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Norbornene-Functionalised Chitosan Hydrogels and Microgels via an Unprecedented Photo-Initiated Self-Assembly for Potential Biomedical Applications

preprint
submitted on 20.05.2020 and posted on 21.05.2020 by Sarah michel, Alice Kilner, Jean-Charles Eloi, Sarah E rogers, Wuge H. Briscoe, M. Carmen Galan


Access to biocompatible self-assembled gels and microgels is of great interests for a variety of biological applications from tissue engineering to drug delivery. Here, the facile synthesis of supramolecular hydrogels of norbornene (nb)-functionalised chitosan (CS-nb) via UV-triggered self-assembly in the presence of Irgacure 2959 (IRG) is reported. The in vitro stable hydrogels are injectable and showed pH-responsive swelling behaviour, while their structure and mechanical properties could be tuned by tailoring the stereochemistry of the norbornene derivative (e.g. endo- or -exo). Interestingly, unlike other nb-type hydrogels, the gels possess nanopores within their structure, which might lead to potential drug delivery applications. A gelation mechanism was proposed based on hydrophobic interactions following the combination of IRG on norbornene, as supported by 1H NMR. This self-assembly mechanism was used to access microgels of size 100-150 nm which could be further functionalised and showed no significant toxicity to human dermofibroblast cells.

Funding

We acknowledge the ISIS Muon and Neutron Source for the awarded beamtime under experiment numbers: RB 1820037; data available under 10.5286/ISIS.E.100170413. S.M. is supported by the European Research Council (ERC−COG: 648239) and the Bristol Chemical Synthesis Centre for Doctoral Training (Engineering and Physical Science Research Council (EPSRC) EP/L015366/1). SEM studies were carried out in the Chemical Imaging Facility, University of Bristol with equipment funded by EPSRC under Grant "Atoms to Applications" (EP/K035746/1).

History

Email Address of Submitting Author

m.c.galan@bristol.ac.uk

Institution

University of Bristol

Country

United Kingdom

ORCID For Submitting Author

0000-0001-7307-2871

Declaration of Conflict of Interest

No conflict of interest to disclose

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