08-17-2017, 12:28 AM
Magnetic Drug Delivery
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Many medical conditions, such as chronic pain, cancer and diabetes, require medications that cannot be taken orally, but must be dosed intermittently, on an as-needed basis, over a long period of time. A few delivery techniques have been developed, using an implanted heat source, an implanted electronic chip or other stimuli as an "on-off" switch to release the drugs into the body. But thus far, none of these methods can reliably do all that's needed: repeatedly turn dosing on and off, deliver consistent doses, and adjust doses according to the patient's need.
Introduction
The activity of most drugs against disease suffers from their inability to accumulate selectively at the site of action. Drug targeting is the delivery of drugs to receptors or organ or any other specific part of the body to which one wishes to deliver the drug exclusively. There are many different approaches to targeted drug delivery, which are classified broadly into three categories.
Magnetic Carrier:
Magnetoliposomes :
These are magnetic carrier which can be prepared by entrapment of ferrofluid within core of liposomes 5, 6 Magnetoliposome can also be produced by covalent attachment of ligands to the surface of the vehicles or by incorporation of target lipids in the matrix of structural phospholipids 7 Alternatively magnetoliposomes are prepared using the phospholipid vesicle as a nanoreactor for the in situ precipitation of magnetic nanoparticles 8. Vesicles are also prepared containing didodecyl methyl ammonium bromide, contain an ionic magnetic fluid 9. These magnetoliposomes were effectively used for site specific targeting, cell sorting & as magnetic resonance contrast enhancing agent.
Characterization of Magnetic Particles :
Scanning electron microscopy is used to determine the size & morphology of magnetic nanoparticle whereas Dynamic Light Scattering is used to measure the hydrodynamic diameter44 Magnetic mobility(overall responsiveness or amount of velocity for a given magnetic field & field gradient) of different types of magnetic micropheres is characterize so that their behavior in patient circulation can be predicted.For this purpose stationery setup similar to cell tracking velocimetry system which can be used on standard microscope eqiipped with a digital camera& computer system. The main difference to above system is that there is no flow of the suspension containg the magnetic particles. The geometry & size of the set up & magnet used can be reduced considerably. Furtermore the close combination of the microscope set up with computer allows fully automated data acquisition & processing45.