A dual-mode fluorescence and colorimetric sensing platform for efficient detection of ofloxacin in aquatic products using iron alkoxide nanozyme

Trace detection of ofloxacin (OFL) with high sensitivity, reliability, and visual clarity is challenging. To address this, a novel dual-modal aptasensor with fluorescence-colorimetric capabilities was designed that exploit the target-induced release of 3,3',5,5'-tetramethylbenzidine (TMB) molecules from aptamer-gated mesoporous silica nanoparticles (MSNs), the oxidase-like activity of iron alkoxide (IA) nanozyme, and the fluorescence attributes of core-shell upconversion nanoparticles. Therefore, the study reports a dual mode detection, with a fluorescence detection range for OFL spanning from 0.1 μg/kg to 1000 μg/kg (and a detection limit of 0.048 μg/kg). Additionally, the colorimetric method offered a linear detection range of 0.3 μg/kg to 1000 μg/kg, with a detection limit of 0.165 μg/kg. The proposed biosensor had been successfully applied to the determination of OFL content in real samples with satisfactory recoveries (78.24-96.14 %).

Fate and removal of fluoroquinolone antibiotics in mesocosmic wetlands: Impact on wetland performance, resistance genes and microbial communities

The fate of fluoroquinolone antibiotics norfloxacin and ofloxacin were investigated in mesocosmic wetlands, along with their effects on nutrients removal, antibiotic resistance genes (ARGs) and epiphytic microbial communities on Hydrilla verticillate using bionic plants as control groups. Approximately 99% of norfloxacin and ofloxacin were removed from overlaying water, and H. verticillate inhibited fluoroquinolones accumulation in surface sediments compared to bionic plants. Partial least squares path modeling showed that antibiotics significantly inhibited the nutrient removal capacity (0.55) but had no direct effect on plant physiology. Ofloxacin impaired wetland performance more strongly than norfloxacin and more impacted the primary microbial phyla, whereas substrates played the most decisive role on microbial diversities. High antibiotics concentration shifted the most dominant phyla from Proteobacteria to Bacteroidetes and inhibited the Xenobiotics biodegradation function, contributing to the aggravation in wetland performance. Dechloromonas and Pseudomonas were regarded as the key microorganisms for antibiotics degradation. Co-occurrence network analysis excavated that microorganisms degrade antibiotics mainly through co-metabolism, and more complexity and facilitation/reciprocity between microbes attached to submerged plants compared to bionic plants. Furthermore, environmental factors influenced ARGs mainly by altering the community dynamics of differential bacteria. This study offers new insights into antibiotic removal and regulation of ARGs accumulation in wetlands with submerged macrophyte.

One-step online analysis of antibiotics in highly saline seawater by nano-based slug-flow microextraction

The transition to mass spectrometry (MS) in the analysis of antibiotics in the marine environment is highly desirable, particularly in the enhancement of sensitivity for high-salinity (3.5 wt%) seawater samples. However, the persistence of complex operational procedures poses substantial challenges to this transition. In this study, a rapid method for the online analysis of antibiotics in seawater samples via nano-electrospray ionization (nESI) MS based on slug-flow microextraction (SFME) has been proposed. Comparisons with other methods, complex laboratory setups for sample processing are now seamlessly integrated into a single online step, completing the entire process, including desalination and detection, SFME-nESI-MS provides faster results in less than 2 min while maintaining sensitivity comparable to that of other detection methods. Using SFME-nESI, six antibiotics in high-salinity (3.5 wt%) seawater samples have been determined in both positive and negative ion modes. The proposed method successfully detected clarithromycin, ofloxacin, and sulfadimidine in seawater within a linear range of 1-1000 ng mL-1 and limit of detection (LOD) of 0.23, 0.06, and 0.28 ng mL-1, respectively. The method recovery was from 92.8% to 107.3%, and the relative standard deviation was less than 7.5%. In addition, the response intensity of SFME-nESI-treated high-salinity (3.5 wt%) samples surpassed that of untreated medium-salinity (0.35 wt%) samples by two to five orders of magnitude. This advancement provides an exceptionally simplified protocol for the online rapid, highly sensitive, and quantitative determination of antibiotics in high-salinity (3.5 wt%) seawater.

A novel synchronous fluorescence spectrometry combined with fluorescence sensitization for the highly sensitive and simultaneous detection of enoxacin, ofloxacin and tetracycline hydrochloride residues in wastewater

The synergistic effect of sodium dodecyl sulfate (SDS) and Mg2+ could significantly enhance the fluorescence intensity of enoxacin (ENO) at λex/λem = 269.2 nm/385.6 nm, ofloxacin (OFL) at λex/λem = 290.8 nm/466.2 nm and tetracycline hydrochloride (TCH) at λex/λem = 372.6 nm/514.8 nm. Moreover, when the wavelength difference (Δλ) was chosen 135 nm, the synchronous fluorescence spectra of the three antibiotic complexes could be well separated and the interference of the samples matrix were eliminated primely. Therefore, only one synchronous fluorescence scan was needed to simultaneously determine the three antibiotics. Based on these facts, a synchronous fluorescence spectrometry combining fluorescence sensitization for highly sensitive and selective determination of ENO, OFL and TCH residues in wastewater was developed for the first time. The experimental results showed that the concentrations of ENO, OFL and TCH in the range of 0.5-550 ng mL-1, 1-1500 ng mL-1 and 10-5500 ng mL-1 showed a good linear relationship with fluorescence intensity. The limits of detection were 0.0599 ng mL-1, 0.115 ng mL-1 and 0.151 ng mL-1, respectively. The recoveries of the actual sample were 87.50%-99.99 %, 93.00%-98.50 % and 85.70%-98.42 %, respectively. Overall, the novel synchronous fluorescence spectrometry established in the experiment has the advantages of high sensitivity, good selectivity, fast detection speed and high accuracy. It has been successfully applied to the detection of residual amounts of ENO, OFL and TCH in wastewater with satisfactory results.

A group-targeting biosensor for sensitive and rapid detection of quinolones in water samples

BACKGROUND

Quinolones (QNs) widely exist in the environment due to their wide range of applications and poor metabolic properties, resulting in the generation and spread of resistance genes, posing a potential threat to human health. Traditional analytical methods cannot detect all broad ranges of QNs simultaneously. The development of facile, efficient and reliable method for quantification and assessment of the total QNs is a long-lasting challenge.

RESULTS

We hereby provide a simple, sensitive and instantaneous group-targeting biosensor for the detection of total QNs in environmental water samples. The biosensor is based on a group-specific antibodies with high affinity against QNs. Fluorescent labeled antibodies bound to the coated antigen modified on the surface of the transducer, and excited by the evanescent waves. The detected fluorescent signal is inversely proportional to the QNs concentration. This biosensor exhibited excellent performance with detection limits lower than 0.15 μg L-1 for all five QNs variants, and even lower than 0.075 μg L-1 for ciprofloxacin (CIP) and ofloxacin (OFL). Environmental water samples can be detected after simple pretreatment, and all detection steps can be completed in 10 min. The transducer has a high regenerative capacity and shows no significant signal degradation after two hundred detection cycles. The recoveries of QNs in a variety of wastewater range from 105 to 119%, confirming its application potential in the measurement of total QNs in reality.

SIGNIFICANCE

The biosensor can realize rapid and sensitive detection of total QNs in water samples by simple pretreatment, which overcomes the disadvantage of the traditional methods that require complex pretreatment and time-consuming, and pave the groundwork for expansive development centered around this technology.

Efficient removal of ciprofloxacin and ofloxacin from aqueous solutions using a novel nano-scale adsorbent: Modeling, optimization, and characterization

In the fascinating realm of water purification, our study unveils the remarkable potential of a cutting-edge nano-scale adsorbent-combining graphene oxide (GO), chitosan (CS), and polydopamine (PDA)-in efficiently remove ciprofloxacin (CPF) and ofloxacin (OFL) from aqueous solutions. Our exploration delves deep into the adsorbent's character, utilizing a range of analytical techniques including SEM, RAMAN, FTIR, TGA, BET, XRD, and Zeta potential analyses provided insights into the adsorbent's properties. Modeling the adsorption process with Response Surface Methodology (RSM), Artificial Neural Network (ANN) and General Regression Neural Network (GRNN) indicated excellent predictions by GRNN, with RMSE = 0.0200 and 0.0166, MAE = 0.0082 and 0.0092, as well as AAD = 0.0002 and 0.0006, highlighting its modeling power. Optimization using genetic algorithm (GA) revealed maximum CPF removal efficiency of approximately 95.20% under pH = 6.3, sonication time = 9.0 min, adsorbent dosage = 2.10 g L⁻1, temperature = 45 °C and initial CPF concentration = 90.0 mg L⁻1. Similarly, OFL removal reached about 95.50% under pH = 6.30, sonication time = 8.0 min, adsorbent dosage = 2.0 g L⁻1, temperature = 45 °C and OFL concentration = 115.0 mg L⁻1. RSM optimization closely aligned with GA results. Pseudo-second-order (PSO) kinetic model and Langmuir isotherm model best fitted the experimental data for both antibiotics. Thermodynamic analysis indicated a favorable and spontaneous adsorption process for CPF and OFL. The study concludes that the proposed adsorbents show effectiveness in removing CPF and OFL at lower doses and shorter sonication times compared to various reported adsorbents.

