Polyaniline-coated chitosan-functionalized magnetic nanoparticles: Preparation for the extraction and analysis of endocrine-disrupting phenols in environmental water and juice samples

Insights into mechanism of peroxymonosufate activation by Mo single-atom catalysts: Singlet oxygen evolution and role of Mo-N coordination

Recently, the Fenton-like reaction using peroxymonosulfate (PMS) has been acknowledged as a potential method for breaking down organic pollutants. In this study, we successfully synthesized a highly efficient and stable single atom molybdenum (Mo) catalyst dispersed on nitrogen-doped carbon (Mo-NC-0.1). This catalyst was then utilized for the first time to activate PMS and degrade bisphenol A (BPA). The Mo-NC-0.1/PMS system demonstrated the ability to completely degrade BPA within just 20 min. Scavenging tests and density functional theory (DFT) calculations have demonstrated that the primary reactive oxygen species was singlet oxygen (1O2) produced by Mo-N4 sites. The self-cycling of Mo facilitated PMS activation and the transition from a free radical activation pathway to a non-radical pathway mediated by 1O2. Simultaneously, the nearby pyridinic N served as adsorption sites to immobilize BPA and PMS molecules. The exceptionally high catalytic activity of Mo-NC-0.1 derived from its unique Mo-N coordination, which markedly reduced the distance for 1O2 to migrate to the BPA molecules. The Mo-NC-0.1/PMS system effectively reduced the acute toxicity of BPA and exhibited excellent cycling stability with minimal leaching. This study presented a new catalyst with high selectivity for 1O2 generation and provided valuable insights for the application of single atom catalysts in PMS-based AOPs.

A Critical Review of Analytical Applications of Chitosan as a Sustainable Chemical with Functions Galore

Biomass and biowastes stand as sustainable and cost-effective environmentally benign alternative feedstock. Chitosan is a biocompatible, bioactive, and biodegradable biopolymer derived from chitin to achieve eight aspects out of the 12 green chemistry principles. Chitosan got significant attention in several fields including chemical analysis, in addition to chemical functionally, which enabled its use as adsorbent and its structural crosslinking using various crosslinkers. The physicochemical, technological, and optical properties of chitosan have been extensively exploited in analysis. Mainly, deacetylation degree and molecular weight are controlling its properties and hence controlling its functions. This review presents a structure, properties, and functions relationships of chitosan. It also aims to provide an overview of the different functions that chitosan can serve in each analytical technique such as supporting matrix, catalyst…etc. The contribution of chitosan in improving the ecological performance is discussed in each technique.

A nanocomposite of silica coated magnetite nanoparticles and aniline-anthranilic acid co-polymeric nanorods with improved stability and selectivity for fluoroquinolones dispersive micro solid phase extraction

Adsorbents composed of polyaniline nanostructures or their derivatives immobilized on magnetic nanoparticles had gained increasing interest for application in dispersive micro-solid phase extraction. However, reproducible binding between polymeric PANI nanopaterials and magnetic nanomaterials are still a challenging task. Furthermore, other challenges are the enhancement of physical and chemical stability of adsorbent magnetic nanoparticles as well as improvement of polymeric PANI nanoparticles selectivity towards target analytes. This work described the reproducible preparation of a nanocomposite of aniline-anthranilic acid co-polymeric nanorods with silica coated magnetite nanoparticles by physical mixing of its basic components. The prepared nanocomposite had proven stability against chemical and atmospheric attack. The formed nanocomposite in this work had advantages regarding stability and selectivity towards fluoroquinolones as compared with analogues prepared from polyaniline polymers and/or uncoated magnetite nanoparticles. The selectivity of the formed adsorbent was further optimized for microextraction of four fluoroquinolone antibacterial agents. The application of the prepared nanocomposite was exemplified in microextraction of the studied fluoroquinolones from spiked milk samples to enable their detection down to their stated maximum residue limits.

