[Study on preparation of 3D printing degradable tissue engineering ossicles]

Objective: In combination with 3D printing technology and degradable composite materials, to discuss the preparation method of tissue engineering ossicles for middle ear hearing reconstruction. Methods: Domestic polymer (polylactic acid-glycolic acid copolymer, PLGA) and degradable ceramic material (β-tricalcium phosphate, β-TCP) were selected and prepared by low temperature deposition method according to the design ratio to Program according to the outline design code of the required scaffold to generate appropriate print files, and then the self-developed low-temperature deposition printing device was used to prepare tissue-engineered osseous scaffolds in accordance with the print files in a low-temperature environment. The scaffolds was freeze-dried and sterilized for later use after printing. Light microscopy and scanning electron microscopy were used to observe the apparent characteristics and internal structure of the scaffolds and to check its pore size, porosity and mechanical properties. Results: After printing, a degradable scaffold was obtained. Under the optical microscope, it was a small cylindrical shape with a diameter of 1.5 mm and a length of 6.0 mm, and its surface had micropores. The degradable scaffold had a horizontal and vertical interlaced warp and weft structure, the wire spacing was 1.2 mm, and the pores were connected to each other. The surface could see circular or quadrangular pores with a pore size of about 100-400 μm. The diameter of the inter-pore cross-linked channels was about 50 μm and the diameter of the surrounding circular micropores was about 10-40 μm. β-TCP particles with a size of about 700 nm were attached to the surface of the PLGA material. The average porosity of the whole scaffolds was (83.43±0.01)%, and the content of BMP-2 loaded was about 0.7 μg/mm(3). After freeze-drying, the mechanical strength of the scaffold was moderate, and there was no obvious deformation during stretching and compression, which met the mechanical requirements of tissue engineering ossicles. Conclusions: Using the low-temperature deposition printing method and strictly controlled processes and conditions, a polymer-degradable ceramic ossicle tissue engineering scaffold can be prepared for implantation experiments. The scaffold has suitable porosity and mechanical properties, and can be loaded with osteoinductive factors.