O4 Nanoparticles Research Articles

Development of a new strategy for the synthesis of graphene oxide-alumina nanocomposite as an efficient adsorbent for dispersive solid-phase extraction of parabens.

The present study investigates the synthesis and application of the graphene oxide-alumina nanocomposite as a new adsorbent for the dispersive solid-phase extraction of three parabens and their determination using high-performance liquid chromatography-ultraviolet detection. The characterization of the synthesized material was accomplished and its size, morphology, chemical composition, porosity, and thermal stability were studied. Application of the proposed strategy for the synthesis of the nanocomposite resulted in the incorporation of Al2 O3 nanoparticles into graphene oxide nanosheets, further resulting in the exfoliation of graphene oxide nanosheets increasing their surface area. An orthogonal rotatable central composite design was used to optimize the extraction. Under the optimum conditions, the analytical performance of the method showed a suitable linear dynamic range (0.2-100.0μg/L), reasonable limits of detection (0.03-0.05μg/L), and preconcentration factors ranging from 128 to 173. Finally, the new validated method was applied for the determination of parabens in some real samples including wastewater, cream, toothpaste, and juice samples with satisfactory recoveries (88%-109%), and relative standard deviations less than 8.7% (n=3). Results demonstrated that inserting alumina nanoparticles into graphene oxide nanosheets improved the extraction efficiency of parabens, as polar acidic compounds, by providing additional efficient interactions including hydrogen bonding, dipole-dipole, and Brønsted and Lewis acid-base interactions.

Ultrathin In2 O3 Nanosheets toward High Responsivity and Rejection Ratio Visible-Blind UV Photodetection.

Photoelectrochemical-type visible-blind ultraviolet photodetectors (PEC VBUV PDs) have gained ever-growing attention due to their simple fabrication processes, uncomplicated packaging technology, and high sensitivity. However, it is still challenging to achieve high-performance PEC VBUV PDs based on a single material with good spectral selectivity. Here, it is demonstrated that individual ultrathin indium oxide (In2 O3 ) nanosheets (NSs) are suitable for designing high-performance PEC VBUV PDs with high responsivity and UV/visible rejection ratio for the first time. In2 O3 NSs PEC PDs show excellent UV photodetection capability with an ultrahigh photoresponsivity of 172.36mA W-1 and a high specific detectivity of 4.43 × 1011 Jones under 254nm irradiation, which originates from the smaller charge transfer resistance (Rct ) at the In2 O3 NSs/electrolyte interface. The light absorption of In2 O3 NSs takes a blueshift due to the quantum confinement effect, granting good spectral selectivity for visible-blind detection. The UV/visible rejection ratio of In2 O3 NSs PEC PDs is 1567, which is 30 times higher than that of In2 O3 nanoparticles (NPs) and exceeds all recently reported PEC VBUV PDs. Moreover, In2 O3 NSs PEC PDs show good stability and good underwater imaging capability. The results verify that ultrathin In2 O3 NSs have potential in underwater optoelectronic devices.

Integration of adsorption and simultaneous heterogeneous catalytic oxidation by defective CoFe2O4 activated peroxymonosulfate for efficient As(III) removal: Performance and new insight into the mechanism

The iron-rich Co0.5Fe2.5O4 and stoichiometric CoFe2O4 magnetic nanoparticles with oxygen vacancies were applied to activate peroxymonosulfate (PMS) for adsorption and simultaneous oxidation of As(III) to As(V) in this work. The Co0.5Fe2.5O4/PMS system was effective in As(III) removal with 100 % total arsenic removal efficiency within 15 min. Additionally, the Co0.5Fe2.5O4 exhibited high stability and excellent recyclability in 3 repeated cycles, and the Co0.5Fe2.5O4/PMS system effectively removed total arsenic from arsenic-containing underground water and mineral processing wastewater with residual arsenic below 10 µg/L, meeting the World Health Organization (WHO) guideline. The Fourier transform infrared (FT-IR) and density functional theory (DFT) calculations indicated that surface hydroxyl groups on catalyst were active centers for the As(III) adsorption to form bidentate biconuclear complex. The nonradical active species (1O2 and Fe(IV)) were responsible for As(III) oxidation to As(V). This work proposes the mechanism of CoFe2O4/PMS for As(III) oxidation based on 1O2 and Fe(IV) for the first time, and provides a reliable treatment system for As removal from actual wastewater.

