Photothermal theranostics with glutathione depletion and enhanced reactive oxygen species generation for efficient antibacterial treatment.

Drug-resistant bacteria caused by the abuse of antibiotics have brought great challenges to antimicrobial therapy. Herein an antibiotic-free polydopamine (PDA) modified metal-organic framework (PDA-FDM-23) with photothermal-enhanced chemodynamic effect was developed for synergistic antibacterial treatment. The PDA-FDM-23 antibacterial agent exhibited high peroxidase-like activity. Moreover, the process was significantly accelerated by consuming glutathione (GSH) to generate more efficient oxidizing Cu+. In addition, the photothermal therapy (PTT) derived from PDA improved the chemodynamic therapy (CDT) activity triggering a reactive oxygen species explosion. This PTT-enhanced CDT strategy illustrated 100% antibacterial efficiency against both Staphylococcus aureus and Escherichia coli. Cytotoxicity and hemolysis analyses fully demonstrated the excellent biocompatibility of PDA-FDM-23. Overall, our work highlighted the strong peroxidase catalytic activity, excellent GSH consumption and photothermal performance of PDA-FDM-23, providing a new strategy for antibiotic-free reactive oxygen species (ROS) synergistic sterilization.

Magnetic N-doped 3D graphene-like framework carbon for extraction of cephalexin monohydrate and ceftiofur hydrochloride.

Magnetic N-doped 3D graphene-like framework carbon (Fe3O4@N-3DFC) was prepared via direct pyrolysis of sodium citrate and further hydrothermal reaction, and employed in the extraction of two cephalosporin antibiotics including cephalexin monohydrate and ceftiofur hydrochloride. The scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction were employed to confirm the successful synthesis of 3DFC-based adsorbents (3DFCs) including 3DFC, Fe3O4@3DFC and Fe3O4@N-3DFC. Fe3O4@N-3DFC sorbent with 3D graphene-like honeycomb architecture combined magnetic and N doping shows the attractive features including graphene carbon sheets, hierarchical porous structure, good wettability and higher surface affinity for cephalosporin antibiotics. Furthermore, the comparison of extraction efficiency with raw 3DFC and Fe3O4@3DFC sorbent also confirmed the superiority of Fe3O4@N-3DFC sorbent. Under optimized conditions, good linearity lines were obtained with the determination coefficients from 0.9953 to 0.9995. The limit of detections were in the range of 0.20-0.45 µg L-1 and 0.03-0.10 µg L-1 for cephalexin and ceftiofur, respectively. The spiked extraction recoveries were between 81.59% and 98.35% with the relative standard deviation values less than 6.98%. Combined with high performance liquid chromatography, Fe3O4@N-3DFC based magnetic solid-phase extraction was successfully applied in river water and zebrafish samples analysis.

Bioaccumulation investigation of bisphenol A in HepG2 cells and zebrafishes enabled by cobalt magnetic polystyrene microsphere derived carbon based magnetic solid-phase extraction.

A magnetic solid-phase extraction (MSPE) technique coupled with high performance liquid chromatography (HPLC) was developed and used for bioaccumulation investigation of bisphenol A (BPA) in HepG2 cells and zebrafishes. Cobalt magnetic polystyrene microsphere derived carbon (C-Co@PST) as an adsorbent was prepared by in situ polymerization reaction and further annealing treatment. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction were employed to confirm successful synthesis of C-Co@PST. A series of extraction parameters including the amount of the sorbent, the type of elute, extraction time and elution time were investigated to achieve high extraction efficiency. C-Co@PST based MSPE combined with HPLC was successfully established for bioaccumulation research of BPA in living creatures. It was found that the bioconcentration values of BPA in HepG2 cells underwent an increase, then a decrease, and finally reached an equilibrium level of 11.60 µg kg-1 at 8 h. The concentration of BPA in zebrafishes increased ranging from 6.05 µg kg-1 to 31.84 µg kg-1 over a culture time from 1 h to 12 h. Furthermore, linear and exponential models were employed to analyse the bioconcentration variation of BPA in organisms over the exposure time. Mathematical models have been developed to predict the transfer characteristics of BPA.

