136 results about "Iron oxide nanoparticles" patented technology

The invention relates to the technical field of wastewater treatment, and discloses a high-salinity wastewater treatment method and device for achieving bacterium-alga granulation and synergistic denitrification, the high-salinity wastewater treatment method for achieving bacterium-alga granulation and synergistic denitrification comprises the following steps: placing microalgae and aerobic granular sludge in a photobioreactor for initial culture; after initial culture, adding magnetic iron oxide nanoparticles into the photobioreactor, and carrying out enhanced culture, so as to obtain the algal-bacterial symbiotic aerobic granular sludge, and carrying out denitrification treatment on wastewater by utilizing the bacteria-algae symbiotic aerobic granular sludge. The magnetic iron oxide nanoparticles are added in the growth process of bacteria and algae, so that the problems of slow aggregation and nucleation of bacteria and algae, low activity of photosynthetic electron carriers of algae cells under high salt stress, reduction of denitrification efficiency and the like in the ABGS formation process can be effectively solved; rapid aggregation and nucleation of bacteria-algae cells can be synchronously enhanced, the electron transfer efficiency of an algae cell photosynthetic system under high salt stress is improved, and the denitrification efficiency of microorganisms is improved.

The invention discloses a method for detecting multiple biomarkers based on a nano-enzyme chemiluminescence technology, and the method comprises the following steps: preparing iron oxide nano-particles as a nano-enzyme core, and coating the surfaces of the nano-particles with substrate molecules to form a nano-enzyme-substrate compound; mixing and incubating the nano enzyme-substrate compound and a sample to be detected, adding a hydrogen peroxide solution, transferring to a microplate, and collecting a chemiluminescence signal by using a microplate reader; extracting characteristic parameters including peak value luminous intensity, peak reaching time, half-peak width, rising rate, attenuation rate, integral intensity and / or wavelength ratio in the collected luminous curve, wherein the characteristic parameters comprise the peak value luminous intensity, the peak reaching time, the half-peak width, the rising rate, the attenuation rate and the integral intensity; and constructing and training a multi-layer neural network model so as to predict the concentration of the multiple biomarkers based on the characteristic parameters of the sample data. By means of the scheme, multiple biomarkers can be detected at the same time, and the detection accuracy is improved.

The invention discloses a preparation method and application of a high-density iron-nitrogen-carbon monatomic catalyst. The method specifically comprises the following steps: S1, uniformly mixing nitrogen-doped carbon and ferrous oxalate; s2, in an inert atmosphere, carrying out a first pyrolytic reaction at 340-360 DEG C to obtain an intermediate, and meanwhile, carrying out etching on the carbon carrier by using CO2 gas generated by the reaction, so that a plurality of microporous structures are formed on the carbon carrier; s3, the intermediate continues to be subjected to a second pyrolytic reaction in the inert atmosphere at the temperature of 850-950 DEG C, the FeOx nano-particles are converted into Fe-N4 active sites, and a pyrolytic product is obtained; and S4, naturally cooling to room temperature to obtain the high-density iron-nitrogen-carbon monatomic catalyst. Superfine ferric oxide (FeOx) nano-particles are generated through a precursor to serve as intermediates, carbon defects are created through CO2 gas released in the decomposition process of the FeOx nano-particles, and therefore the oxygen reduction reaction performance of the catalyst is remarkably improved, and the catalyst is applied to fuel cells.

The invention provides a manganese-doped ferrocobalt oxide nano particle-coated carbon-nitrogen cubic composite material as well as a preparation method and application of the manganese-doped ferrocobalt oxide nano particle-coated carbon-nitrogen cubic composite material. The preparation method comprises the following steps: firstly doping ferrous sulfate and manganese chloride into ZIF-8, then mixing the ZIF-8 with cobalt nitrate and 2-methylimidazole in methanol, carrying out centrifugal separation to obtain a product, and finally carrying out one-step calcination to realize carbonitriding of the composite material, doping of manganese and generation of nano particles from ferrocobalt oxide. And finally, the manganese-doped ferrocobalt oxide nanoparticle-coated carbon-nitrogen cubic composite material is obtained. Compared with the traditional preparation method, the method disclosed by the invention is simple, mild in reaction condition and high in yield, and the prepared composite material is uniform in morphology and has excellent electro-catalytic performance on the water electrolysis oxygen evolution reaction.

