Polymers can have many uses in healthcare. For example, polymer gels are used in dressings for burns and other wounds. Wound dressings create a sealed environment around the injury, preventing it getting infected, and promote healing by keeping the environment moist.
Poly(vinyl alcohol) (PVA) is commonly used to make wound dressings, because it can form a crosslinked gel which is biologically inert.
PVA is also used to make glues. The chemical structure of PVA is:
The crosslinks in PVA gels can be formed by the addition of the borate ion [B(OH)4]-. The borate ion can form weak bonds between the OH groups on the polymer chains:
The resulting gels can be loaded with other chemicals that help the healing process, like antibacterial drugs.
The gels are examples of drug delivery systems. Drug delivery systems can make drugs more effective, by increasing the proportion of the drug that reaches the intended site of action.
Drug delivery systems can:
- protect drugs from their surroundings
- make drugs more easily absorbed
- provide control over how the drug is released
In some cases, like a wound dressing, we would like a drug to be released over a sustained period. In other cases we would like the drug to be transported to its site of action, then released all at once, in response to a trigger from the surroundings.
Challenge: make your own model drug delivery system!