Abstract: BACKGROUND: Marine collagen can promote the proliferation and differentiation of periodontal ligament fibroblasts and the proliferation of vascular endothelial cells. However, simple collagen membranes have low mechanical strength and rapid degradation, necessitating composite materials. Polylactic acid, a biodegradable medical material approved by the US Food and Drug Administration for implantation, can be composited with collagen to improve the mechanical strength of simple collagen.
OBJECTIVE: To prepare a polylactic acid/collagen electrospinning bilayer guided tissue regeneration membrane and investigate its biocompatibility. 
METHODS: A 7% polylactic acid solution was used as the spinning dope for the dense layer and a 14% polylactic acid-collagen solution was used as the spinning dope for the loose layer. The polylactic acid/collagen double-layer guided tissue regeneration membrane was prepared by electrospinning technology. The membranes were characterized for micromorphology, pore size, and porosity. The membranes were cross-linked using three methods: glutaraldehyde vapor, glutaraldehyde solution, and carbodiimide/hydroxysuccinimide. Tensile tests were performed to identify the membranes with the best mechanical properties for subsequent experiments. The hydrophilic and hydrophobic properties of the polylactic acid/collagen bilayer guided tissue regeneration membrane were evaluated by characterizing water contact angles. The biocompatibility of the polylactic acid/collagen bilayer guided tissue regeneration membrane was evaluated by cytotoxicity, pyrogen, hemolysis, acute systemic toxicity, subchronic systemic toxicity, sensitization, and intradermal stimulation tests.
RESULTS AND CONCLUSION: The fiber diameter of the dense layer of the collagen/polylactic acid electrospinning bilayer guided tissue regeneration membrane was (0.45±0.11) μm, and the fiber diameter of the loose layer was (0.85±0.19) μm. The pore size of the dense layer was (2.43±1.31) μm, with a porosity of (29.86±2.89)%, while the pore size of the loose layer was (11.71±4.41) μm, with a porosity of (48.54±1.33)%. Based on the tensile strength, elastic modulus, and elongation at break results from the tensile test, glutaraldehyde vapor crosslinking was ultimately selected for crosslinking, achieving a crosslinking degree of (17.42±1.67)%. The loose layer of the polylactic acid/collagen bilayer guided tissue regeneration membrane exhibited hydrophilicity, while the dense layer was hydrophobic. The polylactic acid/collagen electrospinning bilayer guided tissue regeneration membrane was non-cytotoxic, non-hemolytic, non-pyrogenic, non-potentially toxic, non-irritating, and non-sensitizing, demonstrating excellent biocompatibility.

Key words: electrospinning, polylactic acid, collagen, guided tissue regeneration membrane, biocompatibility, oral bone defect repair, biomaterial