Controlled Release Drug Therapy
Cancer drugs have become increasingly more effective at killing cancerous tumors, but the major obstacle preventing widespread use is their debilitating effects to healthy cells. Methods for achieving controlled drug release have shown promise. Earlier methods involve loading a temperature sensitive material into low-density lipoproteins often referred to as “bad cholesterol.” Another method involves loading the mixture into gold nanocages. Both have disadvantages in the way the materials used to encapsulate the drugs interact with the body.
Researchers at the Georgia Institute of Technology have published a study reporting on nanoscale silica bottles, a five hundredth of the diameter of a hair, that can be used to deliver cancer fighting drugs to targeted parts of the body. These bottles filled with cancer specific drugs and a temperature sensitive material could be used for drug delivery to kill malignant cancer cells in certain parts of the body without debilitating side effects.
The silicon based spheres, 200 nanometers in size, were created with a tiny hole in the surface. The spheres can hold a range of drugs that could be released at a certain temperature. To keep the sphere’s payload in place until it reaches the designated spot, the drug is mixed with fatty acids and an infrared dye. The fatty acids remain solid at human body temperature, but melt a few degrees above. When a doctor wants to release the drug, an infrared laser will target the relevant area. The dye absorbs the heat from the laser, melts the fatty acid and releases the drug through the hole. Research showed that without the use of the laser, the drug did not release, remaining encapsulated. This prevents the drug from leaking into healthy cells. Following the release of the specific amount of the cancer fighting drug, the remainder remains encapsulated by the solid fatty acid inside the bottles, which are biocompatible and biodegradable.
Jichuan Qui, a postdoctoral fellow in the Xia group who conducted the survey, stated, “This controlled release system enables us to deal with the adverse impacts associated with most chemotherapeutics by only releasing the drugs at a dosage above the toxic level inside the diseased site. This approach holds great promise for medical applications that require drugs to be released in a controlled fashion and has advantages over other methods of controlled release.”
The tiny spheres are made of polystyrene with a small gold nanoparticle embedded in its surface. It is then coated with a silica based material covering everything except the gold nanoparticle. The gold and polystyrene are then removed, leaving a hollow sphere with a small opening that can be used for delivery. The size of the hole can be adjusted enabling the sphere to release their cancer fighting drugs at different rates.
The spheres are loaded when the bottle is soaked in a solution containing the mixture, removing trapped air and washing away excess material with water. The result of this is an even mixture of temperature sensitive material, the anticancer drug and the dye.
Chemotherapy often causes debilitating side effects as the drugs travel through the body killing healthy cells in addition to cancer cells. This system comprised of tiny bottles, releases the drugs in a controlled fashion once its reached the intended target, therefore avoiding the destruction of normal healthy cells.
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