A new redox-free electrochemical approach for driving the deposition of two-dimensional (2D) layered MoS2 nanosheets is described. First, poly(acylic acid) (PAA) functionalized layered MoS2 nanosheets (PAA-MoS2) is prepared to form a stable aqueous PAA-MoS2 dispersion, which is subsequently used for the electrochemical deposition. In contrast to previous electrodeposition methods of MoS2, which involve the redox of molecular precursors of Mo and S, herein we introduce an electrochemical approach for the deposition of 2D layered MoS2 nanosheets directly from their nanometric building blocks, namely from their aqueous dispersion. This ‘‘nano to nano’’ approach is based on altering the ionic strength at the vicinity of the electrode surface by applying a potential. Specifically, the electrogeneration of Cue-1 ions, cause the PAA-MoS2 nanosheets in the dispersion to aggregate and deposit on the copper electrode. Scanning electron microscopy, X-ray diffraction, Raman and X-ray photoelectron spectroscopy analysis show clearly that the deposited layered MoS2 maintains its original structure. Furthermore, the ;electrodeposited PAA-MoS2 nanosheets on copper show excellent catalytic activity for the hydrogen evolution reaction with low overpotential. Hence, we believe that these findings could lead to a generic approach for the formation of thin films or patterns of 2D nanomaterials. (C) 2017 Elsevier Ltd. All rights reserved.

Sensitive and selective detection of cancer biomarkers is vital for the successful diagnosis of early stage cancer and follow-up treatment. Surface Plasmon Resonance (SPR) in combination with different amplification strategies is one of the analytical approaches allowing the screening of protein biomarkers in serum. Here we describe the development of a point-of-care sensor for the detection of folic acid protein (FAP) using graphene-based SPR chips. The exceptional properties of CVD graphene were exploited to construct a highly sensitive and selective SPR chip for folate biomarker sensing in serum. The specific recognition of FAP is based on the interaction between folic acid receptors integrated through pi-stacking on the graphene coated SPR chip and the FAP analyte in serum. A simple post-adsorption of human serum:bovine serum albumin (HS:BSA) mixtures onto the folic acid modified sensor resulted in a highly anti-fouling interface, while keeping the sensing capabilities for folate biomarkers. This sensor allowed femtomolar (fM) detection of FAP, a detection limit well adapted and promising for quantitative clinical analysis. (C) 2016 Elsevier B.V. All rights reserved.

Sensitive and selective detection of cancer biomarkers is vital for the successful diagnosis of early stage cancer and follow-up treatment. Surface Plasmon Resonance (SPR) in combination with different amplification strategies is one of the anal. approaches allowing the screening of protein biomarkers in serum. Here we describe the development of a point-of-care sensor for the detection of folic acid protein (FAP) using graphene-based SPR chips. The exceptional properties of CVD graphene were exploited to construct a highly sensitive and selective SPR chip for folate biomarker sensing in serum. The specific recognition of FAP is based on the interaction between folic acid receptors integrated through π-stacking on the graphene coated SPR chip and the FAP analyte in serum. A simple post-adsorption of human serum:bovine serum albumin (HS:BSA) mixts. onto the folic acid modified sensor resulted in a highly anti-fouling interface, while keeping the sensing capabilities for folate biomarkers. This sensor allowed femtomolar (fM) detection of FAP, a detection limit well adapted and promising for quant. clin. anal. [on SciFinder(R)]

Molybdenum trioxide is an interesting inorganic system in which the empty 4d states have potential to hold extra electrons and therefore can change states from insulating opaque (MoO3) to colored semimetallic (HxMoO3). Here, we characterize the local electrogeneration and charge transfer of the synthetic layered two-dimensional 2D MoO3-II (a polymorph of MoO3 and analogous to alpha-MoO3) in response,to two different redox couples; i.e., [Ru(NH3)(6)](3+) and [Fe(CN)(6)](3-) by scanning electrochemical microscopy (SECM). We identify the reduction of [Ru(NH3)(6)](3+) to [Ru(NH3)(6)](2+) at the microelectrode that leads to the reduction of MoO3-11 to conducting blue-colored molybdenum bronze H MoO3. It is recognized that the dominant conduction of the charges occurred preferentially at the edges active sites of the sheets, as edges of the sheets are found to be more conducting. This yields positive feedback current when approaching the microelectrode toward 2D MoO3-II-coated electrode. In contrast, the [Fe(CN)(6)](4-), which is reduced from [Fe(CN)(6)](3-), is found unfavorable to reduce MoO3-II due to its higher redox potential, thus showing a negative feedback current. The charge transfer on MoO3-II is further studied as a function of applied potential. The results shed light on the charge transfer behavior on the surface of MoO3-II coatings and opens the possibility of locally tuning of their oxidation states.

