Layer-by-layer self-assembly and clinical application in orthopedics

Orthopedic implants for the treatment of bone defects from various causes have been challenged by insufficient osseointegration,bacterial infection,oxidative stress,immune rejection,and insufficient individualized treatment.These challenges not only impact treatment outcomes but also severely impact patients’daily lives.Layer-by-Layer(LbL)serves as a simple surface coating technique,in simple terms,to functionalize implants by sequentially adsorbing oppositely charged materials onto a substrate.In orthopaedics,LbL self-assembly technology solves some of the challenges by loading various drugs or biological agents on the implant surface and controlling their release precisely to the site of bone defects in a personalized way.This review will introduce the basic principle and the development of LbL in orthopaedics,review and analyze the chemical strategy of LbL in the preparation of bone implants to ensure the stability of the implant,and introduce the use of LbL bone implants in orthopaedics in recent years.The application of LbL includes the realization of programmed drug delivery and sustained release,thereby promoting osseointegration and the formation of new blood vessels,antibacterial,antioxidant,etc.This review focuses on the LbL technology,involving the technology selection for the preparation of bone implants,the chemical strategies of the stability guarantee of LbL implants,the pharmacological properties,loading and release mechanisms of loaded drugs,and the molecular mechanisms of osteogenesis and angiogenesis.The aim of this review is to provide an overview of current research advances,and a prospect in this field was also described.

Engineered three-dimensional scaffolds for enhanced bone regeneration in osteonecrosis

Osteonecrosis,which is typically induced by trauma,glucocorticoid abuse,or alcoholism,is one of the most severe diseases in clinical orthopedics.Osteonecrosis often leads to joint destruction,and arthroplasty is eventually required.Enhancement of bone regeneration is a critical management strategy employed in osteonecrosis therapy.Bone tissue engineering based on engineered three-dimensional(3D)scaffolds with appropriate architecture and osteoconductive activity,alone or functionalized with bioactive factors,have been developed to enhance bone regeneration in osteonecrosis.In this review,we elaborate on the ideal properties of 3D scaffolds for enhanced bone regeneration in osteonecrosis,including biocompatibility,degradability,porosity,and mechanical performance.In addition,we summarize the development of 3D scaffolds alone or functionalized with bioactive factors for accelerating bone regeneration in osteonecrosis and discuss their prospects for translation to clinical practice.

Poly(lactic-co-glycolic acid)-based composite bone-substitute materials

Research and development of the ideal artificial bone-substitute materials to replace autologous and allogeneic bones for repairing bone defects is still a challenge in clinical orthopedics.Recently,poly(lactic-co-glycolic acid)(PLGA)-based artificial bone-substitute materials are attracting increasing attention as the benefit of their suitable biocompatibility,degradability,mechanical properties,and capabilities to promote bone regeneration.In this article,we comprehensively review the artificial bone-substitute materials made from PLGA or the composites of PLGA and other organic and inorganic substances,elaborate on their applications for bone regeneration with or without bioactive factors,and prospect the challenges and opportunities in clinical bone regeneration.