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 %).

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.

Adsorption, natural attenuation, and microbial community response of ofloxacin and oxolinic acid in marine sediments

The pollution of quinolone antibiotics in the marine environment has attracted widespread attention, especially for ofloxacin (OFL) and oxolinic acid (OXO) due to their frequent detection. However, few studies have been conducted to assess the behaviors and microbial community response to these antibiotics in marine sediments, particularly for potential antibiotic-resistant bacteria. In this work, the adsorption characteristics, natural attenuation characteristics, and variation of microbial communities of OFL and OXO in marine sediments were investigated. The adsorption process of antibiotics in sediments occurred on the surface and internal pores of organic matter, where OFL was more likely to be transferred from seawater to sediment compared with OXO. Besides, the adsorption of two antibiotics on sediment surfaces was attributed to physisorption (pore filling, electrostatic interaction) and chemisorption (hydrogen bonding). The natural attenuation of OFL and OXO in marine sediment followed second-order reaction kinetics with half-lives of 6.02 and 26.71 days, respectively, wherein biodegradation contributed the most to attenuation, followed by photolysis. Microbial community structure in marine sediments exposure to antibiotics varied by reducing abundance and diversity of microbial communities, as a whole displaying as an increase in the relative abundance of Firmicutes whereas a decrease of Proteobacteria. In detail, Escherichia-Shigella sp., Blautia sp., Bifidobacterium sp., and Bacillus sp. were those antibiotic-resistant bacteria with potential ability to degrade OFL, while Bacillus sp. may be resistant to OXO. Furthermore, functional predictions indicated that the microbial communities in sediment may resist the stress caused by OFL and OXO through cyano-amino acid metabolism, and ascorbate and aldarate metabolism, respectively. The research is key to understanding fate and bacterial resistance of antibiotics in marine sediments.

Ofloxacin weakened treatment performance of rural domestic sewage in an aerobic biofilm system by affecting biofilm resistance, bacterial community, and functional genes

Ofloxacin (OFL) is a typical fluoroquinolone antibiotic widely detected in rural domestic sewage, however, its effects on the performance of aerobic biofilm systems during sewage treatment process remain poorly understood. We carried out an aerobic biofilm experiment to explore how the OFL with different concentrations affects the pollutant removal efficiency of rural domestic sewage. Results demonstrated that the OFL negatively affected pollutant removal in aerobic biofilm systems. High OFL levels resulted in a decrease in removal efficiency: 9.33% for chemical oxygen demand (COD), 18.57% for ammonium (NH4+-N), and 8.49% for total phosphorus (TP) after 35 days. The findings related to the chemical and biological properties of the biofilm revealed that the OFL exposure triggered oxidative stress and SOS responses, decreased the live cell number and extracellular polymeric substance content of biofilm, and altered bacterial community composition. More specifically, the relative abundance of key genera linked to COD (e.g., Rhodobacter), NH4+-N (e.g., Nitrosomonas), and TP (e.g., Dechlorimonas) removal was decreased. Such the OFL-induced decrease of these genera might result in the down-regulation of carbon degradation (amyA), ammonia oxidation (hao), and phosphorus adsorption (ppx) functional genes. The conventional pollutants (COD, NH4+-N, and TP) removal was directly affected by biofilm resistance, functional genes, and bacterial community under OFL exposure, and the bacterial community played a more dominant role based on partial least-squares path model analysis. These findings will provide valuable insights into understanding how antibiotics impact the performance of aerobic biofilm systems during rural domestic sewage treatment.

Adverse reactions induced by MDT/WHO (Rifampicin+Clofazimine+Dapsone) and ROM (Rifampicin+Ofloxacin+Minocycline) regimens used in the treatment of leprosy: a cohort study in a National Reference Center in Brazil

Background: Recommended standard treatment for leprosy is multidrugtherapy (MDT/WHO), consisting Rifampicin+Dapsone+Clofazimine. Other medications are recommended in cases of resistance, adverse reactions and intolerances, including ROM regimen, Rifampicin+Ofloxacin+Minocycline. Therefore, pharmacovigilance is an important tool in understanding these adverse drug reactions (ADRs), supporting pharmacotherapy management and medication safety. This study seeks to evaluate ADRs comparing two therapeutic regimens, MDT and ROM, used in treatment of patients with leprosy, analyzing prognostic factors regarding risk and safety. Methods:A retrospective cohort study was performed by assessing medical records of 433 patients diagnosed with leprosy from 2010 to 2021 at a National Reference Center in Brazil. They were subject to 24 months or more of treatment with MDT or ROM regimens. ADR assessments were analyzed by two experienced researchers, who included clinical and laboratory variables, correlating them with temporality, severity and the causality criteria of Naranjo and WHO. Results: The findings observed an average of 1.3 reactions/patient. Out of individuals experiencing reactions, 67.0% (69/103) were utilizing MDT/MB, while 33.0% (34/103) were using ROM. The median time for ADR of 79 days for MDT and 179 days for ROM. In first reaction, Dapsone was the most frequently involved medication; the most affected system was hematopoietic. As compared to Clofazimine, results indicated that use of Dapsone was associated with 7% increased risk of ADR occurrence (HR: 1.07; p = 0.866). Additionally, Rifampicin was linked to 31% increased risk of ADRs (HR: 1.31; p = 0.602); and Ofloxacin showed 35% elevated risk (HR: 1.35; p = 0.653). Conversely, results for Minocycline indicated 44% reduction in the risk of ADRs (HR: 0.56; p = 0.527), although statistical significance was not reached. The use of MDT conferred 2.51 times higher risk of developing ADRs in comparison to ROM. Conclusion: The comparison between MDT and ROM revealed that MDT caused more ADRs, and these reactions were more severe, indicating less safety for patients. Dapsone was the most common medication causing ADRs, followed by Rifampicin. The combination with Clofazimine was associated with an additional risk of ADRs, warranting further studies to confirm this hypothesis. Given the high magnitude of ADRs, healthcare teams need to monitor patients undergoing leprosy treatment with focus on pharmacovigilance.

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.

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.

