Ofloxacin Research Articles

Unveiling the structure–activity relationships of ofloxacin degradation by Co3O4-activated peroxymonosulfate: From microstructures to exposed facets

As a fluoroquinolone antimicrobial agent, ofloxacin (OFX) has been widely used, consequently causing serious damage to the ecological environment. Advanced oxidation processes based on persulfate activation (SR-AOPs) are widely applied to degrade stubborn organic contaminants in wastewater treatment. Co3O4 is being extensively investigated as a promising persulfate catalyst in SR-AOPs. In this work, four Co3O4 polycrystals with specific morphologies were synthesized and used to activate peroxymonosulfate (PMS) for OFX degradation. The obtained samples and corresponding precursors were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and N2 adsorption/desorption isotherms. Experimental results showed that 30 mg·L-1 OFX could be completely removed in the lamella-like Co3O4/PMS system within 30 min under ordinary conditions. The underlying degradation mechanism was elaborated by high-resolution TEM (HRTEM) combined with density functional theory (DFT) calculations. Based on quenching experiments and the electron paramagnetic resonance (EPR) technique, sulfate radicals were identified as the dominant reactive oxygen species (ROS) in the lamella-like Co3O4/PMS system, and superoxide radicals, hydroxyl radicals, and singlet oxygen made minor contributions to the degradation of OFX. Possible degradation pathways were proposed based on DFT calculations and Fukui theory and confirmed by ultrahigh-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UHPLC-QTOF/MS). Furthermore, quantitative structure–activity relationship (QSAR) prediction was used to evaluate the developmental toxicity of the corresponding intermediates.

Synergistic mineralization of ofloxacin in electro-Fenton process with BDD anode: Reactivity and mechanism

This study aimed at exploring the performance of the electro-Fenton (EF) process with a boron-doped diamond (BDD) anode and an electrochemically exfoliated graphene-based cathode (EEGr), for removal of antibiotic ofloxacin (OFLO) from contaminated water. Compared with anodic oxidation (AO) process with BDD anode, the EF process with BDD anode (EF-BDD) could improve the decay kinetics of OFLO by 1.4–2.6 times and reduce the disposal cost by 28 %–41 %. Removal efficiency of TOC in EF-BDD process under 4.2 mA cm−2 was better than in AO process under 8.3 mA cm−2, pointing out that the cost effectiveness of the EF process for mineralization of OFLO under low current density conditions. This advantage is due to the simultaneous formation of homogeneous (•OH) and heterogeneous (BDD(•OH)) hydroxyl radicals in the process. The synergistic factor of •OH and BDD(•OH) for mineralization of OFLO decreased with the current density rising from 4.2 (0.28) to 16.6 mA cm−2 (-0.08). Decay kinetics of OFLO in the EF-BDD and AO were more converging under higher current densities owing to the production of large amount of BDD(•OH). In the EF-BDD, a trade-off should be considered between accumulated BDD(•OH) on the surface of BDD anode and H2O2 generation on the cathode. Absolute rate constant for oxidation of OFLO by •OH (kOFLO) was calculated to be 3.86 × 109 M−1 s−1. Evolution of carboxylic acids and inorganic ions as well as toxicity assessment were followed during the treatment of OFLO solutions. Results obtained proved that the EF-BDD process is outstanding for oxidative degradation of OFLO thanks to the synergistic effect of •OH and BDD(•OH). These very strong oxidants being non-selective, this result can be extended to the treatment of antibiotic organic pollutants.