Zinc ferrite nanoparticles embedded in hydroxyapatite for magnetic hyperthermia and sensitive to ionizing radiation

Here we report the development of a bifunctional magnetic composite that induces magnetic hyperthermia and shows stable paramagnetic defects after the irradiation with X-ray source. The composite is formed by Zn0.16Fe2.84O4 nanoparticles of 18 (3) nm of diameter embedded in a micrometric carbonated hydroxyapatite matrix. As the magnetic nanoparticles are fixed in the matrix, their magnetic properties were adjusted by the size and composition in order to induce local heating by magnetic losses in presence of an AC magnetic field due to the Néel relaxation mechanism. This behavior was confirmed by measuring the Specific Power Absorption (SPA) of 0.1 wt% of magnetic nanoparticles dispersed in media with different viscosity as chloroform (η = 0.56 cP) and butter oil (η = 174 cP) obtaining ~111(15) W/g in both cases. Consistently, the magnetic hydroxyapatite composite presents a comparable SPA= 126(19) W/g value. On the other hand, the carbonated hydroxyapatite and the magnetic carbonated hydroxyapatite composite were subjected to X-ray radiation with an equivalent dose of 3 kGy and the generated paramagnetic defects were evaluated by electron paramagnetic resonance spectroscopy. It was observed that the CO2− radical is the main defect produced by the irradiation, and its concentration stabilized after a month. These results confirm the potential of this composite to act as a local nanoheater and as a sensor of ionizing radiation, showing interesting possibilities to be used in studies of nanomedicine where the combination of magnetic hyperthermia and radiotherapy is proposed for oncological treatments.

The Catalytic Reduction of Nitroanilines Using Synthesized CuFe2 O4 Nanoparticles in an Aqueous Medium.

The primary objective of this research is to investigate the reduction of 4-nitroaniline (4-NA) and 2-nitroaniline (2-NA) using synthesized copper ferrite nanoparticles (NPs) via facile one-step hydrothermal method as a heterogeneous nano-catalyst. Nitroanilines were reduced in the presence and without the catalyst with a constant amount (100 mg) of reducing agent of sodium borohydride (NaBH4 ) at room temperature in water to amino compounds. To characterize the functional groups, size, structure, and morphology of as-prepared magnetic NPs, FTIR, XRD, SEM, and TEM were employed. The UV-Vis spectrum was utilized to explore the catalytic effect of CuFe2 O4 . The outcomes revealed that the synthesized CuFe2 O4 as a heterogeneous magnetic nano-catalyst catalyzed the reduction of 4-NA and 2-NA significantly faster than other candidate catalysts. The outcomes demonstrated that the catalyst catalyzed 4-nitroaniline to para-phenylenediamine (p-PDA) and 2-nitroaniline to ortho-phenylenediamine (o-PDA) with a constant rate of 7.49×10-2 s-1 and 3.19×10-2 s-1 , and conversion percentage of 96.5 and 95.6, in 40 s and 90 s, sequentially. Furthermore, the nanoparticles could be recovered by a magnetic separation method and reused for six consecutive cycles without remarkable loss of catalytic ability.

The function of chitosan/agarose biopolymer on Fe2 O3 nanoparticles and evaluation of their effects on MCF-7 breast cancer cell line and expression of BCL2 and BAX genes.