A direct electrochemical sensor based on covalent organic frameworks/platinum nanoparticles for the detection of ofloxacin in water

A direct electrochemical sensor based on covalent organic frameworks (COFs)/platinum nanoparticles (PtNPs) composite was fabricated for the detection of ofloxacin (OFX) in water. Firstly, the COF material was synthesized via the condensation reaction of 1,3,5-tris(4-aminophenyl)benzene (TAPB) with terephthalaldehyde (TPA) and integrated with PtNPs by in situ reduction. Then, TAPB-TPA-COFs/PtNPs composite was loaded onto the surface of the glassy carbon electrode (GCE) by drip coating to construct the working electrode (TAPB-TPA-COFs/PtNPs/GCE). The electrochemical performance of TAPB-TPA-COFs/PtNPs/GCE showed a significant improvement compared with that of TAPB-TPA-COFs/GCE, leading to a 3.2-fold increase in the electrochemical signal for 0.01 mM OFX. Under optimal conditions, the TAPB-TPA-COFs/PtNPs/GCE exhibited a wide linear range of 9.901 × 10-3-1.406 µM and 2.024-15.19 µM with a detection limit of 2.184 × 10-3 µM. The TAPB-TPA-COFs/PtNPs/GCE-based electrochemical sensor with excellent performance provides great potential for the rapid and trace detection of residual OFX.

Nitrogen and sulfur functionalized microporous carbon nanomaterial derived from waste coconut husk for the efficient detection and removal of ofloxacin

This study uses waste coconut husk to synthesize carbon quantum dots decorated graphene-like structure for sustainable detection and removal of ofloxacin. The XRD spectrum shows the carbon nanomaterial's layered structure with turbostratic carbon stacking on its surface. The FESEM and HRTEM studies claim the successful development of quantum dots decorated 2D layered structure of carbon nanomaterial. The functionalization of sulfur and nitrogen is well observed and studied through XPS, while Raman spectra have provided insight into the surface topology of the as-synthesized nanostructure. The BET surface area was found to be 1437.12 m2/g with a microporous structure (pore width 2.0 nm) which interestingly outcompete many reported carbon-based nanomaterials such as graphene oxide, reduced graphene oxide and quantum dots. The detection and removal processes are monitored through UV-visible spectroscopy and the obtained detection limit and adsorption capacity were 2.7 nM and 393.94 mg/L respectively. Additionally, 1 mg carbon nanomaterial has removed 49 % ofloxacin from water in just 1 h. In this way, this study has successfully managed the coconut husk waste after its utilization for environmental remediation purposes.

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.

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.

High frequency of ofloxacin resistance patterns of Mycobacterium leprae from India: An indication to revisit second line anti-leprosy treatment regimen

OBJECTIVES

Drug resistance in leprosy is an emerging concern, leading to treatment failures, recurrences, and potential spread of resistant Mycobacterium leprae in the community. In this study, we aimed to assess drug resistance prevalence and patterns amongst leprosy patients at a tertiary care referral hospital in India.

METHODS

Mutations in drug resistance determining regions for dapsone, rifampicin, and ofloxacin of the M. leprae genome in DNA extracted from skin biopsies of 136 leprosy patients (treatment-naive = 67, with persistent skin lesions = 35, with recurrence = 34) were analysed by polymerase chain reaction followed by Sanger sequencing. Wild-type strain (Thai-53) was used as a reference strain.

RESULTS

Resistance mutations were identified in a total of 23 patients, constituting 16.9% of the cohort. Within this subset of 23 cases, resistance to ofloxacin was observed in 17 individuals (12.5%), while resistance to both dapsone and rifampicin was detected in three patients each (2.2% for both). The occurrence of ofloxacin resistance showed minimal disparity between recurrent and treatment-naive cases, at 17.6% and 16.4%, respectively. Dapsone resistance emerged in two treatment-naive cases and one case with persistent skin lesions. Notably, none of the treatment-naive cases or those with recurrence/relapse exhibited rifampicin resistance. Subsequently, no statistically significant correlation was identified between other clinical variables and the presence of antimicrobial resistance.

CONCLUSIONS

The occurrence of resistance to the current multidrug therapy regimen (specifically dapsone and rifampicin) and to ofloxacin, a secondary antileprosy medication in M. leprae, represents a concerning scenario. This calls for an expansion towards bactericidal drug options and the establishment of robust surveillance for drug resistance in countries burdened with high leprosy rates. Moreover, the introduction of stringent antimicrobial stewardship initiatives is imperative. As a single centre study, it represents a limited, cross-sectional view of the real situation in the field.

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.

Fabrication of an electrochemical sensor based on eggshell waste recycling for the voltammetric simultaneous detection of the antibiotics ofloxacin and ciprofloxacin

In this work, an accurate, highly sensitive, and economical electrochemical sensor based on a carbon paste electrode modified by Ca2CuO3 nanostructure (Ca2CuO3 NS) was constructed using Eggshell waste recycling as a cheap source of calcium. The Ca2CuO3 NS was analyzed using FTIR, SEM, and XRD measurements. The synthesized nanomaterials utilized for the first time to enhance the electrocatalytic efficiency of carbon paste electrode (CPE) toward fluoroquinolones antibiotics ofloxacin (OFL) and ciprofloxacin (CIP), The drugs used to treat pneumonia caused by COVID-19. The synthesized Ca2CuO3 NS dramatically enhanced the anodic peak response of CPE toward both drugs compared to the unmodified one and other modified electrodes. The simultaneous detection of the two antibiotics was performed in the linear range of 0.09-1.0 μM for OFL and 0.05-0.8 μM for CIP with the LOD of 0.027 μM and 0.012 μM, respectively. The suggested method was applied successfully to determine OFL and CIP in real samples.

Strong coupling of super-hydrophilic and vacancy-rich g-C3N4 and LDH heterostructure for wastewater purification: Adsorption-driven oxidation

Adsorption and wettability are crucial components of catalytic oxidation. To increase the reactive oxygen species (ROS) generation/utilization efficiency of peroxymonosulfate (PMS) activators, defect engineering and 2D nanosheet characteristics were used to regulate electronic structures and expose more active sites. Two-dimensional (2D) super-hydrophilic heterostructure by connecting cobalt species modified nitrogen vacancy-rich g-C₃N₄ (V_n-CN) and LDH (V_n-CN/Co/LDH) with high-density active sites and multi-vacancies, as well as high conductivity and adsorbability, to expedite ROS generation. The degradation rate constant of ofloxacin (OFX) was 0.441 min^-1 via the V_n-CN/Co/LDH/PMS system, which was 1-2 orders greater than in the previous studies. Confirmation of the contribution ratios of various reactive oxygen species (ROS), SO₄^·- and ¹O₂ in bulk solution, O₂^·- on the catalyst surface was the most abundant ROS. The catalytic membrane was constructed utilizing Vn-CN/Co/LDH as the assembly element. The 2D membrane achieved the continuous effective discharge of OFX in the simulated water after 80 h/4 cycles of continuous flowing-through filtration-catalysis. This study provides fresh insights into designing a PMS activator for environmental remediation activated on demand.