An immunochromatographic strip sensor for marbofloxacin residues

Marbofloxacin (MBF) was once widely used as a veterinary drug to control diseases in animals. MBF residues in animal food endanger human health. In the present study, an immunochromatographic strip assay (ICSA) utilizing a competitive principle was developed to rapidly detect MBF in beef samples. The 50% inhibitory concentration (IC50) and the limit of detection (LOD) of the ICSAs were 2.5 ng/mL and 0.5 ng/mL, respectively. The cross-reactivity (CR) of the MBF ICSAs to Ofloxacin (OFL), enrofloxacin (ENR), norfloxacin (NOR), and Ciprofloxacin (CIP) were 60.98%, 32.05%, 22.94%, and 23.58%, respectively. The CR for difloxacin (DIF) and sarafloxacin (SAR) was less than 0.1%. The recovery rates of MBF in spiked beef samples ranged from 82.0% to 90.4%. The intra-assay and interassay coefficients of variation (CVs) were below 10%. In addition, when the same authentic beef samples were detected in a side-by-side comparison between the ICSAs and HPLC‒MS, no statistically significant difference was observed. Therefore, the proposed ICSAs can be a useful tool for monitoring MBF residues in beef samples in a qualitative and quantitative manner.

Quantitative monitoring ofloxacin in beef by TLC-SERS combined with machine learning analysis

Ofloxacin is one kind of quinolone antibiotic drugs, the abuse of ofloxacin in livestock and aquaculture may bring bacterial resistance and healthy problem of people. The illegally feeding cattle with ofloxacin will help it keep health, but the sedimentation of ofloxacin could bring problem in food safety. The accurate, simple and instant monitoring ofloxacin from beef by portable sensor was of vital issue in food quality. A simple and reliable method was proposed for instant and quantitative detecting ofloxacin in beef, in which the thin-layer chromatography (TLC) -surface-enhanced Raman scattering (SERS) spectroscopy was in tandem with machine learning analysis base one principal component analysis-back propagation neural network (PCA-BPNN). The TLC plate was composed with diatomite, that was function as the stationary phase to separate ofloxacin from beef. The real beef juice was directly casted onto the diatomite plate for separating and detecting. The directly monitor ofloxacin from beef was achieved and the sensitivity down to 0.01 ppm. The PCA-BPNN was used as reliable model for quantitative predict the concentration of ofloxacin, that shown superior accuracy compared with the traditional model. The results verify that the diatomite plate TLC-SERS combined with machine-learning analysis is an effective, simple and accurate technique for detecting and quantifying antibiotic drug in meat stuff to improve the food safety.

Monospecific and ultrasensitive detection of ofloxacin: A computational chemistry-assisted hapten screening strategy and analysis of molecular recognition mechanism

Contamination in food and the environment with fluoroquinolones (FQs) has become a serious threat to the global ecological balance and public health safety. Ofloxacin (OFL) is one of the most widely utilized sterilization agents in FQs. In the process of monitoring OFL, broad-spectrum monoclonal antibodies (mAb) cannot meet the demand for monospecific detection. Here, a computational chemistry-assisted hapten screening strategy was proposed in this study. Differences in the properties of antigenic epitopes were precisely extracted through a comprehensive comparative study of 16 common FQs molecules and a monospecific and ultrasensitive mAb-3B4 for OFL was successfully prepared. The screened fleroxacin (FLE) hapten was applied in a heterologous competition strategy resulting in a 20-fold improvement in the half inhibitory concentration (IC50) of mAb-3B4 to 0.0375 μg L-1 and cross-reacted only with marbofloxacin (MAR) in regulated FQs. In addition, a single-chain variable fragment (scFv) for OFL was constructed for the first time with an IC50 of 0.378 μg L-1. Molecular recognition mechanism studies validated the reliability of this strategy and revealed the key amino acid sites responsible for OFL specificity and sensitivity. Finally, ic-ELISA and GICA were established for OFL in real samples. This work provides new ideas for the preparation of monospecific mAb and improves the monitoring system of FQs.

Synthesis and characterization of polysiphonia/cerium oxide/nickel oxide nanocomposites for the removal of toxins from contaminated water and antibacterial potential

Due to massive industrial development, organic and inorganic wastes are very common in most industrial effluents from the pharmaceutical industry. Even in low concentrations, they are very dangerous and harmful to humans and other living organisms. Antibiotics are frequently detected in surface waters, in soil, in wastewater from sewage treatment plants, and even in drinking water. The major environmental threat they pose has prompted to search for effective and environmentally friendly means of eliminating these toxins. The biogenic synthesis of nanomaterials using natural herbal extracts has attracted considerable attention due to their low-cost, environmentally friendly and non-toxic nature, and as a reversal of various physical and chemical processes. The ceria nanoparticles (CeO2 NPs), nickel oxide nanoparticles (NiO NPs), and CeO2/NiO nanocomposites (CeO2/NiO NCS) were successfully prepared by simple biosynthetic routes using Polysiphonia urceolata algae extract as green surfactants and tested for toxic ofloxacin removal efficiency. The formed nanostructures were identified and characterized by various microscopic (FESEM-EDX, TEM, XRD, BET, and XPS) and spectroscopic (UV-Vis, FTIR, and TGA) methods. The adsorption/desorption of ofloxacin (OFX) on the surface of the nanomaterials was investigated under optimized conditions (initial dose 20 mg/L, agitation speed 250 rpm, pH 12, adsorbent dose 0.5 mg/L, and contact time 120 min). The removal efficiencies were 78%, 86%, and 94% for CeO2 NPs, NiO NPs and CeO2/NiO NCS, respectively, where OFX removal was found to be spontaneous, followed by Freundlich isotherm and pseudo-second order kinetic reaction model. The OFX adsorption mechanism on the nanomaterials involved the surface complexation via specific electrostatic attraction and H-bonding. The biogenic nanomaterials were also tested for their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis and Staphylococcus aureus. The CeO2/NiO NCS exhibited the highest antibacterial activity with zone of inhibition (31.12 ± 0.59 mm) against S. epidermidis, followed by CeO2NPs and NiONPs with zones of inhibition (25.53 ± 1.2 mm) and (21.42 ± 0.6 mm) against P. aeruginosa and S. epidermidis, respectively. This study demonstrated the efficiency of the synthesized nanomaterials in removing toxins such as OFX from contaminated water and can serve as potential antibacterial and antioxidant agents. Notably, the heterogeneous nanomaterials demonstrated remarkable stability across a broad pH range, promising reusability and indicated tremendous potential of waste biomass reduction and OFX effluent treatment.

Removal of ofloxacin using a porous carbon microfiltration membrane based on in-situ generated •OH

This study investigated the removal performance of ofloxacin (OFL) by a novel electro-Fenton enhanced microfiltration membrane. The membranes used in this study consisted of metal-organic framework derived porous carbon, carbon nanotubes and Fe2+, which were able to produce hydroxyl radicals (•OH) in-situ via reducing O2 to hydrogen peroxide. Herein, membrane filtration with bias not only concentrated the pollutants to the level that could be efficiently treated by electro-Fenton but also confined/retained the toxic intermediates within the membrane to ensure a prolonged contact time with the oxidants. After validated by experiments, the applied bias of -1.0 V, pH of 3 and electrolyte concentration of 0.1 M were the relatively optimum conditions for OFL degradation. Under these conditions, the average OFL removal rate could be reach 75% with merely 5% membrane flux loss after 4 cycles operation by filtrating 1 mg/L OFL. Via decarboxylation reaction, piperazinyl ring opening, dealkylation and ipso substitution reaction, etc., OFL could be gradually and efficiently degraded to intermediate products and even to CO2 by •OH. Moreover, the oxidation reaction was preferred to following first-order reaction kinetics. This research verified a possibility for antibiotic removal by electro-enhanced microfiltration membrane.

The role of type VI secretion system genes in antibiotic resistance and virulence in Acinetobacter baumannii clinical isolates

Introduction

The type VI secretion system (T6SS) is a crucial virulence factor in the nosocomial pathogen Acinetobacter baumannii. However, its association with drug resistance is less well known. Notably, the roles that different T6SS components play in the process of antimicrobial resistance, as well as in virulence, have not been systematically revealed.

Methods

The importance of three representative T6SS core genes involved in the drug resistance and virulence of A. baumannii, namely, tssB, tssD (hcp), and tssM was elucidated.

Results

A higher ratio of the three core genes was detected in drug-resistant strains than in susceptible strains among our 114 A. baumannii clinical isolates. Upon deletion of tssB in AB795639, increased antimicrobial resistance to cefuroxime and ceftriaxone was observed, alongside reduced resistance to gentamicin. The ΔtssD mutant showed decreased resistance to ciprofloxacin, norfloxacin, ofloxacin, tetracycline, and doxycycline, but increased resistance to tobramycin and streptomycin. The tssM-lacking mutant showed an increased sensitivity to ofloxacin, polymyxin B, and furazolidone. In addition, a significant reduction in biofilm formation was observed only with the ΔtssM mutant. Moreover, the ΔtssM strain, followed by the ΔtssD mutant, showed decreased survival in human serum, with attenuated competition with Escherichia coli and impaired lethality in Galleria mellonella.

Discussion

The above results suggest that T6SS plays an important role, participating in the antibiotic resistance of A. baumannii, especially in terms of intrinsic resistance. Meanwhile, tssM and tssD contribute to bacterial virulence to a greater degree, with tssM being associated with greater importance.

