Osteogenesis and angiogenesis promoting bioactive ceramics

Bioinspired Nanoscale 3D Printing of Calcium Phosphates Using Bone Prenucleation Clusters

Calcium phosphates (CaPs) are ubiquitous in biological structures, such as vertebrate bones and teeth, and have been widely used in biomedical applications. However, fabricating CaPs at the nanoscale in 3D has remained a significant challenge, particularly due to limitations in current nanofabrication techniques, such as two-photon polymerization (2pp), which are not applicable for creating CaP nanostructures. In this study, a novel approach is presented to 3D print CaP structures with unprecedented resolution of ≈300 nm precision, achieving a level of detail three orders of magnitude finer than any existing additive manufacturing techniques for CaPs. This advancement is achieved by leveraging bioinspired chemistry, utilizing bone prenucleation nanoclusters (PNCs, average size of 5 nm), within a photosensitive resin. These nanoclusters form a highly transparent photoresist, overcoming the light-scattering typically associated with larger calcium phosphate-based nanoparticles. This method not only allows for nanopatterning of CaPs on diverse substrates, but also enables the precise control of microstructure down to the level of submicron grains. The method paves the way for the developing of bioinspired metamaterials, lightweight damage-tolerant materials, cell-modulating interfaces, and precision-engineered coatings.

Development of a Photocrosslinkable Collagen-Bone Matrix Hydrogel for Bone Tissue Engineering

Bone tissue engineering aims to restore lost bone and create an environment conducive to new bone formation. To address this challenge, we developed a novel biomimetic hydrogel that combines maleic anhydride-modified type I collagen (ColME) with maleic anhydride-modified demineralized and decellularized porcine bone matrix particles (mDBMp), forming a composite ColME-mDBMp (CMB) hydrogel. Chemical modification of collagen resulted in a high degree of substitution, thereby enhancing its photocrosslinkability. Integration of mDBMp into the ColME hydrogel via photocrosslinking resulted in enhanced physiological stability, reduced shrinkage, and improved mechanical strength compared to gelatin methacrylate (GelMA)-based hydrogels. Moreover, mineralization of the CMB hydrogel promoted the formation of pure hydroxyapatite (HAp) crystals, providing superior stiffness while maintaining ductility relative to GelMA-based hydrogels. In vitro, human bone marrow mesenchymal stem cells (hBMSCs) encapsulated in CMB hydrogels exhibited enhanced proliferation, cell-matrix interactions, and osteogenic differentiation, as evidenced by increased calcium deposition and histological analysis. These results demonstrate that the CMB hydrogel, enriched with extracellular matrix (ECM) components, shows considerable promise over current GelMA-based hydrogels for bone tissue engineering.

Injectable biocomposite cement: A dual-setting formula with magnesium potassium phosphate and κ-carrageenan hydrogel for orthopedic advancements

Magnesium phosphate-based cements are highly regarded for their bioactive properties, making them excellent candidates as bone substitutes. Despite their promising attributes, challenges such as high reaction temperature, limited injectability, and brittleness limit their application. This study introduces a dual-setting biocomposite cement, which encompasses both cement hydration and hydrogel's cross-linking. The composition features magnesium potassium phosphate (MKP) combined with ionically cross-linked kappa-carrageenan (kC) plasticized with sorbitol (Sor). The investigation delves into the properties of the resultant biocomposite, with a particular focus on evaluating kC incorporation's influence on the main MKP properties. Our findings reveal that those biocomposites offer multiple benefits over traditional ceramic cements. The main advantages include: a longer setting time (up to ~15 min), lower setting temperature (~45 °C), different crystalline phase (bobierrite), better wettability (~22°), and improved injectability of the paste characterized by more stable cohesion. Specifically, the MKP (4:1 Mg/P ratio) with 1.5 % kC and Sor hydrogel obtained with 3.0 g/mL powder-to-liquid ratio demonstrated the most promising properties with no adverse effects on the microstructure diversity, the mechanical strength, the porosity, the biodegradation rate, and the osteoblasts cytocompatibility. Overall, our research indicates that these innovative cements hold significant potential for biomedical applications, especially minimally invasive orthopedic procedures.