Question

1) Evaluate passive targeting of tumor cells using nano-medcines.

2) Evaluate the benefits and hindrances associated with protein pegylation

include +ve and -ve for both answers

Answer 1

1) Passive targeting of tumor cells (using nanomedicines) refers to the delivery of the nanomedicine into the surroundings of the tumor (mainly the tumor microvasculature), in order to enhance selective uptake of the medicine by the tumor cell. The targeting of the nanomedicine depends upon characteristics of the tumor and the nanomedicine (size, shape, etc) both.

Passive targeting means that the substance (in this case, the nanomedicine) is allowed to deposit in the neoplastic tissue, especially on the overexpressed receptors (for better uptake). The enhanced permeability and retention (EPR) phenomenon, based upon nanoparticle size and the characteristics of the neoplastic tissue, allows the uptake and retention of the accumulated nanomedicine by the cancer cells. Passive targeting helps in achieving accurate delivery, better uptake and absorption, all without afflicting severe side effects.

2) Pegylation refers to the attachment (covalent or non-covalent) of polyethylene glycol (PEG) to molecules such as therapeutic proteins or drugs. In this process, PEG helps in masking the molecule (drug/ therapeutic protein) from the immune system of the host, hence helping in making it easier for the molecule to reach its target uninterrupted. Also, peglylation increases the hydrodynamic size of the molecule, which reduces the renal clearance of the molecule and hence, makes it last longer in blood circulation. Furthermore, this process can be used to make hydrophic drugs soluble in water. The only limitation is that of the low clearance rate of the molecule, which may lead to its accumulation in the liver.