Gatifloxacin Research Articles

Dual Detection of Norfloxacin and Gatifloxacin by Excitation Tuning Strategy Based on Yellow Carbon Dots.

Fluoroquinolones (FQs) are widely used in hospitals, animal husbandry and aquaculture for the treatment of infectious diseases. However, overuse of FQs poses a potential threat to the environment and human. Detection of antibiotics is of great importance in various fields. In this paper, bright yellow fluorescence carbon dots (y-CDs) with quantum yield of 32% were synthesized via a simple and rapid microwave-assisted method using o-phenylenediamine and salicylic acid as raw materials. The fluorescence properties of y-CDs varied under different excitation wavelengths. It is discovered that the excitation wavelength is a critical factor to develop a dual functional fluorescence probe. Under selected excitation wavelength (355nm), y-CDs can realize dual detection of norfloxacin (NOR) and gatifloxacin (GAT) with good selectivity and high sensitivity in a "turn-on" mode. The detection limits of NOR and GAT are 0.0881 µM and 0.0125 µM, respectively. y-CDs prove practical application in the detection of NOR and GAT in milk and egg samples.

Simultaneous detection of moxifloxacin and gatifloxacin by Cu-TCPP/rGO electrochemical sensor

Moxifloxacin (MOX) and gatifloxacin (GAT) are structurally similar and possess close oxidation peak potentials, making it difficult for simultaneous detection by electrochemical methods. To address this, an electrochemical sensor was constructed with reduced graphene oxide (rGO) and copper porphyrin complex (Cu-TCPP), achieving signal amplification and simultaneous detection of MOX and GAT. The linear relation range from 5.00 to 600.00 μmol·L−1 for MOX (LOD is 1.34 μmol·L−1) and 10 to 300 μmol·L−1 for GAT (LOD is 0.59 μmol·L−1). When applied to water samples, it achieved recoveries of 100.09–112.02 % with a relative standard deviation (RSD) of less than 6 % for MOX, and 97.27–110.72 % with an RSD of less than 4 % for GAT. Further calculations indicated that the electro-oxidation of GAT involved two protons and two electrons.

Adsorption behavior and quantum chemical analysis of surface functionalized polystyrene nano-plastics on gatifloxacin.

In this paper, the adsorption of gatifloxacin (GAT) by three types of polystyrene nano-plastics (PSNPs), including 400 nm polystyrene (PS), amino-modified PS (PS-NH2), and carboxyl-modified PS (PS-COOH) was studied and the adsorption mechanism were assessed. Experimental findings revealed that the equilibrium adsorption capacity of PSNPs to GAT followed the order PS-NH2 > PS-COOH > PS. The adsorption was regulated by both physical and chemical mechanisms, with intra-particle and external diffusion jointly controlling the adsorption rate. The adsorption process was heterogeneous, spontaneous, and entropy-driven. Sodium chloride (NaCl), alginic acid, copper ions (Cu2+), and zinc ions (Zn2+) inhibited adsorption, with Cu2+ and Zn2+ having the strongest effect on PS-NH2. Theoretical computations indicated that π-π and electrostatic interactions dominated PS adsorption of GAT, while PS-COOH and PS-NH2 adsorbed GAT through electrostatic interactions, hydrogen bonds, and van der Waals (vdW) forces. The surface electrostatic potential of PS-COOH and PS-NH2 was considerably higher than that of PS, with the maximum vdW penetration distance of GAT-PS-NH2 being 1.20 Å. This study's findings provide a theoretical foundation for the migration and synergistic removal of antibiotics, micro-plastics (MPs), and nano-plastics (NPs).

Roles of direct and indirect photodegradation in the photochemical fates of three 3rd generation fluoroquinolones