DEVELOPMENT, CHARACTERIZATION AND ANTIBACTERIAL PROPERTIES OF SILVER NANOPARTICLES LOADED SODIUM ALGINATE/XANTHAN GUM MICROBEADS FOR DRUG DELIVERY APPLICATIONS

Objective: The aim of this study is to create pH-responsive drug carriers, which are useful because they have the potential to improve treatment efficacy by controlling the release rate of ofloxacin from the polymer matrix. Methods: In the first step, silver nanoparticles (Ag NPs) were synthesized from silver nitrate using leaf extract of phyllanthus urinaria L as a reducing agent. In the second step, Ag-NPs-loaded polymeric microbeads were synthesized using sodium alginate (SA) and xanthan gum (XG) for controlled release of ofloxacin (OFLX). The developed microbeads were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-RD), transition electron microscopy (TEM), Selected Area Electron Diffraction (SAED), and scanning electron microscopy (SEM). Swelling and in vitro release studies were performed at pH 2.0 and 7.4 at 37 °C. The in vitro antibacterial activity of microbeads were tested against S. mutans, K. pneumoniae, and B. subtilis. The release kinetics and mechanism were analyzed by fitting the release data into different kinetic models and the korsmeyer-peppas equation. Results: FTIR confirms the generation of silver nanoparticle and also the generation of polymeric microbeads. SEM studies reveal the developed microbeads are spherical in shape with rough surfaces. TEM studies reveal the size of 20-40 nm. XRD analysis reveals the molecular dispersion of DOX and the presence of silver nanoparticles in the polymeric matrix. Investigations of in vitro release and swelling studies show that the developed microbeads are relatively suitable for intestinal drug delivery because higher release rate was observed at pH 7.4. The developed microbead follows non-Fickian diffusion drug release mechanism. The created samples exhibited antimicrobial activity against S. mutans, K. pneumoniae, and B. subtilis. Conclusion: The results indicate that microbeads containing OFLX and silver nanoparticles are effective drug-delivery vehicles. A further warrant is required for the use of manufactured microbeads in drug delivery applications.

ZnO Promoted Persulfate Activation in Discharge Plasma System for Ofloxacin Degradation

This paper aims to investigate the promotion of persulfate (PS) activation by ZnO in discharge plasma systems for the degradation of ofloxacin (OFX). Scanning electron microscopy and transmission electron microscopy showed that ZnO nanoparticles were successfully prepared by a hydrothermal method. With an increase in the PS dosage, the removal efficiency of OFX first increased and then decreased. With an increase in the ZnO dosage, the removal efficiency of OFX showed a similar trend. Under the optimum 595 mg/L PS dosage and 295 mg/L ZnO dosage, the removal efficiency of OFX by plasma, plasma/ZnO, and plasma/ZnO/PS systems reached 53.6%, 82.8%, and 98.9%, respectively. Increasing the input power was beneficial to the degradation of OFX. ESR results showed that the addition of ZnO could further stimulate PS to produce more ·OH and ·SO4− than that of plasma alone. The capture agent experiment proved that ·OH, ·SO4−, ·O2−, and 1O2 all participated in the degradation of OFX. A total organic carbon (TOC) removal of 49.6% was obtained in the plasma/ZnO/PS system. Based on liquid chromatography-mass spectrometry (LC-MS) and the Toxicity Estimation Software Tool (TEST), degradation pathways and toxicity were analyzed. Compared to other technologies, it can be concluded that the plasma/ZnO/PS system is a promising technology for pollutant remediation.

Occurrence and Distribution of Antibiotics in a Tropical Mariculture Area of Hainan, China: Implications for Risk Assessment and Management.

