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The photocatalytic degradation of fumonisins B1 and B2 was studied, by subjecting them to Ultraviolet radiation with titanium dioxide. Photo-degradation of fumonisin standards at 120 min of treatment was 97%. Samples with ultraviolet irradiation showed an erratic behavior, maybe because of the complex food matrix where reactions of starch rupture and elongation take place, facilitating the bioavailability of fumonisins and causing an increase in their detections after the treatment with ultraviolet radiation. The indirect effects of radiation can be originated by radicals produced from fat content in the sample. [ABSTRACT FROM AUTHOR]

Ciprofloxacin (CIP) has been widely used to treat bacterial infections, generating biofluid residues and it endangers health via the food chain; thus, the determination of CIP is essential in food samples. In this work, CPE/ZnO/CQD was prepared from ZnO nanoparticles (ZnO NPs) and carbon quantum dots (CQD) derived from cat hair and modified the graphite carbon paste electrode (CPE); the above electrode sample was further modified by incorporating ionic liquid (IL) to give CPE/ZnO/CQD@IL. The above materials were employed as electrochemical sensors for the recognition of CIP in milk and eggs after the characterization by different analytical techniques (XRD, FT‐IR, SEM, TEM, and EDS). The results show that the presence of nanoparticles in the CPE has improved the electrocatalytic properties, giving a greater heterogeneous electron transfer rate constant (k0=6.51×10−4 cm/s) for CPE/ZnO/CQD as compared to unmodified CPE (3.94×10−4 cm/s), and for CPE/ZnO/CQD/IL, with modification of sample by IL, the rate constant has been further increased to k0=8.34×10−4 cm/s. Thereafter, CPE/ZnO/CQD and CPE/ZnO/CQD@IL were employed for the detection of CIP in food samples such as milk and eggs, observing a maximum oxidation current for CIP at pH 3.0; the limit of detection (LOD) was 0.24, and 0.30 μM for CPE/ZnO/CQD, and CPE/ZnO/CQD@IL, respectively, and those values are much lower than those reported due to the synergistic effect generated by the combination of ZnO/CQD and IL. Furthermore, cell images were developed using ZnO/CQD and ZnO/CQD@IL in real samples like Saccharomyces cerevisiae cells in the presence of CIP. [ABSTRACT FROM AUTHOR]

Abstract: A new sensor 1 bearing mixed imine and amide linkages is synthesized with simple condensation reaction of diode amine with catechol carbaldehyde. The amide linkages may define the receptor pseudo cavity as these linkages are generally considered to provide rigidity to receptor design. The imine linkages are expected to be responsible for providing binding site as well as fluorescent signaling sub-unit. The 1 is evaluated for their sensor activities in a diverse range of solvents and it has shown the selective binding affinity for Cs+. In order to evaluate the sensor activity in aqueous medium, fluorescent organic nanoparticles (FONs) of receptor 1 are formed using re-precipitation method. FONs of 1 has shown AIE phenomenon in aqueous medium with enhancement in fluorescence intensity at λ max = 412 nm. Fluorescence emission profiles of these FONs have shown some changes in low and high pH range; however it remains stable in pH range 4–9, thus making them appropriate to use in environmental/biological samples. To the best of our knowledge, 1is representing the first example of FONs as chemosensor for nanomolar detection of Cs+ in aqueous media. [Copyright &y& Elsevier]

ZnO nanoparticles (NPs) were prepared and characterized by different analytical methods and then they were used to decorate with N, N´-bis(salicylidene)ethylenediamine (salen) in order to perform as receptor for the metal ions in an aqueous medium. The results show that ZnO-salen selectively detects Al3+ ions in aqueous medium since the intensity of fluorescence has been enhanced significantly. However, the presence of K+ in the medium further intensified the fluorescence emission for the [ZnO-salen-Al3+] system. The above system has been applied to recognize Al3+ and K+ in cells by developing the cell images, for which, the fluorescence image is brightened if a human glioblastoma U251 cell contains [ZnO-salen-Al3+] + K+ ions, consisting of the fluorescence titration. The binding global constant for Al3+ and the subsequent recognition of K+ by ZnO-salen resulted in β2(Al3+) = 6.61 × 103 and β2(K+) = 3.71 × 103 with a detection limit of 36.51 µM for Al3+ and 17.39 µM for K+. In the cell toxicity analysis, the cell viability was over 85% for the ZnO-salen even in the concentration as high as 100 mM. [ABSTRACT FROM AUTHOR]