Fluoroquinolones (FQs) are widely prescribed antibiotics that are commonly detected in aquatic environments, but the persistence, fates, and ecotoxicities of new generation FQs have yet to be fully investigated. We investigated the direct and indirect (hydroxyl radical (·OH), singlet oxygen (O21), and excited stated of organic matter (3CDOM*)) photodegradation of three 3rd generation FQs, moxifloxacin (MOX), gatifloxacin (GAT), and sparfloxacin (SPAR). The photodegradation rates and photolytic quantum yields (ΦFQ) of the FQs depended on their dissociation species at different pH in a range of 1×10−4 to 1×10−3 M mol-photon-1. Unlike MOX and GAT whose zwitterions had the highest ΦFQ, the anionic form of SPAR had the highest ΦFQ. The k·OH,FQ values were in the order of: k·OH,SPAR > k·OH,GAT ≈ k·OH,MOX with the 1010M−1s−1 order of magnitude. The kO21,FQ values were in the order of: kO21,SPAR (∼108M−1s−1) > kO21,MOX (∼107M−1s−1) > >> kO21,GAT (insignificant). Higher kLC*3,FQ values were observed for MOX (109 to 1010M−1s−1) compared to GAT and SPAR (108 to 109M−1s−1). The zwitterions had the highest reactivities with ·OH and the lowest reactivities with O21 and 3CDOM*. Reactions with ·OH enhanced the formation of transformation products (TPs) from decarboxylation and sidechain oxidation pathways, whereas reactions with O21 and 3CDOM* enhanced the formation of TPs from sidechain oxidation pathways. Some of the TPs were predicted to exhibit aquatic ecotoxicity and environmental persistence. The half-lives of the FQs were estimated to be 0.42 to 0.67 h for MOX and SPAR, and 4.6 to 4.9 h for GAT. Their half-lives and main photochemical fates depended on the surface water pH and water column depth. These results highlight the key roles that photodegradation plays in removing new generation FQs from aquatic environments, though this might lead to the formation of TPs that are harmful to aquatic ecosystems.

Dual drug molecular salt of antibacterial: Formulation, physicochemical properties study, theoretical calculations and evaluation of antibacterial activity

A molecular salt combined with the fluoroquinolone antibacterial gatifloxacin (GAT) and the sulfonamides antibacterial sulfamerazine (SMZ) is designed and synthesized successfully, which is the first report of the dual-drug cocrystallization of gatifloxacin. The precise structure of the acquired molecule salt GAT-SMZ has been characterized via single crystal X-ray diffraction and other techniques. Single crystal diffraction analysis displays that due to the transfer of protons from SMZ to GAT, the molecular salt of GAT-SMZ is formed, and the supramolecular network is dominated by charge-assisted one-dimensional hydrogen bond chain and two-dimensional accumulation layer in the crystal. Such structural feature endows molecular salt with superior physicochemical properties, including enhanced solubility and permeability. More importantly, the superior pharmaceutical performances of the dual-drug salt resulted in enhanced antibacterial activity against the tested strains. These observations are strongly supported by theoretical studies based on Hirshfeld surface and molecular docking analyses. Thus, this contribution not only highlights the validity of combining theory with experiment to drive the problem of physicochemical properties of drugs through co-crystallization methods, but also fills in the previous studies gatifloxacin dual-drug salt synergistic antibacterial research blank.

Pharmacokinetic Analysis of Gatifloxacin and Dexamethasone in Rabbit Ocular Biofluid Using a Sensitive and Selective LC-MS/MS Method.

Bacterial keratitis (BK) is an infection that causes inflammation of the cornea and, if severe, can result in blindness. Topical fluoroquinolones combined with corticosteroids have been shown to be useful in the treatment of BK. A rapid, selective, and sensitive bioanalytical method for simultaneous quantification of Gatifloxacin (GAT) and Dexamethasone (DEX) has been developed and validated using tandem mass spectrometry (LC-MS/MS). Optimal separation was accomplished in under 5 min using an Agilent Zorbax C18 column (100 mm × 4.6 mm, 3.5 μm). The mobile phase was composed of a blend of 0.2% formic acid in triple distilled water and methanol with a flow rate of 0.65 mL/min in isocratic mode. GAT and DEX were detected in positive electrospray ionization multiple reaction monitoring mode (MRM), and the retention time was found to be at 1.64 and 2.93 min, respectively. The linearity of GAT and DEX was found to be in the range of 1.56-400 ng mL-1 with good precision and accuracy. The method was validated according to USFDA regulatory guidelines. The validated method was effectively utilized for preclinical pharmacokinetic analysis of GAT and DEX in rabbit tear fluid following the topical application of a commercial formulation.

