Ferroferric Oxide Nanoparticles Research Articles

Response of anammox consortia to inhibition from high ferroferric oxide nanoparticles concentration and potential recovery mechanism

The substantial discharge of ferroferric oxide nanoparticles (Fe3O4 NPs) into sewage threatens the survival of functional microorganisms in wastewater treatment. This study elucidated responses of anaerobic ammonium oxidation (anammox) consortia to inhibition from high Fe3O4 NPs concentration and recovery mechanisms. The nitrogen removal efficiency decreased by 20.3 % and recovered after 55 days under 1000 mg/L Fe3O4 NPs concentration. Toxicity was attributed to reactive oxygen species (ROS) production. The excessive ROS damaged membrane integrity, nitrogen metabolism, and DNA synthesis, resulting in the inhibition of anammox bacteria activity. However, recovery mechanisms of anammox consortia activity were activated in response to 1000 mg/L Fe3O4 NPs. The increase of heme oxygenase-1, thioredoxin, and nicotinamide adenine dinucleotide-quinone oxidoreductase genes alleviated oxidative stress. Furthermore, the activation of metabolic processes associated with membrane and DNA repair promoted recovery of anammox bacteria activity. This study provided new insights into NPs contamination and control strategies during anammox process.

Dual-functional metal-organic frameworks-based hydrogel micromotor for uranium detection and removal

Self-propelled micro/nanomotors have attracted great attention for environmental remediation, however, their use for radioactive waste detection and removal has not been addressed. Engineered micromotors that are able to combine fast detection and highly adsorptive capability are promising tools for radioactive waste management but remain challenging. Herein, we design self-propelled micromotors based on zeolite imidazolate framework (ZIF-8)-hydrogel composites via inverse emulsion polymerization and show their potential for efficient uranium detection and removal. The incorporation of magnetic ferroferric oxide nanoparticles enables the magnetic recycling and actuation of the single micromotors as well as formation of swarms of worm-like or tank-treading structure. Benefited from the enhanced motion, the micromotors show fast and high-capacity uranium adsorption (747.3 mg g−1), as well as fast uranium detection based on fluorescence quenching. DFT calculation confirms the strong binding between carboxyl groups and uranyl ions. The combination of poly(acrylic acid-co-acrylamide) with ZIF-8 greatly enhances the fluorescence of the micromotor, facilitating the high-resolution fluorescence detection. A low detection limit of 250 ppb is reached by the micromotors. Such self-propelled micromotors provide a new strategy for the design of smart materials in remediation of radioactive wastewater.

Fabrication of Fe3O4@GO@ZIF-8 nanohybrids via in-situ self-assembly with magnetic collectability for efficient adsorption of As(III) and As(V)

Fe3O4@GO@ZIF-8 nanohybrids were successfully fabricated as a novel magnetic graphene adsorbent via in-situ self-assembly of ZIF-8 and graphene oxide (GO) onto magnetic ferroferric oxide nanoparticles. The adsorbent was thoroughly characterized using various techniques. The results showed that Fe3O4@GO@ZIF-8 exhibits strong magnetic properties, abundant functional groups and a large specific surface area of 779.48 m2 g−1. Additionally, the effects of time, pH, initial concentration and temperature on the adsorption performances of Fe3O4@GO@ZIF-8 for trivalent arsenite (As(III)) and pentavalent arsenate (As(V)) were explored. The results revealed that Fe3O4@GO@ZIF-8 possesses fast reaction kinetics (reaching saturation in approximately 180 min for As(III) and 120 min for As(V)), as well as excellent adsorption capabilities (achieving adsorption capacities of 87.621 mg g−1 for As(III) and 113.37 mg g−1 for As(V)). Furthermore, recycling experiments demonstrated that Fe3O4@GO@ZIF-8 exhibits favorable adsorption ability, enabling easy recovery under an applied magnetic field. These results highlight the magnetic properties, good reusability, and adsorption capacity of Fe3O4@GO@ZIF-8, rendering it highly practical for extracting arsenic wastes in harsh environments.