Genome-based assessment of antimicrobial resistance reveals the lineage specificity of resistance and resistance gene profiles in Riemerella anatipestifer from China

Riemerella anatipestifer (R. anatipestifer) is an important pathogen that causes severe systemic infections in domestic ducks, resulting in substantial economic losses for China's waterfowl industry. Controlling R. anatipestifer with antibiotics is extremely challenging due to its multidrug resistance. Notably, large-scale studies on antimicrobial resistance (AMR) and the corresponding genetic determinants in R. anatipestifer remain scarce. To solve this dilemma, more than 400 nonredundant R. anatipestifer isolates collected from 22 provinces in China between 1994 and 2021 were subjected to broth dilution antibiotic susceptibility assays, and their resistance-associated genetic determinants were characterized by whole-genome sequencing. While over 90% of the isolates was resistant to sulfamethoxazole, kanamycin, gentamicin, ofloxacin, norfloxacin, and trimethoprim, 88.48% of the isolates was resistant to the last-resort drug (tigecycline). Notably, R. anatipestifer resistance to oxacillin, norfloxacin, ofloxacin, and tetracycline was found to increase relatively over time. Genome-wide analysis revealed the alarmingly high prevalence of blaOXA-like (93.05%) and tet(X) (90.64%) genes and the uneven distribution of resistance genes among lineages. Overall, this study reveals a serious AMR situation regarding R. anatipestifer in China, with a high prevalence and high diversity of antimicrobial resistance genes, providing important data for the rational use of antibiotics in veterinary practice.IMPORTANCERiemerella anatipestifer (R. anatipestifer), an important waterfowl pathogen, has caused substantial economic losses worldwide, especially in China. Antimicrobial resistance (AMR) is a major challenge in controlling this pathogen. Although a few studies have reported antimicrobial resistance in R. anatipestifer, comprehensive data remain a gap. This study aims to address the lack of information on R. anatipestifer AMR and its genetic basis. By analyzing more than 400 isolates collected over two decades, this study reveals alarming levels of resistance to several antibiotics, including drugs of last resort. The study also revealed the lineage-specificity of resistance profiles and resistance gene profiles. Overall, this study provides new insights and updated data support for understanding AMR and its genetic determinants in R. anatipestifer.

Abatement of antibiotics and resistance genes during catalytic ozonation enhanced sludge dewatering process: Synchronized in volume and hazardousness reduction

Based on the efficiency of the catalytic ozonation techniques (HDWS+O3 and MnFe2O4 @SBC+O3) in enhancing the sludge dewaterability, the effectiveness in synchronized abatement antibiotics and antibiotic resistance genes (ARGs) was conducted to determine. The results revealed that catalytic ozonation conditioning altered the distribution of target antibiotics (tetracycline (TC), oxytetracycline (OTC), norfloxacin (NOR), ofloxacin (OFL)) in the dewatered filtrate, the dewatered sludge cake and the extra-microcolony/cellular polymers (EMPS/ECPS) layers, achieving the redistribution from solid-phase adsorption to liquid-phase dissolution. The total degradation rate was over 90% for TC and OTC, 72-78% for NOR and OFL; the abatement efficiency of eleven ARGs reached 1.47-3.01 log and 1.64-3.59 log, respectively, and more than four eARGs were eliminated. The effective abatement of the absolute abundance of Mobile genetic elements (MGEs) (0.91-1.89 log) demonstrated that catalytic ozonation conditioning could also significantly inhibit horizontal gene transfer (HGT). The abundance of resistant bacteria was greatly reduced and the signal transduction of the typical ARGs host bacteria was inhibited. The highly reactive oxidation species (ROS) generated were responsible for the abatement of antibiotics and ARGs. These findings provided new insights into the sludge conditioning for ideal and synchronized reduction in volume and hazardousness by catalytic ozonation processes in sludge treatment.

Trends in antibiotic resistance in ocular samples in a tertiary eye centre in Saudi Arabia in 2003-2019

OBJECTIVE

The aim of this study was to analyze the antibiotic resistance in ocular samples over a 16-year period.

METHODS

This was a retrospective cohort study conducted at King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia (2003-2019). The study included corneal and conjunctival swabs and aqueous and vitreous samples.

RESULTS

Coagulase-negative staphylococci exhibited a significant trend of increasing resistance over time to erythromycin (p < 0.001), oxacillin (p < 0.001), fusidic acid (p < 0.001), and moxifloxacin (p = 0.003). Staphylococcus aureus also showed a significant increase in oxacillin (p = 0.001), ofloxacin (p = 0.003), and moxifloxacin (p = 0.001) resistance patterns. Streptococcus pneumoniae demonstrated a significant increase in resistance to erythromycin (p = 0.01) and ofloxacin, which jumped from 0.80% in 2003 to 80% in 2019 (p = 0.015). No statistically significant increase in antibiotic resistance trend was observed for Pseudomonas.

CONCLUSIONS

An increasing antibiotic resistance pattern was demonstrated, particularly among gram-positive organisms. Such findings warrant revision of the common ocular antibiotic prescribing strategy and consideration of alternative antibiotics.

Prevalence and antimicrobial resistance of Enterobacteriaceae in the north of Kazakhstan

Background

An increasing number of drugs are used each year in the treatment of small pets (cats and dogs), including medicines (cephalosporins and fluoroquinolones) used in human therapy.

Aim

The purpose of this study was to isolate and explore the antibiotic resistance of opportunistic Enterobacteriaceae (Escherichia coli, Klebsiella, Proteus, Ci trobacter, Enterobacter) from cats and dogs, and to isolate resistance genes in the microorganisms.

Methods

In 2021, 808 samples of biological material from small domestic animals were collected in veterinary clinics in Kostanay. From these, 210 microorganisms were isolated and identified.

Results

A large majority of the strains sampled belonged to E. coli-149 (70.9%), Enterobacter-11 (5.2%), Klebsiella-28 (13.3%), Proteus-12 (5.7%) and 10 Citrobacter isolates (4.8%). In all isolates identified, antibiotic resistance/sensitivity was determined by disc-diffusion method to ampicillin, cefoxitin, gentamicin, levomycetin, tetracycline, ciprofloxacin, norfloxacin, ofloxacin, cefoperazone, cefpodoxime, streptomycin, kanamycin, doxycycline, gemifloxacin, nalidixic acid, furazolidone, furadonine, amoxicillin, and enrofloxacin.

Conclusion

The study has demonstrated that the greatest number of Enterobacteriaceae were sensitive to the action of meropenem, which belongs to the group of beta-lactam antibiotics; resistance was demonstrated against tetracycline, doxycycline, ampicillin, amoxicillin, ofloxacin, and cefpodoxime. The most common genes encoding antimicrobial resistance were as follows: BlaTEM and OXA in 41 and 28 isolates, respectively, encoding resistance to beta-lactams; StrA and StrB in 45 and 48 isolates encoding aminoglycosides; and tetA and tetB in 43 and 28 isolates encoding tetracyclines. Obtained data demonstrate that uncontrolled and frequent use of beta-lactam and tetracycline antibacterials, in cats and dogs, results in the spread of genotypic resistance among micro-organisms of the family Enterobacteriaceae.

Antimicrobial resistance rates of urogenital Mycoplasma hominis and Ureaplasma species before and during the COVID-19 pandemic: results from a Greek survey, 2014 to 2022

The prevalence of antibiotic-resistant urogenital mycoplasmas and ureaplasmas has been gradually increasing over the years, leading to greater concern for accurate diagnosis and treatment. In this study, the antimicrobial resistance trends in Greece were analyzed using 2992 Ureaplasma spp. and 371 M. hominis isolates collected between 2014 and 2022. Antibiotic sensitivity was determined using eight different antimicrobial agents (josamycin, pristinamycin, clindamycin, ofloxacin, azithromycin, tetracycline, erythromycin, and doxycycline), with the data analyzed using descriptive statistical methods. Resistance rates to clindamycin and erythromycin increased for both M. hominis and Ureaplasma spp., while remaining relatively low for Tetracycline, Doxycycline, and Ofloxacin. For Ureaplasma spp., high susceptibility was observed to pristinamycin, tetracycline, doxycycline, azithromycin, and josamycin, and intermediate susceptibility to erythromycin. However, the resistance rate for clindamycin dramatically increased from 60% in 2014 to a peak of 98.46% in 2021, and the erythromycin resistance rate increased from 9.54% in 2018 to 22.13% in 2021. M. hominis exhibited consistently high resistance rates to Erythromycin, while Azithromycin resistance significantly increased over time, from 52.78% in 2017 to 97.22% in 2022. The alarming escalation in antibiotic-resistant urogenital mycoplasmas and ureaplasmas in the Greek population is a significant concern. Antibiotic overconsumption may have played a crucial role in increasing resistance trends. The implementation of nationwide surveillance systems, proper antibiotic stewardship policies, and appropriate culture-based therapy policies are necessary to effectively control this emerging risk.

The Synthesis of carbon dots//zincoxide (CDs/ZnO-H400) by using hydrothermal methods for degradation of ofloxacin antibiotics and reactive red azo dye (RR141)

The development of photocatalytic powders to remove contaminants from air solutions is an important field of research in the field of environmental conservation. CD/ZnO-H400, a heterogeneous photocatalytic production, is utilized to degrade the reactive red dye and the antibiotic ofloxacin found in wastewater. This study explains the synthesis of carbon dots (CDs) derived from coconut air and zinc oxide (ZnO) using a hydrothermal method at a temperature of 180 °C with a duration of 4 h and subsequently calcinated at a 400 °C temperature for 4 h. This shows a significant improvement in photocatalytic performance due to improved delivery efficiency at the interface. The cost-efficient use of solar energy allows the comprehensive elimination of harmful pollutants through detoxification. The removal of the contaminant takes place through the first-order reaction, with RR141 showing the highest constant rate at 0.03 min-1, while ofloxacin has a constant speed at 0.01 min-1. The photocatalytic stability is measured after five cycles. The study also tested the impact of sunlight on degradation, showing a degrading rate of 98% for RR141 and 96% for ofloxacin. This study displays a new catalyst powder synthesized from carbon dots derived from the air, coconut and ZnO, showing remarkable photoactivity to completely remove harmful dyes and antibiotics from the surrounding environment.

