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)]

The detection of disease markers is considered an important step for early diagnosis of cancer. We design in this work a novel electrochem. sensing platform for the sensitive and selective detection of folic acid protein (FP). The platform is fabricated by electrophoretic deposition (EPD) of reduced graphene oxide (rGO) onto a gold electrode and post-functionalization of rGO with folic acid. Upon FP binding, a significant current decrease can be measured using differential pulse voltammetry (DPV). Using this scheme, a detection limit of 1 pM is achieved. Importantly, the method also allows the detection of FP in serum being thus an appealing approach for the sensitive detection of biomarkers in clin. samples. [on SciFinder(R)]

Calcium phosphate (CaP) ceramics are used in orthopedics and dentistry due to their excellent osseointegration and biocompatibility. The electrodeposition of CaP on titanium alloy covered with self-assembled monolayers (SAMs) was studied with respect to the influence of chain length, end-group charge, and anchoring group. SAMs with end-groups similar to the functional groups on the side chains of collagen were selected. This study is divided to three parts: (1) studying the effects of SAMs on the titanium substrate, (2) studying the process of nucleation and growth of the CaP on specific SAMs, and (3) characterizing the CaP coatings using various surface anal. techniques. It was concluded that the nucleation and growth behavior of CaP changed in the presence of the SAMs. Different surface energies and crystallog. phases were assocd. with this change. Although the nucleation remained progressive, the growth changed from three-dimensional on bare surfaces to two-dimensional on SAMs-covered surfaces. Moreover, the deposition kinetics was slower on SAMs-covered surfaces, with phases contg. a higher Ca/P ratio. Examn. of the coating revealed that different SAMs lead to different surface morphologies of the coating while maintaining its degree of crystallinity. Yet, the phase content changes from hydroxyapatite and octacalcium phosphate (HAp + OCP) on the bare electrode to OCP only on the SAMs-covered electrode. These changes may have a substantial effect on the in vivo behavior by changing the coating’s soly. and surface morphol., thus affecting cell adhesion, proliferation, and differentiation processes. [on SciFinder(R)]

{The localized electrodeposition of Ag on Au coated with self-assembled monolayers (SAMs) by scanning electrochem. microscopy (SECM) is reported. The SAMs were ω-functionalized alkanethiols X-(CH2)2SH

Ca phosphate (CaP) ceramics were used in orthopedics and dentistry due to their excellent biocompatibility and osseointegration. Here, the electro-assisted deposition of CaP on two different self-assembled monolayers (SAMs), 2-mercaptoacetic acid (MAA) and 2-mercaptoethanol (ME), was studied both at short (up to 3 min) and long (2 h) deposition periods on well-defined evapd. Au surfaces. The end group of the monolayer has a major effect on the growth of the CaP coating. The deposition was slower and less elec. efficient on MAA SAM, but surface cracking was essentially eliminated due to redn. of the crystallog. mismatch. The carboxylic acid may facilitate CaP growth by attracting Ca2+ ions to the surface, which could explain the higher amt. of side reactions occurring at the beginning of the deposition. [on SciFinder(R)]

Calcium phosphates are of great interest for biomedical applications such as bone tissue engineering, bone fillers, drug and gene delivery, and orthopedic and dental implant coating. Here, the first electrochem. driven coating of medical implants using hydroxyapatite (HAp) nanoparticles (NPs) as building blocks is reported. This uncommon combination offers a simple, straightforward, and economic process with well controllable, pure, single-phase HAp. Cryst., pure HAp NPs are formed by pptn. reaction. The HAp NPs are dispersed by either citrate or poly(acrylic acid) to form pH sensitive dispersion. Controllable and homogeneous coating of medical implants is accomplished by altering the pH on the surface upon applying either a const. potential or current. The process involves protonation of the carboxylic acid moieties, which causes the irreversible aggregation of the HAp NPs due to diminishing the repulsive forces between the particles. Deposition is further demonstrated on a com. dental implant. Moreover, the adhesion of the coating satisfies FDA and international std. requirements. A porous interconnected network of bone-like HAp layer is formed during soaking in a simulated body fluid for 30 d and is similar to bone generation, and it therefore holds promise for further in vivo testing. [on SciFinder(R)]

An aq. suspension of WO3/poly(4-(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid) (PEDTS) hybrid nanoparticles (NPs) is prepd. by air-assisted oxidative polymn. and simultaneous attachment of PEDTS on WO3-NPs, and used for electrochromic (EC) film fabrication via air-brush spraying. The hybrid EC device exhibits enhanced EC properties compared to the ones based on WO3-NP or PEDTS alone. [on SciFinder(R)]

A major component of solar thermal systems is the solar absorber, which converts light into heat. We report on achieving high absorptance, excellent adhesion, and high thermal stability of carbon nanotube-based black coatings by applying a layer of Boehmite (AlOOH) on top of the carbon nanotube (CNT) film by soln.-processed spray deposition. The CNT layer made-up by spraying, functions as an absorbing layer and the AlOOH serves as an anti-reflecting and protecting film. The anti-reflecting property of AlOOH layer effectively increases the absorptance of CNT coating by decreasing the reflectance. The effect of the thickness of AlOOH layer on the absorptance, adhesion, and thermal stability of the resulting CNT/AlOOH coating was investigated. The CNT/AlOOH coating with optimized thickness of AlOOH layer shows very high absorptance (α) of 0.975. The adhesion of the coating is in the range of 95-100% with significant increase of thermal stability. This new approach is expected to open new possibilities for fabricating low-cost, highly efficient and thermally stable solar-thermal devices which are based on simple coating processes. [on SciFinder(R)]