Use of Polyetheretherketone as a Material for Solid Phase Extraction of Hydroxylated Metabolites of Polycyclic Aromatic Hydrocarbons in Human Urine

Antimicrobial Peptide Conjugated on Graphene Oxide-Containing Sulfonated Polyetheretherketone Substrate for Effective Antibacterial Activities against Staphylococcus aureus

In the present study, the antimicrobial peptide nisin was successfully conjugated onto the surface of sulfonated polyetheretherketone (SPEEK), which was decorated with graphene oxide (GO) to investigate its biofilm resistance and antibacterial properties. The PEEK was activated with sulfuric acid, resulting in a porous structure. The GO deposition fully covered the porous SPEEK specimen. The nisin conjugation was accomplished using the crosslinker 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) through a dip-coating method. The surface micrographs of the SPEEK-GO-nisin sample indicated that nisin formed discrete islets on the flat GO surface, allowing both the GO and nisin to perform a bactericidal effect. The developed materials were tested for bactericidal efficacy against Staphylococcus aureus (S. aureus). The SPEEK-GO-nisin sample had the highest antibacterial activity with an inhibition zone diameter of 27 mm, which was larger than those of the SPEEK-nisin (19 mm) and SPEEK-GO (10 mm) samples. Conversely, no inhibitory zone was observed for the PEEK and SPEEK samples. The surface micrographs of the bacteria-loaded SPEEK-GO-nisin sample demonstrated no bacterial adhesion and no biofilm formation. The SPEEK-nisin and SPEEK-GO samples showed some bacterial attachment, whereas the pure PEEK and SPEEK samples had abundant bacterial colonies and thick biofilm formation. These results confirmed the good biofilm resistance and antibacterial efficacy of the SPEEK-GO-nisin sample, which is promising for implantable orthopedic applications.

[Application progress of covalent organic framework materials in extraction of toxic and harmful substances]

Toxic and hazardous substances constitute a category of compounds that are potentially hazardous to humans, other organisms, and the environment. These substances include pesticides (benzoylureas, pyrethroids, neonicotinoids), persistent organic pollutants (polycyclic aromatic hydrocarbons, polychlorinated biphenyls, perfluorinated compounds), plasticizers (phthalate esters, phenolic endocrine disruptors), medicines (sulfonamides, non-steroid anti-inflammatory drugs, tetracyclines, fluoroquinone antibiotics), heterocyclic aromatic amines, algal toxins, and radioactive substances. Discharge of these toxic and harmful substances, as well as their possible persistence and bioaccumulation, pose a major risk to human health, often to the extent of being life-threatening. Therefore, it is important to analyze and detect toxic and hazardous substances in the environment, drinking water, food, and daily commodities. Sample pretreatment is an imperative step in most of the currently used analytical methods, especially in the analysis of trace toxic and harmful substances in complex samples. An efficient and fast sample pretreatment technology not only helps improve the sensitivity, selectivity, reproducibility, and accuracy of analytical methods, but also avoids contamination of the analytical instruments and even damages the performance and working life of instruments. Sample pretreatment techniques widely used in the extraction of toxic and hazardous substances include solid-phase extraction (SPE), solid-phase microextraction (SPME), and dispersed solid-phase extraction (DSPE). The adsorbent material plays a key role in these pretreatment techniques, thereby determining their selectivity and efficiency. In recent years, covalent organic frameworks (COFs) have attracted increasing attention in sample pretreatment. COFs represent an exciting new class of porous crystalline materials constructed via the strong covalent bonding of organic building units through a reversible condensation reaction. COFs present four advantages: (1) precise control over structure type and pore size by consideration of the target molecular structure based on the connectivity and shape of the building units; (2) post-synthetic modification for chemical optimization of the pore interior toward optimized interaction with the target; (3) straightforward scalable synthesis; (4) feasible formation of composites with magnetic nanoparticles, carbon nanotubes, graphene, silica, etc., which is beneficial to enhance the performance of COFs and meet the requirement of diverse pretreatment technologies. Because of the well-defined crystalline porous structures and tailored functionalities, COFs have excellent potential for use in target extraction. However, some issues need to be addressed for the application of COFs in the extraction of toxic and hazardous substances. (1) For the sample matrix, most of the reported COFs are highly hydrophobic, which limits their dispersibility in water-based samples, leading to poor extraction performance. COFs with good dispersibility in water-based samples are urgently required. (2) Besides, COFs rely on hydrophobic interaction, size repulsion, π-π stacking, and Van der Waals forces to extract target substances, but they are not effective for some polar targets. Thus, it is necessary to develop COFs with high affinity for polar toxic and hazardous substances. (3) Methods for the synthesis of COFs have evolved from solvothermal methods to room-temperature methods, mechanical grinding, microwave-assisted synthesis, ion thermal methods, etc. Most of the existing methods are time-consuming, laborious, and environmentally unfriendly. The starting materials are too expensive to prepare COFs in large quantities. More effort is required to improve the synthesis efficiency and overcome the obstacles in the application of COFs for extraction. This article summarizes and reviews the research progress in COFs toward the extraction of toxic and hazardous substances in recent years. Finally, the application prospects of COFs in this field are summarized, which serves as a reference for further research into pretreatment technologies based on COFs.

