An update on hydroxyapatite/collagen composites: What is there left to say about these bioinspired materials?

Abstract

Hydroxyapatite (HAp)/collagen‐based composite materials have been a constant in the development of bioinspired materials for bone tissue engineering. The most fundamental research works focus on combining HAp, due to its chemical similarity with the mineral component of bones, and collagen, which is the most abundant protein in the body. Modern studies have explored different two‐dimensional (2D) and 3D structures, in order to obtain biomaterials with specific physicochemical, mechanical, and biological characteristics that can be applied in distinct biomedical applications. However, as there is already so much work developed with these materials, it is crucial to question: what can still be done? What is the importance of current know‐how for the future of bioinspired materials? In this paper we intend to review and update the available methodologies to synthesize HAp/collagen composites, along with their characteristics. In addition, the future of these materials in terms of applications and their potential as a cutting‐edge technology is discussed.

Guidelines derived from biomineralized tissues for design and construction of high-performance biomimetic materials: from weak to strong

“…Hydroxyapatite and collagen are the most suitable and popular components for bone-defect repair biomaterials, because they exhibit similar chemical composition, and biochemical/biophysical properties to those of bone. 177,[320][321][322] In recent years, the flexoelectric effect of hydroxyapatite has been found. Bone can generate electricity under pressure, and this electromechanical behavior is essential for bone's self-repair and remodeling properties.…”

“…730 Specifically, the ideal artificial materials for bone defect repair should meet the following requirements: (1) possessing a uniform morphology and suitable porous microstructure to From the perspective of component bionics, the major components of bone are hydroxyapatite and collagen; the use of both hydroxyapatite and collagen is more compatible with the composition of bone, and hydroxyapatite and collagen are popular raw materials for the preparation of biomimetic materials for bone defect repair. 320,322,[731][732][733] For instance, Sun et al 403 mimicked the components and ratio of bone to prepare a biomimetic porous nanocomposite consisting of 66.7 wt% ultralong hydroxyapatite nanowires and 33.3 wt% collagen by freeze drying and subsequent chemical cross-linking. Compared with pure collagen as a control sample, the biomimetic This journal is © Royal Society of Chemistry 2024 hydroxyapatite nanowire/collagen elastic porous nanocomposite showed greatly enhanced mechanical properties, and its rehydrated sample showed excellent elastic properties.…”

Advances in osseointegration of biomimetic mineralized collagen and inorganic metal elements of natural bone for bone repair

“…HA is the main inorganic component of bone and may bind various ions [ 29 ], such as Mg (Mg 2+ ), potassium (K + ), Zn (Zn 2+ ) and manganese (Mn 2+ ) [ 30 ]. Nano-hydroxyapatite (n-HA) is similar in size, crystallinity and chemical composition to HA in natural bone and is characterized by a rod-like or needle-like structure of 70–80 nm in length that binds tightly to the surface of recombinant collagen fibrils [ 31 , 32 ]. In addition, n-HA adapts to the adhesion and growth of healthy osteoblasts and osteoclasts, and also promotes the value-added and differentiation of stem cells [ 33 ], which have excellent osteoconductive and osteoinductive activities in biological systems [ 15 , 34 ].…”

Functionalization of biomimetic mineralized collagen for bone tissue engineering

“…Currently, research on MC has progressed from pure and composite biological materials to multifunctional coordination materials that can incorporate specific functional cells, bioactive factors, and drugs for enhanced therapeutic efficacy ( Scheme 1 ). Existing reviews on MC mainly focus on the mechanism of biomineralization, classical and non-classical crystallization theories, in vitro mineralization of collagen, and preparation of the MC scaffolds and MC [ 15 , 16 , [49] , [50] , [51] ]. The construction of more coordinated and multifunctional MC composites for the repair of complex bone defects are a current research hotspot, with a growing number of related studies.…”