Highly efficient degradation of ofloxacin and diclofenac by composite photocatalyst aloe-emodin/PMMA

Photocatalysis is one of the most effective methods to remove pollutants from water. Photocatalyst is the core of photocatalysis. The composite photocatalyst combines the photosensitizer with the support and uses the photosensitivity of the photosensitizer and the stability and adsorption of the support to achieve efficient and rapid degradation of pharmaceuticals in water. In this study, natural aloe-emodin with π-conjugated structure was used as photosensitizer to react with macroporous resin polymethylmethacrylate (PMMA) under mild conditions to prepare composite photocatalysts AE/PMMAs. The photocatalyst underwent photogenerated electron migration under visible light to form ^•O₂^- and holes with high oxidation activity, which could realize efficient photocatalytic degradation of ofloxacin and diclofenac sodium and showed excellent stability, recyclability and industrial feasibility. This research has developed an efficient method of composite photocatalyst and realized the application of a natural photosensitizer in pharmaceutical degradations.

A novel Zn/Eu-MOF for the highly sensitive, reversible and visualized sensing of ofloxacin residues in pork, beef and fish

The study investigates a bimetallic organic framework (Zn/Eu-MOF) based fluorescent probe for visual detection of ofloxacin (OFL) in pork, beef and fish. The developed sensing probe recognizes OFL through internal filtration and cation-π interaction between OFL and Zn/Eu-MOF, resulting in a distinct color change from orange-red to light green. The content of OFL can be determined through RGB analysis by a mobile-phone. The developed sensing probe offers several advantages such as broad linear range (0.1 ∼ 80 μM), rapid response time (30 s), low detection line (0.44 μM). The effectiveness of the sensing probe can last for five rounds with good recovery. Moreover, the application of the sensing probe on pork, beef and fish samples are reliable, with recoveries ranging from 93.4 to 112.1%, and the relative standard deviations (RSD) within 1.17% to 2.06%. These results suggest that the developed sensing probe could have significant potential for practical on-site test in food.

Solar-light-driven photocatalytic degradation of pharmaceutical pollutants utilizing 2D g-C3N4/BiOCl composite

Pharmaceuticals, which have been praised for protecting countless lives, have become a new category of environmental pollutants in recent decades as most of these pharmaceutical compounds are discovered in water bodies in concentrations ranging from ng/L to mg/L. Recently, metal-free g-C₃N₄ (GCN)-based composites have received considerable attention for the degradation of pharmaceutical compounds. In this study, GCN/BiOCl composite was prepared using a simple ultrasonication-assisted stirring method and characterized using various analytical and spectroscopic techniques including XRD, FTIR, PL, Elemental mapping, UV-DRS, FESEM, HRTEM, and TGA. The as-prepared composite was utilized to degrade levofloxacin (LVX) under solar light irradiation and showed excellent stability for the degradation of LVX. Furthermore, the universality of the GCN/BiOCl composite was investigated by degrading diverse pharmaceuticals such as ofloxacin (OFX), norfloxacin (NOX), ciprofloxacin (COX), and ketorolac tromethamine (KTC) in an aqueous phase. Therefore, this work provides an effective method to degrade pharmaceutical contaminants simultaneously in water using GCN/BiOCl composite.

Synthesis of a dual-functional terbium doped copper oxide nanoflowers for high-efficiently electrochemical sensing of ofloxacin, pefloxacin and gatifloxacin

The current effort introduces a facile construction of peony-like CuO:Tb³⁺ nanostructure (P-L CuO:Tb³⁺ NS), whose characterization was determined via techniques of X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. We investigated ofloxacin, pefloxacin and gatifloxacin oxidation electrochemically on P-L CuO:Tb³⁺ NS-modified glassy carbon electrode (P-L CuO:Tb³⁺ NS/GCE), the results of which revealed the irreversible oxidation of drugs through a two-electron oxidation process. An admirable resolution was found for this modified electrode between voltammetric peaks of ofloxacin, pefloxacin and gatifloxacin, suggesting its appropriateness for simultaneous detection of these drugs in pharmaceutical media. In addition, our nanostructure synergistically influenced the electro-catalytic oxidations of these three compounds. Differential pulse voltammetric measurements of ofloxacin, pefloxacin and gatifloxacin through our sensor showed a limit of detection of 1.9, 2.3 and 1.2 nM a as well as a linear dynamic range between 0.01 and 800.0 μM in phosphate buffered solution (0.1 M, pH = 6.0), respectively. Moreover, as-fabricated sensor could successfully co-detect these drugs in real serum and tablets specimens. In addition, since we use animal foods such as milk it is very important to detect their fluoroquinolone residues. For this purpose, the proposed sensor was tested to determine the residues of ofloxacin, pefloxacin and gatifloxacin in milk.

Responses of cyanobacterium Microcystis aeruginosa under single and repeated ofloxacin exposure

Antibiotics are omnipresent and pseudo-persistent in the environment. Yet, their potential ecological risks under repeated exposure, which is more environmentally relevant, are understudied. Therefore, this study used ofloxacin (OFL) as the probe chemical to investigate the toxic effects of different exposure scenarios-single dose of high concentration (4.0 µg/L) and multiple additions of low concentrations-towards the cyanobacterium Microcystis aeruginosa. Flow cytometry was employed to measure a collection of biomarkers, including endpoints related with biomass, single cell properties and physiological status. Results showed that the single dose of the highest OFL level inhibited cellular growth, chl-a content and cell size of M. aeruginosa. In contrast, OFL induced stronger chl-a autofluorescence and higher doses tended to have more remarkable effects. Repeated low OFL doses can more significantly increase the metabolic activity of M. aeruginosa than a single high dose. Viability and cytoplasmic membrane were not affected by OFL exposure. Oxidative stress was observed for the different exposure scenarios, with fluctuating responses. This study demonstrated the different physiological responses of M. aeruginosa under different OFL exposure scenarios, providing novel insights into the toxicity of antibiotics under repeated exposure.

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.

In Vitro Inhibitory Effects and Bioinformatic Analysis of Norfloxacin and Ofloxacin on Piroplasm

PURPOSE

The in vitro inhibitory effect of two fluroquinolone antibiotics, norfloxacin and ofloxacin, was evaluated in this study on the growth of several Babesia and Theileria parasites with highlighting the bioinformatic analysis for both drugs with the commonly used antibabesial drug, diminazene aceturate (DA), and the recently identified antibabesial drugs, luteolin, and pyronaridine tetraphosphate (PYR).

METHODS

The antipiroplasm efficacy of screened fluroquinolones in vitro and in vivo was assessed using a fluorescence-based SYBR Green I assay. Using atom Pair signatures, we investigated the structural similarity between fluroquinolones and the antibabesial drugs.