With the rapid global demand for mariculture products in recent years, the use of antibiotics has increased intensively in the mariculture area. Current research on antibiotic residues in mariculture environments is limited, and less information is available on the presence of antibiotics in tropical waters, limiting a comprehensive understanding of their environmental presence and risk. Therefore, this study investigated the environmental occurrence and distribution of 50 antibiotics in the near-shore aquaculture waters of Fengjia Bay. A total of 21 antibiotics were detected in 12 sampling sites, including 11 quinolones, 5 sulfonamides, 4 tetracyclines, and 1 chloramphenicol; the quinolones pyrimethamine (PIP), delafloxacin (DAN), flurofloxacin (FLE), ciprofloxacin (CIP), norfloxacin (NOR), pefloxacin (PEF), enrofloxacin (ENO), and minocycline (MNO) of the tetracycline class were detected in all sampling points. The total antibiotic residue concentrations in the study area ranged from 153.6 to 1550.8 ng/L, the tetracycline antibiotics were detected in the range of 10 to 1344.7 ng/L, and the chloramphenicol antibiotics were detected in the range of 0 to 106.9 ng/L. The detected concentrations of quinolones ranged from 81.3 to 136.1 ng/L, and the residual concentrations of sulfonamide antibiotics ranged from 0 to 313.7 ng/L. The correlation analysis with environmental factors revealed that pH, temperature, conductivity, salinity, NH3--N, and total phosphorus had a strong correlation with antibiotics. Based on PCA analysis, the main sources of antibiotic pollution in the area were determined to be the discharge of farming wastewater and domestic sewage. The ecological risk assessment indicated that the residual antibiotics in the water environment of the near-shore waters of Fengjiawan had certain risks to the ecosystem. Among them, CIP, NOR, sulfamethoxazole (TMP), ofloxacin (OFL), enrofloxacin (ENO), sulfamethoxazole (SMX), and FLE showed medium to high risk. Therefore, it is recommended to regulate the use of these antibiotics and the discharge and treatment of culturing wastewater, and measures should be taken to reduce the environmental pollution caused by antibiotics and to monitor the long-term ecological risk of antibiotics in the region. Overall, our results provide an important reference for understanding the distribution and ecological risk of antibiotics in Fengjiawan.

Bio-Electrochemical Cell Assisted Production of Biogenic Palladium Nanoparticles with Shewanella oneidensis MR-1 Bacteria for the Catalytic Removal of Ofloxacin (OFX) and Doxycycline (DOX) Micropollutants in Pharmaceutical Industry Wastewaters

In this study, biogenic-palladium nanoparticles (bio-Pd NPs) with Shewanella oneidensis MR-1 bacteria as a heterostructure bio-electrochemical cell catalyts was examined during catalytic degradation process in the efficient removal of Ofloxacin (OFX) and Doxycycline (DOX) micropollutants from pharmaceutical industry wastewater plant, İzmir, Turkey. Different pH values (3.0, 4.0, 6.0, 7.0, 9.0 and 11.0), increasing micropollutants (OFX and DOX) concentrations (5 mg/l, 15 mg/l, 30 mg/l and 45 mg/l), increasing Bio-Pd NPs concentrations (5 mg/l, 10 mg/l, 20 mg/l, 30 mg/l, 40 mg/l and 60 mg/l), different Bio-Pd NPs/cell dry weight (CDW) mass ratios (5/5, 6/4, 7/3, 8/2, 9/1, 1/9, 2/8, 3/7 and 4/6), increasing recycle times (1., 2., 3., 4., 5., 6. and 7.) was operated during catalytic degradation process in the efficient removals of OFX and DOX micropollutants in pharmaceutical industry wastewater. The characteristics of the synthesized NPs were assessed using Diffuse reflectance UV-Vis spectra (DRS), Energy-dispersive X-ray (EDX), Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Inductively coupled plasma mass spectrometry (ICP-MS), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) analyses, respectively. The catalytic activity was first assessed by the degradation of methyl orange. The Bio-NPs showing the highest catalytic activity were selected for the removal of micropollutants (OFX and DOX) from secondary treated municipal wastewater. The catalytic degradation mechanisms of bio-Pd NPs with Shewanella oneidensis MR-1 bacteria as a heterostructure bio-electrochemical cell catalysts and the reaction kinetics of OFX and DOX micropollutants were evaluated in pharmaceutical industry wastewater during catalytic degradation process. ANOVA statistical analysis was used for all experimental samples. The maximum 99% OFX removal efficiency was obtained catalytic removals with bio-electrochemical cell assisted production of bio-Pd NPs with Shewanella oneidensis MR-1 bacteria bio-electrochemical cell catalyts in pharmaceutical industry wastewater, at 30 mg/l OFX concentration, 40 mg/l Bio-Pd NPs concentration, Bio-Pd NPs/CDW mass ratio=6/4, after 24 h catalytic degradation time, at pH=6.0, at 25oC, respectively. The maximum 99% DOX removal efficiency was observed catalytic removals with bio-electrochemical cell assisted production of bio-Pd NPs with Shewanella oneidensis MR-1 bacteria bio-electrochemical cell catalyts in pharmaceutical industry wastewater, at 30 mg/l DOX concentration, 40 mg/l Bio-Pd NPs concentration, Bio-Pd NPs/CDW mass ratio=6/4, after 24 h catalytic degradation time, at pH=9.0, at 25oC, respectively. Finally, the combination of a simple, easy operation preparation process, excellent performance and cost effective, makes this Bio-Pd NPs with Shewanella oneidensis MR-1 bacteria bio-electrochemical cell catalyts a promising option during catalytic degradation process in pharmaceutical industry wastewater treatment.

