Course:advance polymers

Dilshad bajwa

Roll#11

Introduction “Smart polymer” materials that have the ability to

respond to external stimuli, represent one of the most

exciting and immerging class of materials

They are cheaper and more easily handled than metals

or ceramics.

Stimulus-responsive or ‘smart’

polymers

Smart polymers and hydrogels undergo fast,

reversible changes in microstructure from a

hydrophilic to a hydrophobic state with change in

(pH, temperature, ionic strength) etc.

Temperature-responsive polymers

Respond to temperature changes

Types of thermo responsive polymer:

TRP which shows LCSTTRP which shows UCSTe.g poly(acrylonitrile-co-butadiene)

Temperature responsive polymer

The first established LCST is 32oC for poly(N-isopropylacrylamide) (PNIPAAm) in water solutionAt this temp:

•Undergoes a sharp coil-globule transition•Changes from hydrophilic state to hydrophobic state as temperature is increases•In aqueous solutions, it is soluble below LCST and less soluble above it

Gene Therapy:

Gene therapy aims at the treatment of many genetic diseases .Delivery of therapeutic gene (DNA) into the cells that will replace, repair or regulate the defective gene.

Gene therapy aims at the treatment of many genetic diseases .Delivery of therapeutic gene (DNA) into the cells that will replace, repair or regulate the defective gene.

The main steps of gene delivery

using a cationic polymer:

(1) DNA complexation formation

(polyarginine polymer AND PNIPAAm

)above LCST

(2) Complex traversing through cell membrane to the cytoplasm at 37 °C

(3) DNA release into the cytoplasm below LCST

(4) DNA transfer into nucleus

Tissue Engineering

To regenerate or replace biological damaged or diseased tissue or generate replacement organs for a wide range of medical conditions such as heart diseases, diabetes, and spinal cord injury .

Thermoresponsive polymer is mixed at room temperature with cells and then injected into the body.Upon injection due to the temperature increase (to 37 °C) that is above the polymer’s LCST, the polymer forms a physical gel.

Drug delivery through Micelles

The thermoresponsive properties of terpolymers of PEGMA-b-(DMAEMA-co-MMA)

The formation of thermoresponsive micelles with sustained drug release in vitro

Cross Linked Micelles

The formation of micelles above the LCST of PEG-b-PPG-b-PEG triblock copolymersBy incorporating a methacrylate group onto each end of the block copolymers crosslinking.crosslinked layer slowed the release of drug by entrapment but allowed an increase in the release with increased temperature

Formation of nanocages from polymers of PEG (blue) PPG (red) and methacrylate groups (green)

Polymer bilayer film entraps particles and cells.

Conclusion:Thermoresponsive polymers and their uses in gene therapy ,genetic engineering .drug delivery etc. have a definite impact in the medical field.

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