Measurement uncertainty for < 905 > Uniformity of Dosage Units tests using Monte Carlo and bootstrapping methods - Uncertainties arising from sampling and analytical steps

Uniformity of dosage unit (UDU) test is widely used to assess the quality, safety, and effectiveness of dosage forms in unit doses. An increased variability of the amount of drug (API - Active Pharmaceutical Ingredient) in each dose unit may lead to low quality, unsafety, and ineffective medicines. The aim of this work was to evaluate the measurement uncertainty associated with the acceptance value (AV) using the Monte Carlo and Bootstrapping methods, as well as to estimate the risk of false decisions regarding compliance/non-compliance due to uncertainty. Haloperidon 5 mg tablets and ofloxacin 200 mg tablets were subject to content uniformity (CU) and weight variation (WV) tests, respectively. Measurement uncertainty evaluation of UDU tests considered both uncertainties arising from sampling analytical steps. Uncertainty values were quantified using Monte Carlo (sampling) or bootstrapping (resampling) methods. Confidence intervals at 95% confidence level (CI95%) for AV value obtained for haloperidol 5 mg tablets were found to between 8.1 and15.8 and between 8.1 and 16.9 for Boostrapping and Monte Carlo methods, respectively. There is an increased risk of false conformity assessment for haloperidol UDU test (6.5% and 12.1% risk values for Bootstrapping and Monte Carlo methods). Considering the ofloxacin 200 mg tablets, the CI95% for AV value were found to be between 4.0 and 11.3 and between 4.9 and 11.4 for Bootstrapping and Monte Carlo methods, respectively. Uncertainty arising from sampling and analytical steps were both relevant to the overall uncertainty of AV values. Measurement uncertainty evaluation provided relevant information to support conformity assessments with a reduced risk of false decision making.

Fe3O4-carboxyl modified AuNPs-chitosan@AgNPs as a robust surface-enhanced Raman scattering substrate for rapid analysis of tryptamine and ofloxacin in aquatic products

Rapid and accurate quantification of trace targets in complex samples is an extremely challenging issue in fast analysis field. Herein, we developed Fe3O4-carboxyl modified AuNPs-chitosan@AgNPs composite (Fe3O4-AuNCs-Cs@AgNPs) as a robust surface-enhanced Raman scattering (SERS) substrate for rapid analysis of tryptamine (TPA) and ofloxacin (OFX). The substrate possessed abundant surficial active sites of -NH2, -OH and -COOH groups. The substrate exhibited good SERS activity for several different model molecules with enhancement factors (EFs) of 1.2 × 108 for 4-mercaptobenzoic acid. The substrate presented good stability for detection of TPA at pH 6.0 and OFX at pH 8.0, and relative standard deviations less than 5.0% for intra-batch and 6.0% for inter-batch. Also, the substrate possessed good time-stability within 50 days. The substrate integrated advantages of efficient enrichment, fast magnetic separation, and strong localized surface plasmon resonance properties of AgNPs. With versatile merits, TPA and OFX can be enriched and separated within 10 min. SERS methods for analysis of TPA and OFX were developed with detection limits of 35.5 μg/L and 15.8 μg/L, respectively. TPA and OFX were actually found in aquatic product, and recoveries during sample analysis were 89.3%-110% for TPA and 89.3%-96.8% for OFX. The analytical process completed within 30 min via enrichment-separation-detection all-in-one, exhibiting great potential for rapid analysis of toxic biogenic monoamines and antibiotic residues in food.

Pharmaceuticals and personal care products in Tunisian hospital wastewater: occurrence and environmental risk

Despite concerns about the potential risk associated with the environmental occurrence of pharmaceuticals and personal care products (PPCPs), few studies address the emissions of hospitals to aquatic compartments. We examined within a 3-month sampling period the occurrence and environmental risk of PPCPs in seven Tunisian hospital wastewaters. From personal care products, UV filters, main metabolites, and benzotriazoles were quantified, with benzophenone 3 (oxybenzone, BP3) and benzotriazole (BZT) the most frequently found (71%) at median concentrations in the range 2.43 ± 0.87 ngL-1-64.05 ± 6.82 ngL-1 for BP3 and 51.67 ± 1.67 ngL-1-254 ± 9.9 ngL-1 for BZT. High concentrations were also found for 4-hydroxybenzophenone (4HB) (221 ± 6.22 ngL-1), one of the main metabolites of BP3. The antibiotics ofloxacin and trimethoprim, the anti-inflammatory acetaminophen, the antiepileptic carbamazepine, and the stimulant caffeine were present in all the wastewaters. The highest median concentration corresponded to acetaminophen, with 1240 ± 94 mgL-1 in Tunis Hospital, followed by ofloxacin with 78850 ± 39 μgL-1 in Sousse Hospital. For ecotoxicity assessment, acute toxicity was observed for Daphnia magna and Vibrio fischeri. The toxicity data were used in a hazard quotient (HQ) approach to evaluate the risk posed by the target PPCPs to aquatic organisms. The calculated HQs revealed that marbofloxacin (234 for V. fischeri), enrofloxacin (121 for D. magna), and BZT (82.2 for D. magna and 83.7 for V. fischeri) posed the highest risk, concluding that potential risk exists toward aquatic microorganisms. This study constitutes the first monitoring of UV filters in Tunisian hospital effluents and provides occurrence and toxicity data of PPCPs for reference in further surveys in the country.

3D printed monoliths: From powder to an efficient catalyst for antibiotic degradation

To improve the effectiveness and durability of wastewater treatment technologies, researchers are showing a growing interest in 3D printing technology. This technology has attracted significant interest owing to its ability to fabricate challenging complex geometries using different material compositions. This manuscript is focused on the development of 3D monoliths from noncommercial filaments, i.e., a powder blend of iron oxide and polylactic acid (PLA) at 15 wt% of the former. Different monolith designs have been prepared to improve the fluid dynamics of the process, so a simple cylinder (15-Fe3O4@PLA) and a cylinder with double the length and an internal mesh (15-Fe3O4@PLA-DM) were used. These monoliths were characterized by Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC) and Mössbauer spectroscopy, then used for water-based ofloxacin degradation in a continuous down-up flow configuration. Additionally, computational fluid dynamics simulations were performed to estimate the degradation rate constants and analyze the distribution of fluid velocity and pollutant concentration along the 15-Fe3O4@PLA-reactor. The oxidant dose was also optimized to develop the highest degradation rate. The degradation of the target pollutant for those monoliths was 55 and 82 % under optimized conditions. In addition, the 15-Fe3O4@PLA-DM monolith was operated for long term experiments, keeping the degradation performance at a good 67 % for up to 120 h. Finally a fixed-bed reactor was mounted with printed pellets of the mixture (15:85), Fe3O4:PLA, after being ground in a range of 125-200 μm. Under this setup configuration, we observed the total degradation of ofloxacin. 3D printing technology is cheap, reproducible and time saving in the development of supported catalysts in comparison with conventional deposition techniques. Moreover, the leaching of active sites on streams was largely diminished. In fact under continuous operation the leached Fe concentration is below 0.1 ppm, corroborating the good adhesion of the catalyst in the PLA support.

Antibiotics and antibiotic resistance genes in the water sources of the Wuhan stretch of the Yangtze River: Occurrence, distribution, and ecological risks

Given the ubiquitous detection of antibiotics and antibiotic resistance genes (ARGs) in waterbodies worldwide and increasing public attention to water resource safety, this study investigated the presence of antibiotics and ARGs in the water sources of the Wuhan stretch of the Yangtze River (YR) as well as potential ecological risks. In this study, 15 antibiotics and 10 ARGs in a source of drinking water were analyzed using solid-phase extraction-ultra performance liquid chromatography-mass spectrometry technology (SPE-UPLC-MS/MS) and real-time fluorescence quantitative polymerase chain reaction (qPCR). Fourteen antibiotics were detected in the samples from 18 water sources, with the highest concentration detected for tetracycline, reaching up to 1708.33 ng/L. The detection rates of norfloxacin, enrofloxacin, ofloxacin, tetracycline, and roxithromycin were 100%. The concentrations of antibiotics were highest in She Shui, followed by the Wuhan stretch of the lower reaches of the YR, whereas the lowest concentrations were found in the Wuhan stretch of the upper reaches of the YR which were approximately equal to those in the Han River (HR). Ofloxacin and roxithromycin presented a substantial threat to aquatic organisms with high sensitivity at the majority of the sampling sites. The overall abundance of ARGs was notably greater in the lower reaches of the YR compared with the upper reaches and the HR. The highest absolute abundance was observed for sulfa ARGs. Integron intl1 strongly correlated with sul1, sul2, ermB, and qnrS, and antibiotics, strongly correlated with multiple ARGs, suggesting that antibiotics and ARGs are present in water sources in Wuhan and may present a plausible hazard to both human and ecological well-being. Hence, regulating the spread and dissemination of antibiotics and ARGs in the environment is imperative. The findings of this research offer significant insights into the stewardship and safeguarding of aquatic reserves in the Wuhan stretch of the YR.

Iron/nitrogen co-doped biochar derived from salvaged cyanobacterial for efficient peroxymonosulfate activation and ofloxacin degradation: Synergistic effect of Fe/N in non-radical path

A green, low-cost, high-performance Fe/N co-doped biochar material (Fe-N@C) was synthesized using salvaged cyanobacteria without other extra precursors for peroxymonosulfate (PMS) activation and ofloxacin (OFX) degradation. With the increased pyrolysis temperature, the graphitization degree, the specific surface area and the corresponding groups like OH, COO etc. for Fe-N@C tended to increase, resulting in a greater OFX adsorption. However, the total amount of Fe-NX and graphitic nitrogen groups in the Fe-N@C composites was firstly increased and then decreased, which reached the highest at 800 °C (Fe-N@C-800). All these changes of functional species ascribed to the strong interaction between Fe, N and C led to the highest defect degree of Fe-N@C-800, resulting the highest OFX removal efficiency of 95.0 %. OFX removal experiments indicated the adsorption process promoted the total OFX degradation for different functional groups on Fe-N@C composites separately dominated the process of OFX adsorption and PMS catalysis. Radical quenching and electron paramagnetic resonance (EPR) measurements proved free radical and non-free radical pathways participated in Fe-N@C/PMS system. The non-free radicals based on 1O2 and high-valent iron-oxo species played a more important role in OFX degradation, leading to the minimal effect of co-existing anions and the high universality for other antibiotic pollutants. Fe-NX was utilized as the main catalytic sites and graphitic nitrogen contributed more to the electron transfer for PMS activation, whose synergistic effect efficiently facilitated OFX degradation. Finally, the possible degradation route of OFX in the Fe-N@C-800/PMS system was proposed. All these results will provide the new insights into the intrinsic mechanism of Fe/N species in carbon-based materials for PMS activation.