Dual-Responsive Turn-On T1 Imaging-Guided Mild Photothermia for Precise Apoptotic Cancer Therapy.

Apoptosis has gained increasing attention in cancer therapy as an intrinsic signaling pathway, which leads to minimal leakage of waste products from a dying cell to neighboring normal cells. Among various stimuli to trigger apoptosis, mild hyperthermia is attractive but confronts limitations of non-specific heating and acquired resistance from elevated expression of heat shock proteins. Here, a dual-stimulation activated turn-on T1 imaging-based nanoparticulate system (DAS) is developed for mild photothermia (≈43°C)-mediated precise apoptotic cancer therapy. In the DAS, a superparamagnetic quencher (ferroferric oxide nanoparticles, Fe3 O4 NPs) and a paramagnetic enhancer (Gd-DOTA complexes) are connected via the N6-methyladenine (m6 A)-caged, Zn2+ -dependent DNAzyme molecular device. The substrate strand of the DNAzyme contains one segment of Gd-DOTA complex-labeled sequence and another one of HSP70 antisense oligonucleotide. When the DAS is taken up by cancer cells, overexpressed fat mass and obesity-associated protein (FTO) specifically demethylates the m6 A group, thereby activating DNAzymes to cleave the substrate strand and simultaneously releasing Gd-DOTA complex-labeled oligonucleotides. The restored T1 signal from the liberated Gd-DOTA complexes lights up the tumor to guide the location and time of deploying 808nm laser irradiation. Afterward, locally generated mild photothermia works in concert with HSP70 antisense oligonucleotides to promote apoptosis of tumor cells. This highly integrated design provides an alternative strategy for mild hyperthermia-mediated precise apoptotic cancer therapy.

MiR-375 antagonist modified ferroferric oxide nanoparticles inhibited invasion and migration of ovarian cancer cells

This experiment assessed the effect of miR-375 antagonist (mA) modified ferroferric oxide nanoparticles (FONPs) on ovarian cancer cells. SKOV 3 cells were assigned into blank group (normal culture SKOV 3 cells), control group (intervention with FONPs), and intervention group (mA-FONPs), followed by analysis of cell biological behaviors and expressions of Bax, Bcl-2, Caspase-3, E-cadherin, N-cadherin, Vimentin, TL-6, JAK2, and STAT3. The nanoparticles were spherical with excellent dispersion and about 77 nm. Compared with the other two groups, the intervention group showed decreased cell vitality, increased apoptosis (P <0.05). Cell number (44.63+2.37)% and migration quantity (89.75+4.01)% decreased significantly after intervention (P <0.05) along with higher levels of E cadherin, Bax, Caspase 3 activity and lower levels of Bcl-2, N-cadherin, Vimentin, IL-6, JAK2 and STAT3 (P <0.05). miR-375 targeted and inhibited the activity of JAK2/STAT3 pathway, reducing levels of IL-6, p-JAK2, and p-STAT3, up-regulating the expression of Bax and Caspase-3, reducing levels of N-cadherin and Vimentin, and finally regulating cell apoptosis and inhibiting cell migration and invasion.

Femtosecond laser ablation in liquid synthesis of iron-oxidation nanoparticles with saturable absorption performance.

"Naked" ferroferric-oxide nanoparticles (FONPs) synthesized by a femtosecond laser ablation on a bulk stainless steel in liquid were applied to the Nd: YVO4 laser to achieve passive Q-switched pulse laser output. Without the pollution of ligand, the inherent light characteristic of "naked" FONPs was unaffected. The analysis of the morphological characteristics, dominant chemical elements, and phase composition of the FONPs showed that they were mainly composed of Fe3O4, which was spherical with an average diameter of 40 nm. The electron transition and orbital splitting of the iron element's octahedral center position under the laser-driven were considered the primary mechanisms of saturable absorption of Fe3O4 nanoparticles.