The invention discloses iron oxide nanoparticles capable of responding to particle size change in a tumor microenvironment and a preparation method of the iron oxide nanoparticles, and belongs to the technical field of biomedical nano materials. The nano-particle comprises an iron oxide nano-crystal core with the particle size of 3-5nm and a tumor microenvironment response layer coating the surface of the iron oxide nano-crystal core. The response layer contains groups, such as disulfide bonds, enzyme digestion peptide fragments and the like, which can respond to acidic pH, high-concentration reduced glutathione or matrix metalloproteinase and other tumor characteristic stimuli to generate structural changes. In a tumor microenvironment, the hydration particle size of the nanoparticles can be directionally and controllably converted from 3-20 nm to 20-100 nm (or reversely). The preparation method mainly comprises two steps of preparing the core by a thermal decomposition method and modifying the surface response layer. The technical problems of insufficient tumor targeted enrichment capacity, limited imaging contrast and difficulty in balancing permeation and retention caused by fixed particle size of the existing iron oxide nanoparticles are solved, and the accuracy and efficiency of tumor diagnosis and treatment can be remarkably improved.

Provided is an efficient combined nano iron suspension fertilizer. The suspension fertilizer efficient combined nano iron is prepared from ingredients including, in mass percentage: 10.0% to 20.0% of FeSO4; 0.5% to 2.0% of zero-valent iron nanoparticles (nZVI); 5.0% to 10.0% of magnetic iron oxide nanoparticles (Fe3O4-NPs); 30.0% to 50.0% of citric acid; 1.0% to 5.0% of a dispersant 5040; 0.2% to 1.0% of xanthan gum; 1.0% to 5.0% of magnesium aluminum silicate; and water as a balance.

The invention discloses a high-stability magnetic liquid and a preparation method thereof, and belongs to the field of magnetic fluid nano functional materials related to ships. The magnetic liquid comprises a metal-doped iron oxide nano-particle core, a double-layer surface modification layer composed of oleic acid and a silane coupling agent, and a composite carrier liquid formed by compounding poly-alpha olefin synthetic oil and perfluoropolyether and adding nano-diamond. The preparation method comprises the following steps: firstly, coprecipitating and calcining to obtain metal-doped iron oxide nanoparticles, then carrying out double-layer coating modification, and finally carrying out mixed ball milling, ultrasonic treatment and magnetic separation purification on the metal-doped iron oxide nanoparticles and the composite carrier liquid. The saturation magnetization intensity of the magnetic liquid reaches 92-95 emu / g, the magnetic liquid can work for a long time under the high-temperature working condition, the heat conductivity coefficient is increased by 2-3 times, and the redispersibility is excellent. The problems that a traditional magnetic fluid is low in magnetic performance, prone to failure at high temperature, poor in dispersion stability and the like are solved, and the magnetic fluid is suitable for aerospace, high-end manufacturing, ship propulsion and other extreme scenes.

The invention discloses a composite nano sound-sensitive agent as well as a preparation method and application thereof. According to the composite nano sound-sensitive agent provided by the invention, a conjugated system of the narrow-gap semiconductor nano sound-sensitive agent core / the ferric oxide nano functional layer / the surface targeting antibody is constructed, so that multi-mode synergy integrating sonodynamic therapy, ferroptosis induction and immunoregulation is realized. The composite nano sonosensitizer further has precise targeting, efficient sonodynamic effect, ferroptosis enhancement effect and good biocompatibility, a targeting antibody on the surface of the composite nano sonosensitizer can specifically recognize high-expression antigens on the surfaces of tumor cells, and dual-targeting enrichment of a treatment system is achieved in combination with magnetic responsiveness guidance; the coating of the iron oxide nanoparticles obviously enhances the sound-sensitive performance of the inner core of the sound-sensitive agent, improves the ROS generation efficiency, and overcomes the hypoxia limitation of the tumor microenvironment; iron oxide is used as an iron source to continuously release Fe < 2 + >, and cooperates with ROS generated by sonodynamic therapy to induce ferroptosis, so that a ferroptosis enhancing effect is generated.