Facile synthesis of a novel Zn2Ti3O8 aerogel with porous structure for high-efficient degradation of antibiotics under simulated sunlight

Photocatalytic degradation, as advanced oxidation methods with high efficiency and good stability, is considered a promising method to alleviate antibiotic pollution. Herein, we prepared a novel Zn2Ti3O8 aerogel by a simple sol-gel method based on the advantages of the abundant pore structure of aerogel material and the high photocatalytic activity of zinc titanate. The Zn2Ti3O8 aerogel shows a typical homogeneous structure and low band gap width (3.32 eV), which could achieve photogenerated carrier separation and transfer under simulated sunlight. The material has high specific surface area (120.1 m2/g) and abundant pore structure, which can provide multiple diffusion channels for pollutant molecules and generate massive reactive sites. In the absence of cocatalysts, the prepared Zn2Ti3O8 aerogel can achieve more than 95% degradation efficiency for 50 mg/L of ofloxacin (OFL) contaminated solution in 60 min. Electrochemical impedance spectroscopy (EIS) and transient photocurrent test results display that Zn2Ti3O8 aerogel exhibits the highest photocurrent density and lower charge transfer resistance. Meanwhile, the results of density functional theory (DFT) are consistent with the characterization results of electron spin resonance (ESR). The ·OH and ·O2− generated in the catalytic reaction could attack OFL molecules from different regions to achieve the purpose of decomposition. We believe that the as-prepared Zn2Ti3O8 aerogels are expected to be used in the practical treatment of catalytic degradation of OFL and other antibiotic pollutants.

Aerobic granular sludge formation and stability in enhanced biological phosphorus removal system under antibiotics pressure: Performance, granulation mechanism, and microbial successions

Wastewater containing antibiotics can pose a significant threat to biological wastewater treatment processes. This study investigated the establishment and stable operation of enhanced biological phosphorus removal (EBPR) by aerobic granular sludge (AGS) under mixed stress conditions induced by tetracycline (TC), sulfamethoxazole (SMX), ofloxacin (OFL), and roxithromycin (ROX). The results show that the AGS system was efficient in removing TP (98.0%), COD (96.1%), and NH4+-N (99.6%). The average removal efficiencies of the four antibiotics were 79.17% (TC), 70.86% (SMX), 25.73% (OFL), and 88.93% (ROX), respectively. The microorganisms in the AGS system secreted more polysaccharides, which contributed to the reactor's tolerance to antibiotics and facilitated granulation by enhancing the production of protein, particularly loosely bound protein. Illumina MiSeq sequencing revealed that putative phosphate accumulating organisms (PAOs)-related genera (Pseudomonas and Flavobacterium) were enormously beneficial to the mature AGS for TP removal. Based on the analysis of extracellular polymeric substances, extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, and microbial community, a three-stage granulation mechanism was proposed including adaption to the stress environment, formation of early aggregates and maturation of PAOs enriched microbial granules. Overall, the study demonstrated the stability of EBPR-AGS under mixed antibiotics pressure, providing insight into the granulation mechanism and the potential use of AGS for wastewater treatment containing antibiotics.

