Bone-adhesive barrier membranes based on alendronate-functionalized poly(2-oxazoline)s

Fabrication of gelatin-incorporated nanoporous chitosan-based membranes for potential water desalination applications

Membrane technology has extensively been used in diverse phenomena such as separation, purification and controlled transportation. Herein, gelatin-incorporated porous chitosan membranes have been prepared using the sol-gel approach for potential water desalination applications. The porogens of poly(ethylene glycol) and Triton X-100 were employed for the mentioned purpose. The prepared porous membranes have been characterized for surface chemical, structural, thermal, mechanical and functional attributes using appropriate analytical approaches. Electron microscopy expressed porous surface morphologies of the resultant films with an average pore size of 14.5 nm. The infrared analysis demonstrated a successful crosslinking of the precursors in the resulting membranes via maleic anhydride. Differential scanning calorimetry analysis disclosed acceptable thermal stability of the test membranes, workable above ambient temperatures. The membrane expressed a water contact of 68.59°, which indicated moderate hydrophilicity, thus allowing controlled transport of the aqueous media. The resultant gelatin/chitosan porous membrane exhibited a porosity of 98 % against kerosene oil. In contrast, the flowability of 7.14 (ethanol), 5.00 (distilled water) and 0.53 (ethylene glycol) mL/min has been recorded against the mentioned liquids. The membrane efficiently purified the local canal water to permissible limits. Such membranes have been qualified for potential applications in water purification systems.

A long-lasting guided bone regeneration membrane from sequentially functionalised photoactive atelocollagen

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's primary amino groups, preserved triple helices and fast (< 180 s) gelation kinetics, respectively. Hydrogel's 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. STATEMENT OF SIGNIFICANCE: Collagen-based membranes remain a key component in Guided Bone Regeneration (GBR) therapy, but their properties, e.g. proteolytic stability and soft tissue barrier functionality, are still far from optimal. This is largely attributed to the complex molecular configuration of collagen, which makes chemical accessibility and structure-function relations challenging. Here, we fabricated a UV-cured hydrogel network of atelocollagen, whereby triple helices were sequentially functionalised with two distinct ethylenically unsaturated monomers. The effects of the sequential functionalisation and UV-curing on the macroscopic properties, degradation behaviour and GBR capability were investigated in vitro and in vivo. The results highlight the key role of the sequential functionalisation and provide important insights for the design of future, longer-lasting resorbable membranes for GBR therapy.