Our research on the chromium complex of macrocyclic ligands as a precursor for nitric oxide release makes a significant contribution. We detailed the analysis of nitrito chromium complexes, specifically trans-[M(III)L1-5(ONO)2]+, M=Cr(III) and L1-L5 represent different ligands: L1=1,4,8,11-tetraazacyclotetradecane, L2= (5,7-dimethyl-6-benzylcyclam), L3=  (5,7-dimethyl-6-anthracylcyclam), L4= (5,7-dimethyl-6-(p-hydroxymethylbenzyl)-1,4, 8,11-cyclam) and L5= (5,7-dimethyl-6-(1¢-methyl-4´-(1"-carboxymethylpyrene) benzyl)-1,4,8,11-tetraazacyclotetradecane). Our objective is to comprehensively understand the mechanism of NO release and identify the key factors influencing NO delivery. The optimized structure of the complexes at spin states S = 1/2 or 3/2 indicates a decrease in the Cr(III)-O bond length (1.669-1.671 Å) along with an increase in the Cr(III)O-NO bond length (2.735 - 2.741 Å), which facilitates the release of NO. Furthermore, there is a significant change in the bond angle (Cr-O-NO), from 120.4° to 116.9°, with respect to S=3/2, thus enlarging the O-NO bond and supporting the β-cleavage of NO from the complex. The calculated activation energy for the complexes reflects the energy difference between the low-spin doublet and high-spin quartet state due to spin crossover (SCO). Moreover, the Natural Transition Orbitals (NTOs) confirm the involvement of a hole-particle in the excitation. Additionally, TD-DFT reveals the pendant chromophore's role in generating NO, as the chromophore antenna effectively enhances light absorption., (© 2024 Wiley‐VCH GmbH.)

Dopamine (DA) and uric acid (UA), which are vital components in human metabolism, cause several health problems if they are present in altered concentrations; thus, the determination of DA and UA is essential in real samples using selective sensors. In the present study, graphite carbon paste electrodes (CPE) were fabricated using ZnO/carbon quantum dots (ZnO/CQDs) and employed as electrochemical sensors for the detection of DA and UA. These electrodes were fully characterized via different analytical techniques (XRD, SEM, TEM, XPS, and EDS). The electrochemical responses from the modified electrodes were evaluated using cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The results showed that the present electrode has exhibited high sensitivity towards DA, recognizing even at low concentrations (0.12 μM), and no inference was observed in the presence of UA. The ZnO/CQD electrode was applied for the simultaneous detection of co-existing DA and UA in real human urine samples and the peak potential separation between DA and UA was found to be greatly associated with the synergistic effect originated from ZnO and CQDs. The limit of detection (LOD) of the electrode was analyzed, and compared with other commercially available electrodes. Thus, the ZnO/CQD electrode was used to detect DA and UA in real samples, such as Saccharomyces cerevisiae cells.

The capture and storage of CO 2 are of growing interest in atmospheric science since greenhouse gas emission has to be reduced considerably in the near future. The present paper deals with the doping of cations on ZrO 2 , i.e., M-ZrO 2 (M = Li + , Mg 2+ , or Co 3+ ), defecting the crystalline planes for the adsorption of carbon dioxide. The samples were prepared by the sol-gel method and characterized completely by different analytical methods. The deposition of metal ions on ZrO 2 (whose crystalline phases: monoclinic and tetragonal are transformed into a single-phase such as tetragonal for LiZrO 2 and cubic for MgZrO 2 or CoZrO 2 ) shows a complete disappearance of the XRD monoclinic signal, and it is consistent with HRTEM lattice fringes: 2.957 nm for ZrO 2 (101, tetragonal/monoclinic), 3.018 nm for tetragonal LiZrO 2 , 2.940 nm for cubic MgZrO 2 , and 1.526 nm for cubic CoZrO 2 . The samples are thermally stable, resulting an average size of ∼5.0-15 nm. The surface of LiZrO 2 creates the oxygen deficiency, while for Mg 2+ (0.089 nm), since the size of the atom is relatively greater than that of Zr 4+ (0.084 nm), the replacement of Zr 4+ by Mg 2+ in sublattice is difficult; thus, a decrease of the lattice constant was noticed. Since the high band gap energy (Δ E > 5.0 eV) is suitable for CO 2 adsorption, the samples were employed for the selective detection/capture of CO 2 by using electrochemical impedance spectroscopy (EIS) and direct current resistance (DCR), showing that CoZrO 2 is capable of CO 2 capture about 75%. If M + ions are deposited within the ZrO 2 matrix, then the charge imbalance allows CO 2 to interact with the oxygen species to form CO 3 2- which produces a high resistance (21.04 × 10 6 (Ω, Ohm)). The adsorption of CO 2 with the samples was also theoretically studied showing that the interaction of CO 2 with MgZrO 2 and CoZrO 2 is more feasible than with LiZrO 2 , subscribing to the experimental data. The temperature effect (273 to 573 K) for the interaction of CO 2 with CoZrO 2 was also studied by the docking method and observed the cubic structure is more stable at high temperatures as compared to the monoclinic geometry. Thus, CO 2 would preferably interact with ZrO 2 c ( E R S = -19.29 kJ/mol) than for ZrO 2 m (22.4 J/mmol (ZrO 2 c = cubic; ZrO 2 m = monoclinic).