Spatial Distribution and Risk Assessment of Antibiotics in 15 Pharmaceutical Plants in the Pearl River Delta.

Pharmaceutical plants are an essential source of antibiotics emitted into the aqueous environment. The monitoring of target antibiotics in pharmaceutical plants through various regions is vital to optimize contaminant release. The occurrence, distribution, removal, and ecological risk of 30 kinds of selected antibiotics in 15 pharmaceutical plants in the Pearl River Delta (PRD) were investigated in this study. Lincomycin (LIN) showed the highest concentration (up to 56,258.3 ng/L) in the pharmaceutical plant influents from Zhongshan city. Norfloxacin (NFX) showed a higher detection frequency than other antibiotics. In addition, the spatial distribution of antibiotics in pharmaceutical plants showed significant differences, with higher concentrations of total antibiotics found in pharmaceutical plant influents in Shenzhen City than those of different regions in PRD. The treatment processes adopted by pharmaceutical plants were commonly ineffective in removing antibiotics, with only 26.7% of antibiotics being effectively removed (average removal greater than 70%), while 55.6% of antibiotics had removal rates of below 60%. The anaerobic/anoxic/oxic (AAO)-membrane bioreactor (MBR) combined process exhibited better treatment performance than the single treatment process. Sulfamethoxazole (SMX), ofloxacin (OFL), erythromycin-H2O (ETM-H2O), sulfadiazine (SDZ), sulfamethazine (SMZ), norfloxacin (NFX), and ciprofloxacin (CIP) in pharmaceutical plant effluents posed high or moderate ecological risk and deserve particular attention.

Cytochrome P450-mediated co-metabolism of fluoroquinolones by Haematococcus lacustris for simultaneously promoting astaxanthin and lipid accumulation

Microalgae-based antibiotic removal treatment has attracted attention because of its low carbon and sustainable advantages. The microalgal co-metabolism system with a suitable carbon source leads to enhanced performance of pollutant removal. However, currently, limited knowledge is available for the removal of fluoroquinolone using a microalgae-mediated co-metabolism system. In this study, we first investigated that the biotic processes by alga Haematococcus lacustris in the co-metabolism system by adding glycerol would be the main contributors responsible for the removal of 10 mg/L ofloxacin (OFL) with the efficiency of 79.73% and the removal of 10 mg/L enrofloxacin (ENR) with the efficiency of 54.10%, respectively. Furthermore, we found that pyruvate from glycerol was converted into substrates and precursors, thereby resulting in the significant accumulations of microalgal astaxanthin and lipid. The astaxanthin content of H. lacustris was achieved at 4.81% and 4.69% treated with OFL and ENR in the presence of glycerol, with 16.04% and 14.55% of lipid content, respectively. The proposed metabolites and pathways were identified to plausibly explain the biodegradation of fluoroquinolone by H. lacustris. The molecular analyses demonstrated that cytochrome P450 (CYP450) enzymes are responsible for the biodegradation of fluoroquinolone, and it was further verified that fluoroquinolones might insert into CYP450 to finally form an efficient and tight binding conformation by molecular dynamic simulation. These findings provide a microalgae-based route for feasible and sustainable biodegradation of antibiotics using a co-metabolism strategy comprising glycerol as a carbon source, with the synergistic accumulation of valuable products.

Development of New Targeted Nanotherapy Combined with Magneto-Fluorescent Nanoparticles against Colorectal Cancer.

