The NADH Electrochemical Detection Performed at Carbon Nanofibers Modified Glassy Carbon Electrode

In this work, the capability of carbon nanofibers to be used for the design of catalytic electrochemical biosensors is demonstrated. The direct electrochemistry of NADH was studied at a glassy carbon electrode modified using carbon nanofibers. A decrease of the oxidation potential of NADH by more than 300 mV is observed in the case of the assembled carbon nanofiber‐glassy carbon electrode comparing with a bare glassy carbon electrode. The carbon nanofiber‐modified electrode exhibited a wide linear response range of 3×10^?5 to 2.1×10^?3 mol L^?1 with a correlation coefficient of 0.997 for the detection of NADH, a high specific sensitivity of 3637.65 (μA/M cm²), a low detection of limit (LOD=3σ) of 11 μM, and a fast response time (3 s). These results have confirmed the fact that the carbon nanofibers represent a promising material to assemble electrochemical sensors and biosensors.     

Electrochemical Characterization of Carbon Solidlike Paste Electrode Assembled Using Different Carbon Nanoparticles

Solid like carbon paste electrodes (SCPEs) are built using different carbon materials namely carbon black N110, N220, N375, N772 and acetylene black. The electrochemical behavior of these electrodes and the influence of carbon black/paraffin ratio were studied and the results were discussed and compared to other electrodes prepared with graphite, mesoporous carbon and nanopowder carbon. Cyclic voltammetry, amperometry and electrochemical impedance spectroscopy were employed for their electrochemical and analytical characterizations. Amperometric measurements using N110, N220, N375 SCPEs with solid paraffin, showed a linear response of benzoquinone concentration with a detection limit of 75, 32 and 171 nM respectively.     

Adsorption of human serum albumin (HSA) onto colloidal TiO2 particles, Part I

The adsorption of human serum albumin (HSA) onto colloidal TiO2 (P25 Degussa) particles was studied in NaCl electrolyte at different solution pH and ionic strength. The HSA-TiO2 interactions were studied using adsorption isotherms and the electrokinetic properties of HSA-covered TiO2 particles were monitored by electrophoretic mobility measurements. The adsorption behavior shows a remarkable dependence of the maximum coverage degree on pH and was almost independent of the ionic strength. Other characteristic features such as maximum adsorption values at the protein isoelectric point (IEP approximately 4.7) and low-affinity isotherms that showed surface saturation even under unfavorable electrostatic conditions (at pH values far away from the HSA IEP and TiO2 PZC) were observed. Structural and electrostatic effects can explain the diminution of HSA adsorption under these conditions, assuming that protein molecules behave as soft particles. Adsorption reactions are discussed, taking into account acid-base functional groups of the protein and the surface oxide in different pH ranges, considering various types of interactions.     

Proof‐of‐Concept Studies Directed toward the Formation of Metallic Ag Nanostructures from Ag3PO4 Induced by Electron Beam and Femtosecond Laser

In this work, for the first time, the instantaneous nucleation and growth processes of Ag nanoparticles on Ag₃PO₄ mediated by femtosecond laser pulses are reported and analyzed. The investigated samples are pure Ag₃PO₄ sample, electron‐irradiated Ag₃PO₄ sample, and laser‐irradiated sample. Complete characterization of the samples is performed using X‐ray diffraction (XRD), Rietveld refinements, field emission scanning electron microscopy, and energy dispersive spectroscopy (EDS). XRD confirms that the irradiated surface layer remains crystalline, and according to EDS analysis, the surface particles are composed primarily of Ag nanoparticles. This method not only offers a one‐step route to synthesize Ag nanoparticles using laser‐assisted irradiation with particle size control, but also reports a complex process involving the formation and subsequent growth of Ag nanoparticles through an unexpected additive‐free in situ fabrication process.     