In recent decades, magnetic nanoparticles modified with biocompatible polymers have been recognized as a suitable tool for treating breast cancer. The aim of this research was to evaluate the function of chitosan/agarose-functionalized Fe2 O3 nanoparticles on the MCF-7 breast cancer cell line and the expression of BCL2 and BAX genes. Free Fe2 O3 nanoparticles were prepared by hydrothermal method. FTIR, XRD, SEM, DLS, VSM, and zeta potential analyses determined the size and morphological characteristics of the synthesized nanoparticles. The effect of Fe2 O3 free nanoparticles and formulated Fe2 O3 nanoparticles on induction of apoptosis was studied by double-dye Annexin V-FITC and PI. Also, the gene expression results using the PCR method displayed that Fe2 O3 formulated nanoparticles induced BAX apoptosis by increasing the anti-apoptotic gene expression and decreasing the expression of pro-apoptotic gene BCL2, so the cell progresses to planned cell death. In addition, the results showed that the BAX/BCL2 ratio decreased significantly after treatment of MCF-7 cells with free Fe2 O3 nanoparticles, and the BAX/BCL2 ratio for Fe2 O3 formulated nanoparticles increased significantly. Also, to evaluate cell migration, the scratch test was performed, which showed a decrease in motility of MCF-7 cancer cells treated with Fe2 O3 nanoparticles formulated with chitosan/agarose at concentrations of 10, 50, 100, and 200 μg/ml.

Surface-Mediated Production of Complexed •OH Radicals and FeO Species as a Mechanism for Iron Oxide Peroxidase-Like Nanozymes.

Fe3 O4 nanoparticles (NPs) with intrinsic peroxidase-like properties have attracted significant interest, although limitedinformation is available on the definite catalytic mechanism. Here, it is shown that both complexed hydroxyl radicals (•OH) and high-valent FeO species are attributed primarily to the peroxidase-like catalytic activity of Fe3 O4 NPs under acid conditions rather than only being caused by free •OH radicals generated through the iron-driven Fenton/Haber-Weiss reactions as previously thought. The low energy barrier of OO bond dissociation of H2 O2 /•OOH (0.14eV) and the high oxidation activity of surface FeO (0eV) due to the reduced state of Fe on the surface of Fe3 O4 NPs thermodynamically favor both the •OH and FeO pathways. By contrast, high-valent FeO species are the key intermediates in the catalytic cycles of natural peroxidase enzymes. Moreover, it is demonstrated that the enzyme-like activity of Fe3 O4 NPs can be rationally regulated by modulating the size, surface structure, and valence of active metal atoms in the light of this newly proposed nanozyme catalytic mechanism.

Amorphization-Activated Copper Indium Core-Shell Nanoparticles for Stable Syngas Production from Electrochemical CO2 Reduction.

Electrochemical carbon dioxide reduction reaction (CO2 RR) refers to the conversion of carbon dioxide into compounds with added value through electrolysis. It is still a great challenge to design and manufacture efficient CO2 RR catalysts for desired products. Producing syngas via CO2 RR is an environmentally friendly way to reduce CO2 in the atmosphere and the dependence on fossil fuels. Herein, a new class of Cu/In2 O3 nanoparticles (NPs) with controlled phases and structures were successfully prepared as superior electrocatalysts for CO2 RR, where the CO/H2 ratios in syngas on Cu/In2 O3 NPs/C-H2 remained about 1 : 2 at a broad potential range and the total faradaic efficiency of H2 and CO always remained about 90 %. Electronic structural analysis revealed that the excellent performance was attributed to the electronic interaction between amorphous In2 O3 and Cu. This work broadens the horizons for designing and preparing fascinating electrocatalysts for CO2 RR.

Rare-earth doped BiFe0.95Mn0.05O3 nanoparticles for potential hyperthermia applications.

Ionic engineering is exploited to substitute Bi cations in BiFe0.95Mn0.05O3 NPs (BFM) with rare-earth (RE) elements (Nd, Gd, and Dy). The sol-gel synthesized RE-NPs are tested for their magnetic hyperthermia potential. RE-dopants alter the morphology of BFM NPs from elliptical to rectangular to irregular hexagonal for Nd, Gd, and Dy doping, respectively. The RE-BFM NPs are ferroelectric and show larger piezoresponse than the pristine BFO NPs. There is an increase of the maximum magnetization at 300K of BFM up to 550% by introducing Gd. In hyperthermia tests, 3mg/ml dispersion of NPs in water and agar could increase the temperature of the dispersion up to ∼39°C under an applied AC magnetic field of 80mT. Although Gd doping generates the highest increment in magnetization of BFM NPs, the Dy-BFM NPs show the best hyperthermia results. These findings show that RE-doped BFO NPs are promising for hyperthermia and other biomedical applications.

