Biomedical Engineering Reference
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development of these systems will lead to a better understanding of
the processes of protein-folding. It is also expected to give rise to
new synthetic systems capable of mimicking some of the structures
and functions of nature's sophisticated machinery.
In recent work performed by the groups of Hawker and Kim [34],
the synthesis of a random poly(methyl methacrylate) copolymers
having dendritic self-complementary hydrogen-bonding units is
described. The formation of intramolecular H-bonds between the
dendritic units led to the collapse of the polymer coils, giving discrete
and stable spherical SCPNs.
In a more recent work, Meijer and co-workers made use of
2-ureidopyrimidinone (Upy), a very efficient quadruple H-bond-
forming unit, as the intramolecular cross-linking motif for the
fabrication of poly(methyl methacrylate) supramolecular SCPNs
[35]. In this elegant work, the polymer backbone was decorated
with Upy units that were protected with a photo-cleavable group
(Scheme 2.2). The irradiation with UV light released the protecting
group, promoting the collapse of the chains and therefore, the
formation of the nanoparticles.
Scheme 2.2
UV irradiation induced collapse of a single polymer chain into
a nanoparticle via the supramolecular cross-linking of the UPy-urethane
side groups (nitrosoaldehyde side product omitted for clarity). Reproduced
and adapted from ref. [35] with permission of ACS.
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