Ti-6Al-4V alloy is the most commonly used alloy for dental and orthopedic implants. In order to improve osseointegration, different surface modification methods are usually employed, including self-assembled monolayers (SAMs). This study presents an investigation of both active (electroassisted) and passive (adsorption) approaches for the modification of Ti-6Al-4V using alkylphosphonic acid. The monolayers were characterized by cyclic voltammetry, double-layer capacitance, contact angle measurements, X-ray photoelectron spectroscopy, polarization modulation infrared reflection adsorption spectroscopy, electrochemical impedance spectroscopy, and corrosion potentiodynamic polarization measurements. It is shown that the electrochemically assisted monolayers, which are assembled faster, exhibit better control over surface properties, a superior degree of order, and a somewhat higher packing density. The electrosorbed SAMs also exhibit better blockage of electron transfer across the interface and thus have better corrosion resistance.

Construction of structurally defi ned, patterned metal fi lms is a fundamental objective in the emerging and active fi eld of bottom-up nanotechnology. A new strategy for constructing macroscopically organized Au nanostructured fi lms is presented. The approach is based upon a novel phenomenon in which incubation of water-soluble Au(SCN) 4 1 − complex with amine-displaying surfaces gives rise to spontaneous crystallization and concurrent reduction, resulting in the formation of patterned metallic gold fi lms. The Au fi lms exhibit unique nanoribbon morphology, likely corresponding to aurophilic interactions between the complex moieties anchored to the amine groups through electrostatic attraction. Critically, no external reducing agents are needed to initiate or promote formation of the metallic Au fi lms. In essence, the thiocyanate ligands provide the means for surface targeting of the complex, guide the Au crystallization process and, importantly, donate the reducing electrons. It is shown that the Au fi lms exhibit electrical conductivity and high transparency over a wide spectral range, lending the new approach to possible applications in optoelectronics, catalysis, and sensing. In a broader context, a new gold chemistry route is presented in which ligandenabled crystallization/reduction could open the way to a wealth of innovative reaction pathways and applications.

Evidence for considerable stabilization of doped bovine serum albumin (BSA) molecules upon adsorption on gold surfaces is provided. This is compared to the surface-induced conformational changes of the bare BSA and its corresponding monolayer. The BSA unfolding phenomenon is correlated with dehydration, which in turn enables improved monolayer coverage. The stabilization mechanism is found to be partially controllable via nanodoping of the BSA molecules, upon which the dehydration process is suppressed and molecular rigidity can be varied. Our experimental data and calculations further point to the intermixing of structural characteristics and inherent molecular properties in studies of biological monolayers.

Generation of macroscopic phenomena through manipulating nano-scale properties of materials is among the most fundamental goals of nanotechnology research. We demonstrate cooperative “speckle beats” induced through electric-field modulation of gold (Au) nanorods embedded in a transparent sol-gel host. Specifically, we show that placing the Au nanorod/sol-gel matrix in an alternating current (AC) field gives rise to dramatic modulation of incident light scattered from the material. The speckle light patterns take form of “beats”, for which the amplitude and frequency are directly correlated with the voltage and frequency, respectively, of the applied AC field. The data indicate that the speckle beats arise from localized vibrations of the gel-embedded Au nanorods, induced through the interactions between the AC field and the electrostatically-charged nanorods. This phenomenon opens the way for new means of investigating nanoparticles in constrained environments. Applications in electro-optical devices, such as optical modulators, movable lenses, and others are also envisaged.

Direct exploration of the mutually interfering morphological and charge-transport characteristics in self-assembled monolayers (SAMs) is reported. These strongly coupled properties are addressed by means of surface spectroscopy techniques, combined so as to consistently account at high sensitivity for a broad range of surface properties without any use of a top contact. Applied to doped bovine serum albumin (BSA) SAMs, we show how the BSA conformation, its dehydration, and monolayer assembly are all correlated. Moreover, the electrical properties, transport, and charge trapping are highly affected by the SAM compositional and structural state, with a specific role of water molecules. Our results reveal and further demonstrate a useful approach to the complex challenges presented by (bio) molecular electronics.