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Hydrogels prepared from supramolecular cross-linking motifs are appealing for use as biomaterials and drug delivery technologies. The inclusion of macromolecules (e.g., protein therapeutics) in these materials is relevant to many of their intended uses. However, the impact of dynamic network cross-linking on macromolecule diffusion must be better understood. Here, hydrogel networks with identical topology but disparate cross-link dynamics are explored. These materials are prepared from cross-linking with host–guest complexes of the cucurbit[7]uril (CB[7]) macrocycle and two guests of different affinity. Rheology confirms differences in bulk material dynamics arising from differences in cross-link thermodynamics. Fluorescence recovery after photobleaching (FRAP) provides insight into macromolecule diffusion as a function of probe molecular weight and hydrogel network dynamics. Together, both rheology and FRAP enable the estimation of the mean network mesh size, which is then related to the solute hydrodynamic diameters to further understand macromolecule diffusion. Interestingly, the thermodynamics of host–guest cross-linking are correlated with a marked deviation from classical diffusion behavior for higher molecular weight probes, yielding solute aggregation in high-affinity networks. These studies offer insights into fundamental macromolecular transport phenomena as they relate to the association dynamics of supramolecular networks. Translation of these materials from in vitro to in vivo is also assessed by bulk release of an encapsulated macromolecule. Contradictory in vitro to in vivo results with inverse relationships in release between the two hydrogels underscores the caution demanded when translating supramolecular biomaterials into application.
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Nanonetwork photogrowth expansion: Tailoring nanoparticle networks’ chemical structure and local topology
The manipulation of covalent polymer networks in the bulk or in the nanoscale seeks to broaden material property variations from an existing parent structure with the possibility to make fundamental changes in nanoparticle compositions which is otherwise difficult to accomplish through bottom up approaches. In this contribution, a parent nanoparticle network prepared by an intermolecular chain cross-linking process containing trithiocarbonate photoactive cross-linking groups has been investigated in its ability to form various novel nanonetworks through a photogrowth expansion process using 10-phenylphenothiazine (PTH) as a photoredox catayst under violet light irradiation, incorporating statistical copolymers and block copolymers into the existing nanonetwork. Hydrophilic and hydrophobic homo-and statistical copolymer incorporation leads to custom designed, tailored nanonetworks and stimuli-responsive behavior. For example, particles expanded by incorporation of PNIPAAM collapse after thermoresponsive behavior above 32 °C and shrink to approximately half of their original size. Furthermore, ABA triblocks and ABABA pentablocks of MA, TFEA, NIPAAM and t BA are integrated with a high degree of control into a parent particle. In this work, we have demonstrated the feasibility of parent nanonetwork structures to expand their network architecture reaching up to the microscale range to give soluble soft matter networks, containing controlled compositions of homopolymers, statistical copolymers, or pentablock structures. The taught concept gives opportunities to further design and alter the network topology in confined structures to tailor properties and function.
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- Award ID(s):
- 1808664
- PAR ID:
- 10108810
- Date Published:
- Journal Name:
- Polymer Chemistry
- Volume:
- 10
- Issue:
- 28
- ISSN:
- 1759-9954
- Page Range / eLocation ID:
- 3841 to 3850
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/C9PY00639G
