MAGNETIC NANOPARTICLES

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CONTENTS: 

CONTENTS INTRODUCTION MAGNETISM SPECIAL FEATURES OF MNPs TYPES SYNTHETIC METHODS PROTECTION METHODS CHARACTERIZATION APPLICATIONS REFERENCES

MAGNETIC NANOPARTICLES (INTRODUCTION): 

MAGNETIC NANOPARTICLES (INTRODUCTION) “Magnetic nanoparticles are a class of nanoparticles which can be manipulated using magnetic field” Commonly consists of magnetic elements such as Fe, Ni,Co and their compounds. Size:1-100nm. Perform best in the size range of 10-20nm in various applications.

MAGNETISM: 

MAGNETISM “Phenomenon by which a molecule exhibits attractive or repulsive property on the other molecules” Diamagnetic: Quartz Paramagnetic:Pyrite Ferromagnetic:Fe,Ni,Co and their alloys Anti- Ferromagnetic:Mno Ferrimagnetic:Magnitite (Fe3o4)

TYPES OF MAGNETIC MATERIALS: 

TYPES OF MAGNETIC MATERIALS

SPECIAL FEATURES OF MNPs: 

SPECIAL FEATURES OF MNPs 1.Finite Size Effects: single domain limit:A single domain particle is uniformly magnetized with all the spins aligned in same direction. Eg:size of Fe is 15nm Superparamagnetic limit:A superparamagnet is defined as an assembly of giant magnetic moments which are not interacting, and can fluctuate when thermal energy is larger than the anisotropic energy.

Exhibits no remanence and coercivity . 2.Surface Effects: As the particle size decreases, a large proportion of atoms in nanaoparticles are surface atoms which implies that surface spins play a prominent role.

TYPES OF MAGNETIC NANOPARTICLES: 

TYPES OF MAGNETIC NANOPARTICLES 1. OXIDES: Ferrite nanoparticles are the most explored MNPs upto date. surface can be coated with surfactants , silicones,phosphoric acid to stabilise in solution 2. METALLIC: Have great disadvantage of being pyrophoric and reactive to oxidizing agents.

3. METALLIC WITH SHELL: Metallic core of MNPs may be passivated by gentle oxidation,surfactants ,polymers and precious metals. Eg : Co MNPs with gold,graphene Fe with graphene Advantages: higher magnetization higher stability

SYNTHETIC METHODS: 

SYNTHETIC METHODS 1.CO-PRECIPITATION 2.MICROEMULSION 3.THERMAL DECOMPOSITION 4.HYDROTHERMAL

1.CO-PRECIPITATION It is a facile and convenient way to synthesize MNPs(metal oxides and ferrites) from aqueous salt solutions. This is done by addition of a base( NaoH ) at room temperature or at elevated temperature under inert atmosphere

M2+ + 2Fe3+ + 8OH¯ → MFe2O4 + 4H2O (1) Where M can be Fe2+, Mn2+, Co2+, Cu2+, Mg2+, Zn2+ and Ni2+. Complete precipitation should be expected at a pH levels between 8 and 14, with a stoichiometric ratio of 2:1 (Fe3+/M2+) in a non-oxidizing oxygen environment Size,Shape and composition depends upon the type of salts used( eg:Chlorides,Sulphates,Nitrates ) pH,temperature,type of base,mixing rate,ionic strength of media,bubbling of nitrogen gas

LAMER DIAGRAM

2.MICROEMULSION: 

2.MICROEMULSION W/O microemulsions are widely used They are isotropic,thermodynamically stable and consists of three components water,oil and surfactant Water nanodroplets containing reagents undergo rapid coalescence allowing mixing,precipition reaction and aggregation proceses for the synthesis of MNPs

By mixing two identical micro emulsions containing desired reactants the micro droplets will continuously collide,coalesce and break again and finally a precipitate forms in the micelles Size can be controlled by Wo values

3.THERMAL DECOMPOSITION: 

3.THERMAL DECOMPOSITION MNPs can be prepared by high temperature decomposition of organo -metallic precursors such as acetylacetonates, [M(acac)n], (M=Fe, Mn, Co, Ni, Cr; n=2 or 3, acac = acetylacetonate ), metal cupferronates [ MxCupx ] (M=metal ion; Cup= nitrosophenylhydroxylamine , C6H5N(NO)O-), or carbonyls.Fatty acids, oleic acid,and hexadecylamine are often used as surfactants and using organic solvents.