Influence of Manganese Doping on Optical Properties of Barium Ferrites Nanoparticles

The barium hexaferrite magnetic materials Mn-doped BaZn1+x Mnx Fe12-2x O19 (x = 0.4, 0.8, 1.2, 1.6, and 2) were prepared using the ceramic method. The powder samples ferrite were subjected to XRD, FT-IR, and UV-Vis to investigate the nanoparticles' structural changes. UV–Vis spectroscopy is used to obtain the samples' absorption spectrum and calculate the band gap energy. X-ray diffraction patterns and FT-IR investigations confirmed the formation of a single-phase M-type hexagonal structure. The grain size was measured from Scherrer's equation, and it is found in the range of 43-56 nm, with increasing the concentration of Mn ions, which shows the enhancement in the degree of crystallinity and increase in the size of grain size. UV-vis spectroscopy was used to confirm the formation of the BaZn1+x Mnx Fe12-2x O19 nanoparticles. The transmission was found to increase slowly in the 200-290 nm wavelength and then decreased to 332 nm after that increase until the maximum for all samples was about 99% in 480-800 nm wavelengths. The highest transmission will be exclusively used for window layers in solar cells. The band gap energy increased gradually with a rise in Mn ions and a decrease in Zn ion concentration. The refractive index, dielectric constant, and optical dielectric constant decreased with an increase in Mn ions and a decrease in Zn ions concentration.

Au/La Co-Modified In2O3 Nanospheres for Highly Sensitive Ethanol Gas Detection

In this paper, the gas-sensitive properties of co-doping the rare earth element La and noble metal Au in In2O3 nanospheres were investigated for ethanol detection. Through XRD and SEM characterization, the grain size of La-In2O3 and Au/La-In2O3 nanoparticles was smaller than that of pure In2O3. As expected, the smaller grain size sample has shown a higher response for ethanol vapor. Compared with the pure In2O3 nanoparticles, the 2 mol%Au/2 mol%La-In2O3 sample has shown better ethanol-sensing properties, including higher sensitivity (S = 381) and lower operating temperature (210 °C) for 100 ppm ethanol vapor. In addition, the Au/La-In2O3 sensor presented a fast response time (1 s). The enhancement mechanism of the ethanol response was discussed for Au/La-In2O3 nanoparticles. The obtained experimental results would provide a new road for designing higher response sensors.

A study on the structural, optical, magnetization reversal and bipolar magnetic switching behavior of SmCr0.85Mn0.15O3 nanoparticles

SmCr0.85Mn0.15O3 (SCMO) nanoparticles with Pnma space group have been synthesized by the sol-gel auto-combustion method with an average crystallite size of 70 nm. The structural analysis indicates a comparable unit cell volume with that of the bulk compound. The structural distortion is calculated by various factors such as cell distortion factor, octahedral distortion, dodecahedral distortion, strain and tolerance factor, which arise due to the Jahn-Teller (JT) effect and a tilting in the octahedra. The obtained distortion values suggest a larger distortion in the structure due to the nano-size effect compared with the bulk counterpart. The diffuse reflectance spectrum confirms the semiconducting nature of SCMO nanoparticles with an optical bandgap of 2.9 eV, higher than that of the bulk compound. The extinction coefficient of the SCMO nanoparticles exhibits a larger value than that of the bulk, suggesting a higher absorbing character of the nanoparticles. The temperature-dependent magnetization reveals a decrease in the Néel temperature on Mn substitution. The negative magnetization is also observed below the compensation temperature, Tcomp. Moreover, a stable magnetic switching behavior is demonstrated by varying temperatures under ZFC and FC protocols. The semiconducting nature and the stable magnetic switching behavior of SCMO nanoparticles make them suitable for optoelectronic, photovoltaic, and magnetic switching applications.