The need for non-invasive therapies capable of conserving drug efficiency and stability while having specific targetability against colorectal cancer (CRC), has made nanoparticles preferable vehicles and principal building blocks for the development of complex and multi-action anti-tumoral approaches. For that purpose, we herein report the production of a combinatory anti-tumoral nanotherapy using the production of a new targeting towards CRC lines. To do so, Magneto-fluorescent NANO3 nanoparticles were used as nanocarriers for a combination of the drugs doxorubicin (DOX) and ofloxacin (OFLO). NANO3 nanoparticles' surface was modified with two different targeting agents, a newly synthesized (anti-CA IX acetazolamide derivative (AZM-SH)) and a commercially available (anti-epidermal growth factor receptor (EGFR), Cetuximab). The cytotoxicity revealed that only DOX-containing nanosystems showed significant and even competitive cytotoxicity when compared to that of free DOX. Interestingly, surface modification with AZM-SH promoted an increased cellular uptake in the HCT116 cell line, surpassing even those functionalized with Cetuximab. The results show that the new target has high potential to be used as a nanotherapy agent for CRC cells, surpassing commercial targets. As a proof-of-concept, an oral administration form of NANO3 systems was successfully combined with Eudragit® enteric coating and studied under extreme conditions.

Comparative analysis of SilA-laccase mediated degradation of ciprofloxacin, norfloxacin and ofloxacin and interpretation of the possible catalytic mechanism

Fluoroquinolones (FQs) are the most commonly used antimicrobial drugs and regardless of their advantages in the healthcare sector, the pollution of these antimicrobial drugs in the environment has big concerns about human and environmental health. The presence of these antibiotic drugs even at the lowest concentrations in the environment has resulted in the emergence and spread of antibiotic resistance. Hence, it is necessary to remediate these pollutants from the environment. Previously alkaline laccase (SilA) from Streptomyces ipomoeae has been demonstrated to show degrading potentials against two of the FQs, Ciprofloxacin (CIP) and Norfloxacin (NOR); however, the molecular mechanism was not elucidated in detail. In this study, we have analyzed the possible molecular catalytic mechanism of FQ degrading SilA-laccase for the degradation of the FQs, CIP, NOR and Ofloxacin (OFL) using three-dimensional protein structure modeling, molecular docking and molecular dynamic (MD) studies. The comparative protein sequence analysis revealed the presence of tetrapeptide conserved catalytic motif, His102-X-His104-Gly105. After evaluating the active site of the enzyme in depth using CDD, COACH and S-site tools, we have identified the catalytic triad composed of three conserved amino acid residues, His102, Val103 and Tyr108 with which ligands interacted during the catalysis process. By analyzing the MD trajectories, it is revealed that the highest degradation potential of SilA is for CIP followed by NOR and OFL. Ultimately, this study provides the possible comparative catalytic mechanism for the degradation of CIP, NOR and OFL by the SilA enzyme. Communicated by Ramaswamy H. Sarma

Lysine-functionalized layered double hydroxides for the antibiotics’ efficient removal: Controllable fabrication via BBD model and removing mechanism

Lysine-functionalized layered double hydroxides (LDHs) controllable fabrication based on Box-Behnken Design (BBD) model was investigated in this study. Ly @ FeZn presented stable and efficient removal performance for Ciprofloxacin (CIP) removal. Characterizations analysis and batch tests results showed that Ly @ FeZn had significantly different adsorption performance towards CIP and Ofloxacin (OFL). The highest adsorption capacity of CIP was 193.83 mg/g, while that of OFL was 62.12 mg/g due to the bulky structure of OFL, which posed steric hindrance for its interaction with the adsorbent. Furthermore, adsorption kinetics of CIP were better simulated with the pseudo-first-order kinetic model, while that of OFL was better described by the pseudo-second-order. The adsorption thermodynamics of Ly @ FeZn for CIP indicated that the adsorption processes were exothermal, feasible and spontaneous. It was worth noting that the adsorption mechanism of Ly @ FeZn for CIP were the synergistic reaction of surface complexation and interlayer adsorption. Also, this study provided a promising adsorbent for efficient antibiotics removal in practical water remediation.

