Facile preparation of surface-exchangeable core@shell iron oxide@gold nanoparticles for magnetic solid-phase extraction: Use of gold shell as the intermediate platform for versatile adsorbents with varying self-assembled monolayers

Adsorptive remediation of environmental pollutants using magnetic hybrid materials as platform adsorbents

Effective separation and remediation of environmentally hazardous pollutants are burning areas of research because of a constant increase in environmental pollution problems. An extensive number of emerging contaminants in the environmental matrices result in serious health consequences in animals, humans, and plants, even at trace levels. Therefore, it is of paramount significance to quantify these undesirable pollutants, even at a very low concentration, from the natural environment. Magnetic solid-phase extraction (MSPE) has recently achieved huge attention because of its strong magnetic domain and easy separation through an external magnetic field compared with simple solid-phase extraction. Therefore, MSPE appeared the most promising technique for removing and pre-concentration of emerging pollutants at trace level. Compared to the normal solid-phase extraction, MSPE as magnetic hybrid adsorbents offers the unique advantages of distinct nanomaterials and magnetic hybrid materials. It can exhibit efficient dispersion and rapid recycling when applying to a very complex matrix. This review highlights the possible environmental applications of magnetic hybrid nanoscale materials as effective MSPE sorbents to remediate a diverse range of environmentally toxic pollutants. We believe this study tends to evoke a variety of research thrust that may lead to novel remediation approaches in the forthcoming years.

Adsorption, degradation, and mineralization of emerging pollutants (pharmaceuticals and agrochemicals) by nanostructures: a comprehensive review

This review discusses a fresh pool of research findings reported on the multiple roles played by metal-based, magnetic, graphene-type, chitosan-derived, and sonicated nanoparticles in the treatment of pharmaceutical- and agrochemical-contaminated waters. Some main points from this review are as follows: (i) there is an extensive number of nanoparticles with diverse physicochemical and morphological properties which have been synthesized and then assessed in their respective roles in the degradation and mineralization of many pharmaceuticals and agrochemicals, (ii) the exceptional removal efficiencies of graphene-based nanomaterials for different pharmaceuticals and agrochemicals molecules support arguably well a high potential of these nanomaterials for futuristic applications in remediating water pollution issues, (iii) the need for specific surface modifications and functionalization of parent nanostructures and the design of economically feasible production methods of such tunable nanomaterials tend to hinder their widespread applicability at this stage, (iv) supplementary research is also required to comprehensively elucidate the life cycle ecotoxicity characteristics and behaviors of each type of engineered nanostructures seeded for remediation of pharmaceuticals and agrochemicals in real contaminated media, and last but not the least, (v) real wastewaters are extremely complex in composition due to the mix of inorganic and organic species in different concentrations, and the presence of such mixed species have different radical scavenging effects on the sonocatalytic degradation and mineralization of pharmaceuticals and agrochemicals. Moreover, the formulation of viable full-scale implementation strategies and reactor configurations which can use multifunctional nanostructures for the effective remediation of pharmaceuticals and agrochemicals remains a major area of further research.

A bioinspired polydopamine approach toward the preparation of gold-modified magnetic nanoparticles for the magnetic solid-phase extraction of steroids in multiple samples

In this work, a simple, facile, and sensitive magnetic solid-phase extraction method was developed for the extraction and enrichment of three representative steroid hormones before high-performance liquid chromatography analysis. Gold-modified Fe₃ O₄ nanoparticles, as novel magnetic adsorbents, were prepared by a rapid and environmentally friendly procedure in which polydopamine served as the reductant as well as the stabilizer for the gold nanoparticles, thus successfully avoiding the use of some toxic reagents. To obtain maximum extraction efficiency, several significant factors affecting the preconcentration steps, including the amount of adsorbent, extraction time, pH of the sample solution, and the desorption conditions, were optimized, and the enrichment factors for three steroids were all higher than 90. The validity of the established method was evaluated and good analytical characteristics were obtained. A wide linearity range (0.8-500 μg/L for all the analytes) was attained with good correlation (R²  ≥ 0.991). The low limits of detection were 0.20-0.25 μg/L, and the relative standard deviations ranged from 0.83 to 4.63%, demonstrating a good precision. The proposed method was also successfully applied to the extraction and analysis of steroids in urine, milk, and water samples with satisfactory results, which showed its reliability and feasibility in real sample analysis.

A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices

In this study, graphene oxide was covalently immobilized on silica-coated magnetite and then modified with 2-phenylethylamine to give a nanocomposite of type Fe₃O₄@SiO₂@GO-PEA that can be applied to the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The resulting microspheres (Fe₃O₄@SiO₂@GO-PEA) were characterized by Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), CHNS elemental analysis, and vibrating sample magnetometry (VSM) techniques. The adsorbent possesses the magnetic properties of Fe₃O₄ nanoparticles that allow them easily to be separated by an external magnetic field. They also have the high specific surface area of graphene oxide which improves adsorption capacity. Desorption conditions, extraction time, amount of adsorbent, salt concentration, and pH were investigated and optimized. Following desorption, the PAHs were quantified by gas chromatography with flame ionization detection (GC-FID). The limits of detection (at an S/N ratio of 3) were achieved from 0.005 to 0.1μg/L with regression coefficients (R²) higher than 0.9954. The relative standard deviations (RSDs) were below 5.8% (intraday) and 6.2% (inter-day), respectively. The method was successfully applied to the analysis of PAHs in environmental water samples where it showed recoveries in the range between 71.7% and 106.7% (with RSDs of 1.6% to 8.4%, for n=3). The results indicated that the Fe₃O₄@SiO₂@GO-PEA microspheres had a great promise to extraction of PAHs from different water samples.

Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications

Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

Magnetic solid phase extraction of polycyclic aromatic hydrocarbons and chlorophenols based on cyano-ionic liquid functionalized magnetic nanoparticles and their determination by HPLC-DAD

The extraction of CPs & PAHs on MNP@CN/IL provides highly percent recovery with good precision and enrichment factor of i.e., 100 & 200 for CPs and PAHs respectively.

Magnetic solid-phase extraction based on modified ferum oxides for enrichment, preconcentration, and isolation of pesticides and selected pollutants

Recently, a simple, rapid, high-efficiency, selective, and sensitive method for isolation, preconcentration, and enrichment of analytes has been developed. This new method of sample handling is based on ferum oxides as magnetic nanoparticles (MNPs) and has been used for magnetic solid-phase extraction (MSPE) of various analytes from various matrices. This review focuses on the applications of modified ferum oxides, especially modified Fe3O4 MNPs, as MSPE adsorbent for pesticide isolation from various matrices. Further perspectives on MSPE based on modified Fe3O4 for inorganic metal ions, organic compounds, and biological species from water samples are also presented. Ferum(III) oxide MNPs (Fe2O3) are also highlighted.

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.