RESULTS

Both fluroquinolones significantly inhibited (P < 0.05) the in vitro growths of Babesia bovis (B. bovis), B. bigemina, B. caballi, and Theileria equi (T. equi) in a dose-dependent manner. The best inhibitory effect for both drugs was observed on the growth of T. equi. Atom Pair fingerprints (APfp) results and AP Tanimoto values revealed that both fluroquinolones, norfloxacin with luteolin, and ofloxacin with PYR, showed the maximum structural similarity (MSS). Two drug interactions findings confirmed the synergetic interaction between these combination therapies against the in vitro growth of B. bovis and T. equi.

CONCLUSION

This study helped in discovery novel potent antibabesial combination therapies consist of norfloxacin/ofloxacin, norfloxacin/luteolin, and ofloxacin/PYR.

Fenton degradation of ofloxacin antibiotic using calcium alginate beads impregnated with Fe3O4-montmorillonite composite

The primary aim of this study is to develop an economical, stable, and effective heterogeneous catalyst for wastewater remediation via the Fenton oxidation process. For this purpose, Fe₃O₄-montmorillonite alginate (FeMA) composite beads were synthesized by entrapping Fe₃O₄-montmorillonite in calcium alginate beads. The performance of the catalysts was evaluated via the Fenton degradation of ofloxacin (OFL), an antibiotic that is frequently detected in water bodies. The physiochemical properties of the FeMA composite beads were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). FeMA composite beads were found to have a higher surface area, higher porosity, and better thermal stability compared to pristine alginate beads. The composite beads were subsequently used for Fenton degradation of ofloxacin (OFL) in an aqueous solution. The effects of Fe₃O₄-montmorillonite loading on alginate, FeMA composite beads dosage, initial solution pH, initial OFL concentration, different oxidants, H₂O₂ dosage, reaction temperature, and inorganic salts on Fenton degradation of OFL in aqueous solution was investigated. The results revealed that the percentage of OFL degradation reached about 80 % under optimized conditions, while the total organic carbon (TOC) removal reached about 53 %. The entrapment of Fe₃O₄-montmorillonite in alginate beads results in less iron ions leaching compared to previous observation, and the efficiency remains constant over the five cycles investigated. The kinetics of the Fenton degradation process are best fitted to the pseudo-first-order kinetic model. It is therefore believed that FeMA composite beads can be a promising material for wastewater remediation via the Fenton oxidation process.

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.

Mechanism of downward migration of quinolone antibiotics in antibiotics polluted natural soil replenishment water and its effect on soil microorganisms

Reclaimed water is widely concerned as an effective recharge of groundwater and surface water, but trace organic pollutants produced by traditional wastewater treatment plants (WWTPs) would cause environmental pollution (water and soil) during infiltration. Therefore, the effects of reclaimed water containing ofloxacin (OFL) and ciprofloxacin (CIP) in antibiotics polluted natural soil (APNS) were investigated by simulating soil aquifer treatment systems (SATs). The experiment results showed that OFL and CIP in water were adsorbed and microbially degraded mainly at 30 cm, and the concentration of OFL and CIP in soil increased with depth, which were mainly due to the desorption from APNS. Concurrently, the change in replenishment water concentration also significantly affected OFL and CIP in pore water and soil. Although OFL and CIP inhibited the diversity of soil microbial community, they also promoted the growth of some microorganisms. As the dominant bacteria, Proteobacteria and Acidobacteriota can effectively participate in the degradation of OFL and CIP. The degradation effects of soil microorganisms on OFL and CIP were 45.48% and 42.39%, respectively, indicating that soil microorganisms selectively degraded pollutants. This experiment was carried out on APNS, which provided a reference for future studies on the migration of trace organic pollutants under natural conditions.

Insights into the interaction mechanism of ofloxacin and functionalized nano-polystyrene

Nano-plastics (NPs), an emerging contaminant in the environment, have a larger specific surface area and can act as a carrier of other contaminants. Thus, insights into the interaction mechanisms between NPs and other pollutants are crucial for the assessment of environmental impacts of NPs in the ecosystems. In this study, the interaction mechanism between NPs and ofloxacin (OFL) were investigated via kinetics, fluorescence quenching, and two-dimensional correlation spectroscopy (2DCOS). The adsorption kinetics of OFL on carboxyl-modified polystyrene (PS-COOH) and amine modified polystyrene (PS-NH₂) closely fitted the pseudo-second-order kinetics model (R² = 0.99). Adsorption kinetics indicated that chemical adsorption is dominant mechanism, and the Fourier Transform Infrared Spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS) results showed that the electronic interaction, π-π, and H-binding were also involved in the adsorption process. OFL showed strong fluorescence quenching in the presence of NPs. Stern-Volmer quenching was negatively related with the temperature, which was dominated by the static type of quenching. 2DCOS indicated that the π-π conjugation was dominant in the interaction process, and the interaction process was dependent on the solution pH and salinity. Overall, this work provides new insights into the interaction mechanism of NPs and antibiotics in the aquatic ecosystems.

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.

MXene-based composites as an electrochemical sensor for ultrasensitive determination of ofloxacin

Sensitive determination of ofloxacin (OFL) is very essential for human health and environmental protection. Here, a novel composite of gold nanoparticles(nAu)@MXene(Ti₃C₂T_x)/poly-p-aminobenzene sulfonic acid (PABSA) was fabricated on the surface of glassy carbon electrode (GCE) and used to sensitively determine OFL. The results of experiments showed that the obtained nAu@Ti₃C₂T_x/PABSA/GCE electrode could be used as an electrochemical sensor to directly detect ofloxacin (OFL) by differential pulse voltammetry (DPV). Under the optimal conditions, the proposed electrode displayed a broader linear range and a lower detection limit (LOD) for OFL determination when it was compared to those similar sensors. The linear range was from 5.0 × 10^-8 to 5.0 × 10^-4 mol/L and the LOD was 3.7 × 10^-8 mol/L (S/N = 3). The nAu@Ti₃C₂T_x/PABSA/GCE electrode also showed good selectivity, repeatability, and reproducibility. Finally, the proposed electrode was used to detect OFL in commercial samples by the standard addition method. The obtained recovery was from 97.3% and 105.7% showing its potential applications in actual sample analysis.

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.

