Silane-modified hydroxyapatite nanoparticles incorporated into polydioxanone/poly(lactide-co-caprolactone) creates a novel toughened nanocomposite with improved material properties and in vivo inflammatory responses

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

The goal of this review is to present a wide range of hybrid formulations and composites containing calcium orthophosphates (abbreviated as CaPO4) that are suitable for use in biomedical applications and currently on the market. The bioactive, biocompatible, and osteoconductive properties of various CaPO4-based formulations make them valuable in the rapidly developing field of biomedical research, both in vitro and in vivo. Due to the brittleness of CaPO4, it is essential to combine the desired osteologic properties of ceramic CaPO4 with those of other compounds to create novel, multifunctional bone graft biomaterials. Consequently, this analysis offers a thorough overview of the hybrid formulations and CaPO4-based composites that are currently known. To do this, a comprehensive search of the literature on the subject was carried out in all significant databases to extract pertinent papers. There have been many formulations found with different material compositions, production methods, structural and bioactive features, and in vitro and in vivo properties. When these formulations contain additional biofunctional ingredients, such as drugs, proteins, enzymes, or antibacterial agents, they offer improved biomedical applications. Moreover, a lot of these formulations allow cell loading and promote the development of smart formulations based on CaPO4. This evaluation also discusses basic problems and scientific difficulties that call for more investigation and advancements. It also indicates perspectives for the future.

Surface-Modified Diopside-Reinforced PCL Biopolymer Composites with Enhanced Interfacial Strength and Mechanical Properties for Orthopedic Applications

The phase separation of ceramics in a biopolymer matrix makes it challenging to achieve satisfactory mechanical properties required for orthopedic applications. It has been found that silane coupling agents can modify the surface of the bioceramic phase by forming a molecular bridge between the polymer and the ceramic, resulting in improved interfacial strength and adhesion. Therefore, in the present study, silane-modified diopside (DI) ceramic and ε-polycaprolactone (PCL) biopolymer composites were fabricated by injection molding method. The silane modification of DI resulted in their uniform dispersion in the PCL matrix, whereas agglomeration was found in composites containing unmodified DI. The thermal stability of the silane-modified DI-containing composites also increased. The Young's modulus of the composite containing 50% w/w DI modified by 3% w/w silane increased by 103% compared to composites containing 50% w/w unmodified DI. The biodegradation of the unmodified composites was significantly high, indicating their weak interfacial strength with the PCL matrix (p ≤ 0.001). The osteoconductive behavior of the composites was also validated by in vitro cell-material studies. Overall, our findings supported that the silane-modified composites have improved surface roughness, mechanical, and osteoconductive properties compared to the unmodified composite and have the potential for orthopedic applications.

Organic-Solvent-Resistant Polyimide/Hydroxyapatite Mixed Matrix Membranes for Lysozyme Adsorption

This work reports new mixed matrix membranes (MMMs) for the adsorption of enzymes from organic solvents. In this work, polyimide/hydroxyapatite (PI/HAP) MMMs were prepared via phase inversion method and further crosslinked with 3-aminopropyl triethoxysilane (APTES). The chemical and structural stability of the crosslinked PI/HAP MMMs were improved and applied for lysozyme (LZ) adsorption in organic solvent. PI/HAP MMMs were crosslinked by changing the 3-aminopropyltriethoxysilane (APTES) concentration and crosslinking time. The optimal APTES crosslinking condition for PI/HAP MMMs is 6% of concentration for 8 h. The LZ adsorption performance was studied by changing solvent types. PI/HAP MMMs possessed a high LZ adsorption in organic-solvent-aqueous solutions, and the LZ adsorption capacity reached 34.1 mg/g. The MMMs had a high desorption capacity and recovery ability. The MMMs maintained 60% of their adsorption capacity and 58% of their desorption at the fourth cycle of adsorption and desorption. The MMMs provided a new technology for the purification and separation of enzymes or proteins by MMMs in organic solvents.