Radical to non-radical conversion during PMS activation triggered by optimized electronic structure: Orientational regulation of oxidation pathway for water remediation

The orientational regulation of non-radical pathways is significant in the peroxymonosulfate (PMS)-based AOP for practical potential, but remains challenge. Here, the Se-doped Co(OH)2 hollow spheres (CoHS-Se-CR) were designed for PMS activation to rapidly degrade gatifloxacin (GAT) antibiotic, with over 95 % GAT removal in 20 min. DFT and experimental trials reveal the downshift of d-band center of Co 3d and O − H bond stretch in PMS via Se doping of Co(OH)2. The active HSO5•− generated via the breaking of O–H bond triggers the radical to the non-radical conversion of the degradation mechanism, dominated by 1O2 and assisted by electron transport process. Both oxygen vacancy and Se(Ⅵ) were involved in 1O2 generation and Co(III)/Co(II) cycle. The CoHS-Se-CR/PMS system showed high efficiency for GAT removal in a wide pH range and strong resistance to anionic interference. This work provides a new strategy for designing PMS activators to construct orientational non-radical AOP.

Monitoring concentration of quinolones in human serum by fluorescence and colorimetric analysis based on red carbon dots

Bacterial infections are common and predominant concern after surgical operation despite surgical techniques have improved significantly. Monitoring of antibiotics concentration can provide critical feedback in clinical treatment so as to achieve rapid and effective treatment and avoid bacterial resistance. Quinolones (QNs) are synthetic broad-spectrum antibiotics to treat bacterial infections. In this work, we developed a high-yield (50.67 %) red-emitting carbon dots (R-CDs) as fluorescence probe for sensing of three quinolone antibiotics, ofloxacin (OFL), gatifloxacin (GAT), and ciprofloxacin (CIP). R-CDs were prepared in 30 min using tartaric acid and o-phenylenediamine as precursors via an economical and efficient microwave-assisted method. At excitation of 339 nm, R-CDs show sensing performance towards OFL, GAT, CIP. Ofloxacin can be detected in the range of 0.25–30 μM with limit of detection (LOD) of 27.01 nM. Detection concentration range of gatifloxacin is between 0.25–40 μM and LOD is 23.73 nM. Ciprofloxacin can be detected in the range of 0.75–35 μM with LOD of 75.23 nM. A smartphone-assisted analysis platform was developed based on colorimetric phenomenon which applicable in three quinolones concentration monitoring in human serum. This research setup an efficient and promising therapeutic drug monitoring method for clinical treatment and widen the applications of carbon dots.

A ratiometric fluorescent probe for the determination of quinolone antibiotics in milk based on N and S co-doped carbon quantum dots

Quinolone antibiotics are widely used to prevent and treat diseases caused by bacterial infection. However, overuse of antibiotics may lead to their residue in the environment and food, posing potential threats to human health. In this study, a ratiometric fluorescent probe based on nitrogen and sulfur co-doped carbon quantum dots (N, S-CQDs) was synthesized, which can realize the detection of moxifloxacin (MXF), gatifloxacin (GAT) and ofloxacin (OFX) in milk. After addition of these antibiotics, the fluorescence at 440 nm originating from N, S-CQDs was significantly quenched due to the fluorescence resonance energy transfer (FRET), while the fluorescence at 525 nm (MXF), 500 nm (GAT) and 515 nm (OFX) were enhanced due to aggregation induced emission (AIE). The fluorescence changes were completed within 30 s and stabilized for at least 14 days. Good linear relationships between the fluorescence intensity ratios (F525/F440 for MXF, F500/F440 for GAT and F515/F440 for OFX) and the antibiotic concentrations ranging from 0.1 to 100 mg L−1 were obtained, with R2 above 0.99. The limits of quantitation were in the range of 1.67–6.20 μg L−1, and MXF, GAT and OFX can be well identified by linear discriminant analysis. The probe enabled quantitative analysis of MXF, GAT and OFX in milk samples, with recoveries ranging from 82% to 107%. A test strip based on the ratiometric fluorescence probe was successfully applied for the detection of MXF and GAT in milk in combination with a smartphone. This method exerted high specificity and sensitivity, which has the potential to achieve in-site detection of MXF, GAT and OFX in milk.

