Supramolecular Hydrogels for Controlled Drug Release based on Affinity Modification

Hydrogels are biomaterials showing a hydrophilic character. They have the ability to absorb high quantities of water without dissolution. They can be formed by covalent bonds leading to thermally stable networks, whereas physical interactions (non-covalent bonds) are often reversible, offering unique properties such as responsiveness to stimuli, facile tunability, and faster biodegradability.1 Injectable drug-loaded hydrogels offer minimal invasiveness at the target site, allowing spatio-temporal controlled drug release.
Here, supramolecular hydrogels are prepared with poly(ethylene glycol) (PEG) functionalized with ureido-pyrimidinone (UPy) units, showing pH- and temperature responsive behavior facilitating injection in the liquid state. Once injected and exposed to the in-vivo physiological pH a hydrogel is formed.2 A bifunctional UPy-PEG hydrogelator acts as base material complemented with 3 different monofunctional compounds either modified with a UPy-moiety, a cholesterol or alkyl tail; all displaying a different affinity for the bifunctional UPy-PEG base material. We hypothesize that introduction of these three different monofunctional compounds influence the hydrogel material dynamics and the release of model drug compounds. The release and erosion profiles of the prepared hydrogels are examined using these monofunctional model drug compounds functionalized with a sulfo-cyanine5 amine (Cy5) dye. Secondly, further exploration of the mechanical properties are performed with rheology measurements.

References

1. Li, J. & J. Mooney, D. Nature Reviews Materials 1, (2016).
2. Dankers, P. Y. W. et al. Adv. Mater. 24, 2703–2709 (2012).