Aromaticity-Driven Access to Cycloalkyl-Fused Naphthalenes

We report the efficient synthesis of cycloalkyl-fused naphthalenes through the [4 + 2]-cycloaddtion/decarboxylative aromatization of alkyne-tethered aryne insertion adducts. These scaffolds were difficult to synthesize using conventional reactions. The reaction proceeds via the formation of a benzopyrylium intermediate followed by intramolecular [4 + 2] cycloaddition and a subsequent decarboxylation pathway. This method is also compatible with allene-tethered substrates to afford similar products. In addition, the one-pot synthesis of polysubstituted naphthalenes via aryne insertion/benzannulation has also been developed in good yield.

Facile fabrication of composited solid phase microextraction thin membranes for sensitive detections of trace hydroxylated polycyclic aromatic hydrocarbons in human urine

Solid phase microextraction (SPME) has potential to be used for the high-performance enrichments of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs), which are important biomarkers of PAH exposure. By choosing suitable adsorbent, it is conducive to fabricate new-type of SPME device for improved extraction efficiencies towards OH-PAHs. In this study, a novel method of surface solvent evaporation has been proposed to fabricate SPME thin membrane, integrating the advantages of polydimethylsiloxane (PDMS) and different porous adsorbents. The powdery metal organic framework (Uio66-NH₂), porous polymer (powdery polymer aerogel, PPA) and ordered mesoporous carbon (OMC) have been chosen as typical adsorbents and fabricated as thin membranes successfully, indicating the universality of the proposed method for membrane fabrication. Comparing the extraction efficiencies of three prepared membranes towards OH-PAHs, the OMC-PDMS membrane has demonstrated best enrichment efficiencies. The OMC-PDMS membrane was used for the enrichments of trace OH-PAHs in human urine of both smokers and nonsmokers, combining with liquid chromatographic tandem mass spectrometry (LC-MS/MS). The detection limits were in the range of 0.15-0.39 ng L^-1, and satisfactory recoveries were found to be 82.1%-115%. It can be seen that the universal strategy to fabricate SPME membrane is helpful to achieve broad-spectrum or selective enrichments of target analytes from complex matrix by simple modulation of membrane components.

Supramolecular solvent-based high-throughput sample treatment platform for the biomonitoring of PAH metabolites in urine by liquid chromatography-tandem mass spectrometry

Monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs), present in human urine at trace concentrations (viz. from ng L^-1 to μg L^-1), are considered the main biomarkers of human exposure to PAHs. In this work, we report a simple and high-throughput sample treatment platform to facilitate the biomonitoring of OH-PAHs by making it easier, greener and most cost-effective. This platform is based on the integration of analyte extraction and sample cleanup in a single step by the use of supramolecular solvents with restricted access properties (SUPRAS-RAM). The SUPRAS was spontaneously formed in situ in the urine by the addition of a colloidal suspension of decanoic acid in THF. Metabolites from naphthalene, fluorene, phenanthrene and pyrene were quantitatively extracted (absolute recoveries in the range 91-109%). Polysaccharides and proteins in the urine were excluded from extraction by physical and chemical mechanisms, which allowed the direct analysis of the SUPRAS extract by liquid chromatography tandem mass spectrometry. Absolute matrix effects for OH-PAHs were in the range 92-103%. Method quantification limits for OH-PAHs, without the need for evaporation of the SUPRAS extracts, were in the interval 1.0-6.7 ng L^-1. The precision, evaluated in terms of repeatability and reproducibility, varied between 1.1 and 13.8%. The method was successfully applied to the analysis of urine from 16 smoking and non-smoking volunteers. Both analytical and operational features of this method make it suitable to evaluate human exposure to PAHs.