Multifunctional Hydroxyapatite Nanobelt Haystacks Integrated Neural Stem Cell Spheroid for Rapid Spinal Cord Injury Repair

AbstractDue to the unwarranted lifespan and differentiation, applying neural stem cells (NSCs) in spinal cord injury (SCI) remains challenging. In this study, 3D bioactive hydroxyapatite (HAp) nanobelt haystack‐mouse NSC (mNSC) hybrid spheroids are customized in which the specific nanobelt haystack framework provided the structural function of hypoxia alleviation in the spherical core and biological process of neural differentiation promotion. Commodified with superparamagnetic ferroferric oxide (Fe3O4) nanoparticles and a polydopamine (PDA) coating, the HAp nanobelts are endowed with magnetic field‐driven properties and enhanced cell‐nanobelt adhesion. The engineered bioresponsive 3D nanobelt haystack‐mNSC hybrid spheroids effectively repair SCI in vivo, showing new potential for stem cell therapy by incorporating nanomaterials in 3D culture based on cell‐material interactions.

Design of an Injectable Magnetic Hydrogel Based on the Tumor Microenvironment for Multimodal Synergistic Cancer Therapy.

Conventional tumor chemotherapy is limited by its low therapeutic efficacy and side effects, which severely hold back its further application. Drug delivery systems (DDSs) based on nanomaterials have attracted wide interest in cancer treatment; especially, the system can realize efficient synergistic therapies. Here, we designed a smart hydrogel drug delivery system with multiple responses to enhance the tumor treatment effect. By cross-linking oxidized hydroxypropyl cellulose with carboxymethyl chitosan, an injectable hydrogel was obtained, into which artesunate (ART), ferroferric oxide (Fe3O4) nanoparticles, and black phosphorus nanosheets (BPs) were preloaded. This DDS has multiple functions including magnetic targeting, pH sensitivity, chemodynamic therapy, and photothermal response. This nanoparticle-composited hydrogel not only preserved excellent rheological properties but also allowed for an accurate stable drug release at tumor sites and synergistic effects of multiple therapies. The in vitro and in vivo experiments revealed that this DDS could efficiently eliminate the HepG2 tumor with good biocompatibility. Taken together, this study clarifies the possible antitumor mechanism of this ART-loaded nanoparticle-composited hydrogel and provides a new strategy for synergistic photothermal-chemo-chemodynamic therapy.

Multiplex strategy electrochemical platform based on self-assembly dual-site DNA tetrahedral scaffold for one-step detection of diazinon and profenofos

In the work, based on self-assembly dual-site DNA tetrahedral scaffold (DTS), thionine (Thi), and 6-(Ferrocenyl)hexanethiol (Fc6S), a multiplex strategy electrochemical platform was fabricated for the simultaneous detection of profenofos (PFF) and diazinon (DZN). Thi and Fc6S were used to label aptamers for the synthesis of probes respectively. Notably, Thi and Fc6S engendered recognizable DPV peaks at different potentials to achieve simultaneous detection of PFF and DZN. In addition to increasing the conductivity of the electrode, the combination of carboxylic acid functionalized multi-walled carbon nanotubes and ferroferric oxide nanoparticles could also increase its higher specific surface area of the electrode interface to adsorb more DTS. Because of the mechanical rigidity of the DTS, the DTS could keep a complementary chain upright and provide more binding sites for aptamers, the binding efficiency between the complementary chain and 2 binding aptamers could be improved. Comparing the aptasensors performance of single-strand DNA with that of the DTS with complementary strands, the benefits of the DTS were highlighted in this system. Under optimal conditions, the detection limits of PFF and DZN were both 3.33 pg/mL and the detection ranges were both 1.00 × 101–1.00 × 107 pg/mL. Meanwhile, the recoveries of PFF and DZN were 87.15%–117.34% and 91.20%–114.19%, respectively. The aptasensor could realize the simultaneous detection of PFF and DZN in vegetables. Furthermore, the aptasensor also had good stability and selectivity. This strategy could provide a good reference for developing effective aptasensors for the simultaneous detection of other small molecules and toxins.