Effect of ofloxacin levels on growth, photosynthesis and chlorophyll fluorescence kinetics in tomato

Antibiotic pollution has become a global environmental pollution problem. Chlorophyll fluorescence is one of the most important indicators reflecting the degree to which plants are influenced by the environment. Ofloxacin (OFL) is a highly toxic antibiotic pollutant, and there are few reports on the effects of changes in OFL levels on tomato chlorophyll fluorescence parameters. In this study, we investigated the responses of tomato growth, photosynthetic activity and chlorophyll fluorescence kinetics to exogenous OFL exposure (as the concentrations of 0, 2.5, 5, 10 and 20 mg L^-1). The results showed that lower concentrations of OFL (2.5 mg L^-1) had little impact on tomato growth, while plant growth was inhibited with the OFL concentration increasing. At higher OFL concentrations (5, 10 and 20 mg L^-1), chloroplasts ruptured, and chlorophyll became degraded, resulting in leaf etiolation. Furthermore, the photosynthetic and photochemical efficiency and electron transfer rate were significantly inhibited by OFL. Moreover, damage to the oxygen-evolving complex on the donor side of PSⅡ prevented electron transfer from QA to QB and led to photoinhibition. In conclusion, higher OFL concentration reduced photosynthesis by destroying the photosynthetic mechanism in tomato, resulting in tomato leaf etiolation and plant growth inhibition.

Microbiological Profile and Antibiotic Sensitivity of 100 Cases of Otitis Externa

Otitis externa is a common condition encountered in the ENT outdoors. For long, it was thought to be of fungal etiology but after World War II, bacterial pathogens were found to be most commonly involved. Pseudomonas has been described as the most common causative organism in the literature. This prospective study aimed to study the microbiological profile and antibiotic sensitivity of 100 patients of otitis externa. 100 diagnosed cases of otitis externa were included in the study after informed consent. Swabs were taken from the external acoustic canal maintaining asepsis. The swabs were analysed using microscopy, culture and sensitivity testing. The samples were cultured on blood agar, MacConkey agar and Sabourad's dextrose agar with antibiotics. Antimicrobial susceptibility testing was done by Kirby-Bauer disc diffusion method. The most common bacteria identified was Pseudomonas aeruginosa (36.36%), followed by Staphylococcus aureus (15.45%), Escherichia coli (2.73%), Klebsiella (1.82%), and Proteus sp (1.82%). Aspergillus sp (19.09%) and Candida albicans (8.18%) were the fungal species identified. Pseudomonas showed excellent sensitivity to imipenem, piperacillin and ofloxacin, while Staphylococcus showed good sensitivity to vancomycin, ofloxacin and netilmycin. Topical fluoroquinolones can be used as empirical treatment in most cases of bacterial otitis externa. In resistant cases, culture and antibiotic sensitivity should be done to manage the infection.

Removal of ofloxacin from wastewater by chloride electrolyte electro-oxidation: Analysis of the role of active chlorine and operating costs

Electro-oxidation (EO) has received increasing attention as an efficient and green method for removing pollutants from wastewater. Chloride anions (Cl^-), which commonly exist in wastewater, can act as an electrolyte for the EO process. However, the role of reactive chlorine species (RCS) generated near electrodes is often underestimated. In this study, we generated hydroxyl radicals (OH) and RCS in a boron-doped diamond (BDD) electrode system and investigated its degradation mechanism for ofloxacin (OFX) removal. The findings suggested that OFX degradation was dominated by OH existing near the anode in solution, with RCS playing a supporting role. Based on the produced intermediates, we proposed an OFX decomposition pathway. The biological toxicities of the intermediates were evaluated through the ECOSAR and T.E.S.T. procedure. Nearly half of the intermediates are less toxic than the parent compound. After optimizing the operating parameters by the response surface methodology, 20 mg/L OFX was almost completely degraded after 10 min of reaction in 1.45 g/L NaCl with a current density (j) of 18 mA/cm², and the total organic carbon was decreased by 30.55 %. The energy consumption and current efficiency were 0.648 kW·h/g_TOC and 8.65 %, respectively. Comparing the operating costs of the proposed and other EO methods, our method emerged as a viable new treatment scheme for similar polluted wastewaters. This study aims to comprehensively understand the potential application value of BDD electrodes in the treatment of Cl^- containing organic wastewater.

Removal of ofloxacin from water by natural ilmenite-biochar composite: A study on the synergistic adsorption mechanism of multiple effects

The preparation cost is one of the major constraints for adsorbent applied to practical situations. Here, a novel, economical and eco-friendly ilmenite biochar composite (ILM-BC) was successfully prepared by co-cracking of natural ilmenite and corn stover for the removal ofloxacin from water. The adsorption experiments indicated that the removal ofloxacin by ILM-BC was chemisorption and belonged to a spontaneous and entropy-increasing heat absorption process. Among composites, ILM-BC5 had superior adsorption capacity and stability, with a removal rate 1.6 times higher than that of biochar, and it could remove more than 90% ofloxacin in the pH range of 2-10. Multiple characterization results indicated that the adsorption of ILM-BC was the result of the synergistic effect of pore filling, hydrogen bonding, and π-π interactions. The introduction of ilmenite promoted hydrogen bonding formation and π-π interactions by enriching -OH and -COO on the surface of ILM-BC, which could enhance the adsorption capacity of ILM-BC.

Adsorption and fenton-like oxidation of ofloxacin in wastewater using hybrid MOF bimetallic Fe/Ni nanoparticles

Since ofloxacin (OFX) is one of many common antibiotics, which effluxes into aquatic environment in relatively high concentration, it has become of significant environmental concern due to the potential for increased antibiotic resistance. In this study, an innovative functional Fe/Ni@ZIF-8 composite was successfully used for the Fenton-like oxidation of OFX, with a OFX removal efficiency >98% under optimal conditions. FTIR analysis confirmed that OFX removal occurred via adsorption to Fe/Ni@ZIF-8 by a combination of π-π bond intercalation and electrostatic interaction, while XPS revealed that the Fe/Ni NPs in Fe/Ni@ZIF-8 were also involved in oxidation. Furthermore, LC-MS analysis identified the presence of several OFX degradation products post exposure, which indicted that Fe/Ni NPs in Fe/Ni@ZIF-8 reacted with H₂O₂ to form •OH, leading to Fenton-like oxidation of OFX. Thus overall, OFX removal by Fe/Ni@ZIF-8 involved both adsorption to ZIF-8 and Fenton-like oxidation by Fe/Ni NPs. A synergistic mechanism for OFX removal by Fe/Ni@ZIF-8 was thus proposed. The removal efficiency of the synthesized catalysts remained high (above 65%) even after a 5th reuse cycle, which reflected the high stability of Fe/Ni@ZIF-8. Overall, this study demonstrated that Fe/Ni@ZIF-8 had significant potential for the removal of OFX from wastewaters with a removal efficiency >90%.

