Biomedical Engineering Reference
In-Depth Information
Scheme1 Releasable
PEGylation based on the FMS
principle
Scheme 2 Drug-PEG
conjugate via a benzyl
carbamate linkage and its
thiolytic cleavage
modulator. Half-lives of molecules prepared using this approach range from several
hours to several weeks.
The concept of de-PEGylation can be applied to the development of nanoparti-
cle-based drug delivery systems. PEG is used for the modification of liposomes to
increase their blood circulation time [
38
]. However, it also prevents cellular uptake,
resulting in a decrease in therapeutic efficiency; thus, modifications of the liposome
surface with PEG interfere with membrane fusion to the cell membrane and
liposome decomposition [
39
]. One of the possible strategies to solve this problem
is to cleave the PEG chains after the nanoparticle reaches the target site (Fig.
9
).
This system of de-PEGylation of liposomes is also useful in avoiding the immune