A Telomerase-Activated Magnetic Resonance Imaging Probe for Consecutively Monitoring Tumor Growth Kinetics and In Situ Screening Inhibitors.

Telomerase has long been considered as a biomarker for cancer diagnosis and a therapeutic target for drug discovery. Detecting telomerase activity in vivo could provide more direct information of tumor progression and response to drug treatment, which, however, is hampered by the lack of an effective probe that can generate an output signal without a tissue penetration depth limit. In this study, using the principle of distance-dependent magnetic resonance tuning, we constructed a telomerase-activated magnetic resonance imaging probe (TAMP) by connecting superparamagnetic ferroferric oxide nanoparticles (SPFONs) and paramagnetic Gd-DOTA (Gd(III) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) complexes via telomerase-responsive DNA motifs. Upon telomerase-catalyzed extension of the primer in TAMP, Gd-DOTA-conjugated oligonucleotides can be liberated from the surface of SPFONs through a DNA strand displacement reaction, restoring the T1 signal of the Gd-DOTA for a direct readout of the telomerase activity. Here we show that, by tracking telomerase activity, this probe provides consistent monitoring of tumor growth kinetics during progression and in response to drug treatment and enables in situ screening of telomerase inhibitors in whole-animal models. This study provides an alternative toolkit for cancer diagnosis, treatment response assessment, and anticancer drug screening.

Electrical Treeing and Its Suppression Method of SiR in High Magnetic Field

This paper investigates the effects of high magnetic field on electrical treeing of silicone rubber (SiR). Experimental results show that electrical trees are more easily to be initiated and spread further along the direction of electric field under the effects of high magnetic field. When the direction of high magnetic field is perpendicular to that of electric field, magnetic field with higher magnetic flux density also results in larger accumulated damage area. Splitting of energy band structure and changes in polarization characteristics result in a lower interface barrier and more serious partial discharge, thus causing the weakened resistance to electrical treeing in high magnetic field. Based on the insulation degradation mechanism, SiR was modified by adding ferroferric oxide (Fe3O4) nanoparticles to improve its insulation performance in high magnetic field. Moderate addition amount of Fe3O4 nanoparticles is proved to be able to suppress electrical treeing in high magnetic field by forming quantum dots, modifying polarization properties and partial discharge behavior. Excessive addition of Fe3O4 nanoparticles has negative effects on suppressing electrical treeing due to the magnetization of the nanocomposites.

Manipulation and elimination of circulating tumor cells using multi-responsive nanosheet for malignant tumor therapy.

Tumor recurrence caused by metastasis is a major cause of death for patients. Thus, a strategy to manipulate the circulating tumor cells (CTCs, initiators of tumor metastasis ) and eliminate them along with the primary tumor has significant clinical significance for malignant tumor therapy. In this study, a magnet-NIR-pH multi-responsive nanosheet (Fe3O4@SiO2-GO-PEG-FA/AMP-DOX, FGPFAD) was fabricated to capture CTCs in circulation, then magnetically transport them to the primary tumor, and finally perform NIR-dependent photothermal therapy as well as acidic-environment-triggered chemotherapy to destroy both the CTCs and the primary tumor. The FGPFAD nanosheet consists of silica-coated ferroferric oxide nanoparticles (Fe3O4@SiO2, magnetic targeting agent), graphene oxide (GO, photothermal therapy agent), polyethylene glycol (PEG, antifouling agent for sustained circulation), folic acid (FA, capturer of CTCs) and antimicrobial-peptide-conjugated doxorubicin (AMP-DOX, agent for chemotherapy), in which the AMP-DOX was bound to the FGPFAD nanosheet via a cleavable Schiff base to achieve acidic-environment-triggered drug release for tumor-specific chemotherapy. Both in vitro and in vivo results indicated that the effective capture and magnetically guided transfer of CTCs to the primary tumor, as well as the multimodal tumor extermination performed by our FGPFAD nanosheet, significantly inhibited the primary tumor and its metastasis.

