4. Polvmers for Nanomedicine: Researchers are considering the use of porous nano

Question

4. Polvmers for Nanomedicine: Researchers are considering the use of porous nanoparticles that have "trap doors" for cancer therapy. The "trap door" is achieved by having polymer chains attached to the particle surface around the pores. As shown in the cartoon below, the "trap doors" remain closed at physiological pH (7.4), but open up at a pH corresponding to cancer tissue (~ 6.0). Once the "trap doors" open, the drug contained in the particles gets released. (a) Should the "trap doors" be based on a nonionic polymer, a cationic polymer that is rich in amine (-NH2) groups, or an anionic polymer rich in carboxylic acid groups (-COOH)? Explain (b) What is the physical mechanism behind the opening and closing of the "trap doors" Explain. oy pH 7.4 Trap doors" closed. Drug remains inside nanoparticle pH 6.0 "Trap doors" open. Drug released from nanoparticle

Explanation / Answer

a) Polymer should be rich in carboxyl group to maintain positivity in low pH. b) polybasic polymer is unswollen in high pH since the polymer looses proton and become unionized. When pH decreases positively charged polymer will swell and this changes solute permeability as well as crosd linking density and drug will deliver in the media.

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