Polycaprolactone scaffolds or anisotropic particles: The initial solution temperature dependence in a gelatin particle-leaching method

Biodegradable Anisotropic Microparticles for Stepwise Cell Adhesion and Preparation of Janus Cell Microparticles

The biomimetic anisotropic particles have different physicochemical properties on the opposite two sides, enabling diverse applications in emulsion, photonic display, and diagnosis. However, the traditional anisotropic particles have a very small size, ranging from submicrons to a few microns. The design and fabrication of anisotropic macron-sized particles with new structures and properties is still challenging. In this study, anisotropic polycaprolactone (PCL) microparticles well separated with each other were prepared by crystallization from the dilute PCL solution in a porous 3D gelatin template. They had fuzzy and smooth surfaces on each side, and a size as large as 70 μm. The fuzzy surface of the particle adsorbed significantly larger amount of proteins, and was more cell-attractive regardless of the cell types. The particles showed stronger affinity toward fibroblasts over hepatocytes, which paved a new way for cell isolation merely based on the surface morphology. After a successive seeding process, Janus cell microparticles with fibroblasts and endothelial cells (ECs) on each side were designed and obtained by making use of the anisotropic surface morphology, which showed significant difference in EC functions in terms of prostacyclin (PGl2) secretion, demonstrating the unique and appealing functions of this type of anisotropic microspheres.

Preparation of polycaprolactone microspheres-aggregated scaffold with ultra big pores and fuzzy sphere surface by a one-step phase separation method

A microspheres-aggregated scaffold with ultra big pores (over 300 μm) and fuzzy microspheres is fabricated by incubating polycaprolactone (PCL)/tetrahydrofuran (THF) solution in a -20°C refrigerator, following by freeze-drying. Formation of the scaffold is mainly governed by the crystallization of the PCL polymer at appropriate conditions. All the 10-20% PCL/THF solutions yield the microspheres-aggregated scaffolds when the initial solution temperature is higher than 37°C, whereas the 10-15% solutions form dense membranes when the initial solution temperature is below 25°C. The size of the microspheres and pores is as large as 70-150 μm and 170-816 μm, respectively. The PCL microspheres-aggregated scaffold can better support the adhesion and proliferation of bone marrow mesenchymal stem cells (BMSCs) compared to the traditional porous scaffold obtained by a porogen leaching method. The tendencies of chondrogenesis and osteogenesis differentiation of BMSCs are observed on the microspheres-aggregated scaffold and the ordinary porous scaffold, respectively.