  The fast degradation of collagen-based membranes in the biological
environment remains a critical challenge, resulting in underperforming Guided
Bone Regeneration (GBR) therapy leading to compromised clinical results.
Photoactive atelocollagen (AC) systems functionalised with ethylenically
unsaturated monomers, such as 4-vinylbenzyl chloride (4VBC), have been shown to
generate mechanically competent materials for wound healing, inflammation
control and drug delivery, whereby control of the molecular architecture of the
AC network is key. Building on this platform, the sequential functionalisation
with 4VBC and methacrylic anhydride (MA) was hypothesised to generate UV-cured
AC hydrogels with reduced swelling ratio, increased proteolytic stability and
barrier functionality for GBR therapy. The sequentially functionalised
atelocollagen precursor (SAP) was characterised via TNBS and ninhydrin
colourimetric assays, circular dichroism and UV-curing rheometry, which
confirmed nearly complete consumption of collagen primary amino groups,
preserved triple helices and fast (within 180 s) gelation kinetics,
respectively. Hydrogel swelling ratio and compression modulus were adjusted
depending on the aqueous environment used for UV-curing, whilst the sequential
functionalisation of AC successfully generated hydrogels with superior
proteolytic stability in vitro compared to both 4VBC functionalised control and
the commercial dental membrane Bio-Gide. These in vitro results were confirmed
in vivo via both subcutaneous implantation and a proof-of-concept study in a
GBR calvarial model, indicating integrity of the hydrogel and barrier defect,
as well as tissue formation following 1-month implantation in rats.