Burden of enteric fever and antibiotic sensitivity in Nepalese Children Prior to Typhoid Vaccine in National Immunization Program

BACKGROUND

Enteric fever is a major public health problem in developing and under developed countries. Case fatality rate without treatment is 10-30% and with appropriate treatment is only 1-4%. Gold standard for diagnosis is isolation of Salmonella enterica from blood or bone marrow. Antibiotics resistance is skyrocketing with emergence of multidrug resistance S. typhi and extensively drug resistant S. typhi.

METHODS

The blood culture done in Kanti children hospital in last six years were taken from the data base and the culture positive cases were taken from which the salmonella species positive cases along with the drug sensitivity pattern were used in our study.

RESULTS

The culture positivity rate was 2.8% and 7.6% (n=136) among the culture positive cases were Salmonella species. Salmonella typhi (121; 88.9%) was the most frequently isolated species, followed by Salmonella paratyphi A (13; 9.5%) and Salmonella paratyphi B (2;1.4%). Children with age 5-10 years was the most affected age group for infection with Salmonella, 50.0% (n=68). Nalidixic acid is resistant in 89.9% Salmonella typhi; followed by ciprofloxacin (31.8%), ofloxacin (18.2%), ampicillin (9.6%), azithromycin (8.4%), chloramphenicol (8.2%), cotrimoxazole (5.4%), cefixime (4%), ceftriaxone (2.5%) and cefotaxime (0.0%). Cefixime, ceftriaxone, cefotaxime are 100% sensitive to Salmonella paratyphi, followed by cotrimoxazole (92.9%), ofloxacin (81.8%), chloramphenicol (75%), azithromycin (66.7%), ampicillin (60%), ciprofloxacin (50%) and Nalidixic acid (23.1%).

CONCLUSIONS

Salmonella species culture isolatation are declining every year. Fluoroquinolones have more resistance than first line drugs of typhoid, azithromycin resistance is rising but 3rd generation cephalosporins are sensitive to Salmonella species.

Activation of Peracetic Acid by CoFe2O4 for Efficient Degradation of Ofloxacin: Reactive Species and Mechanism

Peroxyacetic acid (PAA)-based advanced oxidation processes (AOPs) have attracted much attention in wastewater treatment by reason of high selectivity, long half-life reactive oxygen species (ROS), and wider applicability. In this study, cobalt ferrite (CoFe2O4) was applied to activate PAA for the removal of ofloxacin (OFX). The degradation of OFX could reach 83.0% via the CoFe2O4/PAA system under neutral conditions. The low concentration of co-existing anions and organic matter displayed negligible influence on OFX removal. The contributions of hydroxyl radicals (·OH), organic radicals (R-O·), and other reactive species to OFX degradation in CoFe2O4/PAA were systematically evaluated. Organic radicals (especially CH3C(O)OO·) and singlet oxygen (1O2) were verified to be the main reactive species leading to OFX destruction. The Co(II)/Co(III) redox cycle occurring on the surface of CoFe2O4 played a significant role in PAA activation. The catalytic performance of CoFe2O4 remained above 80% after five cycles. Furthermore, the ecotoxicity of OFX was reduced after treatment with the CoFe2O4/PAA system. This study will facilitate further research and development of the CoFe2O4/PAA system as a new strategy for wastewater treatment.

leaves extract for spectroscopic estimation of ofloxacin and ciprofloxacin in commercial formulations

The current study describes the biogenic synthesis of two metal oxides zinc oxide (ZnO), aluminum oxide (Al2O3) nanoparticles using Camellia sinensis, and Origanum vulgare L. leaves extract, respectively. The synthesized metal oxide nanoparticles were investigated using spectroscopic and microscopic techniques to confirm the formation of their nanostructures. Accurate and precise spectrofluorometric probes were proposed for the quantification of Ofloxacin (OFX) and Ciprofloxacin (CPFX) in their bulk and commercial formulations. The extraordinary properties of Zinc oxide and aluminum oxide nanoparticles (ZnONPs and Al2O3NPs) enhance the fluorescence intensity in the presence of 0.5 mL and 1.0 mL of sodium dodecyl sulfate (SDS, 1.0% w/v) as organizing agent for the detection of OFX and CPFX, respectively. The optical detection of both drugs at λex/em range 250-700 nm displayed linearity with a main correlation coefficient >0.999 at 1-300 (OFX-SDS-ZnONPs) and 0.5-100 (OFX-SDS-Al2O3NPs) ng mL-1,10-400 (CPFX-SDS-ZnONPs) and 0.1-50 (CPFX-SDS-Al2O3NPs) ng mL-1. The detection and quantification limits were found to be 0.04, 0.03, and 0.02, 0.04 ng mL-1, 0.13, 0.10, and 7.24, 0.09 ng mL-1 for the above-mentioned fluorescence systems, respectively. The suggested spectrofluorometric probes were validated and potentially applied for the estimation of OFX and CPFX in their bulk and commercial formulations.

Raman spectroscopy-based prediction of ofloxacin concentration in solution using a novel loss function and an improved GA-CNN model

BACKGROUND

A Raman spectroscopy method can quickly and accurately measure the concentration of ofloxacin in solution. This method has the advantages of accuracy and rapidity over traditional detection methods. However, the manual analysis methods for the collected Raman spectral data often ignore the nonlinear characteristics of the data and cannot accurately predict the concentration of the target sample.

METHODS

To address this drawback, this paper proposes a novel kernel-Huber loss function that combines the Huber loss function with the Gaussian kernel function. This function is used with an improved genetic algorithm-convolutional neural network (GA-CNN) to model and predict the Raman spectral data of different concentrations of ofloxacin in solution. In addition, the paper introduces recurrent neural networks (RNN), long short-term memory (LSTM), bidirectional long short-term memory (BiLSTM) and gated recurrent units (GRU) models to conduct multiple experiments and use root mean square error (RMSE) and residual predictive deviation (RPD) as evaluation metrics.

RESULTS

The proposed method achieved an [Formula: see text] of 0.9989 on the test set data and improved by 3% over the traditional CNN. Multiple experiments were also conducted using RNN, LSTM, BiLSTM, and GRU models and evaluated their performance using RMSE, RPD, and other metrics. The results showed that the proposed method consistently outperformed these models.

CONCLUSIONS

This paper demonstrates the effectiveness of the proposed method for predicting the concentration of ofloxacin in solution based on Raman spectral data, in addition to discussing the advantages and limitations of the proposed method, and the study proposes a solution to the problem of deep learning methods for Raman spectral concentration prediction.

Online preconcentration and chiral separation of ofloxacin in exhaled breath condensate by capillary electrophoresis

Breath analysis is an effective method of monitoring systemic or respiratory ailments. A simple chiral capillary electrophoresis method coupled with an online field-amplified sample injection stacking method is presented for ultratrace quantification of the enantiomers of ofloxacin in exhaled breath condensate (EBC). The study is focused on the use of EBC as an easily available biological sample to monitor ofloxacin's enantiomers levels with good patient compliance. The proposed method was validated in accordance with FDA guidelines over the concentration range of 0.004-1.0 µg mL-1 of racemic ofloxacin. Inter- and intra-day precision and accuracy were within the acceptable limit (below 8.50 %). The method was specific for routine analysis of ofloxacin's enantiomers. A small volume of EBC samples from seven patients under ofloxacin therapy was analyzed using the proposed method in which the concentrations of "R" and "S" enantiomers were between 0.0026 and 0.056 µg mL-1.

Vacancy-Rich CoSx@LDH@Co-NC Catalytic Membrane for Antibiotic Degradation with Mechanistic Insights

Improving the wettability of carbon-based catalysts and overcoming the rate-limiting step of the Mn+1/Mn+ cycle are effective strategies for activating peroxymonosulfate (PMS). In this study, the coupling of Co-NC, layered double hydroxide (LDH), and CoSx heterostructure (CoSx@LDH@Co-NC) was constructed to completely degrade ofloxacin (OFX) within 10 min via PMS activation. The reaction rate of 1.07 min-1 is about 1-2 orders of magnitude higher than other catalysts. The interfacial effect of confined Co-NC and layered double hydroxide (LDH) not only enhanced the wettability of catalysts but also increased the vacancy concentration; it facilitated easier contact with the interface reactive oxygen species (ROS). Simultaneously, reduced sulfur species (CoSx) accelerated the Co3+/Co2+ cycle, acquiring long-term catalytic activity. The catalytic mechanism revealed that the synergistic effect of hydroxyl groups and reduced sulfur species promoted the formation of 1O2, with a longer lifespan and a longer migration distance, and resisted the influence of nontarget background substances. Moreover, considering the convenience of practical application, the CoSx@LDH@Co-NC-based catalytic membrane was prepared, which had zero discharge of OFX and no decay in continuous operation for 5.0 h. The activity of the catalytic membrane was also verified in actual wastewater. Consequently, this work not only provides a novel strategy for designing excellent catalysts but also is applicable to practical organic wastewater treatment.