We report the first attempt of using molecularly imprinted polymers (MIPs) in the shape of nanoparticles that were doped with gold nanoparticles (AuNPs) for surface enhanced Raman scattering (SERS)-based sensing of molecular species. Specifically, AuNPs doped molecularly imprinted nano-spheres (AuNPs@nanoMIPs) were synthesized by one-pot precipitation polymerization using Sudan IV as the template for the SERS sensing. The AuNPs@nanoMIPs were characterized by various modes of scanning transmission electron microscopy (STEM) that showed the exact location of the AuNPs inside the MIP particles. The effects of Au concentration and solution stirring on the shape and the polydispersity of the particles were studied. Significant enhancement of the Raman signals was observed only when the MIP particles were doped with the AuNPs. The SERS signal improved significantly with increase in the Au concentration inside the AuNPs@nanoMIPs. Selectivity measurements of the Sudan IV imprinted AuNPs@nanoMIPs carried out with different Sudan derivatives showed high selectivity of the AuNPs-doped MIP particles.

We report the first attempt of using molecularly imprinted polymers (MIPs) in the shape of nanoparticles that were doped with gold nanoparticles (AuNPs) for surface enhanced Raman scattering (SERS)-based sensing of mol. species. Specifically, AuNPs doped molecularly imprinted nano-spheres (AuNPs@nanoMIPs) were synthesized by one-pot pptn. polymn. using Sudan IV as the template for the SERS sensing. The AuNPs@nanoMIPs were characterized by various modes of scanning transmission electron microscopy (STEM) that showed the exact location of the AuNPs inside the MIP particles. The effects of Au concn. and soln. stirring on the shape and the polydispersity of the particles were studied. Significant enhancement of the Raman signals was obsd. only when the MIP particles were doped with the AuNPs. The SERS signal improved significantly with increase in the Au concn. inside the AuNPs@nanoMIPs. Selectivity measurements of the Sudan IV imprinted AuNPs@nanoMIPs carried out with different Sudan derivs. showed high selectivity of the AuNPs-doped MIP particles. [Figure not available: see fulltext.]. [on SciFinder(R)]

We report the first attempt of using molecularly imprinted polymers (MIPs) in the shape of nanoparticles that were doped with gold nanoparticles (AuNPs) for surface enhanced Raman scattering (SERS)-based sensing of molecular species. Specifically, AuNPs doped molecularly imprinted nano-spheres (AuNPs@nanoMIPs) were synthesized by one-pot precipitation polymerization using Sudan IV as the template for the SERS sensing. The AuNPs@nanoMIPs were characterized by various modes of scanning transmission electron microscopy (STEM) that showed the exact location of the AuNPs inside the MIP particles. The effects of Au concentration and solution stirring on the shape and the polydispersity of the particles were studied. Significant enhancement of the Raman signals was observed only when the MIP particles were doped with the AuNPs. The SERS signal improved significantly with increase in the Au concentration inside the AuNPs@nanoMIPs. Selectivity measurements of the Sudan IV imprinted AuNPs@nanoMIPs carried out with different Sudan derivatives showed high selectivity of the AuNPs-doped MIP particles.

Calcium phosphate (CaP) ceramics have been prevalently used as coatings for implants because of their excellent osteoconductive and bioactive properties. Yet, bone regeneration procedures might have complications such as bacterial infection, local inflammation, bone destruction, and impaired bone healing. Here, we present a novel in situ electrodeposition of CaP with chitosan nanoparticles containing antibiotics. The deposition was shown to be fast and efficient. The deposited layer of octacalcium phosphate (OCP) and monotite contained a large amount of gentamicin, which was released gradually over a period of 15 days. These phases may be beneficial for bone growth, as OCP has higher solubility than the stoichiometric hydroxyapatite (HAp) and is commonly considered as a precursor to HAp, while monotite has even faster resorbability. In addition, both the cytotoxicity and biomineralization of the coating were studied, and the coating was proven to be noncytotoxic and highly biomimetic.