Photo-transformation of acetaminophen sensitized by fluoroquinolones in the presence of bromide

Fluoroquinolones (FQs) are a class of antibiotics with emerging concern. This study investigated the photochemical properties of two representative FQs, i.e., norfloxacin (NORF) and ofloxacin (OFLO). Results showed that both FQs could sensitize the photo-transformation of acetaminophen under UV-A irradiation, during which excited triplet state (3FQ*) was the main active species. In the presence of 3 mM Br‾, the photolysis rate of acetaminophen increased by 56.3% and 113.5% in the solutions with 10 μM NORF and OFLO, respectively. Such an effect was ascribed to the generation of reactive bromine species (RBS), which was verified by 3,5-dimethyl-1H-pyrazole (DMPZ) probing approach. 3FQ* reacts with acetaminophen through one-electron transfer, producing radical intermediates which then couple to each other. Presence of Br‾ did not lead to the formation of brominated products but the same coupling products, which suggests that radical bromine species, rather than free bromine, were responsible for the accelerated acetaminophen transformation. According to the identified reaction products and assisted with the theoretical computation, the transformation pathways of acetaminophen under UV-A irradiation were proposed. The results reported herein suggest that sunlight-driven reactions of FQs and Br‾ may influence the transformation of coexisting pollutants in surface water environments.

Knowledge of The HILIC Retention Behaviors of Two Quinolone Antibiotics on Sulfobetaine-Type Zwitterionic Stationary Phases

Fluoroquinolones treat infections of the urinary, respiratory, gastrointestinal, skin, bone, and joint systems. This article describes the development of the hydrophilic interaction liquid chromatography (ZIC-HILIC) method to determine norfl oxacin and ofl oxacin retention characteristics. Separation of all analytes was accomplished using ZIC-HILIC1 and ZIC-HILIC4 columns. The mobile phase was 40 mM sodium acetate water solution in acetonitrile pumped at a 0.7 mL/min fl ow rate. The infl uence of acetonitrile concentration, the presence of salt in the mobile phase, and pH on the retention of norfl oxacin and ofl oxacin in the HILIC mode were investigated in this study. When using ZIC-HILIC columns, it was discovered that the retention factors of the analytes were inversely proportional to the amount of water present in the mobile phase, which is representative of a conventional hydrophilic partitioning mechanism. The ZIC-HILIC based strategies described in this article represent a signifi cant step toward more sensitive drug analysis. We observed that zwitterionic materials could govern the separation of materials, as shown by the infl uence of the chain length between the zwitterion groups, which contributed to the explanation of the variation in the retention period of the materials to be separated.

Construction of Covalent Organic Framework Nanofiber Membranes for Efficient Adsorption of Antibiotics.

Techniques beyond crystal engineering are critical for manufacturing covalent organic frameworks (COFs) and to explore them for advanced applications. However, COFs are normally obtained as insoluble, unmeltable, and thus nonprocessible microcrystalline powders. Therefore, it is a significant challenge to implement COFs into larger architectures and structural control on different length scales. Herein, a facile strategy is presented to prepare flexible COF nanofiber membranes by in-situ growth of COFs on polyacrylonitrile (PAN) nanofiber substrates via a reversible polycondensation-termination approach. The obtained PAN@COF nanofiber membranes with vertically aligned COF nanoplates combine a large functional surface with efficient mass transport, thus making it a promising adsorbent, for example, for water purification. The antibiotic pollutant ofloxacin (OFX) is removed from water with a superior absorption capacity of ≈236mg g-1 and removal efficiency as high as 98%. The here presented in-situ growth of COFs on nanofiber membranes can be extended to various Schiff base-derived COF materials with different compositions, providing a highly efficient way to construct flexible COF-based membranes for several applications.