Visible-light-driven photocatalytic degradation of ofloxacin by BiOBr nanocomposite modified with oxygen vacancies and N-doped CQDs: Enhanced photodegradation performance and mechanism

The rapid recombination of photogenerated carriers and weak light absorption capacity are two major challenges for bismuth-based photocatalysts. Here, N-CQDs/BiO_1-xBr micro-flower photocatalysts with the visible-light activity were fabricated through the ethylene glycol solvothermal method for the first time, and oxygen vacancies (OVs) and N-doped carbon quantum dots (N-CQDs) were simultaneously introduced on the surface of BiOBr. OVs were introduced to form defective BiOBr (BiO_1-xBr). N-CQDs and BiO_1-xBr formed a strong binding effect. Then, the composition, morphology, crystal structure and photoelectric property of photocatalysts were studied, and the mechanism and pathway of ofloxacin (OFL) photodegradation were studied. N-CQDs/BiO_1-xBr-4 was a micro-flower composed of nanosheets with a thickness of about 60 nm, this structure produced multiple light reflections. Photoelectrochemical analysis confirmed that the synergistic effect of OVs and N-CQDs significantly promoted the electron-hole separation (3 times vs BiOBr) and enhanced the light absorption range (Eg = 2.96 eV vs 3.24 eV). Meanwhile, the removal rate of OFL by N-CQDs/BiO_1-xBr-4 was 6 times higher than that by BiOBr (K_obs of N-CQDs/BiO_1-xBr-4 was 32 times higher than that of BiOBr). Electron spin resonances analysis and radical quenching experiments showed that ·O₂^- and h⁺ played dominant roles in the OFL photodegradation system, and their contribution rates were 89.84% and 70.31%, respectively. There were main degradation pathways for OFL, including oxidation, dealkylation, hydroxylation and decarboxylation. This study explored the synergistic and complementary effects between OVs and N-CQDs, and provided a promising strategy for the photodegradation of toxic antibiotics by visible-light-driven photocatalysts.

Visible-light-induced photocatalytic response of easily recoverable Mn2O3/SiO2 monolith in centimeter-scale towards degradation of ofloxacin: Performance evaluation and product analysis

Monolithic-photocatalysts being easily recoverable are a suitable alternative to powdered materials for pollutant treatment. This study was conducted to prepare Mn₂O₃/SiO₂ monoliths by wet-impregnating Mn(NO₃)₂^․4H₂O in SiO₂ monoliths. The crystallinity of oxide was affirmed via XRD analyses, whereas EDS and elemental-mapping, and XPS studies revealed the constituent elements and their oxidation states. FESEM images confirmed porous morphology, while BET-analysis confirmed its mesoporous nature (∼8.44 nm) and enormous surface area (∼241 m²/g). The DRS and PL studies disclosed that Mn₂O₃/SiO₂ monoliths consisted of narrow band-gap of ∼2.14 eV and had suitable electron/hole separation. The photocatalytic effectiveness of the monolith had been checked by degrading model dye methylene blue (MB) and antibiotic ofloxacin (OF). The influence of various reaction parameters for degradation, i.e., monolith dose, solution-pH, illumination-area, scavengers, etc., was noted. At optimal reaction conditions, outstanding competence was achieved for MB (95.23%; 0.0225 min^-1) and decent results were obtained for OF-degradation (73.2%; 0.0096 min^-1). The recyclable nature of the catalyst (∼12.7%-reduction in effectiveness after 10 successive cycles) was vindicated by several characterization studies after reusability. The O₂^•-radicals participated majorly in the degradation reaction. The reaction intermediates plus products, generated after the degradation of had been identified via LC/MS study. The mineralization extent of the OF and MB was also gauged through TOC analyses. The photocatalytic treatment of raw textile wastewater manifested ∼57.8% COD and 53% TOC-removal. This study emphasizes the competence of Mn₂O₃/SiO₂ monoliths for the photocatalytic abatement of refractory organic contaminants.

Quantitative assessment of interactions of hydrophilic organic contaminants with microplastics in natural water environment

The interaction between microplastics (MPs) and hydrophilic organic contaminants (HOCs) in natural water environment has recently raised great public attentions due to the potential toxicity to humans. However, the quantitative assessment is less studied. In this study, the interaction between ciprofloxacin (CIP) and ofloxacin (OFL) (two important HOCs) and virgin and aged polystyrene (PS) was investigated. The aged PS showed higher adsorption rate and capacity than the virgin PS, due to its larger surface area and more O-containing groups. The pH-dependent adsorption of CIP was higher than OFL on both virgin and aged PS; the maximum adsorption for both HOCs occurred at pH 5. The sequential orders of functional groups for the adsorption were discovered according to the study by the 2D correlation Fourier transform infrared spectroscopy. Several mechanisms existed for the interaction: (1) at 3.0 < pH < 5.0, the electrostatic attraction (EA) was inhibited while H-bond (HB) was dominant, accounting for > 60% of the total uptake; (2) at 5.0 < pH < 8.0, the contribution of EA increased to around 50-60% while HB decreased to 30-40%; (3) at 8.0 < pH < 10.0, EA, HB and π-π conjugation caused 30-40%, 25-40% and 20-45% of the total uptake, respectively; (4) at 10.0 < pH < 12.0, π-π conjugation accounted for 90-100%. Notably, higher adsorption of CIP was mainly attributed to the presence of secondary amino groups and its higher pK_a value, correspondingly leading to the additional ordinary HB and negative charge-assisted HB, and EA interactions with PS. This study further provides clear evidences on the risk of MPs and HOCs on humans and aqueous living organisms.

Synthesis of adjustable {312}/{004} facet heterojunction MWCNTs/Bi5O7I photocatalyst for ofloxacin degradation: Novel insights into the charge carriers transport

Multi-wall carbon nanotubes (MWCNTs) with high electrical conductivity are commonly accounted as the ideal additives to enhance the charge surface migration efficiency in photocatalysis. Theoretically, the MWCNTs-modified binary photocatalysts have potential for the change of nanocrystal structure. Herein, we reports an adjustable {312}/{004}facet heterojunction MWCNTs/Bi₅O₇I nanocomposite. Interestingly, the synergistic effect of {312}/{004}facet heterojunction and MWCNTs can effectively accelerate the spatial charge carriers transport. A novel {312}/{004}facet "S-scheme" pathway was proven to be the dominated pathway for the enhancement of spatial charge carriers. As a result, the MWCNTs-{312}/{004}Bi₅O₇I composites exhibited superior photocatalytic oxidation efficiency for a representative antibiotics ofloxacin photodegradation. Density functional theory (DFT) calculation and LC-MS/MS analysis confirmed that the possible dealkylation and oxidation pathways could be found in OFL degradation. This work provides novel insights for the relationship between charge carrier transport and facet structure-property.

