A system to package and deliver drugs to each cell of your body, depending on its needs, has been developed at IISc. “Nanocapsules” made from a special type of material can now deliver drugs right inside cancer affected cells in the body.
“Drug delivery systems” are mechanisms that can be programmed to release drug molecules at targeted cells in the body, using physiological cues present in the body itself. The major hurdle has been that these local cues are not consistent between cells; one needs systems that respond to multiple such cues. Prof. Ashok M Raichur and his team of scientists at the Indian Institute of Science, Bangalore, have demonstrated one of the very few systems that can respond to multiple cues.
There are three ideal characteristics that a drug delivery system should have: (1) the entire drug molecule should be encapsulated, which would prevent its premature release or degradation (2) it should carry the drug safely -- and specifically -- to the target site and (3) at the target site, it should release the drug molecules using the local physiological cues available.
Hollow nanocapsules were fabricated from special materials called biopolymers, which are materials that do not react with body tissues. These nanocapsules contain components that can respond to local cues integrated in the walls. To avoid premature release of the drug, the walls are crosslinked; this sort of architecture gives scope to load large amounts of drugs into the capsule. The wall structure also makes it possible for a small amount of local cues, like enzymes, to trigger the release of a large number of drug molecules.
The Food and Drug Administration(FDA) approved drug, polypeptide protamine (PRM), used to treat heparin induced toxicity, is one of the stimuli responsive components which is identified and actively cleaved into smaller fragments by trypsin like enzymes. The second component, chondroitin sulphate is susceptible to cleavage by enzyme hyaluronidase and has been used in the treatment of arthritis.
The Layer by Layer (LbL) assembly method used for fabrication of nanocapsules is carried under highly controlled mild conditions and thereby capable of incorporating the sensitive components (biopolymers) used here. It has the capacity to take up an array of materials ranging from small proteins to inorganic molecules. The nanocapsule surface was combined with a molecule used to identify cancer cells, folic acid (Vitamin B9, as we know it).
The drug delivery system was demonstrated using a population of cells in the lab – something called a “cell line”.
About the authors
Ashok Raichur is from the Department of Materials Engineering, IISc. Krishna Radhakrishnan is his student. Dipshikha Chakravortty is from the Department of Microbiology and Cell Biology, IISc and Divya P. Gnanadas is her student. Jasaswini Tripathy was a post doc at IISc and is now with KIIT University, Bhubaneswar.
The paper appeared in the international journal RSC Advances on 17th September. http://pubs.rsc.org/en/content/articlelanding/2014/ra/c4ra07815b#!divAbs...