Electrospun biocompatible Chitosan/MIL-101 (Fe) composite nanofibers for solid-phase extraction of Δ9-tetrahydrocannabinol in whole blood samples using Box-Behnken experimental design

Enhanced adsorption of Bismark Brown R dye by chitosan conjugated magnetic pectin loaded filter mud: A comprehensive study on modeling and mechanisms

Herein, a polymer-based bioadsorbent was prepared by cross-linking chitosan to filter mud and magnetic pectin (Ch-mPC@FM) for the removal of Bismark Brown R dye (BB-R) from wastewater. Morphological characterization analysis indicated that Ch-mPC@FM had a higher surface area and better pore structure than its components. The Artificial Neuron Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) were employed to evaluate the simulation and prediction of the adsorption process based on input variables like temperature, pH, dosage, initial BB-R dye concentration, and contact time. ANFIS and ANN demonstrated significant modeling and predictive accuracy, with R2 > 0.93 and R2 > 0.96, and root mean square error < 0.023 and <0.020, respectively. The Langmuir isotherm and the pseudo-second-order kinetic models provided the best fits to the equilibrium and kinetic data. The thermodynamic assessment showed spontaneous and endothermic adsorption with average entropy and enthalpy changes of 119.32 kJ mol-1 K and 403.47 kJ mol-1, respectively. The study of BB-R dye adsorption on Ch-mPC@FM revealed multiple mechanisms, including electrostatic, complexation, pore filling, cation-π interaction, hydrogen bonding, and π-π interactions. The approximate production cost of US$ 5.809 Kg-1 and excellent adsorption capability render Ch-mPC@FM an inexpensive, pragmatic, and ecologically safe bioadsorbent for BB-R dye removal from wastewater.

Development of electrospun nanofibers based on Poly (vinyl alcohol) for thin film solid-phase microextraction of antidepressant drugs in biological samples

Today, antidepressants are widely used and it is important to determine their trace amounts due to harmful consequences. Here, a new nano sorbent was reported for the simultaneous extraction and determination of three types of antidepressant drugs (Clomipramine (CLO), Clozapine (CLZ), and Trimipramine (TRP) by the thin-film solid-phase micro-extraction (TFME-μSPE) method followed by the Gas Chromatography-flame ionization detector (GC-FID) analysis. So, the compound poly (vinyl alcohol) (PVA)/citric acid(CA)/β-cyclodextrin/Bi₂S₃@g-C₃N₄ nano sorbent was constructed by electrospinning technique. Then, nano sorbent was studied to optimize the many parameters impacting the extraction performance. Electrospun nanofiber has a large surface area, high porosity, and homogeneous morphology with a uniform bead-free structure. In optimal conditions, the limits of detection and quantification were calculated to be 0.15-0.03 ng mL^-1 and 0.5-0.1 ng mL^-1, respectively. The dynamic linear range (DLR) was in the range of 0.1 to 1000 ng mL^-1 for CLO and CLZ, and 0.5 to 1000 ng mL^-1 for TRP with correlation coefficients (R²) of 0.999. The relative standard deviations (RSDs) were achieved in the range of 4.9-6.8% (intra-day, n = 4) and 5.4-7.9% (inter-day, n = 3) in the period of 3 days. Finally, the capability of the method was evaluated to simultaneously measure trace amounts of antidepressants aqueous sample with desirable extraction efficiency (78 to 95%).

Development of poly(vinyl alcohol)/chitosan/aloe vera gel electrospun composite nanofibers as a novel sorbent for thin-film micro-extraction of pesticides in water and food samples followed by HPLC-UV analysis

Schematic presentation of applying PVA/CA/CS/AV composite nanofibers as the extraction phase in thin-film micro-extraction (TFME) of six pesticide compounds prior to HPLC-UV analysis.