Spatial and temporal distribution characteristics of antibiotics and heavy metals in the Yitong River basin and ecological risk assessment

Due to rapid socioeconomic development, antibiotic pollution and heavy metal pollution are receiving increasing amounts of attention. Both antibiotics and heavy metals in the environment are persistent and toxic, and the interactions between the pollutants create potential long-term hazards for the ecological environment and human health as mixed pollutants. In this study, the surface water of the Yitong River in Changchun was used as the research object, and the hazards associated with antibiotics and heavy metals in the surface water were assessed by analyzing the spatial and temporal distribution characteristics of antibiotics and heavy metals and by using ecological risk assessment and human health risk assessment models. The results showed that ofloxacin (OFL) and norfloxacin (NOR) varied seasonally according to the seasonal climate, with total concentrations ranging from 17.65 to 902.47 ng/L and ND to 260.49 ng/L for OFL and NOR, respectively, and from 8.30 to 120.40 μg/L, 1.52 to 113.41 μg/L and 0.03 to 0.04 μg/L for copper (Cu), zinc (Zn) and cadmium (Cd), respectively. In terms of spatial distribution, the concentration of antibiotics in the urban sections, which had intensive human activities, was higher than that in the suburban sections, while the concentration of heavy metals in the suburban sections, which had intensive agricultural operations, was greater than that in the urban section. Ecological risk evaluation showed that NOR and OFL were present in the water bodies at a high-risk level, Cd was at a low pollution level, and the heavy metal Cd was the primary pollutant associated with health risks toward for adults and children, and it was mainly at a medium risk level. Additionally, both antibiotics and heavy metals posed higher health risks for children than for adults.

Three developed spectrophotometric methods for determination of a mixture of ofloxacin and ornidazole; application of greenness assessment tools

This work is dedicated to the greenness estimation of three proposed spectrophotometric techniques [e.g., ratio difference (RD), mean centering of ratio spectra (MCR) and continuous wavelet transform of ratio spectra (CWT)] for the determination of a binary combination named Ofloxacin (OFL) and Ornidazole (ORN). Applying the green analytical chemistry methods to assess the proposed methods has widely attained the analytical community care. The greenness assessment was performed via three evaluation approaches; the “Analytical Eco-Scale”, the “National Environmental Method Index” (NEMI) and “Green Analytical Procedure Index” (GAPI). Following the examination of the zero spectrum of OFL and ORN, it is observed that OFL and ORN spectra are overlapped, so they can be detected by the methods mentioned previously. The ratio difference method was carried out at wavelengths of 294.6 nm and 265.6 nm for OFL, 292 nm and 315 nm for ORN. The linear range was (2–15 µg/mL) for OFL and (3–30 µg/mL) for ORN. The MCR method based on the use of mean centered ratio spectra in dual steps and calculating the second ratio spectra mean centered values at 294.6 nm for OFL and 315 nm for ORN. The continuous wavelet transformation which carried out using MATLAB at wavelengths of 265 nm for OFL and 306 for ORN. These techniques were intended for the binary mixture analysis in bulk powder and pharmaceutical formulations with high recoveries. The developed methods were validated according to ICH guidelines. All techniques were statistically compared to either an official method for OFL or a reported method for ORN and the results indicate that there were not any significant differences.

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.

Development of Electro-Reduced AgNPs/MnO2/rGO Composite toward a Robust Sensor for the Simultaneous Determination of Piroxicam and Ofloxacin

The presented investigation attempts to offer a robust, simple, cost-effective AgNPs/MnO2/ErGO composite to simultaneously determine piroxicam (PRX) and ofloxacin (OFX). The material is prepared via facile depositions of MnO2 and Ag species on graphene oxide followed by an electroreduction. The achieved composite (i.e., AgNPs/MnO2/ErGO) exhibits intimate interfacial contacts, promoting charge transfer and mass transport. Consequently, the sample AgNPs/MnO2/ErGO-decorated glassy carbon (GC) electrode (denoted AgNPs/MnO2/ErGO-GCE) signifies a remarkable capability to monitor PRX and OFX using differential pulse adsorptive anodic stripping voltammetry (DP-AdASV) technique. Indeed, the sensitivity values (MLD) have been found to be 0.063 and 0.077 μM for PRX and OFX, respectively, while maintaining high sensitivity, selectivity, repeatability, and stability. Impressively, the obtained electrode endows a remarkable performance in the determination of real antibiotic and water samples, which are compatible with the HPLC analysis, paving the way toward a high-performance electrochemical sensor for antibiotics.