Complete abatement of the antibiotic ciprofloxacin from water using a visible-light-active nanostructured photoanode.

The wide use of the fluoroquinolone antibiotic ciprofloxacin (CIP), combined with its limited removal in wastewater treatment plants, results in a dangerous accumulation in natural water. Here, the complete degradation of CIP by photoelectrocatalysis (PEC), using an FTO/ZnO/TiO2/Ag2Se photoanode that is responsive to blue light, has been investigated. A slow antibiotic concentration decay was found in 0.050 M Na2SO4 under the oxidizing action of holes and OH photogenerated at the anode surface. The degradation was strongly enhanced in 0.070 M NaCl due to mediated oxidation by electrogenerated active chlorine. The latter process became faster at pH 7.0, with total abatement of CIP at concentrations below 2.5 mg L-1 operating at a bias potential of +0.8 V. The performance was enhanced when increasing the anodic potential and decreasing the initial drug content. The use of solar radiation from a simulator was also beneficial, owing to the greater lamp power. In contrast, the electrochemical oxidation in the dark yielded a poor removal, thus confirming the critical role of oxidants formed under light irradiation. The generation of holes and OH was confirmed from tests with specific scavengers like ammonium oxalate and tert-butanol, respectively. The prolonged usage of the photoanode affected its performance due to poisoning of its active centers by degradation by-products, although a good PEC reproducibility was obtained upon surface cleaning.

Synthesis, characterization and bio-functionalization of magnetic nanoparticles to improve the diagnosis of tuberculosis.

Mycobacterium tuberculosis is the cause of one of the diseases with the highest mortality and morbidity rate in the Americas and in the world. In developing countries, the diagnosis of tuberculosis (TB) is based on baciloscopy and bacteriological cultures. The first method has a low sensitivity, and the second can take several weeks to reach a confirmatory diagnosis. The lack of a rapid diagnosis compromises the efforts to control this disease and favors the transmission of tuberculosis to the susceptible population. In this work, we present the synthesis, amine-silanization, characterization and bio-functionalization of magnetic nanoparticles (MNPs) to develop a sandwich ELISA to detect and concentrate antigens from M. tuberculosis. For this purpose, a recombinant mycobacterial heat shock protein Hsp16.3, which contributes to the persistence of TB, was cloned and expressed in the E. coli system. Polyclonal antibodies anti-Hsp16.3 were produced in a rabbit and in mice. Magnetic nanoparticles were synthesized by co-precipitation, amine-functionalized and characterized by several physical-chemical methods. The XRD, Mossbauer spectroscopy, zeta potential, TEM, and FTIR all proved the successful preparation of the MNPs showing a diffraction crystal diameter of 10.48 ± 2.56 nm, superficial net charge of [Formula: see text]: +23.57 ± 2.87 mV, characteristic patterns of magnetite and a structure similar to a sphere. Additionally, it showed a magnetization saturation of 37.06 emu.g-1. For the functionalization of nanoparticle surfaces with anti-Hsp16.3, the active ester method was used for bond formation, and parameters such as time of incubation, coupling agents ratio (EDC/NHS) and concentration as well as surface saturation level of amine-silanized MNPs (MNP@Si@NH2) were standardized. Finally, bio-functionalized MNPs were used to detect, fix and concentrate the recombinant antigen Hsp16.3 from M. tuberculosis in a sandwich ELISA-MNP assay.