Gas–Liquid Reactions to Synthesize Positively Charged Fe3O4 Nanoparticles on Polyurethane Sponge for Stable and Recyclable Adsorbents for the Removal of Phosphate from Water

The application of most current phosphate adsorbents is limited by their high cost, low removal capacity, difficulty of recovery, and short lifetime. In this study, we developed a gas–liquid reaction assisted by a coordination method to prepare highly positively charged ferroferric oxide (Fe3O4) nanoparticles loaded on polyurethane sponge. It was found that the gas–liquid reaction drastically decreases the size and increases the loading capacity of Fe3O4 nanoparticles as compared with the conventional liquid method. Further, the use of trimethylamine vapor induced the coordination of Fe3+, facilitated the formation of free Cl ions, and inhibited the hydrolysis of Fe–Cl bonds, thus greatly decreasing the amount of hydroxyl groups and increasing the surface positive charge on Fe3O4 nanoparticles. As a result, the Fe3O4 nanoparticles in this study have a saturated PO43– adsorption capacity of 229.8 mg·g–1, which was appreciably higher than that of conventional Fe3O4 adsorbents (57.8 mg·g–1). Our study further revealed that the introduction of a thin layer of polyurethane coating on the surface of Fe3O4 nanoparticle-composited adsorbents could drastically improve their stability while preserving the adsorption capacity under the impact of water (500 rpm stirring for 72 h). The composited adsorbents also preserve the adsorption capacity after recycling three times. Finally, the adsorption experiment on real river wastewater indicated that the composited adsorbents enable the decrease of phosphate concentration from 0.6 to 0.02 ppm, reflecting the application potential for relieving phosphate pollution in neutral waters.

Research on the all-solid-state passively mode-locked laser with Fe3O4 nanosheets saturable absorber

Ferroferric-oxide nanoparticles(FONP) are a novel saturable absorber(SA) that have been demonstrated in passively mode-locked laser. Recently, our group developed a large-scale Ferroferric-oxide nanosheet(FONS) using a self-assembly method induced by a magnetic field. In this study, large-size FONS were prepared by self-assembly method under magnetic field induction and characterized under microscope, SEM and I-scan system and used for the first time in solid-state passively mode-locking as a saturable absorber. Using this novel saturable absorber in Nd:YVO4 laser, a mode-locked laser with a pulse duration of 506 ps at a repetition rate of 110 MHz at the wavelength of 1064 nm was achieved. The average output power and single pulse energy of the mode-locked laser are 165 mW, 50 nJ, up to 385 mW, 117 nJ.

Novel phenylalanine-modified magnetic ferroferric oxide nanoparticles for ciprofloxacin removal from aqueous solution