Laccase-loaded magnetic dialdehyde inulin nanoparticles as an efficient heterogeneous natural polymer-based biocatalyst for removal and detoxification of ofloxacin

An efficient heterogeneous natural polymer-based biocatalyst was fabricated through the immobilization of laccase onto dialdehyde inulin (DAI)-coated silica-caped magnetic nanoparticles (laccase@DAI@SiO₂@Fe₃O₄⋅MNPs). The carrier was developed using SiO₂@Fe₃O₄⋅MNPs and functionalized with DAI. The construction of immobilized laccase was confirmed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Immobilization yield and efficiency were calculated as 61.0 ± 0.3% and 93.0 ± 0.6%, respectively. The immobilized laccase maintained 50% and 85% of its relative activity after 25 repeated cycles and 20 days of storage at 4 °C, respectively. The prepared biocatalyst effectively eliminated ofloxacin, a fluoroquinolone-type antibiotic, with a 63% removal capacity. Besides, antimicrobial activity study on some soil microorganisms involved in the biodegradation of xenobiotics revealed that the laccase-treated ofloxacin resulted in less toxic metabolites. The obtained data indicated that the fabricated biocatalyst is promising for the removal of ofloxacin or other analogs of fluoroquinolones in the environment.

Efficient ofloxacin degradation via photo-Fenton process over eco-friendly MIL-88A(Fe): Performance, degradation pathways, intermediate library establishment and toxicity evaluation

The high-throughput production of the eco-friendly MIL-88A(Fe) was achieved under mild reaction conditions with normal pressure and temperature. The as-prepared MIL-88A(Fe) exhibited efficient photo-Fenton catalytic ofloxacin (OFL) degradation upon visible light irradiation with good stability and reusability. The OFL (20.0 mg/L) was completely degraded within 50 min under visible light with the aid of MIL-88A(Fe) (0.25 g/L) and H₂O₂ (1.0 mL/L) in aqueous solution (pH = 7.0). The hydroxyl radicals (·OH) are the main active species during the photo-Fenton oxidation process. Meanwhile, the degradation intermediates and the corresponding degradation pathways were identified and proposed with the aid of both ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) and density functional theory (DFT) calculations. Finally, the degradation product library was firstly established to identify intermediate transformation products (TPs) with their variation of concentration, and their corresponding toxicologic activities were assessed via Toxtree and T.E.S.T software as well. Finally, the MIL-88A is efficient and stable with four cycles' catalysis operations, demonstrating good potential for water treatment.

Degradation of ofloxacin by potassium ferrate: kinetics and degradation pathways

Drug residues, including various antibiotics, are being increasingly detected in aqueous environments. Ofloxacin (OFX) is one such antibiotic that is widely used in the treatment of several bacterial infections; however, chronic exposure to this antibiotic can have adverse impacts on human health. Hence, the identification of an effective OFX degradation method is essential. Thus, in this study, the degradation performance of OFX using potassium ferrate (Fe(VI)) under the influence of different initial concentrations, pH, temperature, and common ions in water was investigated. OFX degradation by Fe(VI) was directly proportional to the concentration of Fe(VI) and temperature and inversely proportional to the pH. Among the common ions in water, Fe³⁺ and NH₄⁺ could significantly promote the degradation of OFX by Fe(IV), while humic acid (HA) significantly inhibited it. Under the conditions of [Fe(VI)]:[OFX] = 15:1, T = 25℃, and pH = 7.0, the removal efficiency of 8 μM OFX reached more than 90% in 4 min. Seven intermediates were identified by quadrupole time-of-flight tandem ultra-performance liquid chromatography mass spectrometry (Q-TOF LC/MS), and two possible pathways for the degradation of OFX by Fe(VI) were proposed. Overall, the results suggest that advanced oxidation technology using Fe(VI) is effective for treating wastewater containing OFX.

Simultaneous determination of ofloxacin and bromfenac in combined dosage form using four different spectrophotometric methods

Four simple, precise, accurate and validated spectrophotometric methods have been developed for the simultaneous determination of ofloxacin (OFL) and bromfenac sodium (BROM). Firstly, first and second derivative spectrophotometric methods (¹D &²D) using a zero-crossing technique utilizing 309.3 and 257.5 nm for OFL and 290.7 and 246.5 nm for BROM as optimum working wavelengths in a binary mixture, respectively. Secondly, the first derivative ratio spectrophotometric method (¹DD) in which peak amplitudes at 297.3 nm and 260.7 nm were chosen to simultaneously estimate OFL and BROM, respectively. Thirdly, dual wavelength (DW) method based on two selected wavelengths for each drug in such a way that the difference in absorbance is zero for the second one. At wavelengths 296.4, 348.4 nm BROM has equal absorbance values, therefore, these two wavelengths have been used to determine OFL. Similarly, 271.7 nm and 313.1 nm were selected to determine BROM in the combined formulation. Finally, the fourth method depends on ratio difference spectrophotometry (RDSM), in which the difference between amplitudes at 305.6 nm and 326.5 nm on the ratio spectrum of the mixture was directly proportional to the concentration of OFL; independent of the interfering components. Similarly, the difference between amplitudes at 265.1 nm and 275.4 nm on the ratio spectrum was used for the determination of BROM. The linearity was confirmed in the range of 4 - 18 µg/ml for OFL and BROM for the four methods. The proposed methods were used to determine both drugs in their laboratory prepared mixture and combined formulation with mean percentage recoveries of 99.41 ± 1.35% for OFL and 99.98 ± 1.30 % for BROM in method (A). In method (B), the mean percentage recoveries were 101.70 ± 1.61% for OFL and 101.90 ± 1.45% for BROM. In method (C) OFL was 99.57 ± 1.61% and 100.90 ± 1.62% for BROM. Finally, in method (D) the mean percentage recoveries were 99.37 ± 1.67% for OFL and 100.70 ± 1.59% for BROM. The developed methods were successfully employed for determination of OFL and BROM in laboratory prepared mixtures and combined formulation showing satisfactory recoveries. Methods validation was performed according to the International Conference on Harmonization (ICH) guidelines. The obtained results conformed to the accepted ranges of recovery, precision and repeatability.