Theranostic Platforms Based on Silica and Magnetic Nanoparticles Containing Quinacrine, Chitosan, Fluorophores, and Quantum Dots

In this paper, we describe the synthesis of multilayer nanoparticles as a platform for the diagnosis and treatment of ischemic injuries. The platform is based on magnetite (MNP) and silica (SNP) nanoparticles, while quinacrine is used as an anti-ischemic agent. The synthesis includes the surface modification of nanoparticles with (3-glycidyloxypropyl)trimethoxysilane (GPMS), the immobilization of quinacrine, and the formation of a chitosan coating, which is used to fix the fluorophore indocyanine green (ICG) and colloidal quantum dots AgInS₂/ZnS (CQDs), which serve as secondary radiation sources. The potential theranostic platform was studied in laboratory animals.

Optimization of anti-corrosion performance of novel magnetic polyaniline-Chitosan nanocomposite decorated with silver nanoparticles on Al in simulated acidizing environment using RSM

The suitability of newly synthesized magnetic polyaniline-Chitosan nanocomposite decorated with silver nanoparticles (Ag@PANI-CS-Fe₃O₄) as a robust corrosion inhibitor for Aluminum (Al) in a 5 M HCl environment has been investigated via Weight Loss (WL), Alternating Current (AC)-Impedance Spectroscopy (IS), Potentiontiodynamic polarization (Tafel plots), and Scanning Electron Microscopy (SEM) techniques. The protection efficiency (PE) was mathematically modeled using the Response Surface Methodology (RSM) to fit an empirical relation in terms of temperature, nanocomposite concentration, and time using the face-centered central composite design. The model was accurate with a coefficient of determination (R² = 99.27%). The negative Gibb's free energy of adsorption (ΔG_ads) values confirmed the spontaneity of Freundlich adsorption isotherm process on Al in 5 M HCl solution. The optimization simulation yielded maximum protection efficiency (of 97.88%) at 5 mg/L nanocomposite concentration, 1 h time, and an intermediate temperature of 304.8 K. Furthermore, the sensitivity of PE was evaluated to find that the low temperature 303 K is favorable for PE, whereas higher temperature will act adversely on PE. The results obtained by the RSM model are in agreement with the experimental observations.

Magnetic porous carbon nanocomposite derived from cobalt based-metal-organic framework for extraction and determination of homo and hetero-polycyclic aromatic hydrocarbons

Herein, a novel magnetic porous carbon nanocomposite derived from a cobalt based-metal-organic framework was synthesized and evaluated for simultaneous preconcentration of homo and hetero-polycyclic aromatic hydrocarbons. Briefly, magnetite nanoparticles (MNPs) were synthesized and then were coated with a metal-organic framework layer. Finally, the magnetic nanocomposite was carbonized under an inert atmosphere to obtain the magnetic porous carbon (MPC). Various characterization techniques such as FT-IR spectroscopy, transmission and scanning electron microcopies, vibrating sample magnetometry, and X-ray diffraction were employed. Applicability of the MPC was explored using benzothiophene, dibenzothiophene, 9,10-dimethylanthracene, and benz[α]anthracene as the model analytes. Limits of detection and linearities were achieved in the range of 0.06-0.18 μg L^-1 and 0.25-500 μg L^-1, respectively. Precision of the method as RSDs was evaluated which was in the range of 4.2-7.0% (within-day, n = 5) and 8.2-11.3% (between-day, n = 3). Ultimately, the method was applied to analyze two seawater samples and satisfactory results (RSDs%, 5.0-9.0%; relative recoveries, 89-104%) were obtained.

Preparation, surface functionalization and application of Fe3O4 magnetic nanoparticles

This paper reviews recent developments in the preparation, surface functionalization, and applications of Fe₃O₄ magnetic nanoparticles. Especially, it includes preparation methods (such as electrodeposition, polyol methods, etc.), organic materials (such as polymers, small molecules, surfactants, biomolecules, etc.) or inorganic materials (such as silica, metals, and metal oxidation/sulfide, functionalized coating of carbon surface, graphene, etc.) and its applications (such as magnetic separation, protein fixation, magnetic catalyst, environmental treatment, medical research, etc.). In the end, some existing challenges and possible future trends in the field were discussed.