The pollution of natural water bodies by pharmaceutical compounds has led to serious concerns regarding ecological and public health safety. In this study, novel recyclable phenylalanine (Phe)-modified magnetic ferroferric oxide nanoparticles (Fe3O4@Phe NPs) were successfully synthesized for the first time using a simple one-pot method to remove ciprofloxacin (CIP) from aqueous solutions. Fe3O4 and Fe3O4@Phe NPs were characterized using different techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Turbiscan analysis and vibrating-sample magnetometry (VSM). The results show that Fe3O4 NPs are fully encapsulated by Phe, exhibiting an average diameter of 200 nm, a high specific surface area (35.79 m2 g-1), good dispersion and superparamagnetic properties. The effects of Phe content, initial pH and ionic strength on CIP adsorption onto Fe3O4 and Fe3O4@Phe NPs are investigated. The maximal adsorption capacity of CIP onto Fe3O4@Phe NPs is determined to be 49.27 mg g-1. The adsorption kinetics and isotherms show that the adsorption process follows the pseudo-second-order-kinetic and Langmuir isotherm models, respectively. This indicates that the adsorption involves a rate-controlled monolayer chemisorption process. The regeneration experiments show that Fe3O4 and Fe3O4@Phe NPs exhibit good reusability for CIP adsorption. Adsorption mechanisms include electrostatic interactions, hydrogen bonding, hydrophobicity and π-π interactions. This study presents a promising strategy for the design and preparation of multifunctional nanoparticles to remove contaminants from the environment.

Phototoxic Effect of UVA-Responsive Fe3O4@ZnO Nanoparticles on Squamous Skin Cell

Zinc oxide (ZnO) is a resource-rich metal oxide with a certain degree of phototoxicity toward cancer cells using ultraviolet light radiation. Therefore, it is a promising photosensitizer for photodynamic therapy against cancer. The current study synthesized core-shell structure nanoparticles using Fe3O4 as the core and ZnO as the shell. The core–shell nanoparticles were spherical-like and superparamagnetic, with a zeta potential of −22.7±7.6 mV. ZnO-coated ferroferric oxide nanoparticles (Fe3O4@ZnO NPs) under ultraviolet A (UVA) irradiation could induce a lot more reactive oxygen species in the squamous skin cells causing the evident inhibitory effect. In contrast, they indicated no toxicity to skin squamous cells without UVA radiation. Therefore, it can be inferred that their great potential as the targeting photosensitizer for photodynamic therapy on skin squamous cell carcinoma is due to their good biocompatibility without UVA radiation and excellent toxicity under UVA radiation on skin squamous cells.

Mode-locked Tm-doped fiber laser induced by ferroferric-oxide nanoparticles and a D-shaped fiber

• We demonstrate a passively mode-locked laser operating at 2 um region based on a saturable absorber (SA) of FONPs deposited on the D-shaped fiber (DF). This is the first use of FONPs to achieve mode-locking at 2um. • The mode-locking operates in 1931 nm, the 3 dB bandwidth is 5.9 nm, the repetition frequency is 24 MHz, and the pulse width is 1.29 ps. In addition, the signal-to-noise ratio is ∼67 dB, indicating the stability of the output spectrum. As a unique type of transition metal oxides, ferroferric-oxide nanoparticles (FONPs) have attracted much attention due to their outstanding physical and chemical properties. In this paper, we demonstrate a passively mode-locked laser operating at 2 um region based on a saturable absorber (SA) of FONPs deposited on the D-shaped fiber (DF). FONPs were deposited on DF to form FONP-DF SA devices. As inserted into the thulium-doped fiber laser (TDFL), a mode-locked pulse was realized at 1931 nm. For all we know, this is the first demonstration of FONP-DF SA in fiber lasers at 2 um region. This work fills the gap of FNOP in the realization of 2 um mode-locking and lays the foundation for us to use FNOP-DF for magnetic field sensing in the future.

Magnetic solid-phase extraction method with modified magnetic ferroferric oxide nanoparticles in a deep eutectic solvent and high-performance liquid chromatography used for the analysis of pharmacologically active ingredients of Epimedium folium

