Biomedical Engineering Reference
In-Depth Information
Other methods utilize controlled/living free radical polymerization e.g.
living free radical nitroxide-mediated polymerization, atom transfer radi-
cal polymerization and reversible addition-fragmentation chain transfer
(RAFT) polymerization [30]. Atom transfer radical polymerization (ATRP)
refers to a system where equilibrium between dormant species and radi-
cals is established [31]. Reversible addition fragmentation chain transfer
(RAFT)
is a reversible deactivation of radical polymerization. h ese radical
polymerisation methods of generating co-polymers normally yield com-
plex polymers which have a predetermined MW with a narrow distribution
and a known composition. Nonradical methods include the ring opening
polymerization of chitosan followed by a nucleophilic attack on the amino
groups present on the polymer backbone [28].
Table 5.1:
Selected co-polymers and the associated improved properties.
Polymer Grat ed onto chitosan
Property
Reference
Methyl methacrylate
Improved biocompatibility
[32, 28]
Polyethylene glycol (PEG)
Improved solubility,
stability and blood
residence time
[33, 28]
Vinyl acetate (VAc)
Improved swelling and
antifungal activity
[34]
Polyethylenimine (PEI)
Increased transfection
ei ciency and reduced
toxicity of PEI polyplexes
[35]
Poly(
N
-
isopropylacrylamide(PNIPAM)
Temperature sensitivity
[28]
Polystyrene
Increased solubility
[36]
Polyvinylpyrrolidone
Enhanced hydrophobicity
[37]
Poly(Lactic acid (LA))
pH sensitivity
[38]
Polyaniline
Conductivity and improved
stability
[39]
Polyamidoamine (PAMAM)
dendrimer
Improved solubility and
antibacterial activity
[40]