Coupling of micro-solid-phase extraction and internal extractive electrospray ionization mass spectrometry for ultra-sensitive detection of 1-hydroxypyrene and papaverine in human urine samples

Quantification of ultra-trace analytes in complex biological samples using micro-solid-phase extraction followed by direct detection with internal extractive electrospray ionization mass spectrometry (μSPE-iEESI-MS) was demonstrated. 1-Hydroxypyrene (1-OHP) and papaverine at attomole levels in human raw urine samples were analyzed under negative and positive ion detection mode, respectively. The μSPE was simply prepared by packing a disposable syringe filter with octadecyl carbon chain (C18)-bonded micro silica particles, which were then treated as the "bulk sample" after the analytes were efficiently enriched by the C18 particles. Under the optimized experimental conditions, the analytes were readily eluted by isopropanol/water (80/20, V/V) at a high voltage of ± 4.0 kV, producing analyte ions under ambient conditions. The limit of detection (LOD) was 0.02 pg/L (9.2 amol) for 1-hydroxypyrene and 0.02 pg/L (5.9 amol) for papaverine. The acceptable linearity (R² > 0.99), signal stability (RSD ≤ 10.7%), spike recoveries (91-95%), and comparable results for real urine samples were also achieved, opening up possibilities for quantitative analysis of trace compounds (at attomole levels) in complex bio-samples. Graphical abstract.

HPLC-fast scanning fluorimetric detection determination of risk exposure to polycyclic aromatics hydrocarbons biomarkers in human urine

Aim: An HPLC method for the determination of 2-hydroxyfluorene (2-OHF), various hydroxyphenanthrene metabolites (1-, 2-, 3-, 4- and 9-hydroxyphenanthrene, OHPhs), 1-hydroxypyrene (1-OHPy) and 3-hydroxybenzo[a]pyrene (3-OHB[a]Py) in human urine, has been developed using fast scanning fluorimetric detection and gradient elution mode. Materials & methods: All reagents were of analytical grade. Standard solutions were prepared separately, by exact weighing or dilution with ultrapure acetonitrile, and were stored at 4 ºC in darkness. The standard addition method was used for the analysis of urine samples. Results: In the optimized conditions, 2- and 3-hydroxyphenanthrene, and 1- and 9-hydroxyphenanthrene metabolites eluted at the same retention time; however, all other hydroxy-polycyclic aromatic hydrocarbons were well resolved. Multi-emission detection allows us to monitor each metabolite at its most sensitivity emission wavelength. Detection limits ranged between 0.9 and 4.26 ng ml-1. Conclusion: Fortified urine samples of nonexposure and nonsmoker volunteers, previous precipitation step with acetonitrile, were used to test the proposed method. The obtained results confirm the goodness of the method.

Organic monolith frits encased in polyether ether ketone tubing with improved durability for liquid chromatography

This study introduces a preparation method for polymer-encased monolith frits with improved durability for liquid chromatography columns. The inner surface of the polyether ether ketone tubing is pretreated with sulfuric acid in the presence of catalysts (vanadium oxide and sodium sulfate). The tubing was rinsed with water and acetone, flushed with nitrogen, and treated with glycidyl methacrylate. After washing, the monolith reaction mixture composed of lauryl methacrylate, ethylene glycol dimethacrylate, initiator, and porogenic solvent was filled in the tubing and subjected to in situ polymerization. The tubing was cut into thin slices and used as frits for microcolumns. To check their durability, the frit slices were placed in a vial and a heavy impact was applied on the vial by a vortex mixer for various periods. The frits made in the presence of catalysts were found to be more durable than those made without catalysts. Furthermore, when the monolith-incorporated tubing was used as a chromatography column, the column prepared in the presence of catalysts resulted in a better separation efficiency. The separation performance of the columns installed with the polyether ether ketone encased monolith frits was comparable to that of the columns installed with the commercial stainless-steel screen frits.

A gold nanoparticle-based colorimetric probe for rapid detection of 1-hydroxypyrene in urine

Direct and rapid detection of 1-hydroxypyrene (1-OHP) is of great importance owing to its high carcinogenicity, teratogenicity and toxicity.

A novel facile method using polyetheretherketone as a solid phase extraction material for fast quantification of urinary monohydroxylated metabolites of polycyclic aromatic hydrocarbons

A novel facile method using polyetheretherketone (PEEK) as a solid phase extraction (SPE) material to extract urinary monohydroxylated metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) has been successfully demonstrated.