Preparation of magnetic carbonized polyaniline nanotube and its adsorption behaviors of xanthene colorants in beverage and fish samples.

Magnetic carbonized polyaniline nanotube composite (Fe3O4@c-PANI) was synthesized via a self-assemble approach for the extraction and determination of three xanthene colorants including erythrosine B (EB), phloxine B (PB) and rhodamine B (RB). The scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy and X-ray diffraction were adopted to confirm the successful synthesis of Fe3O4@c-PANI. When Fe3O4@c-PANI was applied for extracting three xanthene colorants, satisfactory extraction recoveries ranging from 89.48% to 94.15% were obtained with the relative standard deviation value of 1.09%-4.01%. Compared with Fe3O4, c-PANI and commercial adsorbents, Fe3O4@c-PANI achieved better retraction recovery for three colorants. Furthermore, adsorption kinetics and isotherms studies were analyzed to prove the adsorption mechanism of anionic and cationic colorants on Fe3O4@c-PANI. The graphite layers and pyrrole groups of the as-prepared composite can provide hydrophobic, π-π and hydrogen bonding interaction with xanthene colorants. Fe3O4 nanoparticles played dual-functional roles contributing to the separation and adsorption. Coupled with high performance liquid chromatography, the established magnetic solid phase extraction method was used for the analysis of beverage and fish samples.

A porous polyaniline nanotube sorbent for solid-phase extraction of the fluorescent reaction product of reactive oxygen species in cells, and its determination by HPLC.

A method is described for extracting and detecting the fluorescent reaction product (2',7'-dichlorofluorescein, DCF) that is formed by reaction of reactive oxygen species (ROS) with dichlorodihydrofluorescein diacetate (DCFH-DA). DCF is extracted by using porous polyaniline nanotubes (PPN) which have a large specific surface and pore volume which favor the adsorption capacity. Additional attractive features include an appropriate pore size distribution, hydrophobic surface, and electron-attracting groups which contribute to DCF adsorption. A variety of methods was applied to characterize the morphology of PPN. Under optimal conditions and by performing DCF in 0.08-1.0 µM concentrations, the correlation coefficient of the calibration plot is 0.999. The limits of detection for standard DCF solutions is 20 nM. Compared with commercial sorbents for solid-phase extraction (SPE) such as commercially available carbon or Welchrom® C18, the use of the new sorbent results in better retraction recovery (92%) and longer reuse times (30 times). Doxorubicin and X-ray radiation were used to externally stimulate the ROS production in HepG2 and Hela cells. ROS was stabled by DCFH-DA and quantified by DCF. Following SPE, DCF was detected by HPLC and the concentration ROS was calculated. Graphical abstract ᅟ.

ß-Cyclodextrin-modified three-dimensional graphene oxide-wrapped melamine foam for the solid-phase extraction of flavonoids.

A new three-dimensional graphene oxide-wrapped melamine foam was prepared and used as a solid-phase extraction substrate. ß-Cyclodextrin was fabricated onto the surface of three-dimensional graphene oxide-wrapped melamine foam by a chemical covalent interaction. In view of a specific surface area and a large delocalized π electron system of graphene oxide, in combination with a hydrophobic interior cavity and a hydrophilic peripheral face of ß-cyclodextrin, the prepared extraction material was proposed for the determination of flavonoids. In order to demonstrate the extraction properties of the as-prepared material, the adsorption energies were theoretically calculated based on periodic density functional theory. Static-state and dynamic-state binding experiments were also investigated, which revealed the monolayer coverage of flavonoids onto the ß-cyclodextrin/graphene oxide-wrapped melamine foams through the chemical adsorption. 1 H NMR spectroscopy indicated the formation of flavonoids-ß-cyclodextrin inclusion complexes. Under the optimum conditions, the proposed method exhibited acceptable linear ranges (2-200 µg/L for rutin and quercetin-3-O-rhamnoside; 5-200 µg/L for quercetin) with correlation coefficients ranging from 0.9979 to 0.9994. The batch-to-batch reproducibility (n = 5) was 3.5-6.8%. Finally, the as-established method was satisfactorily applied for the determination of flavonoids in Lycium barbarum (Goji) samples with relative recoveries in the range of 77.9-102.6%.