Biodegradable materials and control release II

What are 3 characteristics that define a hydrogel?

Water insoluble, 3D network of polymeric chain, cross-linked by chemical or physical bonding

How can degree of swelling be quantified(2)?

Ratio of sample volume in the swollen state to volume in the dry state, weight degree of swelling(Also Ratio)

Why is the degree of swelling important? (4)

Solute diffusion coefficient through the hydrogel, surface properties and surface mobility, optical properties, Mechanical properties

What allows the ability of gels to maintain their original shape during and after swelling

Covalent bond, thermodynamically driven swelling force is counterbalanced.

What are 2 types of dried hydrogel

Aerogel: liquid of gel is replaced by gas so there can be no shrinkage, and xerogel: liquid of gel removed by evaporation shrinking solid.

what is the use of chitosan?

Useful in bandages to reduce bleeding and antibacterial agent with its delivery of drugs through skin.

List 5 hydrogel features

Highly polyionic polymers, large volumetric changes, Hydrophilic, Decreased permeability to large molecules, structurally strong

What are 2 volume determining forces on hydrogels

Repulsive electrostatic(hydrophobic) and Attractive

List 4 Hydrogel examples

Jello, Extracellular matrix. DNA/RNA, Blood clot

What are 4 Hydrogel applications?

Drug delivery, Surface modification, biosensors, soft contact lens

How are hydrogels used in drug delivery(HOW)?

Drug gets trapped in hydrogel during polymerization, drug introduce during swelling in water