Publications

Abstract Swept-source optical coherence tomography (SSOCT) is a noncontact, noninvasive bioimaging tool that uses various probes to obtain high contrast images. Rare-earth based upconversion particles (UCPs) provide a unique platform to enhance the capabilities of bioimaging techniques. The UCPs can act as contrast enhancers for the SSOCT with additional optical functionality, and hence in this work upconversion emission optimized polyvinylpyrrolidone (PVP)/NaGdF4:Er3+/Yb3+ UCPs were synthesized and then injected into chicken breast tissues to enhance the SSOCT images. As-synthesized samples have shown good biocompatibility toward HEK293, HeLa cell lines and showed apparent enhancement in contrast to SSOCT images. Additionally, compared to the bare NaGdF4:Er3+/Yb3+ UCPs the polyvinylpyrrolidone-stabilized UCPs have shown 3-fold enhancement in the frequency of upconverted green and red light intensity under 976 nm diode laser excitation (26 W/cm(2)).

Abstract Disinfection is crucial to control and prevent microbial pathogens on surfaces. Nonetheless, disinfectants misuse in routine disinfection has increased the concern on their impact on bacterial resistance and cross-resistance. This work aims to develop a formulation for surface disinfection based on the combination of a natural product, cinnamaldehyde, and a widely used biocide, cetyltrimethylammonium bromide. The wiping method was based on the Wiperator test (ASTM E2967-15) and the efficacy evaluation of surface disinfection wipes test (EN 16615:2015). After formulation optimization, the wiping of a contaminated surface with 6.24 log(10) colony-forming units (CFU) of Escherichia coli or 7.10 log(10) CFU of Staphylococcus aureus led to a reduction of 4.35 log(10) CFU and 4.27 log(10) CFU when the wipe was impregnated with the formulation in comparison with 2.45 log(10) CFU and 1.50 log(10) CFU as a result of mechanical action only for E. coli and S. aureus, respectively. Furthermore, the formulation prevented the transfer of bacteria to clean surfaces. The work presented highlights the potential of a combinatorial approach of a classic biocide with a phytochemical for the development of disinfectant formulations, with the advantage of reducing the concentration of synthetic biocides, which reduces the potentially negative environmental and public health impacts from their routine use.

Abstract In this investigation, hybrid-biocomposites "ZnO-Chitosan" were synthesized using a chitosan biomaterial and various amounts of ZnO particles (7 and 93 wt percent). The chitosan was obtained from the exoskeletons of shrimp shells, which were collected from the fishmongers in Meknes city (Morocco). Several techniques including X-ray diffraction, Fourier transform infrared spectroscopy, differential thermal analysis and thermogravimetric analysis, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy coupled with energy dispersive spectroscopy were used for the characterization of the synthesized hybrid-biocomposites. The obtained experimental results showed the existence of a strong interaction between Zn-2(+), and the amino and hydroxyl groups of chitosan only for the hybrid-biocomposite containing 7 wt percent of ZnO. This suggests that the structure of this sample is probably formed via a complexation between Zn-2(+) ions which are linked to -NH2, -OH groups of chitosan, and H2O molecules. The photocatalytic activity of the asprepared hybrid-biomaterials was then evaluated by measuring the degradation efficiency of methyl orange (MO) and paranitrophenol (pNP) under both UV-A and visible light irradiation. The obtained results indicated that the photocatalytic performance was significantly improved by adding an optimum amount of ZnO (7 wt %) to the chitosan biomaterial, and suggested that the photocatalytic activity depended closely on the ZnO weight percent. The role of the active species (electrons, holes and hydroxyl radicals) in the photocatalytic process has been studied and the probable degradation mechanisms of MO and pNP under both UV-A and visible light illuminations were proposed.

Abstract In this work, we combined electrochemical techniques with SPR (eSPR) for the label-free detection of cancer biomarker miRNA-145. Detection was performed in a simple two-step assay. In the first step, the gold sensor surface, previously functionalized with a self-assembled monolayer (SAM) of thiolated RNA probes is incubated with the sample containing the target RNA biomarker. In this step, hybridization of RNA fragments with complementary immobilized probes was monitored in real-time by SPR. In the second step, eSPR measurements were performed to improve the sensitivity of the hybridization assay. Potential-induced deposition of a redox probe at the sensor surface resulted in enhanced SPR response promoted by the electrochemical process, thereby allowing the detection of miRNA-145 at femtomolar level (LOD = 0.56 fM), without sample derivatization or post-hybridization treatment for signal amplification. Good linearity was achieved (R-2 = 0.984) over the concentration range from 1.0 fM and 10 nM. Furthermore, the developed eSPR biosensor showed high selectivity towards single-base and two-base mismatch sequences and detection of target miRNA-145 in synthetic human serum was successful achieved.