Calcium phosphate (CaP) ceramics have been prevalently used as coatings for implants because of their excellent osteoconductive and bioactive properties. Yet, bone regeneration procedures might have complications such as bacterial infection, local inflammation, bone destruction, and impaired bone healing. Here, we present a novel in situ electrodeposition of CaP with chitosan nanoparticles containing antibiotics. The deposition was shown to be fast and efficient. The deposited layer of octacalcium phosphate (OCP) and monotite contained a large amount of gentamicin, which was released gradually over a period of 15 days. These phases may be beneficial for bone growth, as OCP has higher solubility than the stoichiometric hydroxyapatite (HAp) and is commonly considered as a precursor to HAp, while monotite has even faster resorbability. In addition, both the cytotoxicity and biomineralization of the coating were studied, and the coating was proven to be noncytotoxic and highly biomimetic.

Scanning electrochemical microscopy (SECM) offers an alternative approach for precise local electrodeposition of micro and nanometer structures driven by electrochemistry. The tip generation and substrate collection mode of SECM has been applied to deposit sub-micron palladium structures by using a Pd microelectrode. This was compared with a different approach based on scanning ion conductance microscopy (SICM). The latter was utilized also for the localized electrochemical deposition of Pd patterns using a pulled micropipette as a tip. The micropipette was filled with PdCl42- and biased versus a reference electrode placed in a NaCl solution. The application of a negative potential to the micropipette causes negatively charged ions, PdCl4-, to egress the pipette, which were electrochemically reduced on a conducting surface. The Pd patterns locally deposited by SECM and SICM were used for the local electroless deposition of Cu. Comparison between the two techniques shows that SICM is superior to SECM in terms of resolution and ease of tip preparation.

Post-surgery infections are considered the most challenging complication in the orthopedic and dental field. The local release of antibiotics is evidently highly efficient in delivering the drug to the vicinity of the infected area without the risk of systemic toxicity. Bioactive materials, such as hydroxyapatite (HAp) among other calcium phosphates, are reputed as superior antibiotic vehicles, and combine drug-delivery properties and enhanced osteoconductivity. Here, we report on the single-step electrophoretic deposition (EPD) of drug-loaded HAp nanoparticles (NPs) on titanium implants. This approach provides a purely bioactive coating with drug delivery properties in a simple, economic, and fast process. We synthesized pure HAp NPs with 12.5% and 12.8% loading weight percentages of gentamicin sulfate (Gs) and ciprofloxacin (Cip), and electrophoretically deposited them on a titanium substrate. Furthermore, we co-deposited Gs-HAp and Cip-HAp in one-step to yield a drug-loaded system consisting of two types of antibiotics. The drug- loaded NPs as well as the coatings were carefully characterized. The release profiles of the Gs-HAp and Cip-HAp NP coatings showed prolonged release of up to 10 and 25 days, respectively. The bioactivity test revealed superior bioactivity with enhanced precipitation of HAp crystals along with inorganic minerals, such as Mg2+, Na+, and Cl-. The antibacterial in vitro tests of the Cip and Gs-HAp coatings showed efficient inhibition of Pseudomonas aeruginosa bacteria.

A flow-through electrode made of a C nanotubes (CNT) film deposited on a polytetrafluoroethylene (PTFE) membrane was assembled and employed for the detn. of low concn. of Cu as a model system by linear sweep anodic stripping voltammetry (LSASV). CNT films with areal mass ranging from 0.12 to 0.72 mg cm-2 were characterized by measurement of sheet resistance, H2O permeation flux and capacitance. Also, CNT with two different sizes and PTFE membrane with two different pore diams. (0.45 and 5.0 μm) were evaluated during the optimization of the electrode. Thick layers made of small CNT exhibited the lowest sheet resistance and the greatest anal. response, whereas thin layers of large CNT had the lowest capacitance and the highest permeation flux. Electrodes made of 0.12 mg cm-2 of large CNT deposited on 5.0 μm PTFE enabled sufficiently high mass transfer and collection efficiency for detecting 64 ppt of Cu(II) within 5 min of deposition and 4.0 mL min-1 flow rate. The anal. response was linear over 4 orders of magnitude (10-9 to 10-5 M) of Cu(II). The excellent performance of the flow-through CNT membrane integrated in a flow cell makes it an appealing approach not only for electroanal., but also for the electrochem. treatment of waters, such as the removal of low concns. of heavy metals and orgs. [on SciFinder(R)]