Development of C18-functionalized magnetic silica nanoparticles as sample preparation technique for the determination of ergosterol in cigarettes by microwave-assisted derivatization and gas chromatography/mass spectrometry

Colorimetric determination of trace orthophosphate in water by using C18-functionalized silica coated magnetite

In this study, we customized magnetic sorbents by functionalizing silica coated magnetite with octadecyl(C₁₈)silane (Fe₃O₄@SiO₂@C₁₈). This sorbent was intended for the determination of trace orthophosphate (o-PO₄³⁻) in unpolluted freshwater samples. The o-PO₄³⁻ was transformed to phosphomolybdenum blue (PMB), a known polyoxometalate ion. Then the PMB were coupled with cetyl trimethyl ammonium bromide (CTAB), cationic surfactant, in order to hydrophobically bound with the Fe₃O₄@SiO₂@C₁₈ particles through dispersive magnetic solid-phase extraction (d-MSPE) as part of sample preconcentration. The PMB–CTAB–magnetic particles are simply separated from the aqueous solution by the external magnet. The acidified ethanol 0.5 mL was used as PMB-CTAB eluent to produce an intense blue solution, which the absorbance was measured using a UV–Vis spectrophotometer at 800 nm. The proposed method (employing 2 mg of Fe₃O₄@SiO₂@C₁₈) yielded an enhancement factor of 32 with a linear range of 1.0–30.0 µg P L⁻¹. Precision at 6.0 µg P L⁻¹ and 25.0 µg P L⁻¹ were 3.70 and 2.49% (RSD, n = 6) respectively. The lower detection limit of 0.3 µg P L⁻¹ and quantification limit of 1.0 µg P L⁻¹ allowed trace levels analysis of o-PO₄³⁻ in samples. The reliability and accuracy of the proposed method were confirmed by using a certified reference material. Our method offers highly sensitive detection of o-PO₄³⁻ with simple procedures that can be operated at room temperature and short analysis time.

Influence of Calcium Silicate and Hydrophobic Agent Coatings on Thermal, Water Barrier, Mechanical and Biodegradation Properties of Cellulose

Thin films of cellulose and cellulose–CaSiO₃ composites were prepared using 1-ethyl-3-methylimidazolium acetate (EMIMAc) as the dissolution medium and the composites were regenerated from an anti-solvent. The surface hydrophilicity of the resultant cellulose composites was lowered by coating them with three different hydrophobizing agents, specifically, trichloro(octadecyl)silane (TOS), ethyl 2-cyanoacrylate (E2CA) and octadecylphosphonic acid (ODPA), using a simple dip-coating technique. The prepared materials were subjected to flame retardancy, water barrier, thermal, mechanical and biodegradation properties analyses. The addition of CaSiO₃ into the cellulose increased the degradation temperature and flame retardant properties of the cellulose. The water barrier property of cellulose–CaSiO₃ composites under long term water exposure completely depends on the nature of the hydrophobic agents used for the surface modification process. All of the cellulose composites behaved mechanically as a pure elastic material with a glassy state from room temperature to 250 °C, and from 20% to 70% relative humidity (RH). The presence of the CaSiO₃ filler had no effect on the elastic modulus, but it seemed to increase after the TOS surface treatment. Biodegradability of the cellulose was evaluated by enzyme treatments and the influence of CaSiO₃ and hydrophobic agents was also derived.

Sonochemical versus reverse-precipitation synthesis of CuxO/Fe2O3/MoC nano-hybrid: removal of reactive dyes and evaluation of smartphone for colorimetric detection of organic dyes in water media

