Preparation of ice microspheres and their application in the preparation of porous poly(l-lactic acid) (PLLA) scaffolds

Abstract

Pure ice particles have been used as porogens to prepare bone tissue engineering scaffolds for several years. However, it is difficult to prepare an ideal spherical ice porogen to improve the pore structure of the porous scaffolds. In this work, sublimable ice-based microspheres were prepared by spraying the 1,4-dioxane/water (70/30, v/v) solution through a syringe needle into liquid nitrogen. Ice-based microspheres have suitable melting points (− 4 °C) and high sublimation rate. The sieved ice-based microspheres with a size of 380–500 μm were used as a porogen to prepare porous PLLA scaffold. The calculation results show that the surface tension of the solution and the interfacial tension between the solution and liquid nitrogen are small when the volume ratio of the 1,4-dioxane/water is 70/30. The 1,4-dioxane/water solution can be effectively dispersed into small droplets in liquid nitrogen and rapidly frozen into microspheres. Scanning electron microscope images show that the porous PLLA scaffold had good pore connectivity. Macropores and micropores can be observed in the cross section of the PLLA scaffold. The pore wall has a special rough structure, and many micro-/nano-PLLA fibers can be found on the surface of the pore wall.