Porous electrospun microfibers for low flow-resistant solid phase extraction of fluoroquinolones in tap water, egg and milk samples

In this work, porous electrospun microfibers (PEMFs) were prepared using a polyimide/polyvinylpyrrolidone/polyethylene glycol (PI/PVP/PEG) solution mixture with coaxial ultrasonic water vapor spraying. After removing PVP and PEG by ultrasonic water washing, the PEMFs were successfully demonstrated as adsorbents for solid phase extraction (SPE). Most non-porous electrospun nanofibers are hundreds of nanometers in diameter, with a specific surface area of dozens of square meters per gram. In contrast, the diameter of the as-prepared PEMFs was tuned between 3 and 8 μm, the specific surface area was 76 m²g^-1 and the pore size was ca 25 nm. Therefore, the flow resistance of the PEMF-SPE cartridges was similar to those of conventional commercial SPE cartridges, and much lower than those of SPE cartridges packed with electrospun nanofibers. Using the PEMF-SPE cartridges with ultra-performance liquid chromatography-fluorescence detector (UPLC-FLD), five fluoroquinolones (FQs) in tap water, egg and milk samples were extracted and quantified successfully. After optimizing the extraction conditions, FQs in water samples were extracted and eluted with high recoveries of 84.8-114.8%. The inter-batch and intra-batch relative standard deviation (RSD) values for the FQs were in the range of 1.9-9.5% (n=3), and the limits of detection were between 0.0024-0.014 μg L^-1. The method was linear in the concentration range of 0.005-10 μg L^-1. The reliability of the developed method was validated by analyzing tap water, egg and milk samples, and the recovery values were found to be in the range of 74.8-116.6% under the optimized conditions.

Fabrication of attapulgite/magnetic aminated chitosan composite as efficient and reusable adsorbent for Cr (VI) ions

An efficient composite was constructed based on aminated chitosan (NH2Cs), attapulgite (ATP) clay and magnetic Fe3O4 for adsorptive removal of Cr(VI) ions. The as-fabricated ATP@Fe3O4-NH2Cs composite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analyzer (TGA), Scanning Electron Microscope (SEM), Zeta potential (ZP), Vibrating Sample Magnetometer (VSM), Brunauer-Emmett-Teller method (BET) and X-ray photoelectron spectroscope (XPS). A significant improve in the adsorption profile was established at pH 2 in the order of ATP@Fe3O4-NH2Cs(1:3) > ATP@Fe3O4-NH2Cs(1:1) > ATP@Fe3O4-NH2Cs(3:1) > Fe3O4-NH2Cs > ATP. The maximum removal (%) of Cr(VI) exceeded 94% within a short equilibrium time of 60 min. The adsorption process obeyed the pseudo 2nd order and followed the Langmuir isotherm model with a maximum monolayer adsorption capacity of 294.12 mg/g. In addition, thermodynamics studies elucidated that the adsorption process was spontaneous, randomness and endothermic process. Interestingly, the developed adsorbent retained respectable adsorption properties with acceptable removal efficiency exceeded 58% after ten sequential cycles of reuse. Besides, the results hypothesize that the adsorption process occurs via electrostatic interactions, reduction of Cr(VI) to Cr(III) and ion-exchanging. These findings substantiate that the ATP@Fe3O4-NH2Cs composite could be effectively applied as a reusable adsorbent for removing of Cr(VI) ions from aqueous solutions.

Preparation of chitosan-modified magnetic Schiff base network composite nanospheres for effective enrichment and detection of hippuric acid and 4-methyl hippuric acid

Chitosan-modified magnetic Schiff base network composite nanospheres (Fe₃O₄@SNW@Chitosan) were prepared for the enrichment and detection of hippuric acid (HA) and 4-methyl hippuric acid (4-MHA) via magnetic solid phase extraction (MSPE) connected with HPLC. The SNW was one of the covalent organic framework, which constructed through covalent bonds, shown comprising solvent stability, low density and accessible pores. The obtained Fe₃O₄@SNW@Chitosan has many merits as a magnetic sorbent, including a hydrophilic surface, uniform pore size, unique ordered channel structure, and superparamagnetism. The favourable linearity of this MSPE-HPLC method was in the range of 1-1000 μg L^-1, and LODs of HA and 4-MHA were 0.3 μg L^-1 and 0.2 μg L^-1, respectively. The recoveries in urine samples were range from 95.3 to 109.0 % with the RSD less than 9.6 %. When employed for the enrichment of HA and 4-MHA, Fe₃O₄@SNW@Chitosan exhibited great potential as a candidate for preconcentration.