In the present work, an ultrasound-assisted reverse-precipitation method was applied as a new approach for the synthesis of Cu_xO/Fe₂O₃/MoC. In the sonication method, a bath type sonicator as a simple, cost-effective, and low intensity sonicator was used. To determine the influence of ultrasonic waves on the morphology and application of nano-hybrid as nano-sorbent, it was also synthesized using the reverse precipitation method. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR), transmission electron microscopy (TEM), Zeta-potential measurement, and vibrating sample magnetometer (VSM) techniques. The XRD analysis confirmed that the sono-synthesized sample has higher crystallinity than the conventional one and CuO/Cu₂O/MoC/Fe₂O₃ phase was obtained under ultrasound. According to the TEM and FESEM, sono-synthesized nanoparticles were rod-like with a width and length of 3 nm and 40 nm, respectively. Also, a well-dispersed shape and uniform morphology of nanoparticles were obtained using sonication. In comparison with the conventional nano-hybrid, this structure results in more void and accessible sites for adsorption of pollutants. The efficiency of resulting nanoparticles in adsorption of reactive dyes as a model of the pollutant was evaluated by sorption and sono-sorption processes. The sono-synthesized sample removed the pollutants more efficient than the conventional sample. The removal efficiencies were about 99% for the removal of reactive dyes using the sono-synthesized sample and sono-sorption method. Besides, determining factors including pH, pollutant concentration, temperature, and contact time were optimized in the sono-sorption and sorption processes. A colorimetric method based on RGB value was used to determine dye concentration in aqueous media. The images were taken by a smartphone and analyzed by ImageJ software. The accuracy of RGB results was confirmed by a UV-Vis spectrophotometer. Graphical abstract The figures on the left side show the FESEM images of nano-sorbent synthesized in the presence of ultrasonic irradiation (US method) and the absence of it (MS method). A well-dispersed shape and uniform morphology of nanoparticles were obtained using sonication. The scheme on the right side illustrates the process of sono-sorption for the removal of dyes and determination of their concentration using the colorimetric method. A colorimetric method based on RGB value was used to determine dye concentration in aqueous media. The graph shows the removal efficiencies of RY84 onto nanosorbent. The removal efficiencies were about 99% for the removal of reactive dye using the sono-synthesized sample and sono-sorption method.

Bacillus subtilis CF-3 Volatile Organic Compounds Inhibit Monilinia fructicola Growth in Peach Fruit

In this study, we evaluated the effects of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 in inhibiting Monilinia fructicola in vitro and in vivo. In the in vitro experiments, the effect of VOCs on the growth of the pathogenic fungi was explored by using plate enthalpy test; mycelial morphology was studied by scanning electron and transmission electron microscopy; and fatty acid contents in the cell membrane were assessed by gas chromatography-mass spectrometry (GC-MS). The results indicated that treatment with benzothiazole and CF-3 for 24 h, in the form of a fermentation broth (24hFB), significantly inhibited the germination of fungal spores, modified hyphal and cell morphology, and decreased the cell membrane fluidity and integrity. In the in vivo experiments, the effect of VOCs on the defense mechanism of peach fruit toward M. fructicola was studied, and we found that benzothiazole and CF-3 24hFB inhibited the activity of the pathogenic enzymes (pectinase, cellulase) secreted by M. fructicola to reduce the decomposition of plant tissues, activate the antioxidant enzymes (peroxidase, polyphenol oxidase, catalase, and superoxide dismutase) in the fruit to eliminate excessive reactive oxygen species in order to reduce plant cell damage, and trigger the disease-resistant enzymes (phenylalanine ammonia-lyase, chitinases, and β-1,3-glucanase) to enhance the resistance of peach fruit to M. fructicola and inhibit its growth. This study suggests that CF-3 VOCs could activate disease-resistant enzymes to prevent the invasion of pathogenic fungi and induce resistance in peach, thereby providing a theoretical basis for future applications.

Volatile organic compounds (VOCs) from Bacillus subtilis CF-3 reduce anthracnose and elicit active defense responses in harvested litchi fruits