The application discloses iron oxide coated silica core-shell nanoparticles and a preparation method and application thereof. The iron oxide coated silica core-shell nanoparticles comprise silica nanoparticles as an inner core and iron oxide nanoparticles as an outer shell coated on the inner core surface of the silica nanoparticles; the particle size is 22-112 nm; and the particle uniformity is 0.08-0.3. The preparation method of the iron coated silica nanoparticles provided by the application adopts the measure of adjusting the pH of slurry for multiple times, avoids the agglomeration of nanoparticles in a solution near the isoelectric point, and is thus favorable for finally obtaining core-shell nanoparticles with uniform monodispersity. No surfactant is used in the preparation process, and there is no complicated post-treatment process, thereby reducing the production cost. The uniformly monodispersed nanoparticles prepared by the method have great potential in the field of chemical mechanical polishing.

The invention discloses a visual efficient chloride ion removal adsorbing material and a preparation method and application thereof.The adsorbing material is prepared by the steps that hollow glass microspheres serve as a carrier, and hollow glass porous particles are synthesized from a mixture of hollow glass microsphere powder and a pore forming agent through a sol-gel method; the preparation method comprises the following steps: modifying the surface of a porous adsorption material through a low-temperature plasma bombardment technology to enhance the adsorption performance on chloride ions, and loading magnetic iron oxide nanoparticles on the porous adsorption material to prepare the chloride ion adsorption material; the adsorption material has the characteristic of environmental friendliness, not only can efficiently adsorb chloride ions in a water body, but also can realize the visualization of the adsorption process through the density difference before and after adsorption, has the characteristics of repeated use and easiness in regeneration, and has relatively high market application prospect and economic value.

The application discloses a seminal plasma metabolic biomarker combination for male infertility spermatogenesis obstacle typing diagnosis, and relates to the field of biological science and technology.The application records the metabolic fingerprints of 475 seminal plasma samples by means of nanoparticle-enhanced laser desorption / ionization mass spectrometry, and constructs a seminal plasma metabolic fingerprint database related to spermatogenesis obstacle (SPGF). Then, through machine learning and statistical analysis, six metabolic biomarkers for SPGF typing diagnosis are screened and identified in the seminal plasma, and the six metabolic biomarkers can realize accurate typing of SPGF (AUC=0.814). The application has the advantages of simple sample pretreatment, fast analysis speed and low cost by means of recording the metabolic fingerprints of seminal plasma by means of nanoparticle-enhanced laser desorption / ionization mass spectrometry. Through the synthesized iron oxide nanoparticles as a matrix, small molecule metabolites in the seminal plasma can be efficiently captured and ionized, and complex pretreatment steps such as deproteinization and chromatographic separation are not needed, so that super-fast analysis, super-high sensitivity, extremely low sample consumption and excellent repeatability detection are realized.

The invention discloses an auxiliary protein composition, iron oxide nanoparticles, a preparation method and application, the composition comprises an SC protein with an amino acid sequence as shown in SEQ ID NO: 1 and an ST protein with an amino acid sequence as shown in SEQ ID NO: 2, and the composition can be used for modifying the iron oxide nanoparticles. The auxiliary protein composition can effectively promote endocytosis of the iron oxide nanoparticles, and assists the iron oxide nanoparticles to realize lysosome escape; moreover, the iron oxide nanoparticles modified by the auxiliary protein composition are good in biocompatibility and long in retention and storage time in cells, can be used for long-time labeling of the cells, and have wide clinical transformation and application prospects as a cell tracer agent.

The invention relates to a method for preparing superfine magnetic iron oxide nanoparticles by using liquid nitrogen as a reaction medium, which comprises the following steps: S1, dropping a mixed aqueous solution containing Fe < 3 + > and Fe < 2 + > as a precursor solution and ammonia water into the liquid nitrogen at the same time; s2, stirring while adding ammonia water, and when the mixed solution becomes black, adding oleic acid for particle coating to obtain nanoparticles; and S3, sequentially washing the nano-particles with deionized water and acetone, collecting, filling liquid nitrogen into the obtained nano-particles, and freeze-drying to obtain the superfine magnetic iron oxide nano-particles. The method is easy to operate, the agglomeration phenomenon is effectively prevented under the low-temperature condition of liquid nitrogen, and the prepared nanoparticles have better dispersity and magnetism; due to the use of liquid nitrogen in the reaction process and a subsequent freeze-drying method, the formation of superfine nano-particle powder with uniform size is effectively realized, and the obtained nano-particles have superparamagnetism; the method is environment-friendly and low in cost.

