[Properties of surface coatings for 3D printed high density polyethylene scaffolds]

BACKGROUND: High density polyethylene has been widely used as a repair material for cranial and maxillofacial bone defects, but its preparation method and surface activity still need further improvement.
OBJECTIVE: To optimize the preparation method of high density polyethylene and improve the surface activity of high density polyethylene.
METHODS: The high density polyethylene scaffolds were prepared by extrusion 3D printing technology, and the scaffolds were immersed in dopamine solution and simulated body fluid successively to be coated with polydopamine and hydroxyapatite. The microstructure, hydrophilicity and compression modulus of the scaffolds before and after coating were characterized. Mouse embryonic osteogenic precursor cells (MC3T3-E1) and human umbilical vein endothelial cells were inoculated on the surface of the scaffold to evaluate the cytocompatibility and early osteogenic and angiogenic differentiation of the scaffold before and after coating.
RESULTS AND CONCLUSION: (1) The 3D printed high density polyethylene scaffold’s fibers were arranged regularly and pores were uniform. Characterization results showed that polydopamine and hydroxyapatite coatings were successful on the surface of the scaffolds. Compared with the unmodified scaffold, the surface water contact angle of the scaffold modified with polydopamine coating and polydopamine + hydroxyapatite coating decreased significantly (P < 0.05), and the compressive modulus did not change significantly. (2) Compared with the unmodified scaffold, the modified scaffold with polydopamine coating and polydopamine + hydroxyapatite coating could promote the adhesion of MC3T3-E1 cells and human umbilical vein endothelial cells (P < 0.05). The cell adhesion promoting effect of double coating modified group was better than that of single coating modified group (P < 0.05). Compared with the unmodified scaffold, the modified scaffold with polydopamine coating and polydopamine + hydroxyapatite coating could promote the proliferation of MC3T3-E1 cells and human umbilical vein endothelial cells (P < 0.05). The proliferation promoting effect of double coating modified group was better than that of single coating modified group (P < 0.05). Compared with unmodified scaffolds, the scaffolds modified with polydopamine coating and polydopamine + hydroxyapatite coating could promote the osteogenic differentiation of MC3T3-E1 cells (P < 0.05), and increase the expression of angiogenic factor CD31 in human umbilical vein endothelial cells. The double-coating modified group was more obvious. (3) The results showed that the high density polyethylene scaffolds coated with polydopamine and hydroxyapatite based on 3D printing technology have good cytocompatibility and early osteogenic and angiogenic differentiation ability.