Complexation of polyacrylates by Ca2+ ions. Time-resolved studies using attenuated total reflectance Fourier transform infrared dialysis spectroscopy

The attenuated total reflectance Fourier transform infrared dialysis technique is introduced for the time-resolved investigation of the binding processes of Ca2+ to polyacrylates dissolved in water. We observed transient formation of intermediates in water with various types of coordination of the carboxylate group to Ca2+ throughout the complexation steps. Time-resolved changes in the spectra were analyzed with principal component analysis, from which the spectral species were obtained as well as their formation kinetics. We propose a model for the mechanisms of Ca2+ coordination to polyacrylates. The polymer chain length plays an important role in Ca2+ binding.     

Cyclopalladated complexes of 4-aryl-2,1,3-benzothiadiazoles: new emitters in solution at room temperature

The cyclopalladation of the 4-aryl-2,1,3-benzothiadiazoles 1a-c with palladium acetate in acetic acid afforded the novel dimeric complexes 2a-c in good yields. These were then converted into the monomeric pyridine-, chloro-coordinated cyclometallated complexes 3a-c through reaction with lithium chloride in acetone and then pyridine in dichloromethane. All complexes were fully characterized by means of NMR, IR and elemental analysis. The X-ray structure of complex 2c revealed that it presents transoid geometry, whereas the X-ray structure of 3c shows that the pyridine ligand and the thiazole ring are mutually trans. Photophysical properties were investigated by means of UV-Vis absorption and fluorescence emission in solution. Solid-state diffuse reflectance UV-Vis spectra (DRUV) were also applied in order to better characterize the complexes photophysics in the solid state. All complexes present intense absorption at around 300 nm (λ(1)) via(1)LC transitions located in BTD ligands, and additional low energy absorption bands, higher than 450 nm (λ(2)) of (1)MLCT character. The complexes are fluorescent in solution at room temperature, where two emission bands could be observed, a high energy band (excitation @ λ(1)) ascribed to the ligand emission and an additional red shifted low intense band (excitation @ λ(2)) due to the complex emission.     

Effective cell uptake of nanoassemblies of a fluorescent amphiphilic cyclodextrin and an anionic porphyrin

An emitting nanoassembly composed of a novel amphiphilic cyclodextrin functionalised with a covalently appended fluorophore and an anionic porphyrin internalizes effectively in tumor cells, allowing simultaneously the detection of carrier and photosensitiser.     

Olive Trees By-Products as Sources of Bioactive and Other Industrially Useful Compounds: A Systematic Review

The need to produce an ever-increasing quantity of material products and food resulting from the planet globalization process has contributed to the spread of modern agriculture based on a linear production resulting in the generation of tons of waste. This huge amount of waste is generally accumulated in landfills, causing different environmental problems. Hence, researchers moved on to study the processes used to recover agro-industrial by-products within a circular and sustainable bio-economy concept. A systematic quest on Scopus and PubMed databases was performed to identify the data available to date on recycling agro-industrial by-products of Olea europaea L. This systematic review summarizes the knowledge regarding the use of olive trees by-products for producing animal feed, biocomposites, bioethanol, cellulose pulp, activated carbon, and as a fuel source for energy production. Furthermore, the data regarding the potential biological activity of extracts from olive roots, wood, bark, and pruning were analyzed. Olive trees by-products are, indeed, rich in molecules with antioxidant, antimicrobial, cardioprotective, and anticancer activity, representing a promising candidate for treat several human diseases.     

Large-Scale Production and Purification of Ascochyta caulina Phytotoxins and a New HPLC Method for their Analysis

The toxins produced by Ascochyta caulina have potential as a natural herbicide. They are three basic non-protein amino acids. Considering the need to optimize and maximize their production by fermentation in order to obtain large amounts of toxins, a new, simple, and inexpensive HPLC method was developed. This new process allows rapid evaluation of the toxin content in the fungal culture filtrates. The simplification and scaling up of the entire process include a single-step purification of the filtrates by cationic exchange chromatography by using a reusable resin with a high exchange capacity and distilled water and dilute ammonia as eluents. This process allows the fast and easy purification of large volumes of filtrates and the harvest of large amounts of a mixture containing the three pure toxins. These methods are described here and their potential to be scaled up to a pre-industrial level is discussed.