The invention provides an iron-based nano material, a preparation method and application, the material comprises magnetic iron oxide nano particles and a functional modification layer on the surface, the magnetic iron oxide nano particles are Fe3O4, the particle size is 10-30 nm, and the magnetic iron oxide nano particles have specific oxygen vacancy concentration, 337 nm laser absorptivity and saturation magnetization; the functional modification layer is an amino-containing polymer layer, such as a polydopamine or cysteine-polyethyleneimine copolymer, and can reduce salt ion interference. The material solves the problems of low molecular weight region background interference, non-uniform crystallization, low ionization efficiency, poor salt tolerance and the like during detection of 100-400Da small molecular metabolites in trace samples such as tears and the like by optimizing magnetic responsiveness, photo-thermal conversion capability and salt resistance of an existing matrix; the method realizes high sensitivity and high repeatability (detection), and is suitable for metabonomics analysis of trace biological samples.

The invention discloses application of iron oxide nanoparticles in target treatment of schistosome eggs, and relates to the cross technical field of nano material target delivery and disease prevention and control. On the basis of paramagnetism, a microtubule structure and surface electrical characteristics of schistosoma japonicum egg shells, electrically neutral Fe3O4 magnetic nanoparticles with the particle size of 8-15 nm or electropositive Fe3O4-NH2 magnetic nanoparticles with the surface modified by amino groups are innovatively adopted, efficient egg penetration is achieved through magnetic targeted enrichment and physical-static synergistic effect, and in-vivo and in-vitro experiments prove that the effect of effectively penetrating through the eggs is achieved. The Fe3O4 and Fe3O4-NH2 nanoparticles have obvious worm egg targeting capability, and the penetrating efficiency of the Fe3O4 and Fe3O4-NH2 nanoparticles on worm eggs exceeds 38%, so that an important experimental basis is provided for subsequent development of a nano-drug delivery system for preventing and treating schistosomiasis.

This disclosure relates to a method for improving the colonization efficiency of rhizosphere growth-promoting bacteria using nanomaterials and a magnetic interaction system. The method includes: S1, mixing modified iron oxide nanoparticles with a suspension of rhizosphere growth-promoting bacteria and then conducting a first culture to obtain modified rhizosphere growth-promoting bacteria; S2, applying a dispersion of magnetic iron oxide nanoparticles to the roots of a plant for a second culture to obtain modified plants; S3, applying the suspension of the modified rhizosphere growth-promoting bacteria to the roots of the modified plants for a third culture; wherein the modified iron oxide nanoparticles are cationic polymer-modified iron oxide nanoparticles. This method constructs a plant-microorganism magnetic interaction system, improving the colonization ability of rhizosphere growth-promoting bacteria in plant roots, and also enhancing the nitrogen-fixing ability of the rhizosphere growth-promoting bacteria, effectively promoting plant growth.

A method of making a ferric oxide (Fe2O3) nanoparticle (NP) composition including providing Rosa rugosa cv. plena (RP) extract; adding the RP extract to a solution of FeCl3 to obtain RP-Fe3Cl4; and activating phytochemical compounds in the RP extract to obtain a phyto-synthesized RP-Fe2O3 NP composition.

The invention discloses a preparation method of a bionic magnetic nano-motor mixed and wrapped by a neutrophile granulocyte membrane and a stem cell exosome. The bionic magnetic nano-motor comprises the neutrophile granulocyte membrane, the stem cell exosome, a polylactic acid-glycolic acid copolymer and an anti-inflammatory drug. According to the method, a layer of polylactic acid-glycolic acid copolymer is wrapped outside magnetic ferroferric oxide nanoparticles and an anti-inflammatory drug by utilizing an ultrasonic emulsification method, and finally the polylactic acid-glycolic acid copolymer is wrapped by utilizing a neutrophile granulocyte membrane and a stem cell exosome, so that the bionic magnetic nano motor is obtained, and the motor has good biocompatibility. Meanwhile, the motor has an immune escape function and can resist phagocytosis of macrophages in blood. And under the control of an external alternating magnetic field, the medicine can accurately reach a spinal cord injury part, and the effects of inflammation inhibition and neuron recovery can be achieved under the mixed action of neutrophile granulocyte membranes, stem cell exosomes and anti-inflammatory drugs.