Facile fabrication of novel magnetic ZIF-67 MOF@aminated chitosan composite beads for the adsorptive removal of Cr(VI) from aqueous solutions

Metal organic frameworks (MOFs) have become premium candidates for the removal of hazardous contaminants from wastewater. However, MOFs have a vast obstacle which is their poor recyclability. In this study, ZIF-67 was decorated with magnetic Fe₃O₄ nanoparticles, and then embedded into aminated chitosan (AmCs) matrix to form core-dual shell Fe₃O₄/ZIF-67@AmCs composite beads. Diverse analysis tools were utilized to ensure the successful fabrication of the magnetic composite beads. The fabricated magnetic composite beads were examined their adsorptive removal aptitude towards toxic Cr(VI) ions. The gained results refereed that a maximum adsorption capacity of 119.05 mg/g was attained by magnetic Fe₃O₄/ZIF-67@AmCs composite beads at 25 °C. The process obeyed both of Langmuir and Freundlich isotherm models, and the pseudo 2nd order was more suitable kinetic model to represent the adsorption process. Besides, Fe₃O₄/ZIF-67@AmCs composite showed an excellent recyclability for the removal of Cr(VI) ions from their aqueous solutions for seven consecutive cycles.

Isotherm, kinetic, and thermodynamic studies for dynamic adsorption of toluene in gas phase onto porous Fe-MIL-101/OAC composite

In the present paper, micro-mesoporous Fe-MIL-101/OAC composite using in situ incorporation of Fe-MIL-101 into oxidized activated carbon was synthesized and characterized by XRD, FT-IR, SEM, EDS, and BET techniques. The adsorption performances of toluene onto adsorbents in the gas phase were studied using a laboratory-scale dynamic adsorption system under moist ambience. The toluene adsorption capacity of Fe-MIL-101/OAC composite and Fe-MIL-101 were 127 and 97.6 mg g^-1, severally. Results revealed that the larger pores in micro-mesoporous Fe-MIL-101/OAC enhanced the molecular diffusion rate. The findings indicated that micro-mesoporous structures played key roles in the capture of toluene molecules. The initial toluene concentration positively affected on toluene adsorption capacity while temperature and humidity negatively affected on toluene adsorption capacity. The Langmuir model and the pseudo-second-order kinetics model described better adsorption process of Fe-MIL-101/OAC composite. Thermodynamic findings determined that toluene adsorption over Fe-MIL-101/OAC was spontaneous, exothermic physisorption. The regeneration of the composite was still up to 72.6% after six cycles. The micro-mesoporous Fe-MIL-101/OAC composite proposes a promising support for the high toluene removal for future. Graphical abstract.

Development of a thin-layer chromatography bioautographic assay for neuraminidase inhibitors hyphenated with electrostatic field induced spray ionisation-mass spectrometry for identification of active Isatis indigotica root compounds

The identification of neuraminidase inhibitors from natural products is a promising strategy in the field of anti-influenza research. In this study, a new thin-layer chromatography (TLC) bioautographic assay for the screening of neuraminidase inhibitors from natural products was developed. This TLC bioassay is based on the one-step reaction of neuraminidase with the sodium salt of 5‑bromo‑4‑chloro‑3-indolyl-α-d-N-acetylneuraminic acid (substrate) and the subsequent formation of blue coloured products. Neuraminidase inhibitory activity was shown by the development of white spots against the blue TLC background. The key factors affecting the assay (such as enzyme concentration, substrate concentration, incubation time, reaction time, and pH) were investigated and optimised by a combination of a one-factor-at-a-time design and a Box-Behnken design/response surface method. The developed TLC bioautographic method was applied to identify neuraminidase inhibitory compounds in the roots of Isatis indigotica. Eleven active compounds including six alkaloids, three lignans, one sterol, and one fatty acid were identified in situ by direct coupling with an electrostatic field induced spray ionisation-mass spectrometry approach through analysis of their MSⁿ (n = 4) data or comparison with reference substances. The developed TLC bioautographic assay is simple, rapid, and efficient for screening potential neuraminidase inhibitors from natural products.