Target-prepared sludge biochar-derived synergistic Mn and N/O induces high-performance periodate activation for reactive iodine radicals generation towards ofloxacin degradation

Converting waste activated sludge into catalysts for the removal of antibiotics in water fulfils the dual purpose of waste-to-resource and hazardous pollution elimination. In this study, sludge-derived biochar (SDB) for efficient periodate (PI) activation was first prepared via one-step pyrolysis of potassium permanganate-polyhexamethylenebiguanide conditioned sludge without additional modification. The SDB (750 °C)-PI system degraded 100% ofloxacin (OFL, 41.5 μM) within 6 min and was almost undisturbed by inorganic ions or humic acids. The experimental results confirmed that the predominant role of reactive iodine species (RIS) and the auxiliary involvement of singlet oxygen (1O2) jointly contributed to the OFL degradation. Theoretical calculations further indicated that the synergy between Mn and N/O induced local charge redistribution and improved electron transfer capability of SDB, leading to the formation of electron-rich Mn sites and enhanced Mn(II)↔Mn(III)↔Mn(IV) redox to promote PI activation. More importantly, the enhanced adsorption and charge transfer of PI on the Mn site of the Mn-N/O-C structures induced the I-O bond stretching and the rapid generation of RIS. This study offered a cost-effective strategy for developing SDB-based catalysts, further advancing the comprehension of sludge management and the intricate mechanisms underlying RIS formation in PI-advanced oxidation processes.

Broad-bandgap porous graphitic carbon nitride with nitrogen vacancies and oxygen doping for efficient visible-light photocatalytic degradation of antibiotics

Effective degradation methods are required to address the issue of antibiotics as organic pollutants in water resources. Herein, a two-stage thermal treatment method was used to prepare porous graphitic carbon nitride (g-C3N4) modified with nitrogen vacancies and oxygen doping at the N-(C)3 position and deep in the g-C3N4 framework. Compared with bulk g-C3N4 (BCN) (7 ± 1 m2/g), the modified sample (RCN-2h) possesses a larger specific surface area (224 ± 1 m2/g), a larger bandgap (by 0.19 eV), and a mid-gap state. In addition, RCN-2h shows 15.4, 11.2, and 9.5 times higher photodegradation rates than BCN for the degradation of 100% ofloxacin (OFX) (within 15 min), tetracycline (within 15 min), and sulfadiazine (within 35 min), respectively. The RCN-2h catalyst also exhibits superior stability and reusability. Systematic characterization and density functional theory calculations demonstrate that the synergistic effect of the porous structure, nitrogen vacancies, and oxygen doping in RCN-2h provides additional reaction sites, improved charge separation efficiency, and shorter diffusion paths for reactants and photogenerated charge carriers. Trapping experiments reveal that •O2- is the main active species in OFX photodegradation, and a possible photodegradation pathway is identified using liquid chromatography-mass spectrometry. Benefiting from the simplicity of synthesis methods and the superiority of elemental doping, carbon nitride materials with functional synergy have great potential for environmental applications.

The Use of Extraction on C18-Silica-Modified Magnetic Nanoparticles for the Determination of Ciprofloxacin and Ofloxacin in Meat Tissues

A simple, fast, and low-cost method of extraction using magnetic nanoparticles was developed for sample preparation in the determination of ciprofloxacin and ofloxacin in meat tissues with the use of capillary electrophoresis. This study is the first utilization of silica-coated magnetic nanoparticles with attached C18 chains to extract fluoroquinolones from meat tissues. This method is therefore characterized by a very simple sample preparation procedure, but on the other hand, by satisfactory precision and accuracy. Magnetic nanoparticles with an appropriately modified surface were placed in an Eppendorf tube, then conditioned with methanol, next rinsed with water and, finally, a homogenized tissue sample was added. At the neutral pH of the sample solution, these compounds do not have a charge and are able to adsorb on the modified particles. After extraction, the nanoparticles were dried and, then, desorption of analytes was conducted with the use of a mixture of 0.1 mol/L HCl and acetonitrile (1:1). This approach made it possible to purify the sample matrix and to obtain satisfactory LOQ levels for the method using the CE technique with UV-Vis detection. In this method, the LOD and LOQ values for both analytes were 0.04 nmol/g tissue and 0.15 nmol/g tissue, respectively. The calibration curves were linear in the entire concentration range, and the accuracy and the recovery of the method were at the satisfactory levels. The square value of the linear correlation coefficients (R2) for Cpx and Ofx were 0.9995 and 0.9992, respectively. The precision value of the method was within the range of 3-11% and accuracy was in the range of 93-110%.

Occurrence, distribution, and risk assessment of quinolone antibiotics in municipal sewage sludges throughout China

A nationwide study of the occurrence, distribution, potential drivers, and ecological risks of 24 quinolone antibiotics (QNs) in 74 Chinese sludge samples from 48 wastewater treatment plants (WWTPs) was conducted. In domestic sludge, the ∑QNs concentrations were <LOD to 21,925.10 ug/kg (mean: 4808.67 ug/kg), and ofloxacin had the highest concentration (<LOD-11,138.52 ug/kg), and detection frequency (98.48%). Of four generations QNs, the levels showed the following order: 2nd-generation QNs > 3rd-generation QNs > 4th-generation QNs > 1st-generation QNs. Meanwhile, abundant veterinary and human/veterinary quinolones (<LOD-2606.96 and <LOD-12,643.47 ug/kg, respectively) were detected in municipal sludge. Interestingly, the relatively low levels of veterinary quinolones (<LOD-299.21 ug/kg) were also found in industrial sludge (the relevant WWTPs receiving ≤ 10% domestic wastewater, without other direct entry of antibiotics). The correlation analysis demonstrated QNs contamination was negatively influenced by the air temperature of sampling days. The positive correlation between moxifloxacin contents and regional economy possibly suggested local regions with relatively high economic levels face a more difficult situation of QNs antibacterial activity. Environmental risk assessment indicated ofloxacin, ciprofloxacin, and moxifloxacin posed high ecological risks to the domestic sludge. This work delineates a valuable nationwide QNs contamination profile to support their safe use and control in China.

Characteristics of antibiotic resistance genes and microbial community distribution in Wanfeng Lake, upper Pearl River, China

Wanfeng Lake, a highland lake in the upper part of the Pearl River Basin, China, has long been disturbed by aquaculture and human activities, resulting in the accumulation of antibiotics and antibiotic resistance genes (ARGs), which pose a major threat to humans and animals. In this study, 20 antibiotics, 9 ARGs, 2 mobile genetic elements (intl1 and intl2), and microbial community structure were investigated in Wanfeng Lake. The results of the study showed that the total concentration of antibiotics in surface water was 372.72 ng/L, with ofloxacin (OFX) having the highest concentration (169.48 ng/L), posing a high ecological risk to aquatic organisms. The total concentration of antibiotics in sediments was 235.86 ng/g, with flumequine (FLU) having the highest concentration (122.54 ng/g). This indicates that the main type of antibiotics in Wanfeng Lake are quinolones. QPCR analysis results of the relative abundance of ARGs in both surface water and sediments showed that sulfonamide resistance genes > macrolide resistance genes > tetracycline resistance genes > quinolone resistance genes, indicating that sulfonamide resistance genes were the dominant type. The metagenomic results showed that the predominant microorganisms in the sediment under the phylum level were Planctomycetes, Proteobacteria, Euryarchaeota, and Chloroflexi. Pearson's correlation analysis showed a significantly positive correlation between antibiotics and environmental factors with ARGs in Wanfeng Lake and a significant positive correlation between antibiotics and ARGs with microorganisms in sediments. This suggests that there is a potential pressure of antibiotics on ARGs, while microorganisms provide the driving force for the evolution and spread of ARGs. This study provides a basis for further research on the occurrence and spread of antibiotics and ARGs in Wanfeng Lake. A total of 14 antibiotics were detected in surface water and sediments. OFX poses a high ecological risk in all points of surface water. Antibiotics and ARGs were significantly positively correlated in Wanfeng Lake. Antibiotics and ARGs in sediments were positively correlated with microorganisms.

Clinical, Bacteriological, and Genetic Characterization of Bone and Joint Infections Involving Linezolid-Resistant Staphylococcus epidermidis: a Retrospective Multicenter Study in French Reference Centers

The choice of the best probabilistic postoperative antibiotics in bone and joint infections (BJIs) is still challenging. Since the implementation of protocolized postoperative linezolid in six French referral centers, linezolid-resistant multidrug-resistant Staphylococcus epidermidis (LR-MDRSE) strains were isolated in patients with BJI. We aimed here to describe clinical, microbiological, and molecular patterns associated with these strains. All patients with at least one intraoperative specimen positive for LR-MDRSE between 2015 and 2020 were included in this retrospective multicenter study. Clinical presentation, management, and outcome were described. LR-MDRSE strains were investigated by MIC determination for linezolid and other anti-MRSA antibiotics, characterization of genetic determinants of resistance, and phylogenetic analysis. Forty-six patients (colonization n = 10, infection n = 36) were included in five centers, 45 had prior exposure to linezolid, 33 had foreign devices. Clinical success was achieved for 26/36 patients. Incidence of LR-MDRSE increased over the study period. One hundred percent of the strains were resistant to oxazolidinones, gentamicin, clindamycin, ofloxacin, rifampicin, ceftaroline, and ceftobiprole, and susceptible to cyclins, daptomycin, and dalbavancin. Susceptibility to delafloxacin was bimodal. Molecular analysis was performed for 44 strains, and the main mutation conferring linezolid resistance was the 23S rRNA G2576T mutation. All strains belonged to the sequence type ST2 or its clonal complex, and phylogenetic analysis showed emergence of five populations corresponding geographically to the centers. We showed the emergence of new clonal populations of highly linezolid-resistant S. epidermidis in BJIs. Identifying patients at risk for LR-MDRSE acquisition and proposing alternatives to systematic postoperative linezolid use are essential. IMPORTANCE The manuscript describes the emergence of clonal linezolid-resistant strains of Staphylococcus epidermidis (LR-MDRSE) isolated from patients presenting with bone and joint infections. Incidence of LR-MDRSE increased over the study period. All strains were highly resistant to oxazolidinones, gentamicin, clindamycin, ofloxacin, rifampicin, ceftaroline, and ceftobiprole, but were susceptible to cyclins, daptomycin, and dalbavancin. Susceptibility to delafloxacin was bimodal. The main mutation conferring linezolid resistance was the 23S rRNA G2576T mutation. All strains belonged to the sequence type ST2 or its clonal complex, and phylogenetic analysis showed emergence of five populations corresponding geographically to the centers. LR-MDRSE bone and joint infections seem to be accompanied by an overall poor prognosis related to comorbidities and therapeutic issues. Identifying patients at risk for LR-MDRSE acquisition and proposing alternatives to systematic postoperative linezolid use become essential, with a preference for parenteral drugs such as lipopeptids or lipoglycopeptids.