A novel magnetic adsorption nanomaterial was synthesized by the copolymerization of a deep eutectic solvent (DES) and chitosan (CS)-modified Fe3O4 particles. This material was proposed for the magnetic solid-phase extraction (MSPE) of flavonoids from an aqueous extract solution of herbal Epimedium folium without pretreatment. Coupled with high-performance liquid chromatography (HPLC), a rapid, environmentally friendly, and efficacious method was established and successfully applied for the enrichment, separation, and quantification of five quality marker flavonoids (viz. icariin, epimedin A, epimedin B, epimedin C, and baohuoside Ⅰ, respectively) in herbal E. folium collected from four species and 18 habitats. In addition, the physicochemical properties and morphology of Fe3O4-CS-DES were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and vibrating sample magnetometry. Furthermore, key parameters, including adsorbent amount, elution solvent, and desorption factor, were optimized. Under the optimal experimental conditions, the five flavonoids were adsorbed rapidly on MSPE, which were released easily using methanol-acidified formic acid. A reversed-phase C18 column with gradient mobile phases comprising acetonitrile and formic acid water was used for analyte separation and elution. Limits of detection for the five analytes ranged from 0.5 to 2.1 ng mL−1. Coefficients of determination in analyses ranged from 0.99994 to 0.99999. Intra-day and inter-day precision ranged from 0.75 to 5.18% (n = 6) and from 2.88 to 7.52% (n = 3), respectively. Recoveries of the five analytes ranged from 80 to 110%, with relative standard deviation values of less than 10%. To the best of our knowledge, as a new adsorbent, Fe3O4-CS-DES nanoparticles were synthesized and used for the first time for the preconcentration and separation of flavonoids. This study provided a new approach for the enrichment and detection of Epimedium flavonoids in real samples.

Multifunctional management of gold nanoparticles for improved applications

Increasingly, nanotechnology has the potential to be applied in disease detection or treatment. Nanotechnology advancements have resulted in novel and improved biomedical nanomaterials. Liposomes, polymeric micelles, graphene, carbon nanotubes, quantum dots, ferro ferric oxide nanoparticles, gold nanoparticles (Au NPs), and so on are some of the most commonly used nanomaterials in biomedical applications. Because of its unique optical, electrical, sensing and biological capabilities, Au NPs have been regarded as the most fascinating nanomaterial. Medical imaging, drug administration and tumour therapy are all possible applications of Au NPs in the early identification and diagnosis and treatment of illnesses. This review focuses on some recent breakthroughs in the management of Au NPs as drug carriers for the intracellular delivery of therapies and as molecular nanoprobes for the detection and monitoring of target molecules.

Ultrahigh efficient and selective adsorption of U(VI) with amino acids-modified magnetic chitosan biosorbents: Performance and mechanism

Exploiting eco-friendly, highly controlled preparation and convenient solid-liquid separation adsorbent to separate uranium from aquatic medium is of importance and in demand. In this study, magnetic ferroferric oxide nanoparticles synthesized through a facile hydrothermal reaction was cross-linked with chitosan. The intermediate product was subsequently chemically grafting with four amino acids such as alanine, serine, glycine or L-cysteine to produce Ala-MCS, Ser-MCS, Gly-MCS and Cys-MCS. The resultants were verified by SEM, EDS, XRD, VSM, FT-IR and XPS. Adsorption of uranium with amino acids-modified magnetic chitosans were carried out. The parameters that affected the adsorption ability, selectivity toward uranium, and reusability have been illustrated. pH 6.5 was the most beneficial for the adsorption. The saturation adsorption capacity of Ala-MCS, Ser-MCS, Gly-MCS, Cys-MCS were found as 658.88 mg/g ± 1.0 %, 616.10 ± 0.3 % mg/g, 646.38 ± 1.8 % mg/g, 653.96 ± 3.4 % mg/g and 409.15 ± 4.6 % mg/g, respectively. The adsorption process was analyzed using kinetics (pseudo-first-order, pseudo-second-order and intraparticle diffusion models) and isotherms models (Langmuir and Freundlich models). The adsorption of uranium on Ala-MCS, Ser-MCS, Gly-MCS and Cys-MCS happened on monolayer and were controlled by chemisorption. The certified high adsorption amount and efficient solid-liquid separation proved amino acids-modified magnetic chitosan are promising adsorbents for removal of uranium from wastewater.