Abstract In this work, three universally used redox probes in amperometric biosensing devices, [Fe(CN)(6)](3-)/[Fe(CN)(6)](4-), Ru[(NH3)(6)](3+), and ferrocenedimethanol (FDM), were selected to evaluate the stability of electrochemical signals provide by the reporting systems. Studies were carried out at disposable gold screen-printed electrode (AuSPE) biosensing platforms, commonly used for screening chemical and biological relevant biomolecules. Firstly, electrochemical combined-surface plasmon resonance (eSPR) studies were performed to evaluated adsorption reversibility and/or formation of redox probe complexes at the bare gold surface when routinely used electrochemical techniques, namely cyclic voltammetry (CV) and square-wave voltammetry (SWV), are recorded. Then, the results obtained were compared with those obtained at the AuSPE under the same electrochemical conditions. Based on our findings, best experimental conditions, including the type of electrochemical technique used, are speculated for each reporting system in order to improve the analytical signal stability. Finally, a methodology based on SWV technique was applied to modified electrodes to provide a simple and easy tool to ensure diffusion controlled permeability of probes thorough the films to electrode surface.

Abstract The authors regret the existence of an error on one of the results reported in the original and published manuscript. The error has been identified and rectified as follows: • In Abstract, page 2469: the half-life period of “23.8 ± 0.6 s” should be read as “47.6 ± 1.1 s”. • In page 2472, section Results and discussion, second paragraph: the half life was “23.8 ± 0.6 s” should be read as “47.6 ± 1.1 s”. • In page 2478, section Conclusions, first paragraph: the half life period of “23.8 ± 0.6 s” should be read as “47.6 ± 1.1 s”. The authors would like to apologise for any inconvenience caused to the editorial staff and the editor of the Journal of Environmental Chemical Engineering, as well as all its valuable readers and followers.

Abstract UV photodecomposition of azidomethyl methyl sulfide (AMMS) yields a transient S-methylthiaziridine which rapidly evolves to S-methyl-N-sulfenylmethanimine at 10 K. This species was detected by infrared matrix isolation spectroscopy. The mechanism of the photoreaction of AMMS has been investigated by a combined approach, using low-temperature matrix isolation FTIR spectroscopy in conjunction with two theoretical methods, namely, complete active space self-consistent field and multiconfigurational second-order perturbation. The key step of the reaction is governed by a S-2/S-1 conical intersection localized in the neighborhood of the singlet nitrene minimum which is formed in the first reaction step of the photolysis, that is, N-2 elimination from AMMS. Full assignment of the observed infrared spectra of AMMS has been carried out based on comparison with density functional theory and second-order perturbation Moller-Plesset methods.

Abstract Pharmaceuticals are invaluable tools for the prevention and treatment of human and animal diseases. Human evolution led to the increase of life expectancy, which promoted the increase of consumption of pharmaceuticals. These compounds are consistently detected in superficial waters, and whilst degradation processes are expected to mitigate their levels, they also induce the formation of potentially harmful by-products. The compounds studied in this work were acetaminophen, 17 alpha-ethynylestradiol and carbamazepine. High-performance liquid chromatography coupled with ultraviolet diode-array detection was used to follow the degradation reactions, whilst liquid chromatography associated with ultraviolet diode-array detection and mass spectrometry was applied in the determination of by-products. Ethynylestradiol proved to be the most reactive (t(1/2) = 38.6 +/- 1.9 seconds) and carbamazepine the least reactive (t(1/2) = 481.4 +/- 16.7 minutes) when exposed to active chlorine. In relation to disinfection by-products, two monochlorinated analogues were detected for acetaminophen, one monochlorinated for carbamazepine, and one mono- and one trichlorinated for ethynylestradiol. Chlorine levels and water pH proved to be the most influential variables on the degradation of the compounds, with and without dissolved organic matter in solution. All pharmaceuticals displayed significant photostability towards artificial solar radiation, with acetaminophen being slightly more stable.

Abstract <p>A greener and efficient one-pot methodology for the assembly of Glypromate® and its structurally-related analogues by tandem sequential peptide coupling.</p>

Abstract This work reports the role of different dispersants, namely, polyethylene glycol (PEG 200 2%), ethylene glycol 5%, ethanol 2%, dimethyl sulfoxide (DMSO 5%), and polyvinyl alcohol (PVA 5%) in the toxicity profile of several commercial nanomaterials (NM), such as hydrophilic and hydrophobic TiO2, hydrophilic SiO2, SiO2 in aqueous suspension (aq), and ZnO towards the bioluminescent bacterium Aliivibrio fischeri. The majority of NM showed tendency to form agglomerates in the different dispersants. Although some particle agglomeration could be detected, DMSO at 5% was the best dispersant for hydrophobic TiO2 NM while PVA at 5% was the most effective dispersant for the other types of NM. Average size was not the most relevant aspect accounting for their toxicity. A remarkable reduction in average size was followed by a decrease in NM toxicity, as demonstrated for SiO2 aq. in PVA 5%. Contrarily, despite of high particle agglomeration, ZnO NM showed a higher toxicity to bacteria when compared with other tested NM. Independently of the average particle size or surface charge, the dispersant either enhanced the toxicity to bacteria or acted as physical barrier decreasing the NM harmful effect to A. fischeri.