In-Class Cross-Reactivity among Hospitalized Patients with Hypersensitivity Reactions to Fluoroquinolones

Results from this large, multicenter study suggest that patients with a confirmed ciprofloxacin, moxifloxacin, or levofloxacin hypersensitivity reaction are likely to tolerate other fluoroquinolones. Avoiding different fluoroquinolones in patients labeled with a ciprofloxacin, moxifloxacin, or levofloxacin allergy may not always be mandatory. This was a study of patients with a ciprofloxacin, moxifloxacin, or levofloxacin hypersensitivity reaction and a documented electronic medical record administration of a different fluoroquinolone. Numerically, the most common reaction risk occurred with a challenge to moxifloxacin (2/19; 9.5%), followed by ciprofloxacin (6/89; 6.3%), and levofloxacin (1/44; 2.2%).

Mechanisms for the increase in lipid production in cyanobacteria during the degradation of antibiotics

This study evaluated the responses of cell density, photosynthesis activity, dry cell weight, lipid productivity, proteome and metabolome in two non-toxic cyanobacterial species (Synechococcus sp. and Chroococcus sp.) exposed to two frequently detected antibiotics (sulfamethoxazole and ofloxacin) at test concentrations of 0.2-20.0 μg L^-1 in a 4-day culture period. Upregulated antioxidant enzymes and oxidoreductases contributed to antibiotic biodegradation in Synechococcus sp.; whereas, upregulated carotenoid protein contributed to antibiotic biodegradation in Chroococcus sp. The 4-day removal efficiencies of sulfamethoxazole and ofloxacin by cyanobacteria were 35.98-66.23% and 33.01-61.92%, respectively. In cyanobacteria, each antibiotic induced hormetic responses, such as increase in cell density, dry cell weight, and photosynthetic activity; upregulation of photosynthesis-related proteins; and elevation of lipid expression by up to 2.05-fold. Under antibiotic stress, the two cyanobacterial species preferred to store energy in the form of lipids rather than ATP, with fructose-bisphosphate aldolase playing an essential role in lipid synthesis. The downregulation of lipid transporters also facilitated lipid accumulation in Synechococcus sp. In general, the two non-toxic cyanobacterial species achieved a good combination of lipid deposition and antibiotic treatment performance, especially in Chroococcus sp. exposed to sulfamethoxazole.

Hybrid process of adsorption and electrochemically based green regeneration of bentonite clay for ofloxacin and ciprofloxacin removal

Removal of emerging contaminants, such as antibiotics, from wastewater by adsorption is a simple, low-cost, and high-performance process; however, regeneration and reuse of the exhausted adsorbent are necessary to make the process economically viable. This study aimed to investigate the possibility of electrochemical-based regeneration of clay-type materials. For this, the calcined Verde-lodo (CVL) clay was saturated with the antibiotics ofloxacin (OFL) and ciprofloxacin (CIP) in one-component systems by an adsorption process and then subjected to photo-assisted electrochemical oxidation (0.45 A, 0.05 mol/L NaCl, UV-254 nm, and 60 min), which promotes both pollutant degradation and adsorbent regeneration. The external surface of the CVL clay was investigated by X-ray photoelectron spectroscopy before and after the adsorption process. The influence of regeneration time was evaluated for the CVL clay/OFL and CVL clay/CIP systems, and the results demonstrate high regeneration efficiencies after 1 h of photo-assisted electrochemical oxidation. Clay stability during regeneration was investigated by four successive cycles in different aqueous matrices (ultrapure water, synthetic urine, and river water). The results indicated that the CVL clay is relatively stable under the photo-assisted electrochemical regeneration process. Furthermore, CVL clay was able to remove antibiotics even in the presence of natural interfering agents. The hybrid adsorption/oxidation process applied here demonstrated the electrochemical-based regeneration potential of CVL clay for the treatment of emerging contaminants, since it can be operated quickly (1h of treatment) and with lower consumption of energy (3.93 kWh kg^-1) than the traditional method of thermal regeneration (10 kWh kg^-1).

Fate of ofloxacin in rural wastewater treatment facility: Removal performance, pathways and microbial characteristics

Ofloxacin (OFL) with high biological activity and antimicrobial degradation is a kind of the typical high concentration and environmental risk antibiotics in rural sewage. In this paper, a combined rural sewage treatment facility based on anaerobic baffled reactor and integrated constructed wetlands was built and the removal performance, pathway and mechanism for OFL and conventional pollutants were evaluated. Results showed that the OFL and TN removal efficiency achieved 91.78 ± 3.93 % and 91.44 ± 4.15 %, respectively. Sludge adsorption was the primary removal pathway of OFL. Metagenomics analysis revealed that Proteobacteria was crucial in OFL removal. baca was the dominated antibiotic resistance genes (ARGs). Moreover, carbon metabolism with a high abundance was conductive to detoxify OFL to enhance system stability and performance. Co-occurrence network analysis further elucidated that mutualism was the main survival mode of microorganisms. Denitrifers Microbacterium, Geobacter and Ignavibacterium, were the host of ARGs and participated in OFL biodegradation.

Visible-light driven excellent photocatalytic degradation of ofloxacin antibiotic using BiFeO3 nanoparticles

The extensive exploration of multiferroic materials for degradation of contaminants and environmental remediation is promptly strengthened because of their distinct applications. BiFeO₃, a prominent class of multiferroics, have received immense attention in recent times. Present study reports the synthesis of a highly crystalline BiFeO₃ via facile combustion method. The prepared catalyst was characterized using different techniques like XRD, FTIR, FESEM, EDS, XPS, DRS and PL. From DRS results, the energy band gap of BiFeO₃ was computed as 2.1 eV which was suitable enough for its exploration as a visible light photocatalyst. Therefore, BiFeO₃ was efficiently utilized for the degradation of ofloxacin drug under the exposure of visible light. The obtained results depicted 80% ofloxacin degradation under optimized conditions (pH 8, 0.5 g/L catalyst dose and 10 mg/L drug concentration) in 180 min. Pseudo first order kinetics was followed with rate constant 0.0097 min^-1, as inferred from the kinetic studies. Furthermore, 64% TOC reduction was attained by utilizing the prepared catalyst under optimum conditions. Additionally, the photocatalytic experiments showed excellent degradation efficiency even after five cycles which demonstrated good stability of the fabricated catalyst.

Insight into different adsorption behaviors of two fluoroquinolone antibiotics by sediment aggregation fractions

Sediment, consisting of different aggregation fractions, is a hotspot site for transport and transformation of various pollutants including antibiotics. However, the fate of different antibiotics in aquatic sediments mediated by sediment aggregation fraction adsorption and the mechanism behinds are still unclear. In this study, we investigated the adsorption behavior of two fluoroquinolone antibiotics (ciprofloxacin and ofloxacin) on four aggregation fractions separated from the sediment of Taihu Lake, a typical lake contaminated by antibiotics in China. The results showed that the adsorption of ciprofloxacin and ofloxacin fitted the Freundlich model, irrespective of sediment aggregation size. The adsorption of ciprofloxacin and ofloxacin was depended on the size of sediment aggregation fractions, and the macroaggregation (> 200 μm) exhibited the strongest capacity, followed by large microaggregation (63-200 μm), medium microaggregation (20-63 μm), and small and primary microaggregation (< 20 μm). This fraction size-dependent effects of sediment aggregations on antibiotic adsorption might be closely related to the differences in their specific surface areas, organic matter contents, and surface functional groups. The adsorption of ciprofloxacin and ofloxacin by sediment aggregation fractions was characterized by a combination of chemical and physical adsorptions, with the former being the dominant process. Compared with ofloxacin, ciprofloxacin could be more rapidly and easily absorbed by four sediment aggregation fractions, and more readily complexed with carboxyl groups on macroaggregation surface. The adsorption of two antibiotics by extracellular polymeric substance showed that tryptophan and tyrosine protein-like, humic-like substance on the surface of sediment could bind to both antibiotics through a complexation reaction. The π-π electron donor-acceptor interaction and hydrogen bonds were responsible for the antibiotic adsorption by sediment aggregation.

Occurrence, fate, and risk assessment of antibiotics in typical pharmaceutical manufactories and receiving water bodies from different regions

This study aimed to investigate the presence and persistence of antibiotics in wastewater of four typical pharmaceutical manufactories in China and receiving water bodies and suggest the removal of antibiotics by the wastewater treatment process. It also evaluated the environmental impact of antibiotic residues through wastewater discharge into receiving water bodies. The results indicated that thirteen antibiotics were detected in wastewater samples with concentrations ranging from 57.03 to 726.79 ng/L. Fluoroquinolones and macrolides were the most abundant antibiotic classes found in wastewater samples, accounting for 42.5% and 38.7% of total antibiotic concentrations, respectively, followed by sulfonamides (16.4%) and tetracyclines (2.4%). Erythromycin-H2O, lincomycin, ofloxacin, and trimethoprim were the most frequently detected antibiotics; among these antibiotics, the concentration of ofloxacin was the highest in most wastewater samples. No significant difference was found in different treatment processes used to remove antibiotics in wastewater samples. More than 50% of antibiotics were not completely removed with a removal efficiency of less than 70%. The concentration of detected antibiotics in the receiving water bodies was an order of magnitude lower than that in the wastewater sample due to dilution. An environmental risk assessment showed that lincomycin and ofloxacin could pose a high risk at the concentrations detected in effluents and a medium risk in their receiving water bodies, highlighting a potential hazard to the health of the aquatic ecosystem. Overall, The investigation was aimed to determine and monitor the concentration of selected antibiotics in 4 typical PMFs and their receiving water bodies, and to study the removal of these substances in PMFs. This study will provide significant data and findings for future studies on antibiotics-related pollution control and management in water bodies.