Enhanced photocatalytic degradation of sulfathiazole via dual-ligand Zr-MOFs: A porphyrin and pyrene-based energy transfer

Energy transfer (EnT) has been identified as an effective method to facilitate charge separation and improve photocatalytic performance. However, EnT has rarely been used in the photocatalytic degradation of pollutants. In this study, the arrangement of organic ligands in metal–organic frameworks (MOFs) was precisely engineered to enable efficient EnT among ligands. The compounds TCx-TB10 (X = 3, 4, 5, 6, 7, 8) were synthesized through solvothermal and technique, employing 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP) and 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy) as ligands for the photocatalytic degradation of sulfathiazole (STZ). Among these, TC4-TB10 achieved the highest degradation efficiency, with a removal rate of 93.09 % for STZ. When similar photocatalytic tests were conducted on ranitidine (RAN), nizatidine (NZT), tetracycline (TC), and gatifloxacin (GAT), TC4-TB10 continued to demonstrate outstanding photocatalytic activity, showing removal efficiencies of 95.85 %, 95.30 %, 86.50 %, and 85.85 %, respectively. The effective EnT mechanism from TBAPy to TCPP in TC4-TB10 was confirmed through fluorescence and photocatalytic oxidation studies. Furthermore, singlet oxygen (1O2) was identified as the main reactive oxygen species involved. Proposed degradation pathways for STZ were outlined based on DFT calculations and UPLC-HRMS analysis. The Toxicity Estimation Software Tool (T.E.S.T.) was used to predict that STZ and its degradation products would largely exhibit low or no toxicity. Notably, 1O2 demonstrated remarkable resistance to interference, not being affected by most inorganic ions and humic acid (HA), which allowed TC4-TB10 to maintain high STZ removal rates even in real water samples. This research extends the potential applications and offers important insights into employing the EnT process for enhancing the photocatalytic capabilities of MOFs.

Green method by National Environmental Methods Index and Eco-Scale Assessment for evaluation of gatifloxacin-based product by HPLC.

The literature reveals gaps in the availability of green analytical methods for assessing products containing gatifloxacin (GFX), a fluoroquinolone. Presently, method development is supported by tools such as the National Environmental Methods Index (NEMI) and Eco-Scale Assessment (ESA), which offer objective insights into the environmental friendliness of analytical procedures. The objective of this work was to develop and validate a green method by the NEMI and ESA to quantify GFX in eye drops using HPLC. The method utilized a C8 column (4.6 × 150 mm, 5 μm), with a mobile phase of purified water containing 2% acetic acid and ethanol (70:30, v/v). The injection volume was 10 μL and the flow rate was 0.7 mL/min in isocratic mode at 25°C, with detection performed at 292 nm. The method demonstrated linearity in the range of 2-20 μg/mL, and precision at intra-day (relative standard deviation [RSD] 1.44%), inter-day (RSD 3.45%), and inter-analyst (RSD 2.04%) levels. It was selective regarding the adjuvants of the final product (eye drops) and under forced degradation conditions. The method was accurate (recovery 101.07%) and robust. The retention time for GFX was approximately 3.5 min. The greenness of the method, as evaluated by the NEMI, showed four green quadrants, and by ESA, it achieved a score of 88.

A green and economically efficient adsorbent made by longan seed for the treatment of fluoroquinolone antibiotics in water

In this study, a green and economically efficient adsorbent was prepared from discarded longan seed. Hydrochloric acid-modified longan seed biochar (HNSB), as the final product, possesses excellent adsorption properties. BET characterization of HNSB demonstrates impressive porous properties with a specific surface area of 420.58 m2/g. Batch adsorption experiments were conducted with gatifloxacin (GAT), norfloxacin (NOR), and lomefloxacin (LOM) as representatives of typical fluoroquinolone antibiotics (FQs). The adsorption capacity of HNSB for FQs exceeded 40% of that of commercial activated carbon. The sustained effective time of HNSB dynamic adsorption for treating high concentrations of FQs wastewater was more than 20 h. Adsorption kinetics and isotherms were fitted by the pseudo-second-order model and the Langmuir model. The adsorption mechanism includes the pore-filling effect, electrostatic attraction, reduction reaction, hydrogen bonding, π-π interaction, and hydrophobicity. This study provides an economic and feasible strategy for the engineering application of agricultural wastes in pharmaceutical wastewater treatment.

