A research group led by Prof. LAI Yuxiao from the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences has developed multi-functional bionic porous scaffolds combining biodegradable polymer lactate-glycolic acid (PLGA) with black phosphorus (BP) using a unique low-temperature 3D printing technology. These scaffolds can promote bone immunomodulation and bone regeneration.

The study was published in Advanced Science on Aug. 24.

The treatment of bone defects remains a major challenge. 3D-printed scaffolds have attracted much attention in orthopedics. However, implanted bone scaffolds often do not integrate successfully with host tissue because they do not elicit a favorable immune response.

BP, a novel 2D material, has attracted more attention to in recent years since it is biocompatible and biodegradable in physiological environment. Although it has been reported that biomaterials based on BP can promote bone regeneration, little is known about whether BP regulates the immunological microenvironment of bone.

"Immunomodulatory properties of orthopedic biomaterials are significant in regulating osteoimmune microenvironment for osteogenesis," said Prof. LAI.

The researchers synthesized innovative porous PLGA/BP scaffolds by 3D printing technology and investigated the effect of BP on osteoimmunomodulation and osteogenesis in site.

The PLGA/BP scaffold showed suitable biocompatibility, biodegradability and mechanical properties, and phosphate anions, nontoxic degradation products of BP, are important for bone tissue mineralization.

Moreover, the researchers found that BP scaffolds could recruit macrophages and stimulate macrophages from M1 to M2 polarization to inhibit inflammation and promote bone regeneration.

Through transcriptome analysis of bone marrow stromal cells, the researchers also demonstrated that the proposed scaffolds could promote IBSP and SPP1 expression, osteogenic differentiation, and osteogenic behavior via the PI3K-AKT pathways.

"Our study may provide a new strategy for the development of biomaterials that can be used to repair bone defects," said Prof. LAI.