This invention belongs to the field of skin-like tissue preparation technology, and relates to a method for constructing ordered skin-like tissue with magnetic field assistance. The method involves directional cryo-casting to prepare a layered ordered hydrogel, providing skin-like seed cells, and culturing and expanding these cells in large quantities using a complete culture medium to obtain skin-like cells. The cultured skin-like cells are then co-cultured with iron oxide nanoparticles to prepare magnetized skin-like cells. These magnetized skin-like cells are then co-cultured with the layered ordered hydrogel, and magnetic fields are applied to both sides to induce the magnetized skin-like cells to enter the layered ordered hydrogel, resulting in a hydrogel scaffold. After washing the obtained hydrogel scaffold, it is transferred to a complete culture medium, and keratinocytes are seeded on the surface of the hydrogel scaffold and cultured to prepare an ordered skin-like tissue. This invention can effectively regulate the migration and arrangement of fibroblasts, providing a physical basis for the arrangement of the extracellular matrix, especially collagen.

This invention discloses a method for preparing cationic and amphiphilic quaternized composite magnetic nanoparticles, comprising the following steps: Step S1, preparing magnetic iron oxide nanoparticles using a hydrothermal method; Step S2, preparing silica-coated magnetic iron oxide nanoparticles using the Stober method; Step S3, preparing cationic and amphiphilic quaternized composite magnetic nanoparticles using an electrostatic self-assembly method. This invention uses low-cost alkane quaternary ammonium salts as functional monomers to achieve a three-layer core-shell structure comprising an iron oxide magnetic core, a silica intermediate bridging layer, and an alkane quaternary ammonium salt functional outer layer. The alkane quaternary ammonium salt is stably loaded onto the silica surface through a non-covalent grafting mechanism of electrostatic self-assembly, thereby achieving mild and efficient grafting. The resulting composite magnetic nanoparticles can achieve efficient separation of emulsified oily wastewater at room temperature and exhibit excellent recyclability, salt tolerance, and wide pH adaptability.

Disclosed are magnetic polymer nanocapsules, which are core-shell polymer nanocapsules carrying hydrophobic active substances, comprising magnetic iron oxide nanoparticles, and their use in anti-cancer therapy.

An improved method of maturation of an unaged or partially aged distilled spirit, the method comprising: exposing the spirit to at least one catalytic material consisting of a group selected from: iron oxide nanoparticles, alumina-supported Fe(II) complexes, Pd / C, multiwalled carbon nanotubes, carbon xerogels, carbon based solid acid catalysts, SO42- / TiO2 / γ-Al2O3, an element selected from the group consisting of: columns 4-12 transition metals except for Fe, column 13 boron group, Si, and mixtures thereof; wherein throughout the exposing, the spirit is not being distilled, and the exposing is allowed until level of at least one maturation congener in the spirit attains predetermined desired congener level / s in the spirit.

The invention discloses a composition with a tumor mitochondrial dual regulation effect, temperature-sensitive hydrogel and application, and belongs to the technical field of biological medicine, the composition is composed of a peroxide initiator and a mitochondrial autophagy inhibitor, the peroxide initiator is used for causing mitochondrial damage, and the mitochondrial autophagy inhibitor is used for causing mitochondrial autophagy. The mitochondrial autophagy inhibitor is used for inhibiting mitochondrial The peroxide initiator is indocyanine green, chlorin, iron oxide nanoparticles or Fe-MOFs (Metal-Organic Frameworks); the mitochondrial autophagy inhibitor is chloroquine, 3-methyladenosine or bajulomycin A1; the tumor is specifically melanoma; the combination of the peroxide initiator and the mitochondrial autophagy inhibitor can better inhibit the energy metabolism of tumor cells and inhibit the occurrence and development of tumors, and after the composition is delivered through the temperature-sensitive hydrogel carrier, the treatment effect of the composition on tumors is further improved.

The presently disclosed subject matter relates to compositions and methods for preventing and / or treating of an oral disease and / or a biofilm-associated disease. In particular, the presently disclosed subject matter provides a composition for preventing and / or treating of an oral disease comprising (a) one or more iron oxide nanoparticles and (b) stannous fluoride (SnF2) that provide synergistic properties, including enhanced solubility, stability, co-delivery and catalytic activity, while creating a protective antibacterial and anti-demineralization layer on the target surface for disease prevention.