Increased Electromagnetic Wave Absorption through Controlled Sonication Processing on BaFe11.2Mg0.4Al0.4O19 Nanoparticles

Electromagnetic waves show rapid development in electronics, telecommunications, and the military. One of the efforts to overcome the effects of electromagnetic interference is by developing microwave-absorbing materials. Barium hexaferrite is the best candidate for development as an absorber material. Microwave absorption in barium hexaferrite can be increased through Mg-Al doping and reducing the particle size. This study aimed to analyze sonication parameters to reduce the particle size by combining destruction methods using mechanical alloying followed by high-power ultrasonic irradiation. Barium hexaferrite was synthesized through mechanical alloying by mixing stoichiometric BaCO3, Fe2O3, Al2O3, and MgO (Sigma-Aldrich p.a 99%) (Mg-Al 0.4%wt). The samples continued the sintering process at 1200 °C for 2 h to grow crystal embryos. The optimal parameters for ultrasonic destruction were using a transducer:reactor diameter ratio of 1:10, a particle density of 5 g/250 mL, and adding a non-ionic surfactant of 0.01% at an amplitude of 55% and a sonication time of 8 h. These methods resulted in the saturation magnetization of 18.50 emu/g and a coercivity of 0.08 Tesla. The reduction in the particle size of BHF doped with Mg-Al was successfully up to 21 nm, resulting in a reflection loss of up to −40.8697 dB at 11.896 GHz (x-band, 8–12 GHz). The BHF nanoparticles doped with Mg-Al effectively absorbed up to 99.99% electromagnetic waves.

Preparation of PEI-modified nanoparticles by dopamine self-polymerization for efficient DNA delivery.

Achieving efficient and safe gene delivery is of greatsignificance to promote the development of gene therapy. In this work, a polydopamine (PDA) layer was coated on the surface of Fe3 O4 nanoparticles (NPs) by dopamine (DA) self-polymerization, and then magnetic Fe3 O4 NPs were prepared by the Michael addition between amino groups in polyethyleneimine (PEI) and PDA. The prepared Fe3 O4 NPs (named Fe3 O4 @PDA@PEI) were characterized by Fourier transform infrared (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM). As an efficient and safe gene carrier, the potential of Fe3 O4 @PDA@PEI was evaluated by agarose gel electrophoresis, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, fluorescence microscopy, and flow cytometry. The results show that the Fe3 O4 @PDA@PEI NPs are stable hydrophilic NPs with a particle size of 50-150nm. It can efficiently condense DNA at low N/P ratios and protect it from nuclease degradation. In addition, the Fe3 O4 @PDA@PEI NPs have higher safety than PEI. Further, the Fe3 O4 @PDA@PEI/DNA polyplexes could be effectively absorbed by cells and successfully transfected and exhibit higher cellular uptake and gene transfection efficiency than PEI/DNA polyplexes. The findings indicate that the Fe3 O4 @PDA@PEI NPs have the potential to be developed into a novel gene vector.

A comprehensive study on structural, magnetic and dielectric properties of Ni0.3Cu0.3Zn0.4Fe1.8Cr0.2O4 nanoparticles synthesized by sol-gel auto combustion route

