the conventional solid-phase binding assay. Furthermore, the developed electrochemical biosensor based on ZIF-8 provides a faster, label-free, and low-cost detection analysis, representing a novel strategy in detecting PPIs.