Precursors with zerovalent metals initially form the metal nanoparticles followed by oxidation to metal oxide nanoparticles Precursors with cationic metal centers form metal oxide NPs directly

4.HYDROTHERMAL: 

4.HYDROTHERMAL Also known as solvothermal method used for preparation of MNPs and ultra fine powders Reactions are performed in aqueous media in reactors or autoclaves were pressure cane be higher than 2000psi and temperature higher than 200 degrees Wang-et-al synthesized nickel ferrite NPs by using ethylene glycol as solvent and sodium acetate by electro static stabilization Size:6-170nm

Summary comparison of the synthetic methods

PROTECTION METHODS: 

PROTECTION METHODS MNPs are sensitive to oxidation and agglomeration due to large specific surface area. ORGANIC COATINGS : SURFACTANTS : Oleic acid,lauric acid,tri-octyl phosphonic acid and pyridine POLYMERS: Natutal : Dextran,chitosan,starch,gelatin,gum arabic Synthetic: PEG,PBA,PLA,PMMA,PAA

INORGANIC COATINGS: METAL OXIDES:Zirconium oxide,titanium oxide,aluminium oxide PRECIOUS METALS: Gold SILICA CARBON

CHARACTERIZATION: 

CHARACTERIZATION SIZE AND MORPHOLOGY Transmission electron microscopy High resolution transmission electron microscopy Scanning electron microscopy Photon correlation spectroscopy STRUCTURE AND ELEMENTAL ANALYSIS Energy dispersive X-ray diffraction X-ray diffraction

TEM images of (a) Fe3O4 particles, (b) Fe3O4@nSiO2, (c-e) Fe3O4@nSiO2@mSiO2 microspheres and (f) SEM image of Fe3O4@nSiO2@mSiO2 microspheres

MAGNETIC PROPERTIES VSM SQUID SURFACE CHARACTERIZATION X-ray photoelectron spectroscopy Zetasizer FT-IR Thermo Gravimetric Analysis

APPLICATIONS: 

APPLICATIONS BIO-MEDICAL APPLICATIONS INVIVO Therapeutic Applications: Hyperthermia: Heating of tissues labeled with magnetic particles to 42 - 46 ºC after exposure to alternating magnetic field It can be local or regional or whole body hyperthermia.

Healthy cells Tumor cell Injection of MNPs Brain tumors

Under alternating magnetic field

With increasing the treatment time, the temperature increases in the tumor cells or tissues, which can damage and kill tumor cells or tissues

Drug Delivery: 

Drug Delivery

Diagnostic Applications: Magnetic resonance imaging(MRI) Super paramagnetic contrast agents have an advantage of producing an enhanced proton relaxation in MRI in comparison with paramagnetic ones eg:ferro fluids as contrast agents produced better images than Resovists (commercially available contrast agent for MRI)

INVITRO Separation and Selection: : 

INVITRO Separation and Selection :

Magnetorelaxometry : Method for evaluation of immuno assays Measures the magnetic viscosity i.e., the relaxation of the net magnetic moment of a system of magnetic nanoparticles after removal of magnetic field Distinguish between free and bound conjugates by their different magnetic behaviour and therefore used as an analytical tool for the evaluation of immuno assays

INDUSRTRIAL APPLICATIONS Magnetic data storage devices Magnetic inks Electronics(recording media) PIGMENTS All three forms of iron oxide are used asa synthetic pigments in paints,ceramics,porcelain Extremely stable and resistant to alkalis and acids Maghemite -brown Magnetite- black,Hematite -red

CATALYSTS Magnetite and Hematite are used as catalysts in Haber process for synthesis of ammonia High temperature water gas shift reaction Desulfurization of natural gas Dehydrogenation of ethyl benzene to styrene Fisher- tropsch synthesis for hydro carbons

ENVIRONMENTAL APPLICATIONS WASTE WATER TREATMENT Attachment of EDTA like chelators to carbon coated metal nanomagnets results in a magnetic reagent for the rapid removal of heavy metals from contaminated water Permeable barriers(containing ZVI) are used treat the ground water ORGANIC POLLUTANTS MNPs are widely used for the removal of high concentrations of organic compounds mostly related to dyes

Dyes are present in the waste water stream of many industrial sectors such as dyeing,textilefactories , paint industry eg:karoon river water was treated with iron oxide nanoparticles coated with cetyltrimethylammonium bromide to remove amaranth INORGANIC POLLUTANTS MNPs are used as sorbents to remove the metal toxins are hazardous metal ions from complicated matrices.

eg:radio -active metal toxins(Uo2) were removed from blood BODIPY-Functionalized magnetic silica NPs to remove lead ions from water and blood

Conclusions and Perspectives Magnetic nanoparticles have become an increasingly important Tool in disease diagnosis and therapy. In the case of MRI, many challenges still remain in pursuit of the Ideal MR imaging probe with imaging ultra sensitivity and disease specificity. Magnetic fluid hyperthermia is a promising way to treat cancer. Magnetic nanoparticle -aided drug delivery is still very much in its infancy. The combination of MRI, hypethermia and drug delivery will provide more significant potential application in biomedicine.

REFERENCES E. L. Salabas , and Ferdi Schüth . "Magnetic Nanoparticles : Synthesis, Protection, Functionalization , and Application". Angew . Chem. Int. Ed. 46 (8) Magnetic Nanoparticles : Synthesis, Stabilization, Functionalization , Characterization and Applications M. Faraji , Y. Yamini * and M. Rezaee Department of Chemistry, Tarbiat Modares University

The preparation of magnetic nanoparticles for applications in biomedicine Pedro Tartaj1, Marıa del Puerto Morales1, Sabino Veintemillas-Verdaguer , Teresita Gonzalez- Carreno and Carlos J Serna Magnetic particles in nanomedicine Etelka Tombacz

ANY QUERIES: 

ANY QUERIES