C3N5/TiO2 S-scheme heterojunction film for efficient photocatalytic removal of gatifloxacin

Constructing efficient and recyclable photocatalysts is a promising method to solve antibiotic pollution. Herein, we designed and fabricated C3N5/TiO2 S-scheme heterojunction film on flexible Ti foils through the self-absorbed. The C3N5 nanosheet was tightly anchored on the TiO2 arrays with an intimate TiO2-C3N5 interface. The heterojunction exhibited an excellent photocatalytic performance and the reaction rate constant of photocatalytic degradation gatifloxacin (GAT) over C3N5/TiO2 up to 0.0252 min−1, which was 1.85 folds that of pure TiO2 arrays. The outstanding photocatalytic performance was ascribed to high-efficiency transfer and separation of photoinduced carriers and highly hydrophilic surfaces. The removal rate of GAT under different parameters suggested that the as-prepared C3N5/TiO2 has high adaptability. Moreover, the three possible GAT degradation pathways over C3N5/TiO2 were proposed based on the results of the liquid chromatograph-mass spectrometer (LC-MS) and density functional theory (DFT). Finally, a reasonable S-scheme heterojunction was proposed based on the results of experiments and DFT calculation. This work may help in designing an S-scheme heterojunction for the degradation of antibiotic pollutants.

Oxidation of selected fluoroquinolones by ferrate(VI) in water: Kinetics, mechanism, effects of constituents, and reaction pathways

In this work, the oxidation of gatifloxacin (GAT), fleroxacin (FLE) and enoxacin (ENO) in aqueous solution by ferrate (Fe(VI)) was systemically investigated. Weak alkaline and high oxidant doses were favorable for the reaction. The pseudosecond-order rate constants were 0.18055, 0.29162, and 0.05476 L/(mg·min), and the activation energies were 25.13, 15.25, and 11.30 kJ/mol at pH = 8.00 and n(Fe(VI)):n(GAT) = 30:1, n(Fe(VI)):n(FLE) = 20:1, n(Fe(VI)):n(ENO) = 40:1 and a temperature of 25 °C. The maximum degradation rates of the GAT, FLE and ENO were 96.72%, 98.48% and 94.12%, respectively, well simulated by Response Surface Methodology. During the oxidation, the contribution of hydroxyl radicals (HO•) varied with time, whereas the final contribution was approximately 20% at 30 min. The removal efficiency was inhibited by anions by less than 10%, and cations by less than 25%, and significantly inhibited by high concentrations of humic acid. Moreover, two or three dominant reaction pathways were predicted, and the ring cleavages of quinolone and piperazine were mainly achieved through decarboxylation, demethlation and hydroxylation, and some pathways ended up with monocyclic chemicals, which were harmless to aquatic animals and plants. Theoretical calculations further proved that the reactions between FeO4− and neutral fluoroquinolone antibiotics were the major reactions. This work illustrates that Fe(VI) can efficiently remove fluoroquinolone antibiotics (FQs) in aqueous environments, and the results may contribute to the treatment of wastewater containing trace antibiotics and Fe(VI) chemistry.

The New Gatifloxacin‐p‐Coumaric Acid Cocrystalline Form for Enhanced In Vitro Pharmaceutical Properties While Improving Oral Bioavailability and Antibacterial Activity

AbstractA molecular salification strategy of double majorization and synergistic improvement efficacy has been submitted, aiming at getting utmost out of the advantages of phenolic acid nutrient p‐coumaric acid (CMA) to improve the pharmaceutical properties of antibacterial agent gatifloxacin (GAT). The present strategy applies the saltforming capacity of CMA interacting with GAT to self‐assemble a new molecular salt, thereby improving the in vitro physicochemical performances of GAT and further perfecting its in vivo pharmacokinetics, as well as enhancing the antibacterial effectiveness of GAT. Guided by this strategy, the novel GAT‐phenolic acid nutrient molecular salt, named GAT‐CMA, is directionally prepared with its precise structure analyzed by single crystal X‐ray diffraction. The results show that proton transfer occurs between the piperazine N of GAT and the carboxyl group of CMA, thus altering the intermolecular interaction mode of GAT itself, breaking the relatively stable zwitterionic state, displaying a circular stacking structure dominated by [GAT+‐CMA−], which is conducive to the improvement of GAT's physicochemical properties. Interestingly, the enhanced properties in vitro effectively translate into pharmacokinetic merits in vivo, showing improved bioavailability. More importantly, due to the synergistic antibacterial effect of GAT and CMA, the antibacterial ability of molecular salt has also been effectively enhanced.