In this study, we investigated the effects of volatile organic compounds (VOCs) produced by Bacillus subtilis CF-3 on the growth and development of Colletotrichum gloeosporioides and evaluated the elicitation of active defense responses in harvested litchi fruits. In vitro experiments were conducted to explore the bacteriostatic effect of VOCs in inhibiting pathogenic fungi by means of plate enthalpy test, scanning electron microscopy, transmission electron microscopy, and gas chromatography-mass spectrometry (GC-MS). The results showed that 2,4-di-tert-butylphenol and CF-3 24-h fermentation broth (24hFB) can significantly inhibit the germination of fungal spores, disrupt hyphal and cell morphology, and decrease cell membrane fluidity and integrity, resulting in the changes of indexes. In addition, the bacteriostasis of VOCs in the defensive ability of litchi fruits to C. gloeosporioides was studied, and it was shown that 2,4-di-tert-butylphenol and CF-3 24hFB can inhibit the activity of the pathogenic enzymes (pectinase and cellulase) secreted by C. gloeosporioides to reduce the decomposition of plant tissues, activate antioxidant enzymes (peroxidase, polyphenol oxidase, catalase, and superoxide dismutase) in the fruit to eliminate excessive reactive oxygen species in fruits in order to reduce plant cell damage and activate disease resistance enzymes (phenylalanineammonialyase, chitinases, β-1,3-glucanase) to enhance the resistance of litchi fruits to C. gloeosporioides and inhibit its growth. This study investigated the bacteriostasis of VOCs in inhibiting C. gloeosporioides and inducing the resistance of litchi fruits, providing a theoretical basis for future applications.

Dispersive Solid Phase Extraction Using Magnetic Nanoparticles Performed in a Narrow-Bored Tube for Extraction of Atorvastatin, Losartan, and Valsartan in Plasma

Purpose: In this investigation, a new version of magnetic solid phase extraction (MSPE) performed in a narrow–bore tube has been proposed. In this study, hydrophobic octyl (C₈) functionalized Fe₃O₄ magnetic nanoparticles (MNPs) stabilized by SiOH groups (Fe₃O₄@SiO₂@C₈) are used as magnetic nano–sorbents for the extraction of cardiovascular drugs from human plasma prior to their determination by high performance liquid chromatography–photodiode array detection.

Methods: After precipitation of the plasma proteins, the supernatant is diluted with deionized water and filled into the narrow–bore tube. Then mg–level of the sorbent is added into the tube. The sorbent is dispersed and moved down through the solution instead of passing the solution from the cartridge. Using an external magnet, the collected nano–sorbents at the bottom of the tube are transferred on top of the solution and released to move down through the solution for three times to increase the extraction efficiency.

Results: The linearity of the assay was ranging from 0.4–500 mg mL^-1. The limits of detection and quantification of the method were obtained in the ranges of 0.05–0.07 and 0.16–0.24 mg L^-1, respectively. The extraction recoveries were obtained in the range of 31–49%. Intra– and inter–day precisions were calculated and obtained in the ranges of 5–8 and 7%–9% for 0.5 mg L^-1 of each analyte, and 5–6 and 6%–8% for 2 mg L^-1 of each analyte, respectively.

Conclusion: The proposed method was successfully used in determination of the studied drugs in patient’s plasmas.

One-Step Preparation of Phenyl Boron-Modified Magnetic Mesoporous Silica for Selective Enrichment of cis-Diol-Containing Substances

For enrichment and separation of cis-diol-containing compounds from biomatrix, a new type of magnetic nanoparticles named MS-48-PBSC, whichwas facilely prepared in a one-step heterogeneous reaction. The morphology results demonstrated that the MS-48-PBSC was a spherical nanomaterial containing a core of silica-coated magnetic particle with a diameter of about 200 nm, and a cover layer of mesoporous silica with a thickness of approximate 50 nm. The characterization results showed that MS-48-PBSC presented a pore size of 4.2 nm, a surface area of 548 m²·g⁻¹, and a pore volume of 0.30 cm³·g⁻¹. The MS-48-PBSC also exhibited magnetism of 42 emu·g⁻¹ that contributed to the easy separation of magnetic nanomaterial within 30 s from the matrix with the aid of the external magnetic field. In addition, the MS-48-PBSC exhibited high adsorption capacity for adenosine, xanthosine, uridine, sialic acid, and teicoplanin with 0.60, 0.51, 0.42, 0.75, and 1.26 mg/g, respectively, and showed a high selectivity for the cis-diol structure compounds, relative to interferences of bovine serum albumin, guanine, uric acid, and xanthine. The recoveries of adenosine, xanthosine, uridine, sialic acid, and teicoplanin were 71.8–114.1% with relative standard deviation (RSD) ≤ 8.6%, and the enrichment factors of them were 8–11. MS-48-PBSC exhibited quick separation capability from matrix, high adsorption capacity and size exclusion for bovine serum albumin, which could meet the requirements of separation and enrichment for substances with a cis-diol structure.