Ecological Risks of Antibiotics in Urban Wetlands on the Qinghai-Tibet Plateau, China

Although the ecological risks of antibiotics have been extensively researched globally, fewer studies have been conducted in sensitive and fragile plateau wetland ecosystems. To evaluate the ecological risk of antibiotics in plateau urban wetlands, 18 water samples, 10 plant samples, and 8 sediment samples were collected in March 2022 in the Xining urban wetlands on the Qinghai-Tibet Plateau. The liquid chromatography-electrospray ionization tandem mass spectrometry method was utilized to measure the concentrations of 15 antibiotics in three categories in three types of environmental media. Risk quotients were adopted to assess the ecological risk of antibiotics, and the principal component analysis-multiple linear regression model was used to analyze the source of antibiotics. The results showed that (1) the maximum concentrations of antibiotics in water samples, plants, and sediments reached 1220.86 ng/L, 78.30 ng/g, and 5.64 ng/g, respectively; (2) Tylosin (TYL), norfloxacin (NFX), ofloxacin (OFX), and ciprofloxacin (CFX) in water were at medium and high-risk levels, and OFX had the highest risk value, of 108.04; and (3) the results of source apportionment indicate that 58.94% of the antibiotics came from the Huangshui river and wastewater treatment plant (WWTP) near the wetlands. The current study may provide a reference for the risks and management of antibiotics in plateau urban wetlands.

FeOCl-confined activated carbon for improving intraparticle Fenton-like oxidation regeneration

Highly efficient oxidation, as non-thermal regeneration technology, is a promising method to solve the regeneration problem of spent activated carbon (AC) in wastewater treatment. In this study, FeOCl was confined into activated carbon (FeOCl/AC) for catalytic oxidation of contaminants on AC during the regeneration process. The characterization results of FeOCl/AC showed that amorphous FeOCl was distributed in micropores, mesopores and macropores of AC. The methylene blue (MB)-adsorbed FeOCl/AC had a regeneration efficiency of 93.7 % at neutral pH in the presence of H₂O₂, much higher than 46.9 % by Fenton oxidation and 33.7 % by H₂O₂ oxidation. Meanwhile, the spent FeOCl/AC after the adsorption of atrazine, 2,4-dichlorophenol, and ofloxacin had the regeneration efficiencies of 71.5 %, 86.4 %, and 100 %, respectively. Moreover, the regeneration efficiency still reached 87 % in the fifth adsorption-regeneration cycle, and was linearly decreased with the increase of adsorbed amounts of MB. During 6 h regeneration of spent FeOCl/AC, 97 % of adsorbed MB was degraded. Electron paramagnetic resonance and radical trapping experiments indicated that both superoxide and hydroxyl radicals were involved in MB oxidation during the regeneration process.

Fractionation of levofloxacin and ofloxacin during their transport in NOM-goethite: Batch and column studies

Adsorption and transport of levofloxacin (LEV) and ofloxacin (OFL) enantiomers in a matrix containing goethite and natural organic matter (NOM) were investigated using batch and column experiments. In batch studies, competition and enantioselectivity were observed in the adsorption of LEV and OFL. Enantioselectivity upon adsorption was investigated by comparing changes in the enantiomer fraction (EF) (the ratio of LEV to the sum of LEV and OFL remaining in the solution) after and before adsorption. At pH < 7, there was hardly any selectivity in adsorption of OFL and LEV to goethite. At pH > 7, OFL showed a stronger adsorption than LEV to goethite, and this preference remained when NOM samples of Leonardite humic acid (LHA) and Elliott Soil fulvic acid (ESFA) were added. However, when Suwannee River NOM (SRNOM) was added, the preference was reversed, and LEV was adsorbed more strongly. In single systems, the presence of different types of NOM increased adsorption of LEV and OFL, especially LEV. In column studies, preloaded NOM decreased the transport of LEV and OFL through goethite-coated sand. The EF values in the effluent increased with retention time and reached the largest values (0.59-0.72) at around 1.5 pore volume (PV), and then decreased again, reaching a stable value at 5.0-30.0 PV. Both batch and column experiments showed that, fractionation of LEV and OFL occurred during adsorption and transport in the presence of NOM-goethite complexes, which would eventually affect their environmental fate.

Active binding sites for ofloxacin resulted from adsorptive fractionation of humic acid on kaolinite

The adsorptive fractionation of humic acid (HA) at the interface between minerals and water can significantly affect the fate of pollutants in water-soil environment. However, the adsorptive fractionation behavior of HA on kaolinite and its effect on the migration of fluoroquinolones (FQs) have not been fully understood. In this study, fluorescence and infrared spectroscopy, combined with two-dimensional correlation analyses, were used to explore the adsorptive fractionation of humic acid (HA) and its effects on ofloxacin adsorption on kaolinite. The results indicated that humic-like, rather than reduced quinone-like and tyrosine-like, was the main adsorptive fractionation component and preferentially bound to the Al-O sites of kaolinite. The adsorption mechanisms of humic-like and tyrosine-like mainly include hydrogen bonds between acidic functional groups and the Si-O or Al-O groups of kaolinite, n-π electron donor-acceptor interaction and electrostatic attraction. At pH 7.0, with addition of 4.0 and 16.0 mg C/L HA in solution, the adsorptive fractionation of HA on kaolinite led to increases in ofloxacin (in zwitterionic form) adsorption capacity by 1.46 and 3.35 mg/g, respectively. The interactions between ofloxacin and the humic-like were mainly hydrogen bonds and electrostatic attraction. Therefore, the influence of adsorptive fractionation of dissolved organic matter on minerals should be considered in estimating FQs environmental behaviors.

Highly efficient activation of peroxymonosulfate by biomass juncus derived carbon decorated with cobalt nanoparticles for the degradation of ofloxacin

The cobalt nanoparticles decorated biomass Juncus derived carbon (Co@JDC) was prepared by facile calcination strategy and applied to activate peroxymonosulfate (PMS) for eliminating ofloxacin (OFX) in the water environment. The results of catalytic experiments show that 97% of OFX degradation efficiency and 70.4% of chemical oxygen demand removal rate are obtained within 24 min at 0.1 g L^-1 Co@JDC, 0.2 g L^-1 PMS, 20 mg L^-1 OFX (100 mL), and pH = 7, which indicates that Co@JDC/PMS system exhibits excellent performance. Meanwhile, the experimental results of affect factor show that Co@JDC/PMS system can operate in a wider pH range (3-9) and Cl^-1, NO₃^-1, and SO₄^2- have an ignorable effect on OFX degradation. The radical identification experiments confirm that SO₄˙^-, ·OH, O₂˙^-, and ¹O₂ are involved in the process of PMS activation, especially SO₄˙^- and ¹O₂ are the main contributors. Furthermore, a possible PMS activation mechanism by Co@JDC was proposed and the degradation pathways of OFX were deduced. Finally, the stable catalytic activity, negligible leaching of Co²⁺, and the outstanding degradation efficiency for other antibiotics prove that Co@JDC possesses good stability and universality.

EEM-PARAFAC as a convenient methodology to study fluorescent emerging pollutants degradation: (fluoro)quinolones oxidation in different water matrices

Commercial (fluoro)quinolones ((F)Qs), ciprofloxacin (CIP), enrofloxacin (ENR), ofloxacin (OFL), oxolinic acid (OA) and flumequine (FLU) (3 μM each), were degraded with solar-photo-Fenton in a compound parabolic concentrator photoreactor (total volume 5 L) in ultra-pure water at pH = 5.0, salty water at pH = 5.0, and simulated wastewater at pH = 5.0 and 7.5. Iron speciation (its hydrolysis and the complexation with (F)Qs 15 μM and/or chlorides 0.5 M) was calculated at pH 5.0, observing, negligible formation of Fe(III)-chloride complexes, and that >99 % of the total (F)Qs are forming complexes stoichiometry 1:1 with Fe(III) (which also increases the percentage of Fe(OH)²⁺), being minoritarian the free antibiotic form. On the other hand, EEM-PARAFAC (fluorescence excitation-emission matrices-parallel factor analysis) was employed to simultaneously study the behaviour of: i) 4 structure-related groups corresponding to parent pollutants and slightly oxidised by-products, ENR-like (including CIP), OFL-like, OA-like, FLU-like; ii) intermediates still showing (F)Q characteristics (exhibiting analogous fluorescent fingerprint to ENR-like one, but shifted to shorter wavelengths); iii) humic-like substances. The scores from the 4 PARAFAC components corresponding to the parent pollutants were plotted vs. accumulated energy, exhibiting slower decay than their individual removals (measured with HPLC-UV/vis) due to the contribution of the aforementioned by-products to the overall fluorescence. Moreover, thiabendazole (TBZ) 3 μM was added as fluorescence interference. The presence of (F)Qs greatly enhanced TBZ degradation due to (F)Q-Fe(III) complex formation, keeping iron active at pH = 5.0 for Fenton process. The EEM-PARAFAC model was able to recognise the former six components plus an additional one attributable to TBZ-like.