Covalent assembly synthesis of covalent organic framework and MXene based composite for the adsorption of fluoroquinolones

Widespread use of fluoroquinolones (FQs) leads to its continuous excretion and release into the environment, resulting in the accumulation in water, animal-derived food etc., and posing a threat to environment and humans. Thus, the development of highly efficient FQs removal methods is of great significance. Herein, a composite (COF@MXene) was manufactured using a covalent assembly synthesis strategy by connecting covalent organic frameworks (COF) and NH2-MXene through a Schiff-base reaction. COF@MXene had the advantages of both COF and MXene, not only had good crystallinity, thermal stability and rich functional group properties, but also had high protein exclusion ability (Exclusion efficiency>97%) and good adsorption capacities for FQs including ciprofloxacin (CIP), lomefloxacin (LOM), moxifloxacin (MOX), gatifloxacin (GAT) and levofloxacin (LEV). The maximal adsorption capacities for them ranged from 54.63 to 147.91 mg·g−1, which were higher than those of COF (15.99–64.06 mg·g−1) and MXene (27.58–33.92 mg·g−1). The adsorption experimental data of adsorption isotherm and kinetics separately followed the Langmuir and pseudo-second-order models. Through density functional theory (DFT), Forcite calculation, UV-Vis and XPS analyses, pore size selectivity, electrostatic and hydrogen bond interactions were determined as the main driving forces for FQs adsorption. Finally, COF@MXene coupled with HPLC-DAD was employed for the analysis of FQs from water, egg and drug samples, and the recoveries were satisfactory. This work reported a covalent assembly synthesis strategy for the preparation of COF@MXene composite for FQs removal. This approach may establish a viable route for gentle fabrication of COF and MXene based composites for various applications.

Gatifloxacin Loaded Nano Lipid Carriers for the Management of Bacterial Conjunctivitis.

Bacterial conjunctivitis (BC) entails inflammation of the ocular mucous membrane. Early effective treatment of BC can prevent the spread of the infection to the intraocular tissues, which could lead to bacterial endophthalmitis or serious visual disability. In 2003, gatifloxacin (GTX) eyedrops were introduced as a new broad-spectrum fluoroquinolone to treat BC. Subsequently, GTX use was extended to other ocular bacterial infections. However, due to precorneal loss and poor ocular bioavailability, frequent administration of the commercial eyedrops is necessary, leading to poor patient compliance. Thus, the goal of the current investigation was to formulate GTX in a lipid-based drug delivery system to overcome the challenges with the existing marketed eyedrops and, thus, improve the management of bacterial conjunctivitis. GTX-NLCs and SLNs were formulated with a hot homogenization-probe sonication method. The lead GTX-NLC formulation was characterized and assessed for in vitro drug release, antimicrobial efficacy (against methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa), and ex vivo permeation. The lead formulation exhibited desired physicochemical characteristics, an extended release of GTX over a 12 h period, and was stable over three months at the three storage conditions (refrigerated, room temperature, and accelerated). The transcorneal flux and permeability of GTX from the GTX-NLC formulation were 5.5- and 6.0-fold higher in comparison to the commercial eyedrops and exhibited a similar in vitro antibacterial activity. Therefore, GTX-NLCs could serve as an alternative drug delivery platform to improve treatment outcomes in BC.

Effectiveness of collagen and gatifloxacin in improving the healing and antibacterial activities of gellan gum hydrogel films as dressing materials

The demand for advanced wound care products is rapidly increasing nowadays. In this study, gellan gum/collagen (GG/C) hydrogel films containing gatifloxacin (GAT) were developed to investigate their properties as wound dressing materials. ATR-FTIR, swelling, water content, water vapor transmission rate (WVTR), and thermal properties were investigated. The mechanical properties of the materials were tested in dry and wet conditions to understand the performance of the materials after exposure to wound exudate. Drug release by Franz diffusion was measured with all samples showing 100 % cumulative drug release after 40 min. Strong antibacterial activities against Staphylococcus aureus and Staphylococcus epidermis were observed for Gram-positive bacteria, while Escherichia coli and Pseudomonas aeruginosa were observed for Gram-negative bacteria. The in-vivo cytotoxicity of GG/C-GAT was assessed by wound contraction in rats, which was 95 % for GG/C-GAT01. Hematoxylin and eosin and Masson's trichrome staining revealed the appearance of fresh full epidermis and granulation tissue, indicating that all wounds had passed through the proliferation phase. The results demonstrate the promising properties of the materials to be used as dressing materials.