The present work demonstrates a simple and sustainable method for forming azo oligomers from low-value compounds such as nitroaniline. The reductive oligomerization of 4-nitroaniline was achieved via azo bonding using nanometric Fe 3 O 4 spheres doped with metallic nanoparticles (Cu NPs, Ag NPs, and Au NPs), which were characterized by different analytical methods. The magnetic saturation ( M s ) of the samples showed that they are magnetically recoverable from aqueous environments. The effective reduction of nitroaniline followed pseudo-first-order kinetics, reaching a maximum conversion of about 97%. Fe 3 O 4 -Au is the best catalyst, its a reaction rate ( k Fe 3 O 4 -Au = 0.416 mM L -1 min -1 ) is about 20 times higher than that of bare Fe 3 O 4 ( k Fe 3 O 4 = 0.018 mM L -1 min -1 ). The formation of the two main products was determined by high-performance liquid chromatography-mass spectrometry (HPLC-MS), evidencing the effective oligomerization of NA through N = N azo linkage. It is consistent with the total carbon balance and the structural analysis by density functional theory (DFT)-based total energy. The first product, a six-unit azo oligomer, was formed at the beginning of the reaction through a shorter, two-unit molecule. The nitroaniline reduction is controllable and thermodynamically viable, as shown in the computational studies., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

This paper describes the crystal interphase impact of ZnFe 2 O 4 -Ag in the photodegradation of Rhodamine B. Prepared ZnFe 2 O 4 nanoparticles (NPs) were deposited with Ag NPs to offer ZnFe 2 O 4 -Ag (0-2.5%). An X-ray diffraction peak corresponding to the Ag NPs was detected if the particle content reached about 2.0%, observing multiple crystalline interphases in HR-TEM. Magnetic saturation (Ms) was increased ∼160% times for ZnFe 2 O 4 -Ag (7.25 to 18.71 emu/g) and ZnFe 2 O 4 (9.62 to 25.09 emu/g) if the temperature is lowered from 298 to 5.0 K; while for Fe 3 O 4 (91.09 to 96.19 emu/g), the Ms increment was just about 5.6%. After analyzing the DFT-Density of State, a decrease of bandgap energy for ZnFe 2 O 4 -Ag 6 from the influence of the size of Ag cluster was seen. Quantum yield (Φ) was 0.60 for ZnFe 2 O 4 , 0.25 for ZnFe 2 O 4 -Ag (1.0%), 0.70 for ZnFe 2 O 4 -Ag (1.5%), 0.66 for ZnFe 2 O 4 -Ag (2.0%), and 0.66 for ZnFe 2 O 4 -Ag (2.5%), showing that the disposition of Ag NPs (1.5-2.5%) increases the Φ to >0.60. The samples were used to photo-oxidize RhB under visible light assisted by photopowered Langmuir adsorption. The degradation follows first-order kinetics ( k = 5.5 × 10 -3 min -1 ), resulting in a greater k = 2.0 × 10 -3 min -1 for ZnFe 2 O 4 -Ag than for ZnFe 2 O 4 (or Fe 3 O 4 , k = 1.1 × 10 -3 min -1 ). DFT-total energy was used to analyze the intermediates formed from the RhB oxidation. Finally, the ZnFe 2 O 4 -Ag exhibits good antibacterial behavior because of the presence of Zn and the Ag components., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

In this paper, we report the combination of two metal oxides (TiO 2 ZnO) that allows mixed density of states to reduce band gap energy, facilitating the photo-oxidation of Congo red dye under visible light. For the oxidation, a possible mechanism is proposed after analyzing the intermediates by GC-MS, and it is consistent with Density Functional Theory (DFT). The nanohybrids were characterized comprehensibly by several analytical techniques such as X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and X-ray Photoelectron Spectroscopy (XPS). For the addition of ZnO to TiO 2 , a dominance of anatase phase was found rather than other phases (rutile or brookite). A broad band (∼550 nm) is observed in UV-Visible spectra for TiO 2 ZnO/Ag NPs nm because of Surface Plasmon properties of Ag NPs. The band gap energy was calculated for TiO 2 ZnO/Ag system, and then it has been further studied by DFT in order to show why the convergence of two semiconductors allows a mixed density of states, facilitating the reduction of the energy gap between occupied and unoccupied bands; ultimately, it improves the performance of catalysts under visible light. Significantly, the interaction of crystal planes (0 0 Ī) of TiO 2 anatase and (0 0 1) of ZnO crucially plays as an important role for the reduction of energy band-gap. Additionally, TiO 2 ZnOAg NPs were used recognize Saccharomyces cerevisiae cells by con-focal fluorescence microscope, showing that it develops bright bio-images for the cells; while for TiO 2 or ZnO or TiO 2 ZnO NPs, no fluorescent response was seen within the cells., (Copyright © 2018 Elsevier Ltd. All rights reserved.)