Architecting an indirect Z-scheme NiCo2O4@CdS-Ag photocatalytic system with enhanced charge transfer for high-efficiency degradation of emerging pollutants

Bimetallic oxides with spinel structure show great prospects in the photocatalysis owing to many active sites. Herein, a novel 500NiCo₂O₄@CdS-5%Ag composite was fabricated via a feasible strategy. Interestingly, the combination with NiCo₂O₄ could significantly enhance the absorption ability of CdS for visible light. Benefiting from the formation of heterojunction structure between NiCo₂O₄ and CdS, the recombination of photogenerated electrons and holes was remarkably restrained. As an effective mediator, deposition of Ag could further promote the transfer of photogenerated charge carriers, thereby accelerating the reaction rate. Meanwhile, light absorption capacity of composite was also improved, owing to the surface plasmon resonance effect of metallic Ag. More importantly, 500NiCo₂O₄@CdS-5%Ag composite with great stability displayed an excellent performance in the photocatalytic degradation of OFX, and its highest removal efficiency was as high as 99.14%. Possible degradation pathways of OFX were given, and most of OFX could be degraded into CO₂, H₂O and other by-products with no toxicity. Significantly, the separation and transfer of photogenerated charge carriers followed indirect Z-scheme heterojunction mechanism. The O₂^-, OH and ¹O₂ were main active species in photocatalytic reaction system. All in all, current work inspired some new ideas for designing novel photocatalytic system in wastewater treatment.

S-scheme BiVO4/CQDs/β-FeOOH photocatalyst for efficient degradation of ofloxacin: Reactive oxygen species transformation mechanism insight

Photocatalysis technology exhibited promising application for advanced treatment of wastewater. Nevertheless, the design of efficient photocatalyst and the mechanism of free radicals in pollutant degradation still remained to be further investigated. Herein, BiVO₄/CQDs/β-FeOOH photocatalyst was fabricated by electrostatic self-assembly method, which exhibited the excellent photocatalytic performance. Under visible-light irradiation, the removal rate of ofloxacin by BiVO₄/CQDs/β-FeOOH (0.25 min^-1) was 1.93 times than pristine BiVO₄, and the removal efficiency in 15 min reached 99.21%. The perfect reusability of BiVO₄/CQDs/β-FeOOH was ascribed to the persistent catalytic active centers provided by the renewable surface oxygen vacancies on the β-FeOOH. As electron transfer channels, CQDs facilitated the transfer of BiVO₄ photogeneration electrons. The matched band structure allowed the construction of S-scheme heterojunctions, and the higher conduction band position was retained while the carrier separation was promoted. More importantly, this work firstly reported the phenomenon that the main reactive groups in the photocatalysis process would be directionally transformed with the change of pH conditions. Based on the analysis of capture and electron paramagnetic resonance experiments, ·O₂^- was the main free radicals to photodegrade OFL in neutral and alkaline conditions. However, when the solution pH turned into acidic, the photodegradation of OFL was dominated by ¹O₂. This innovative phenomenon was due to that acidic condition accelerated the reaction kinetics of spontaneous transformation of ·O₂^- to ¹O₂ and inhibited the direct oxidation of pollutants by ·O₂^-. Accordingly, this research could inspire theoretical study of free radical reaction and the design of S-scheme heterojunction photocatalysts.

Surface modified hexagonal upconversion nanoparticles for the development of competitive assay for biodetection

Up-conversion nanoparticles (UCNPs) of sodium yttrium fluoride with ytterbium and erbium ions as sensitizer and activator (β-NaYF₄/Yb³⁺/Er³⁺) have been synthesised by a solvothermal method. The synthesised particles were found to be highly uniform in size (~50 nm) and of hexagonal crystal phase producing strong up-conversion luminescence dominated in the green wavelength region. During the synthesis, photoluminescence properties of the reaction mixture were monitored at regular intervals to ensure the required particle size distribution and luminescence efficiency. The hydrophobic particles thus obtained were modified by coating with silica, yielding particles that were stable in aqueous media. The silica coated UCNPs were further modified with maleimide-polyethylene glycol-silane (mal-PEG-silane) to provide thiol reactive surface groups. The silanized, maleimide-bearing UCNPs were effective for conjugating to reductively-cleaved half antibodies against ofloxacin, a veterinary antibiotic, to produce photoluminescent nanobiosensors for its detection and quantification. The speed and minimum detection concentration (~10 nM) that we report for a competitive assay of ofloxacin in this study is promising for developing sensors for this and other biomolecules.

Efficient removal of selected fluoroquinolones from the aqueous environment using reduced magnetic graphene oxide/polyaniline composite

In the present study, reduced magnetic graphene oxide/polyaniline (RmGO/PANI) composite was synthesized via in-situ oxidative polymerization method. The synthesized RmGO/PANI was characterized by fourier transform infrared, scanning electron microscope, X-ray diffraction and energy dispersive X-rays techniques. The synthesized RmGO/PANI was explored as an adsorbent for the removal of moxifloxacin (MOX) and ofloxacin (OFL) from the aqueous samples. To inflate removal efficiency of RmGO/PANI, various adsorption effecting parameters such as effect of pH (2-12), RmGO/PANI dosage (2-14 mg), analyte concentration (150-525 μg mL^-1 for MOX and 15-40 μg mL^-1 for OFL), contact time (10-120 min) and temperature (293-343 K) were studied. Moreover, kinetic study exhibits that adsorption of MOX/OFL using RmGO/PANI follows pseudo second order kinetic model. The adsorption of MOX/OFL well-fitted to the Langmuir adsorption isotherm which demonstrates mono-layer adsorption of MOX/OFL on the surface of RmGO/PANI with maximum adsorption capacity of 47.7 mg g^-1 and 27.33 mg g^-1 for OFL and MOX, respectively. Thermodynamic study indicates that the adsorption process was spontaneous and exothermic in nature with the decrease of randomness of the system during the adsorption. On account of its practical applications, RmGO/PANI is considered an excellent adsorbent with 99% and 96% removal efficacy for MOX and OFL, respectively. The synthesized RmGO/PANI was reused for ten consecutive batches as well as applied to the real samples, maintain an excellent removal capacity. The reusable nature of RmGO/PANI declare this solid medium as an innovative adsorbent for real sample applications and wastewater treatment.

Co-degradation of ofloxacin and its impact on solid phase denitrification with polycaprolactone as carbon source

Solid-phase denitrification has been applied for advanced nitrogen removal from wastewater and can co-degrade emerging pollutants. Fluoroquinolones (FQs), broad-spectral antibiotic, are frequently detected in the effluent of conventional wastewater treatment plants. However, it remains unclear whether solid-phase denitrifying bacteria can remove FQs. Thus, this study investigated the removal capacity of ofloxacin (OFX) as a representative of FQs and the microbial community structures of denitrifying sludge acclimated to polycaprolactone and OFX. The Results indicate that OFX had a negative effect on denitrification performance. OFX was degraded, and a possible pathway was revealed based on ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. The dominant genera in the acclimated denitrifying sludge were Microbacterium, Simplicispira, Alicycliphilus, Reyranella, Sediminibacterium, Acidovorax and Thermomonas. Moreover, ABC transporters and cytochrome P450, related to multi-drug resistance and drug metabolism, were highly expressed in the acclimated sludge. This study provides novel insights into antibiotics control.