Shinn-Jyh Ding

The development of osteogenic polymer-based bone implants is increasingly essential for load-bearing applications. Upcycling high-performance polysulfone (PSF) waste is a promising option for environmental sustainability. In this study, PSF derived...

Calcium silicate-based cement is commonly used for bone repair and regeneration. Current research focuses on developing innovative antibacterial materials with radiopacity, which is essential for ensuring successful clinical outcomes in procedures like vertebroplasty and endodontic treatments. Strontium (Sr) has emerged as a powerful additive, stimulating bone formation and inhibiting bone resorption. In this study, we evaluated the impact of varying levels of Sr—5, 10, and 20 mol% (designated as CSSr5, CSSr10, and CSSr20) on critical attributes of bone cement, including radiopacity, setting time, in vitro bioactivity, antibacterial efficacy, and osteogenic activity. The findings indicated that as the Sr content increased, the setting time and radiopacity of the cement increased. Remarkably, the cement formulations containing over 10 mol% Sr achieved radiopacity values surpassing the 3 mm aluminum threshold mandated by ISO 6876:2001 standards. Furthermore, incorporating Sr significantly improved MG63 cell attachment, proliferation, differentiation, and mineralization, while also boosting antibacterial properties in a dose-dependent manner. After 48 h of inoculation with E. coli or S. aureus, the CSSr10 and CSSr20 cements showed a bacteriostatic ratio exceeding 1.7 or 2 times that of the control without Sr. In conclusion, the CSSr10 cement could be a promising bone filler, exhibiting favorable setting time, radiopacity, antibacterial ability, and osteogenic activity.

Bone regeneration in the presence of osteoporosis presents a significant challenge in dental and orthopedic surgery. To tackle this issue, researchers have developed strontium-containing biomaterials. However, preventing bacterial infection is also crucial for successful surgical treatment. In this study, we delved deep into the processing to tailor the composition and structure of new strontium silicates with unique properties to address this challenge. We used chemical precipitation to prepare various strontium silicate particles using varying ammonia concentrations and Sr/Si precursor ratios. The L929 cytotoxicity, differentiation of human mesenchymal stem cells (hMSCs), biological function of RAW 264.7 macrophages, and antibacterial activity against E. coli and S. aureus were evaluated. As a result, higher ammonia concentration led to the formation of SrSiO₃ and Sr₂SiO₄ particles with smaller sizes and higher Sr/Si ratios. These particles exhibited increased antibacterial efficacy and radiopacity, promoting cell viability and osteogenic activity of hMSCs and modulating M1/M2 macrophage polarization. In conclusion, the developed strontium silicate demonstrated superior antibacterial activity, exceptional osteogenic properties, and clear visibility during procedures, making it a promising material for bone regeneration and osteoporosis treatment.

Environmental protection issues have received widespread attention, making material recycling increasingly important. The upcycling of polysulfone (PSF) medical waste, recognized as a high-performance plastic with excellent mechanical properties, deserves promotion. While PSF is suitable for use as an orthopedic implant material, such as internal fixation, its osteogenesis capabilities must be enhanced. Mechanical stability, particularly over the long term, is a significant concern for bone implants in load-bearing applications. This study recycled PSF medical waste to create bone composites by incorporating osteogenic calcium silicate (CaSi) at three different contents: 10%, 20%, and 30%. We evaluated the phase, morphology, weight loss, and three-point bending strength of the PSF-based composites after they were soaked in dynamic simulated body fluid (SBF) at pH levels of 7.4 and 5.0 for up to 12 months. Human mesenchymal stem cells (hMSCs) were utilized to assess the osteogenic activity of these composites. Our findings revealed that, while the bending strength of PSF-based composites declined with prolonged exposure to SBF, the dissolution of CaSi particles led to a manageable weight loss of about 4% after 12 months, regardless of pH 7.4 or 5.0. Importantly, the incorporation of CaSi into the PSF matrix exhibited a positive effect on the attachment and proliferation of hMSCs. The levels of alkaline phosphatase (ALP) and calcium deposits directly correlated with the CaSi content, indicating superior osteogenic activity. Considering biostability and osteogenic ability, the 20% CaSi-PSF composite demonstrated promise as a candidate for load-bearing implant applications.

Polysulfone (PSF) medical waste can be effectively repurposed due to its excellent mechanical properties. Due to the increasing need for load-bearing bone implants, it is crucial to prioritize the development of biocompatible polymer–matrix composites. Calcium silicate (CaSi), known for its osteogenesis and antibacterial properties, is widely used in medical applications. In this study, recycled PSF plastics in fiber or nanoparticle forms and commercial PSF products were used to create PSF-based composites filled with three different amounts (10, 20, and 30 vol%) of CaSi. The green compact was heat-treated at various temperatures. Experimental results showed that the mechanical interlocking of the PSF matrix and CaSi filler occurred due to the liquefaction of PSF fibers or nanoparticles during heat treatment. When the composite contained 20% CaSi, the obtained three-point bending strength exceeded 60 MPa, falling within the reported strength of compact bone. There was a concurrent improvement in the biocompatibility and antibacterial activity of the PSF-based composites with the increasing amount of CaSi. Considering their mechanical properties and antibacterial activity, the 20% CaSi-containing PSF-based composites treated at 240 °C emerged as a promising candidate for bone implant applications. This study demonstrated the feasibility of upcycling medical waste such as PSF as a matrix, opening doors for its potential usage in the medical field.

Calcium silicate (CaSi) bone cement with antibacterial and osteogenic properties has attracted significant interest. However, there is a need to develop a variety of new premixed bone cement to meet the clinical requirements of fast setting time, ease of handling, and efficient antibacterial properties. In this study, different volume ratios of polyethylene glycol (PEG) and lactic acid liquids were added to calcium silicate, and the effects of varying liquid-to-powder ratios (L/P) were examined. This study assessed the physicochemical properties, cytotoxicity, and antibacterial activity against S. aureus and E. coli of this premixed cement. The results from the experiments indicated that lactic acid significantly reduced the setting time of the CaSi-based cement and enhanced its mechanical strength. Furthermore, the appropriate concentration of lactic acid and matching L/P ratio improved its washout resistance. The cell viability of all premixed cement was found to be over 80%. The premixed cement containing PEG and lactic acid exhibited superior antibacterial properties compared to the CaSi control. Based on its setting time, washout resistance, and antibacterial activity, a premixed cement with a liquid phase of 80% PEG and 20% lactic acid at an L/P ratio of 0.4 appeared promising for use in dental and orthopedic practice.