The present application relates to the technical field of water treatment, in particular to a preparation method of a confined carbon film electrode and application thereof. The advanced oxidation technology is a free radical oxidation system mainly with hydroxyl radicals and sulfate radicals. When degrading persistent organic pollutants, the hydroxyl radicals and sulfate radicals are easily consumed by chain reaction with anions in water and also produce toxic byproducts. In view of the above problems, the present application provides a confined carbon film electrode which is formed by depositing Fe2O3 / CNTs composite material on the surface of a microporous filter membrane to form a membrane electrode. The Fe2O3 / CNTs composite material is to confine iron oxide nanoparticles on the sidewall of the hollow pipe of carboxyl functionalized CNTs. The present application combines electrocatalysis technology and membrane separation technology, can more efficiently remove harmful substances such as persistent organic pollutants and heavy metals in water, and has higher water purification efficiency compared with the single electrocatalysis technology and membrane separation technology.

The application discloses a kind of multistage size response type iron-based nano preparation and its preparation method and application, the iron-based nano preparation includes responsive iron-based nanomaterial and the protein drug of load, the responsive iron-based nanomaterial is by magnetic iron oxide nanoparticles surface complex dopamine and dopamine phenylboronic acid ligand, the molar ratio of two ligands is 1:0.52~2.57;Preparation method: magnetic iron oxide nanoparticles is dispersed in solvent, dopamine hydrochloride and dopamine phenylboronic acid are added, and under the condition of 40~80 DEG C reaction, obtain responsive iron-based nanomaterial;Protein drug is mixed with the responsive iron-based nanomaterial obtained in aqueous solvent, and evenly dispersed to obtain target nano preparation.The multistage size response type iron-based nano preparation of the application realizes microenvironment response delivery, deep penetration, lysosome enrichment, efficient iron death trigger and the cascade synergistic effect of immune activation, provides a kind of safe and efficient new strategy for tumor synergistic treatment.

The invention discloses ultra-small magnetic iron oxide nanoparticles taking small molecules as a stabilizer as well as a preparation method and application of the ultra-small magnetic iron oxide nanoparticles, and belongs to the technical field of nano materials. The magnetic iron oxide nanoparticles provided by the invention comprise magnetic iron oxide particles and hydrophilic small molecules connected to the surfaces of the magnetic iron oxide particles, the average molecular weight of the hydrophilic small molecules is less than 1000 Daltons. Hydrophilic small molecules are connected to the surfaces of the magnetic iron oxide particles, good stabilizing and dispersing effects can be achieved, and compared with existing magnetic iron oxide nanoparticles with macromolecules as a stabilizer, the magnetic iron oxide nanoparticles are lower in viscosity, higher in biocompatibility, higher in longitudinal relaxation r1 value and better in stability. The clinical practicability and the development prospect are better, and the preparation of a safe and reliable MRI contrast agent, especially a T1 weighted contrast agent, is facilitated.

The invention discloses a preparation method of a magnetic SERS (Surface Enhanced Raman Scattering) biosensor and application of the magnetic SERS biosensor in ctDNA mutant gene detection, and relates to the technical field of Raman spectrum detection. According to the technical scheme, the method comprises the following steps: (1) synthesizing gold-coated gold nanoparticles which have gap structures and are modified with Raman signal molecules in the gap structures by using a DNA single chain as a skeleton; (2) preparing gold-coated ferroferric oxide nanoparticles marked by Raman signal molecules by a hydrothermal synthesis method; and (3) designing a corresponding hairpin DNA structure according to the mutation sequence of the ctDNA, and respectively modifying the hairpin DNA structure on the surfaces of the gold-coated gold nanoparticles in the step (1) and the gold-coated ferroferric oxide nanoparticles in the step (2) to construct a cyclic amplification system so as to realize the detection of the ctDNA mutant gene. The magnetic SERS biosensor provided by the invention has the advantages of high sensitivity, strong specificity, good stability, no need of enzyme participation and the like, and ctDNA mutant genes can be rapidly detected in a complex reaction system.

A composition that includes a stem cell and a coated iron oxide nanoparticle. The coated iron oxide nanoparticle, being present in the cytoplasm of the stem cell, contains a superparamagnetic iron oxide core that is coated with one or more biocompatible polymers, each of which has a polyethylene glycol group, a silane group, and a linker covalently linking the polyethylene glycol group and the silane group. Also provided is a method for treating an inflammatory disorder in which stem cells are cultured in the presence of coated iron oxide nanoparticles and the cultured stem cells are administered to a subject suffering from an inflammatory disorder. Further disclosed is a method for tracking stem cells in vivo by labeling stem cells with coated iron oxide nanoparticles, administering the labeled stem cell to an individual, and obtaining one or more T2 weighted magnetic resonance images of the individual to track the stem cells.