Magnetic Nanoparticles in Diagnostics and therapeutics

Aditya Kanwal 2012BT09 M.Tech Biotech MNNIT, Allahabad

INTRODUCTION- Magnetic nanoparticles are a class of nanoparticle which can be manipulated using magnetic field. - Consist of magnetic elements such as iron, nickel and cobalt and their chemical compounds. - Are responsive to magnetic eld allowing them to be manipulated, tracked, imaged and remotely heated. - Applications in biotechnology which includes cell separation, magnetic force-based tissue engineering, MRI tracking of transplanted cells and cancerous cells, magnetic drug targeting and hyperthermia.

TYPES OF MAGNETIC NANOPARTICLES:1) METALLIC: Pure Metallic nanoparticles. Disadvantage of being reactive to oxidizing agents to various degrees. Handling difficult and enables unwanted side reactions. 2) METALLIC OXIDES:

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Various metal oxides like Cobalt oxide (CoO, Co2O3, Co3O4), Nickel oxide (NiO, Ni2O3) and Iron oxides (Fe2O3, Fe3O4) nanoparticles etc Often modified by surfactants, silicones or by phosphoric acid derivatives to increase their stability in solution. 3) METALLIC WITH A SHELL: The metallic core of magnetic nanoparticles may be rendered inactive by gentle oxidation, polymers or other metals. Nanoparticles with a magnetic core consisting either of elementary Iron or Cobalt with a nonreactive shell made of graphene have been synthesized recently.

SYNTHESIS OF MAGNETIC NANOPARTICLES:[2]

1) CO-PRECIPITATION: A convenient way to synthesize metal oxides from aqueous Fe2+/Fe3+ salt solutions by the addition of a base under inert atmosphere at room temperature or at elevated temperature. 2) THERMAL DECOMPOSITION: Utilizes the thermal decomposition of organometallic compounds in high-boiling

APPLICATIONS IN DIAGNOSTICS:1) AS MRI CONTRAST AGENT:

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- MRI is a non-invasive and sensitive technique to obtain images by non-ionizing radiation. - The images formed are the result of several parameters such as proton density, relaxation times, water diffusion, nuclear alignment, radio frequency excitation, spatial encoding, etc., - Superparamagnetic particles (like providing a digital representation of tissue characteristics. ferrite nanoparticles) appear as preferred materials evaluation - Specific studies of because at the molecular and cellular level necessitates the use of a contrast agent. (a) they have magnetic characteristics, (b) they are composed of biodegradable Fe, (c) their coating can be functionalized with various ligands,

2) MAGNETIC CELL TRACKING: - For monitoring transplanted cells in vivo and for studying cancerous cells via MRI. - Can be used as a non-invasive tool to provide unique information on the dynamics of cell movements within and away from tissues in vivo. - Alternatively, could be applied in the future to monitor cell therapy in patients. 3) MONITORING GASTROINTESTINAL MOTILITY: - For investigating intestinal movements by Magnetic Marker monitoring. - For obtaining information on disorders like Gastroesophageal reflux disease (GERD), constipation, obstruction etc. - Oral route is employed for delivery.

APPLICATIONS IN THERAPEUTICS:1) MAGNETIC DRUG TARGETING: - One of the major problems related to drug administration is the difficulty in targeting a tissue or an area of the body.

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- Magnetic drug targeting (MDT) presents a solution by using magnetic particles as controllable carriers of therapeutic agents - Uses an external magnetic field source to capture and retain magnetic drug carrier particles at a specific site after being -These are either encapsulated or administered in surface of drugs. attached to the the body. - This approach may represent a new method to treat cancer.

2) MAGNETOFECTION: - A new method for transfection. - Employs magnetic nanoparticles combined with transfection agents to form magnetic gene vectors - These vectors can be rapidly concentrated on the surface of target cells under the attraction of a magnetic field. 3) MAGNETIC EMBOLIZATION: -Further these transfected cells can placed back in the normal tissue. - Consists of injecting (in a blood vessel) a magnetorheological (MR) fluid, which is a suspension of magnetizable particles such as Fe or iron oxide sometimes in combination with drugs. - Microscopic structures of these fluids change in the presence of a magnetic field, which leads to a phase transition from a liquid to a solid. - A seal is formed, which mechanically

4) TISSUE ENGINEERING: - Well-defined spatial cell organization is required in the attempt to reproduce living tissue complexity and succeed in creating functional tissue constructs. - Magnetic force can be utilized to induce two-dimensional patterning of magnetically-labeled cells on submillimetric scales. - Liposomes are used as carriers to introduce magnetite nanoparticles into target cells. - Given that cells labeled with magnetic nanoparticles can be manipulated by using a magnet, labeled cells can be seeded onto a low-adhesive culture surface through the use of magnetic force to form a tissue construct. - Recently, this technique with a few modifications was utilized to create a 3D cell assembly with tuneable size and controlled geometry.

5) MAGNETIC HYPERTHERMIA: - Technique that increases the temperature of the local environment of a tissue. - Results in the change in physiology of diseased cells and finally leading to apoptosis. - Hyperthermia treatment can be classified into different types depending on temperature:

b) Moderate hyperthermia: a) Thermo ablation: Temperature of 40 C 46 C (up Uses lower temperatures T