Reactive species regulation by interlayered Na+/H+ of titanate nanotubes decorated Co(OH)2 hollow microsphere for peroxymonosulfate activation and gatifloxacin degradation

Emerging organic pollutants (EOPs) in water are of great concern due to their high environmental risk, so urgent technologies are needed for effective removal of those pollutants. Herein, a heterogeneous advanced oxidation process (AOP) of peroxymonosulfate (PMS) activation by functional material was developed for degradation of a typical antibiotic, gatifloxacin (GAT). The reactive species including sulfate radical (SO4•−) and singlet oxygen (1O2) in this AOP were regulated by interlayered ions (Na+/H+) of titanate nanotubes that supported on Co(OH)2 hollow microsphere. Both the Na-type (NaTi-CoHS) and H-type (HTi-CoHS) materials achieved efficient PMS activation for GAT degradation, and HTi-CoHS even exhibited a relatively high degradation efficiency of 96.6% within 5 min. Co(OH)2 was considered the key component for generation of SO4•− after PMS activation, while hydrogen titanate nanotubes (H-TNTs) promoted the transformation of peroxysulfate radical (SO5•−) to 1O2 by hydrogen bond interaction. Therefore, when the interlayer ion of TNTs transformed from Na+ to H+, more 1O2 was produced for organic pollutant degradation. H-TNTs with lower symmetry preferred to adsorb PMS molecules to achieve interlayer electron transport through hydrogen bonding, rather than electrostatic interaction of Na+ for Na-TNTs. In addition, the degradation pathway of GAT mainly proceeded by the cleavage of C–N bond at the 8 N site of the piperazine ring, which was confirmed by condensed Fukui index and mass spectrographic analysis. This work gives new sights into the regulation of reactive species in AOPs by the composition of material and promotes the understanding of pollutant degradation mechanisms in water treatment process.

Internal electric field-assisted copper ions chelated polydopamine/titanium dioxide nano-thin film heterojunctions activate peroxymonosulfate under visible light to catalyze degradation of gatifloxacin: Theoretical calculations and biotoxicity analysis

The combination of photocatalysis and peroxymonosulfate (PMS) activation is considered effective in treating organic pollutants in water; however, the photocatalysts currently used to activate PMS are primarily in powder form, which cause secondary contamination because they are difficult to recycle. In this study, copper-ion-chelated polydopamine/titanium dioxide (Cu-PDA/TiO2) nanofilm were prepared for PMS activation on fluorine-doped tin oxide substrates using hydrothermal and in-situ self-polymerization methods. The results showed that Cu-PDA/TiO2 + PMS + Vis degraded 94.8% of gatifloxacin (GAT) within 60 min, and the reaction rate constant reached 4.928 × 10-2 min−1, which was 6.25 and 4.04 folds higher than that of TiO2 + PMS + Vis (0.789 × 10-2 min−1) and PDA/TiO2 + PMS + Vis (1.219 × 10-2 min−1), respectively. The Cu-PDA/TiO2 nanofilm is easily recyclable and activates PMS to degrade GAT with no inferior performance, unlike the powder-based photocatalysts, and simultaneously maintains outstanding stability, which is highly suitable for applications in real aqueous environments. Biotoxicity experiments were conducted using E. coli, S. aureus, and mung bean sprouts as experimental subjects, and the results showed that the Cu-PDA/TiO2 + PMS + Vis system had excellent detoxification ability. In addition, a detailed investigation of the formation mechanism of step-scheme (S-scheme) Cu-PDA/TiO2 nanofilm heterojunctions was conducted by density functional theory (DFT) calculations and in-situ X-ray photoelectron spectroscopy (XPS). Finally, a specific process for activating PMS to degrade GAT was proposed, which provides a novel photocatalysts for practical applications in aqueous pollution.