Magnetic solid phase extraction using Fe3O4@SiO2@C8 nanoparticles performed in a narrow-bore tube followed by dispersive liquid–liquid microextraction for extraction and preconcentration of nine pesticides

In the present work, a new magnetic solid phase extraction method performed in a narrow-bore tube using synthesized Fe₃O₄@SiO₂@C₈ magnetic nanoparticles has been developed.

Current advancements of magnetic nanoparticles in adsorption and degradation of organic pollutants

Nanotechnology is a fast-emerging field and has received applications in almost every field of life. Exploration of new synthetic technologies for size and shape control of nanomaterials is getting immense consideration owing to their exceptional properties and applications. Magnetic nanoparticles (MNPs) are among the most important group of nanoparticles thanks to their diverse applications in medical, electronic, environmental, and industrial sectors. There have been numerous synthetic routes of MNPs including thermal decomposition, co-precipitation, microemulsion, microwave assisted, chemical vapor deposition, combustion synthesis, and laser pyrolysis synthesis. The synthesized MNPs have been successfully applied in medical fields for therapy, bioimaging, drug delivery, and so on. Among environmental aspects, there has been great intimidation of organic pollutants in air and water. Utilization of various wastes as adsorbents has removed 80 to 99.9% of pollutants from contaminated water. MNPs as adsorbents compared to coarse-grained counterparts have seven times higher capacity in removing water pollutants and degrading organic contaminants. This study is focused to introduce and compile various routes of MNP synthesis together with their significant role in water purifications and degradation of organic compounds. The review has compiled recent investigation, and we hope it will find the interest of researchers dealing with nanoparticles and environmental research. Graphical abstract Synthesis and applications of magnetic nanoparticles.

Simultaneous extraction and determination of free and conjugated phytosterols in tobacco

Acid hydrolysis and alkaline saponification were incorporated into a microwave-assisted extraction process for the simultaneous extraction of free and conjugated phytosterols from tobacco. The crude extract of the microwave-assisted extraction was purified by C18 solid-phase extraction and then determined by high-performance liquid chromatography. Phytosterols of cholesterol, ergosterol, stigmasterol, campesterol, and β-sitosterol were determined by chromatographic quantification. The multiple parameters of microwave-assisted extraction were optimized by a uniform design method. The optimal ratio of extraction ethanol solvent to tobacco mass was 30 mL/g. The microwave-assisted extraction acid hydrolysis was carried out in sulfuric acid medium by heating for 10 min at 55°C. The microwave-assisted extraction alkaline saponification was performed after adding excessive sodium hydroxide by heating another 10 min. The repeatability of the proposed method was acceptable with recoveries from 69.68 to 88.17% for the phytosterols. Five target phytosterols were all found in the tobacco samples, and the contents were significantly different in samples from different producing areas.

Octadecyl functionalized core-shell magnetic silica nanoparticle as a powerful nanocomposite sorbent to extract urinary volatile organic metabolites

In this present study, magnetic Fe3O4@SiO2 nanoparticles (MNPs) functionalized with octadecyl groups (Fe3O4@SiO2-C18 NPs) were synthesized, characterized and employed, for the first time, as powerful nanosorbent to extract endogenous volatile organic metabolites (EVOMs) namely, hexanal, heptanal, decanal, benzaldehyde, 4-heptanone, 5-methyl-2-furfural and phenol, described as potential biomarkers of cancer, from human urine. By using co-precipitation, surface modification methods, the carbon-ferromagnetic nanocomposite was synthesized and characterized by infrared spectrum (IR) and transmission electron microscopy (TEM). By coupling with gas chromatography-mass spectrometry (GC-qMS), a reliable, sensitive and cost-effective method was validated. To test the extraction efficiency of the carbon-ferromagnetic nanocomposite toward urinary EVOMs experimental variables affecting the extraction performance, including nanosorbent amount, adsorption time, elution time, and nature of elution solvent, were investigated in detail. The extraction process was performed by dispersing Fe3O4@SiO2-C18 NPs into working solution containing targeted VOMs, and into urine samples, and then eluted with an adequate organic solvent. The eluate was collected, concentrated and analyzed by GC-qMS. Under the optimized conditions, the LODs and LOQs achieved were in the range of 9.7-57.3 and 32.4-190.9ng/mL, respectively. Calibration curves were linear (r(2)≥0. 988) over the concentration ranges from 0.25 to 250ng/mL. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 3 and 11%, respectively. The method also afforded satisfactory results in terms of the matrix effect (72.8-96.1%) and recoveries (accuracy) higher than 75.1% for most of the studied EVOMs. The Fe3O4@SiO2-C18 NPs-based sorbent extraction combined with GC-qMS revealed that the new nanosorbent had a strong ability to retain the target metabolites providing a new, reliable and high throughput strategy for isolation of targeted EVOMs in human urine, suggesting their potential to be applied in other EVOMs.

