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The present study focuses on enhancing the thermomechanical properties of poly(methyl methacrylate) (PMMA), a transparent and biocompatible polymer known for its high strength but limited toughness. The approach involves the development of PMMA/cellulose nanocrystals (CNCs) composites. To improve the interfacial compatibility between PMMA and CNCs, a two‐step process is employed. Initially, the CNCs undergo oxidation using sodium periodate, followed by the introduction of amino groups through reductive amination. The aminated CNCs are then covalently bonded to PMMA via an amidation reaction using the "grafting onto" approach. Subsequently, the grafted CNCs are incorporated into the PMMA matrix using the solvent casting method. The resulting composites are extruded into filaments. Elemental composition analysis confirms CNC modification, revealing the presence of 1.6% nitrogen. The modified CNCs exhibit a higher degradation temperature than unmodified CNCs, showing a 50°C increase. The composites' dynamic mechanical analysis (DMA) reveals a 20% improvement in storage modulus (E′) upon incorporating 1.5% of the grafted CNCs into the PMMA matrix. This enhancement is attributed to the formation of co‐continuous phases in the composite structure. [ABSTRACT FROM AUTHOR]

The mechanical properties of polylactide stereocomplexes (PLA SC) have been primarily studied through tensile testing, with inconsistent results, and the compressive properties of PLA SC compared to homocrystalline or amorphous PLA remain poorly understood. In this study, we coated porous bioactive glass 13–93 scaffolds with amorphous, homocrystalline, or stereocomplex PLA to investigate their mechanical and degradation properties before and after immersion in simulated body fluid. The glass scaffolds had interconnected pores and an average porosity of 76%. The PLA coatings, which were 10–100 μm thick and approximately 3% of the glass scaffold mass, covered the glass to a large extent. The compressive strength and toughness of all PLA‐coated scaffolds were significantly higher than those of uncoated scaffolds, with approximately a fourfold increase before immersion and a twofold increase after immersion. The compressive strength and toughness of PLA SC‐coated scaffolds were similar to those of scaffolds with homocrystalline PLA coating, and significantly higher than for scaffolds with amorphous PLA coating. All PLA coatings moderated the initial pH increase caused by the glass, which could benefit surrounding cells and bone tissue in vivo after implantation. [ABSTRACT FROM AUTHOR]

The two‐stage induced‐membrane (IM) technique is increasingly used for treatment of large bone defects. In stage one, the bone defect is filled with polymethylmethacrylate (PMMA), which induces a membrane around the implant. In stage two, PMMA is replaced with bone graft. Bioactive glasses (BAGs) are bone substitutes with bone‐stimulating and angiogenic properties. We have previously shown that a certain type of BAG can also induce a foreign‐body membrane similar to PMMA. The aim of this study was to evaluate the bone‐forming capacity of sintered BAG‐S53P4 and poly(lactide‐co‐glycolide) (PLGA)‐coated BAG‐S53P4 scaffolds for potential use as bone substitutes in a single‐stage IM technique. Sintered porous rods of BAG‐S53P4, BAG‐S53P4‐PLGA, or PMMA were implanted in rabbit femurs for 2, 4, or 8 weeks. The expression of bone morphogenic protein (BMP)‐2, ‐4, and ‐7 in the IMs of implanted materials were analyzed with real‐time quantitative polymerase chain reaction. Micro‐computed tomography imaging was used to evaluate bone growth and further verified with scanning electron microscopy. BAG‐S53P4 and BAG‐S53P4‐PGLA scaffold IMs show similar or superior expression of BMP‐2, ‐4, and ‐7 compared with PMMA IM. Bone ingrowth into BAG scaffolds increased over time. Active bone formation occurred inside the BAG scaffolds and the respective BMP expressions were similar or superior for the BAG IMs compared with PMMA, thus making BAGs a promising device for single‐stage treatment of bone defects. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res B Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 847–857, 2019. [ABSTRACT FROM AUTHOR]

ABSTRACT Magnesium is important for both bone growth and cartilage formation. However, the postoperative intake of antibiotics such as quinolones may cause a reduction in magnesium levels in tissue. The addition of magnesium to scaffolds may therefore be beneficial for the regeneration of osteochondral defects. In this study, porous composite scaffolds were produced by gas foaming of poly( d, l-lactide-co-glycolide) (PLGA) rods with magnesium-containing bioresorbable glasses and magnesium hydroxide as fillers. The in vitro hydrolytical degradation of the composite scaffolds in Tris buffer was followed over a 10-week period. Mg2+ was released in a controlled manner from the scaffolds with varying release profiles between the different materials. Higher glass content resulted in a reduced mass loss compared to scaffolds with lower glass content. As a result of the foaming method, the scaffolds shrank initially, without evidence that the addition of hydrophilic fillers would decrease the initial shrinkage. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42646. [ABSTRACT FROM AUTHOR]