Use of Nanomaterial-Based (Micro)Extraction Techniques for the Determination of Cosmetic-Related Compounds

The high consumer demand for cosmetic products has caused the authorities and the industry to require rigorous analytical controls to assure their safety and efficacy. Thus, the determination of prohibited compounds that could be present at trace level due to unintended causes is increasingly important. Furthermore, some cosmetic ingredients can be percutaneously absorbed, further metabolized and eventually excreted or bioaccumulated. Either the parent compound and/or their metabolites can cause adverse health effects even at trace level. Moreover, due to the increasing use of cosmetics, some of their ingredients have reached the environment, where they are accumulated causing harmful effects in the flora and fauna at trace levels. To this regard, the development of sensitive analytical methods to determine these cosmetic-related compounds either for cosmetic control, for percutaneous absorption studies or for environmental surveillance monitoring is of high interest. In this sense, (micro)extraction techniques based on nanomaterials as extraction phase have attracted attention during the last years, since they allow to reach the desired selectivity. The aim of this review is to provide a compilation of those nanomaterial-based (micro)extraction techniques for the determination of cosmetic-related compounds in cosmetic, biological and/or environmental samples spanning from the first attempt in 2010 to the present.

Tuning of Shells in Trilaminar Core@Shell Nanocomposites in Controlling Electromagnetic Interference through Switching of the Shielding Mechanism

Fe₃O₄@SiO₂@PPy core-shell nanocomposites were fabricated by the coating of SiO₂ on Fe₃O₄ through base catalyzed hydrolysis of tetraethyl orthosilicate followed by encapsulation of polypyrrole (PPy). Subsequently, these trilaminar composites have been characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller, superconducting quantum interference devices, and measurement of the total shielding efficiency in the frequency range of 2-8 GHz. Our findings showed the highest total shielding efficiency (∼32 dB) of Fe₃O₄@SiO₂@PPy (Fe₃O₄@SiO₂/pyrrole wt/wt = 1:9) and followed reflection as the dominant shielding mechanism. Such performance was attributed to poor impedance matching between the PPy (conducting)/SiO₂ (insulating) and high electrical conductivity of Fe₃O₄@SiO₂@PPy. Alternatively, electromagnetic (EM) waves incident on the SiO₂@PPy interface could also account for enhancing the total shielding efficiency of Fe₃O₄@SiO₂@PPy because of multireflection/refraction. Our earlier work also showed excellent total shielding efficiency of Fe₃O₄@C@PANI nanocomposites, through absorption as the dominant shielding mechanism. These findings clearly suggest that EM interference shielding in Fe₃O₄@SiO₂@PPy and Fe₃O₄@C@PANI trilaminar core@shell nanocomposites is controlled by tuning of the shells through switching of the mechanism.

Hybrid Materials Based on Poly-3-amine-7-methylamine-2-methylphenazine and Magnetite Nanoparticles Immobilized on Single-Walled Carbon Nanotubes

Polymer-metal-carbon hybrid nanomaterials based on thermostable electroactive poly-3-amine-7-methylamine-2-methylphenazine (PAMMP), single walled carbon nanotubes (SWCNT), and magnetite (Fe₃O₄) nanoparticles were synthesized for the first time. Hybrid Fe₃O₄/SWCNT/PAMMP nanomaterial synthesis was carried out via in situ chemical oxidative polymerization of 3-amine-7-methylamine-2-methylphenazine hydrochloride in the presence of metal-carbon Fe₃O₄/SWCNT nanocomposites. Fe₃O₄/SWCNT nanocomposites were obtained by the immobilization of magnetite nanoparticles on the SWCNT surface in the course of Fe₃O₄ nanoparticles synthesis in alkaline medium. The developed nanocomposite materials were characterized by FTIR spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission (FE-SEM) scanning electron microscopy, atomic absorption spectrometry (AAS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and magnetometry. The chemical structure and phase composition, magnetic and electrical properties, and thermal stability of the obtained multifunctional nanomaterials, depending on synthesis conditions, were investigated.

3D-Printed Microflow Injection Analysis Platform for Online Magnetic Nanoparticle Sorptive Extraction of Antimicrobials in Biological Specimens as a Front End to Liquid Chromatographic Assays