Preparation of C18-functionalized Fe3O4@SiO2 core-shell magnetic nanoparticles for extraction and determination of phthalic acid esters in Chinese herb preparations

The extraction and determination of phthalic acid esters (PAEs) residue in Chinese herbal preparations (CHP) by C18-functionalized magnetic nanoparticles (C18-FS-MNP) has been firstly performed. It was synthesized through coating Fe3O4 nanoparticles with sodium silicate, followed by freeze-drying technique and then modified with C18 groups. C18-FS-MNPs prepared via freeze-drying technique were superior to those particles prepared via common vacuum drying method in terms of dispersion and extraction recovery. C18-FS-MNPs demonstrated obvious enrichment effect for four model PAEs and 478-627-fold enrichment factors were obtained. The limit of detection was <1.89ng/mL and relative standard deviation was ranging from 3.7 to 5.8%. It was successfully applied for determination of trace PAEs residue in CHP with good recoveries.

Analysis of N-acylhomoserine lactone dynamics in continuous cultures of Pseudomonas putida IsoF by use of ELISA and UHPLC/qTOF-MS-derived measurements and mathematical models

In this interdisciplinary approach, the dynamics of production and degradation of the quorum sensing signal 3-oxo-decanoylhomoserine lactone were studied for continuous cultures of Pseudomonas putida IsoF. The signal concentrations were quantified over time by use of monoclonal antibodies and ELISA. The results were verified by use of ultra-high-performance liquid chromatography. By use of a mathematical model we derived quantitative values for non-induced and induced signal production rate per cell. It is worthy of note that we found rather constant values for different rates of dilution in the chemostat, and the values seemed close to those reported for batch cultures. Thus, the quorum-sensing system in P. putida IsoF is remarkably stable under different environmental conditions. In all chemostat experiments, the signal concentration decreased strongly after a peak, because emerging lactonase activity led to a lower concentration under steady-state conditions. This lactonase activity probably is quorum sensing-regulated. The potential ecological implication of such unique regulation is discussed.

Rapid screening and analysis of alcohol dehydrogenase binders from Glycyrrhiza uralensis root extract using functionalized magnetic nanoparticles coupled with HPLC−MS/MS

Alcohol dehydrogenase (ADH) is a key enzyme that converts ethanol into acetaldehyde. Its binders could be used to efficiently treat human toxic alcohol poisoning and suppress the acetaldehyde accumulation in alcohol hypersensitive alcoholics. In the present study, a new assay based on ADH-functionalized magnetic nanoparticles coupled with high-performance liquid chromatography − tandem mass spectrometry (HPLC−MS/MS) was developed for the rapid screening and identification of ADH binders. ADH was immobilized on silica-coated Fe3O4 magnetic nanoparticles via covalent bonds and the synthesized nanoparticles were characterized by TEM, XRD, FT-IR, and VSM. The amount of bound ADH onto magnetic nanoparticles was 80.6 μg/mg. The optimum temperature and pH for the enzymatic activity of immobilized ADH were 25 °C and 7.0, respectively. The relative activity of immobilized ADH remained 68.14% after 10 times of recycle, which exhibited good durability. Nine compounds with ADH-binding activity were screened and identified in Glycyrrhiza uralensis root extracts, among which seven compounds were first screened and identified. Experimental results proved that the proposed method could rapidly screen ADH binders from complex mixtures.

