Biomedical Engineering Reference
In-Depth Information
achieved through hydrogen bonding or metal coordination or simultaneously using
both interactions through the addition of small molecule cross-linking agents.
The hydrogen bonding motifs utilized for reversible cross-linking are similarly
based on cyanuric acid residues hydrogen bonded to 2,4-diaminotriazine-based
crosslinking agents. The metal coordination motifs are based on palladated SCS
pincer complexes coordinated to bispyridine cross-linking agents. The rheology of
the polymer networks from a free-flowing liquid to a highly elastic gel can be con-
trolled and the mechanical properties of the gel can be tuned by varying the tem-
perature and ligand displacement agents.
3 Conclusion
This review provides a snapshot of the different types of supramolecular hydro-
gels and their associated potential biomedical applications. The different types of
interactions that drive the formation of these hydrogels have their own advantages
in relation to their application as biomaterials. Hydrogen bonds are important to
the body. For example, the double helix structure of DNA is held by hydrogen
bonds. The folding of proteins, which is necessary for proper protein function, is
also governed by hydrogen bonds. The similarities of the peptide hydrogel systems
with the naturally occurring systems make them highly attractive for bioapplica-
tions. Host-guest complexations for the formation of hydrogels are attractive due
to their ability to be “unlocked” by chemical triggers. This has multiple advan-
tages. On the one hand, such a material can be expected to have multi-stimuli, on
the other hand, these systems offer ease of assembly due to the high binding con-
stants of such systems. On another aspect, with such numerous useful properties,
low molecular weight hydrogels are likely to be widely used in various biomedi-
cal applications. For instance, they can be used to target specific cells and deliver
drugs concurrently. They can also provide a platform to promote the growth of
bone mineral. The ease of mixing low molecular weight components for the for-
mation of a hydrogel could be a clinically attractive option. Recent developments
on hybrid materials have uncovered numerous applications that hybrid hydro-
gels can serve. Through acting as a complement to the embedded substances by
enhancing their natural properties, such hybrid supramolecular hydrogels could
possibly be highly applicable in raising the effectiveness of the current substances
used. The progress of supramolecular soft biomaterials has vast potential in the
landscape of medical care. This area of research is one to watch for the future.
References
1. Lehn, J.M.: Supramolecular chemistry—scope and perspectives molecules, supermolecules,
and molecular devices. Angew. Chem. Int. Ed. Engl.
27
(1), 89-112 (1988). doi:
10.1002/a
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