Photopatternable chitosan-based submicron fibres for peripheral nerve guidance.

Abstract

Peripheral nerve injury (PNI) affects 13.9 per 100,000 people annually. PNI can cause temporary loss of motor function and sensation, with the more severe cases developing permanent loss of function and chronic pain, due to the formation of neuromas. The gold standard treatment for severe peripheral nerve injury has long been considered that of the autologous graft, which utilises healthy sensory nerves from the back of the leg, a process that in itself has additional surgery risk and risk for complications. Current research is being directed towards finding alternatives to this procedure, with a significant effort being put towards fabricating artificial nerve guidance conduits (NGC) that facilitate repair. Different materials have been utilised in the fabrication of commercial NGCs but attempts so far have failed to match the efficacy of the gold standard. This work aims to develop a material with potential uses as an NGC, which combines the stimulatory effects derived from the topography of aligned fibres, with chemotactic guidance cues derived from localised chemical functionalisation of the fibres via photo-click chemistry and UV light projecting. In this work, chitosan, a biodegradable polysaccharide derived from the commonly found chitin, were modified with norbornene moieties, enriching it with alkene groups that can participate in thiol-ene click reactions. The modified chitosan (CTNSB) was then formulated into submicrometric aligned fibrous membranes utilising solution blow spinning (SBS), a low-cost and scalable fibre producing technique, and mixing with PEO to aid fibre formation. The produced fibre membranes were subsequently modified with different functional moieties. Initially, CTSNB fibres were patterned with the thiol-containing fluorophore dansyl-cysteine, with the goal of troubleshooting the UV projection and patterning parameters. Following the troubleshooting and optimisation, the CTSNB fibrous membranes were modified with a synthetic trifunctional peptide containing a thiol moiety, a fluorescent rhodamine B moiety, and a biotin moiety, with the purpose of further modification via a strept(avidin) bridge. The availability of the biotin moiety for further functionalisation was confirmed via conjugation with fluorescently labelled avidin. CTNSB fibrous membranes were also modified with PFDT as a potential avenue to modify the material’s wettability. CTNSB fibrous membranes were also patterned with a synthetic peptide containing the RGD cell adhesion motif. Finally, rat primary Schwann cells and dermal fibroblasts were cultured on the surface of CTSNB fibrous membranes and thin gels.

Date of Award	31 Dec 2023
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Nicola Tirelli (Supervisor), Adam Reid (Supervisor) & Jonny Blaker (Supervisor)