Ni0.3Cu0.3Zn0.4Fe1.8Cr0.2O4 (NCZF) ferrite nanoparticles (NPs) were prepared by sol-gel auto-combustion route. As obtained NCZF powder NPs from sol-get auto combustion route were divided into four parts equally. A non-calcinated part of NCZF NPs was considered as SS1 sample, whereas the three separated parts of NCZF NPs were calcinated at 400°C, 600°C and 800°C, accordingly and were considered as SS2, SS3 and SS4 samples, respectively. X-ray diffraction (XRD) patterns of as-prepared samples were used to evaluate the microstructure parameters. The obtained crystallite sizes were found to be 25, 26.5, 23.4 and 28.1 nm for SS1, SS2, SS3, and SS4 samples, respectively. Transmission electron microscopy images of samples exhibit the spherical shape particles. Average particle size was found to be 6.18, 8.24, 12.7, and 17.14 nm from particles size distributions of SS1, SS2, SS3 and SS4 samples, respectively. The saturation magnetization MS(45.96, 49.84, 48.84 and 50.01 (emu/g), coercivityHC(41.40, 43.00, 44.06, and 43.69 Oe), and remanant magnetization Mr(2.00, 1.85, 1.88 and 1.92 emu/g) were determined from M-H analysis of as-prepared samples. Surface analysis of SS2, SS3 and SS4 samples were examined by X-ray photoemission spectroscopy. Dielectric properties and real value of electric modulus of SS4 sample were reduced drastically as-compared to SS2 sample. Frequency dependent conductivity and impedance of SS4 sample was enhanced as-compared to SS2. Outstanding structural, dielectric and electric, and magnetic properties of NCZF NPs can be used for the multi-layer chip inductor applications.

Response of mixed bacterial culture towards dibenzothiophene desulfurization under the influence of surfactants and microscopically (SEM and TEM) characterized magnetic Fe3 O4 nanoparticles.

Excessive emission of sulfur dioxides from the combustion of coal and other fossil fuels for thermal and industrial purposes has been associated with serious environmental hazards. Biodesulfisation (BDS) can be an effective approach for reducing the impact of toxic gases to its inbuilt operational feasibility under ambient environmental conditions. In the present research, two strategies for BDS of a standard organosulfur compound such as dibenzothiophene (DBT) were investigated under laboratory conditions. In the first treatment, the role of different surfactants such as Tween-20, Tween-80, SDS, and EDTA on the desulfurization of DBT was investigated by the application of bacterial consortium IQMJ-5. In the second treatment, Iron oxidenanoparticles were synthesized and immobilized on the surface of bacteria cells. Shake flask experiments were conducted with immobilized cells, surfactant amended immobilized cells, and control or noncoated cells. Among different surfactant treatments, Tween-80 was found to be the most effective surfactant, showing maximum desulfurization activity at a concentration of 5g/L. The transmission electron microscopy and X-ray diffraction analysis indicated that produced nanoparticles were spherical in shape with a size of about 46 nm and had a stoichiometric ratio of 55.85% and 44.15% between O and Fe, respectively. The nanoparticle treatment enhanced the DBT desulfurization process up to 11.37% as compared to the control, specifically when immobilized cells were used. Therefore, it was concluded that nanoparticles treatments with immobilization of the bacterial cells enhanced the desulfurization rate of DBT under ambient reaction conditions and provide a sustainable alternative for commercial coal BDS.

Multifunctional Modulation of High-Performance Znx Fe3-x O4 Nanoparticles by Precisely Tuning the Zinc Doping Content.

The possibility to precisely control important properties of nanoparticles (NPs) such as their size, morphology, surface charge, or doping content is crucial for enhancing the performance of existing solutions beyond the state-of-the-art and for enabling novel applications. In this work, custom-tailored Znx Fe3- x O4 NPs are synthesized at different Zn doping concentrations to augment and expand their usefulness for high-performance applications in nanomedicine. By precisely increasing the Zn2+ content in the range of 0 ≤ x≤ 2.0, the discussed NPs can sequentially acquire valuable properties enabling magnetic resonance imaging, near-infrared (NIR) photothermal effects, NIR photocatalytic and photoelectric effects, depending on the variation of substitution position of the Zn2+ in the magnetite structure and the emergence of a ZnO/ZnFe2 O4 heterostructure at high doping concentrations. The presented work demonstrates and explainsa facile route for the synthesis and modulation of multifunctional nanomaterials with manifold roles in disease diagnostics and therapy, and provides helpful guidance in designing divalent transition metal ion-doped nanomaterials.