In this work, the concept of 3D-printed microflow injection (3D-μFI) embodying a dedicated multifunctional 3D-printed stator onto a rotary microvalve along with a mesofluidic sample preparation platform is proposed for the first time. A transparent 3D-printed stereolithographic mesofluidic chip device accommodating polyaniline (PANI) decorated magnetic nanoparticles (32.5 ± 3.8 mg) is harnessed to in-line sorptive microextraction as a front end to liquid chromatography with peak focusing. As a proof-of-concept application, the 3D-μFI assembly was resorted to matrix cleanup and automatic programmable-flow determination of organic emerging contaminants (4-hydroxybenzoate analogues and triclosan as antimicrobial model analytes) in human saliva and urine samples. By using a sample volume of 1.0 mL with a loading flow rate of 200 μL min^-1, an eluent volume of 120 μL at 80 μL min^-1, and online HPLC injection of 300 μL of the mixture of eluate and Milli-Q water (in a 1:2 ratio) to prevent band broadening effects of the most polar analytes, the limits of detection (3σ criterion) ranged from 1.1 to 4.5 ng mL^-1 for methylparaben (MP), ethylparaben (EP), propylparaben (PrP), phenylparaben (PhP), butylparaben (BP), and triclosan (TCS). Enhancement factors of 16-25 were obtained for the target analytes. Spike recoveries ranged from 84 to 117% for both saliva and urine samples. The online 3D-μFI hyphenated method is synchronized with the chromatographic separation and features a chip lifetime of more than 20 injections with minimal losses of moderately nonpolar compounds on the walls of the mesofluidic device.

Selective removal and preconcentration of triclosan using a water-compatible imprinted nano-magnetic chitosan particles

A water-compatible magnetic triclosan (TCS) imprinted material (TCS-CTS-Fe⁰-MIPs) was synthesized for selective enrichment and detection of TCS in real complex water samples. The material was synthesized by using chitosan (CTS) as functional monomer, which has rich surface O- and N-containing functional groups. The TCS imprinted CTS was coated on Fe⁰ surface and then cross-linked with glutaraldehyde. Scanning electron microscopy suggested that the imprinted material was covered with a layer of imprinted film, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that the imprinted material had more functional groups (amino and hydroxyl groups) than that of non-imprinted material. The TCS imprinted and non-imprinted materials used in each adsorption experiments were 0.1 mg mL^-1. The maximum adsorption capacity of the TCS imprinted material and non-TCS imprinted material were 20.86 and 15.11 mg g^-1, respectively. The adsorption results showed that selectivity coefficient was 10.151, 1.353, and 8.271 in the presence of p-chlorophenol, 2,4,6-trichlorophenol, and bisphenol-A, respectively. The recoveries of river water and lake water samples were 92.8, 91.3, 92.4, and 81.4, 82.3, 82.1%, respectively, when the samples were spiked with 4, 6, and 8 μg L^-1 of TCS with the imprinted material. The adsorption capacity of the TCS imprinted material and non-TCS imprinted material lost 5.2 and 6.2% after six times of recycling. The high selectivity and excellent adsorption capacity of the imprinted material can be attributed to the presence of sterically complementary imprinted sites and high surface, which would also made it more accessible to TCS than that of non-imprinted material. The present study would provide an environmental friendly and convenient method for the removal and the monitoring of TCS in environmental water samples.

Magnetic nanoparticle modified chitosan for surface enhanced laser desorption/ionization mass spectrometry of surfactants

Chitosan (CTS) modified magnetic nanoparticles (CTS@Fe₃O₄MNPs) offer dual functions for the detection of surfactants using surface enhanced laser desorption/ionization mass spectrometry (SELDI-MS).

Extraction of phenolic compounds from water samples by dispersive micro-solid-phase extraction

In this article, the use of magnetically separable sorbent polyaniline/silica-coated nickel nanoparticles is evaluated under a dispersive micro-solid-phase extraction approach for the extraction of phenolic compounds from water samples. The sorbent was prepared by in situ chemical polymerization of aniline on the surface of silica-modified nickel nanoparticles and was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, and vibrating sample magnetometry. Effective variables such as amount of sorbent (milligrams), pH and ionic strength of sample solution, volume of eluent solvent (microliters), vortex, and ultrasonic times (minutes) were investigated by fractional factorial design. The significant variables optimized by a Box-Behnken design were combined by a desirability function. Under the optimized conditions, the calibration graphs of analytes were linear in a concentration range of 0.02-100 μg/mL, and with correlation coefficients more than 0.999. The limits of detection and quantification were in the ranges of 10-23 and 33-77 μg/L, respectively. This procedure was successfully employed in the determination of target analytes in spiked water samples; the relative mean recoveries ranged from 96 to 105%.