Biocompatible chitosan-zinc oxide nanocomposite based dispersive micro-solid phase extraction coupled with HPLC-UV for the determination of rosmarinic acid in the extracts of medical plants and water sample

In the present research, a procedure was described for the recovery of rosmarinic acid (RA) from medical extract samples using chitosan‑zinc oxide nanoparticles as a biocompatible nanocomposite (CS-ZnO-NC). The dispersive micro-solid phase extraction (D-μ-SPE) of RA from the medical extract samples was investigated by using the prepared biocompatible composite as a solid phase. The HPLC-UV method was used for measuring the extracted RA. The important variables (pH, biocompatible composite mass, contact time, and volume of eluent) associated with the extraction process were analyzed by the application of central composite design (CCD). The achieved optimum values for the mentioned variables were 7.0, 10 mg, 4 min, and 180 μL, respectively. The extraction recovery (99.68%) obtained from the predicted model was in agreement with the experimental data (98.22 ± 1.33%). In addition, under the obtained optimum conditions and over the concentration in the range of 2-3500 ng mL-1, a linear calibration curve was obtained with R2 > 0.993. The limit of detection (LOD) and quantification (LOQ) values were computed, and the obtained ranges were respectively from 0.060 to 0.089 ng mL-1 and 0.201 to 0.297 ng mL-1. In addition, the enrichment factors were obtained in the range of 93.7-110.5 with preconcentration factor of 83.3. Therefore, the D-μ-SPE-HPLC-UV method could be used for analyzing RA in the samples of the extracts obtained from the medical plants and water with the recovery values of the analyte in the range of 96.6%-105.4% and the precision with relative standard deviation <5.7%.

A Rapid Enrichment Technique for the Ultratrace Determination of Nickel in Water Samples Using a Nanofiber-composite Membrane Filter

A new method for the rapid enrichment and highly sensitive determination of nickel ion has been developed by using a nanofiber-composite membrane filter, which was fabricated by stacking a nanofibrous material made of nylon 6 over a water-permeable membrane filter. The noncharged nickel-α-furil dioxime complex was adsorbed on a nanofibrous layer of the membrane filter under significantly higher flow rates than those used for conventional solid-phase extraction techniques. Highly sensitive determinations with detection limits at sub-parts per billion levels were achieved by enrichment from 50 mL of the complex solution, and the enrichment was completed within 3 min. The color that was developed on the membrane filter was successfully subjected to visual colorimetric analysis and quantitative determination by solid-phase spectrophotometry. In addition, colorimetric determination was feasible with a handheld spectrometer after elution of the colored agent with 50 μL of acetone. This combination of rapid enrichment and spectrometric measurement in a small-volume sample provides a useful analytical method suitable for on-site analysis, which requires neither expensive instruments nor high laboratory skills.

Layer-by-layer decoration of MOFs on electrospun nanofibers

The design and fabrication of novel organic–inorganic nanocomposite membranes using metal–organic frameworks as building blocks have attracted numerous scientists. Here, HKUST-1 particles were decorated on crosslinked polymer nanofibers through a layer-by-layer method. The immersion sequence, the crosslinking and the number of the deposition cycles have a significant impact on the formation of the HKUST-1 decorated nanofibrous membranes. Moreover, it has been shown that such a membrane could be applied as a catalyst for visual detection of hydrogen peroxide.

A layer-by-layer method was introduced to fabricate MOF-decorated electrospun nanofibers, which could be used for visual detection of hydrogen peroxide.