Ion coordination to improve ionic conductivity in polymer electrolytes for high performance solid-state batteries

Polymer electrolytes with high ionic conductivity and good mechanical stability, which can be achieved by the incorporation of oxide ceramics into polymer electrolytes, are critical for solid-state batteries. However, it is challenging to obtain selectivity and efficiency of lithium-ion (Li+) transport enhancements in polymer electrolytes by oxide ceramic additives because the free volume increase in the polymer matrix by oxide ceramic-polymer interactions facilitates simultaneous Li+ and anion transport. Herein, cerium-zirconium oxide (ZrxCe(1−x)O2) nanoparticles are demonstrated to be an effective additive for ion coordination modification to selectively improve Li+ transport in poly (ethylene oxide) (PEO) electrolytes. By anion adsorption using ZrxCe(1−x)O2 nanoparticles, the ionic interaction between Li+ and bis(trifluoromethanesulfon)imide (TFSI-) is weakened, the proportion of PEO-TFSI- mixed coordination with Li+ is reduced, and Li+ coordination is modified. Therefore, after Li+ coordination modification, the PEO electrolyte with Zr0.5Ce0.5O2 nanoparticles achieves a high ionic conductivity of 7.3 × 10−5 S cm−1 and a high lithium transfer number of 0.42 at 30 ºC. Our work suggests that ion coordination modification by oxide ceramics can selectively improve the solid diffusion kinetics of Li+. This research provides new insights into the mechanism of Li+ transport.

Biohybrid Response Microparticles Decorated with Trained-MSCs for Acute Liver Failure Recovery.

Microcarrier-based mesenchymal stem cells (MSCs) delivery have attracted increasing attention in acute liver failure (ALF) therapy, while there is still room for improvement in terms of improving cell loading efficiency, enhancing anti-inflammatory features, and controlling cell release. Here, novel lipopolysaccharide (LPS)-composited magnetic-thermal responsive inverse opal particles (MIOPs) are presented for the delivery of MSCs. The MIOPs are composed of a chitosan inverse opal skeleton filled with a hydrogel containing LPS, poly(N-isopropylacrylamide), and Fe3 O4 nanoparticles. Benefitting from the biocompatible chitosan component and the huge specific surface area, the resultant MIOPs can capture MSCs in a nondestructive way. Furthermore, LPS can be released from the MIOPs under the stimulation of an alternating magnetic field, by which the MSCs are activated to gain the feature of "trained immunity." Moreover, this process can be monitored in real-time by the structural color change of the MIOPs. With that, the MSCs-laden MIOPs are employed in rats with ALF, and they exhibit obvious anti-inflammatory and therapeutic efficacy superior to untrained MSCs. These performances make the MIOPs a distinctive cell delivery platform for clinical tissue recovery applications.

Magnetic Alignment for Plasmonic Control of Gold Nanorods Coated with Iron Oxide Nanoparticles.

Plasmonic nanoparticles that can be manipulated with magnetic fields are of interest for advanced optical applications, diagnostics, imaging, and therapy. Alignment of gold nanorods yields strong polarization-dependent extinction, and use of magnetic fields is appealing because they act through space and can be quickly switched. In this work, cationic polyethyleneimine-functionalized superparamagnetic Fe3 O4 nanoparticles (NPs) are deposited on the surface of anionic gold nanorods coated with bovine serum albumin. The magnetic gold nanorods (MagGNRs) obtained through mixing maintain the distinct optical properties of plasmonic gold nanorods that are minimally perturbed by the magnetic overcoating. Magnetic alignment of the MagGNRs arising from magnetic dipolar interactions on the anisotropic gold nanorod core is comprehensively characterized, including structural characterization and enhancement (suppression) of the longitudinal surface plasmon resonance and suppression (enhancement) of the transverse surface plasmon resonance for light polarized parallel (orthogonal) to the magnetic field. The MagGNRs can also be driven in rotating magnetic fields to rotate at frequencies of at least 17Hz. For suitably large gold nanorods (148nm long) and Fe3 O4 NPs (13.4nm diameter), significant alignment is possible even in modest (<500Oe) magnetic fields. An analytical model provides a unified understanding of the magnetic alignment of MagGNRs.