The name Nanobiomagnetism itself implies the combination of magnetism, nanotechnology and life science. It is a branch of science that deals with the application of tiny magnetic particles called Nano magnets in biomedical systems or processes. The Nano-scale size of these particles are comparable with the size of viruses, proteins, cells and genes, making it compatible for study of life processes at cellular level. The magnetic property not only helps us to control the movement of Nano magnets inside the body, localizing its position with the help of an external magnetic field, but also enables heating of local tissues using sufficient strength and optimum frequency. The special properties of Nano magnets have resulted in its extensive use in medicine, revolutionizing the new approach of targeted treatment. Nano magnets can be effectively used for different medical applications like drug targeting, drug delivery and release, hyperthermia and as contrast agents in magnetic resonance imaging (MRI).
The most ideal materials used to make Nano magnet is an iron-carbon composite derived from mechanical milling, chemical reduction or plasma chemical re-condensation. In the body, iron is easily absorbed and the carbon helps in reducing any toxicity resulted. For Nano magnets to be used for any function inside a living body, biocompatibility is the primary requisite. For this, the Nano magnets are usually coated with non-porous, silicon-based materials which will protect the particle from lysosomal enzymatic digestion and improve mechanical properties and chemical stability. Polyethylene glycol and related polymers can adsorb to the surface of nanoparticles and prolong the circulation time in the body by preventing the rapid removal of particles by its hydrophilic surface properties that repel plasma proteins. Recent research have found out that nanoparticles can adhere to the surface of red blood corpuscles, allowing the nanoparticles to retain inside body for 120 days (RBC's life span) and evade macrophages. This can be used for slow release of drugs that remain effective even when attached to RBC, potentially leading to new treatment methods for cancer, blood clots and heart disease.
The major disadvantage of systemic method of treatment like chemotherapy is that all cells are affected, independent of its malignancy. Drug targeting helps to differentiate the cells and treat only specific targeted tissue. This can be done by localizing Nano magnets physically, chemically or magnetically. In physical targeting, surface features of nanoparticles like pH, charge and hydrophobicity is used to adhere to the surface or penetrate into targeted cells by inducing certain reactions. Even though it is non-specific, it has the advantage of using the natural clearance of the living system. In chemical targeting, special targeting agents like proteins, oligonucleotides, lectins, hormones, nucleic acids, receptor ligands, etc. are covalently or non-covalently bound to nanoparticles, functionalizing them and increasing its binding specificity to targeted cells. In magnetic targeting, an external magnetic field is used to guide the nanoparticles, carrying the drugs to a local site of infection. This method uses permanent magnets for tumours on surface or extremities and electromagnets for tumours located deep, that require higher gradients of field strength.
Controlled drug delivery using Nano magnets has increased drug efficacy and reduced the overall drug dosage by 50 to 80 per cent, decreasing unwanted systemic uptake. Nano magnets are used to limit the drug to a particular region using magnetic targeting and release the drug remotely. The drugs are encapsulated, conjugated or adsorbed onto the surface of nanoparticles and released at specific sites by degrading the carrier (e.g. Liposomes), by localized magnetic heating. This 'release on demand' mechanism can be used to treat insulin-dependent diabetes.
Magnetic nanoparticles act as excellent contrast agent that helps in differentiating between types of tissue, used mainly in diagnosis methods like MRI scans. Super paramagnetic and ultra-small super paramagnetic iron oxides are used as contrast agents to study the gastrointestinal tracts, liver and spleen imaging, to detect insufficient blood supply to organs, to find brain tumours and as blood pool agents. Magnetic Nano sensors are also developed, which can help us to observe molecular interactions like enzymatic activity, to detect proteins, mRNA and pathogens in biological medium, using MRI.
Hyperthermia is a characterized heat treatment in which temperature is limited to less than 50 degree Celsius and thermo ablation with higher temperature. Cancer cells are damaged or hindered in their uncontrolled multiplication at a temperature range of 42 to 48 degree Celsius, whereas normal cells can withstand more heat. So, Nano magnets are heated by applying external magnetic field, resulting in the localized heating of the targeted tumour tissues. A combination of the above applications is widely preferred for treatment in specific cases.
It is so true that good things come in small packages. The development of nanotechnology is going to influence all fields of essential science, especially medicine, inspiring a new outlook into the technique of efficient and effective treatment for life threatening diseases.
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