Application of functionalized magnetic nanoparticles in sample preparation

Functionalized magnetic nanoparticles have attracted much attention in sample preparation because of their excellent performance compared with traditional sample-preparation sorbents. In this review, we describe the application of magnetic nanoparticles functionalized with silica, octadecylsilane, carbon-based material, surfactants, and polymers as adsorbents for separation and preconcentration of analytes from a variety of matrices. Magnetic solid-phase extraction (MSPE) techniques, mainly reported in the last five years, are presented and discussed.

Hybridization of commercial polymeric microparticles and magnetic nanoparticles for the dispersive micro-solid phase extraction of nitroaromatic hydrocarbons from water

In this article, the combination of commercial polymeric microparticles (OASIS MCX) and cobalt ferrite nanoparticles is evaluated in dispersive micro-solid phase extraction (D-μSPE) for the determination of six nitroaromatic hydrocarbons in water. The high affinity of the polymeric material toward the target analytes as well as the magnetic behavior of cobalt ferrite nanoparticles are combined in a synergic way to developed an efficient and simple D-μSPE approach. The sorptive performance of the hybrid material is compared with that most usual sorbents and the effect of its synthesis steps on the extraction capability is also evaluated in depth. After the optimization of selected variables, D-μSPE method was assessed in terms of linearity, sensitivity, precision and accuracy. The new extraction method allows the determination of the target compounds with limits of detection in the range from 0.12 to 1.26 μg/L and relative standard deviations lower than 9.6%. The recovery study was performed in two different water samples obtaining percentages from 71 to 103%, which demonstrated the applicability of the hybrid sorbent for the selected analytical problem.

Nano-magnetic particles as multifunctional microreactor for deep desulfurization

Oxidation of dibenzothiophene with hydrogen peroxide using a recyclable amphiphilic catalyst has been studied. The catalyst was synthesized by surfacely covering magnetic silica nanospheres (MSN) with the complexes between 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (AEM) and phosphotungstic acid (PTA). The morphology and components of the composite material were characterized by TEM, EDX, XPS, FT-IR, and VSM, respectively. The effects of several factors on desulfurization reactivity were systematically investigated. The results showed that the composite nanospheres have core/shell structure with the properties of amphiphilicity and superparamagnetism. The composite nanospheres have high catalytic activity in the oxidation of dibenzothiophene to corresponding sulfones by hydrogen peroxide under mild reaction conditions. The sulfur level could be lowered from 487 ppm to less than 0.8 ppm under optimal conditions. Additionally, the amphiphilic catalyst and the oxidized product could be simultaneously separated from medium by external magnetism, and the recovered composite material could be recycled for three times with almost constant activity.

Octyl-functionalized hybrid magnetic mesoporous microspheres for enrichment of low-concentration peptides prior to direct analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Octyl-functionalized hybrid magnetic mesoporous (Fe(3)O(4)·nSiO(2)·meso-hybrid-C8) microspheres were synthesized and applied in the isolation and pre-concentration of low-concentration peptides prior to direct analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Such microspheres possess high surface area (324 m(2)/g), hydrophobic group (C8), relatively large pore volume (0.304 cm(3)/g), uniform pore diameter (~3.7 nm), and magnetic responsivity, which make them a simple and efficient kind of adsorbent for the enrichment of low-concentration peptides. For bovine serum albumin (BSA, 15 fmol μL(-1)) digest, after concentration by Fe(3)O(4)·nSiO(2)·meso-hybrid-C8 microspheres, the enrichment performance was evidently better than those obtained by solvent evaporation and C8-functionalized magnetic particles, and comparable to those obtained by commercial Anchor chip target and ZipTipC18 pipette tip. Such microspheres were further applied in the enrichment of the tryptic digests of rat cerebellum proteins and endogenous peptides of crude human serum, and more peaks with higher signal-to-noise (S/N) ratio were obtained than before pre-concentration. Furthermore, the pre-concentration reproducibility of magnetic microspheres for biological samples was good, and the limit of detection (LOD) for BSA digests by MALDI-TOF MS was decreased by at least one order of magnitude compared with that obtained without pre-concentration. All the above-mentioned results indicate that the synthesized Fe(3)O(4)·nSiO(2)·meso-hybrid-C8 microspheres are promising for the enrichment of low-concentration peptides from complex biosamples.