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.
An appealing alternative approach to the conventional electrochem. deposition is presented, which can be universally utilized to form nanomaterial coatings from their aq. dispersions without involving their oxidn.-redn. It is based on altering the ionic strength by elec. potential in the vicinity of the electrode surface, which causes the nanomaterials to deposit. The concept has been demonstrated for four different systems. [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 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)]
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)]
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, X = OH, NH2, CO2H, SO3H, as well as 4-mercaptobenzoic acid. The SAMs were characterized by XPS and cycling voltammetry (CV). The anodic dissoln. of a Ag microelectrode, which was held within a few microns from the Au surface, formed a well-controlled flux of Ag+. Deposition of Ag nanostructures was driven by the electrochem. redn. of the Ag+ on the Au surface. The effect of the functional group on the Ag local deposition was studied and compared with bulk deposition on the same SAMs. For bulk deposition, the interaction between Ag+ ions and the functional group of the alkanethiols slowed the kinetics of Ag deposition, shifting the deposition to potential that is more neg. and caused the formation of large, well-faceted Ag crystals. A clear correlation between the potential shift value and the morphol. of deposited Ag was obsd. The local deposition of Ag showed distinct difference compared to bulk deposition. A continuous and homogeneous Ag film was formed locally below the Ag microelectrode in the presence of a 3-mercaptopropionic acid monolayer. This was obsd. when a 120 s delay between the electrogeneration of the Ag ions and the application of a neg. potential to the Au surface was applied. Also, the potential applied to the Au surface also affected deposition. The deposited Ag was recollected by the Ag microelectrode by stripping the Ag from the Au surface while holding the microelectrode in the same position. This enabled calcg. the thickness of the Ag film deposited on the Au coated with 3-mercaptopropionic acid. Addnl. expts. clearly indicated that the mechanism of deposition involved complexation of Ag ions by the SAM and their local redn., which commenced prior to applying a neg. potential to the Au surface. [on SciFinder(R)]
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)]