Effects of Steel Slag on the Hydration Process of Solid Waste-Based Cementitious Materials.

Aiming to enhance the comprehensive utilization of steel slag (SS), a solid waste-based binder consisting of SS, granulated blast furnace slag (BFS), and desulfurization gypsum (DG) was designed and prepared. This study investigated the reaction kinetics, phase assemblages, and microstructures of the prepared solid waste-based cementitious materials with various contents of SS through hydration heat, XRD, FT-IR, SEM, TG-DSC, and MIP methods. The synergistic reaction mechanism between SS and the other two wastes (BFS and DG) is revealed. The results show that increasing SS content in the solid waste-based binder raises the pH value of the freshly prepared pastes, advances the main hydration reaction, and shortens the setting time. With the optimal SS content of 20%, the best mechanical properties are achieved, with compressive strengths of 19.2 MPa at 3 d and 58.4 MPa at 28 d, respectively. However, as the SS content continues to increase beyond 20%, the hydration process of the prepared binder is delayed. The synergistic activation effects between SS and BFS with DG enable a large amount of ettringite (AFt) formation, guaranteeing early strength development. As the reaction progresses, more reaction products CSH and Aft are precipitated. They are interlacing and overlapping, jointly refining and densifying the material's microstructure and contributing to the long-term strength gain. This study provides a reference for designing and developing solid waste-based binders and deepens the insightful understanding of the hydration mechanism of the solid waste-based binder.

LSPR sensing for in situ monitoring the Ag dissolution of Au@Ag core-shell nanoparticles in biological environments.

Silver nanoparticles (AgNPs) are extensively used as an antibacterial agent, and monitoring the dissolution behavior of AgNPs in native biological environments is critical in both optimizing their performance and regulating their safety. However, current assessment methods rely on sophisticated analytical tools that are off-site and time-consuming with potential underestimations, due to complicated sample preparation. Although localized surface plasmon resonance (LSPR) sensing offers a facile method for the detection of AgNP dissolution, it is limited by low sensitivity and poor nanoparticle stability in native biological environments. Herein, we constructed a highly sensitive and stable LSPR sensor using gold-silver core-shell nanoparticles (Au@AgNPs), in combination with polymeric stabilizing agents, for the direct measurement of the Ag shell dissolution in native biological media. The high sensitivity was attributed to the acute and large LSPR shift generated by bimetallic nanoparticles. The sensor was used for the real-time monitoring of the Ag dissolution of Au@AgNPs during their co-culture with both bacteria and fibroblast cells. The media pH was found to dominate the Ag dissolution process, where Au@AgNPs exhibited bactericidal effects in the bacteria environment with relatively low pH, but they showed little toxicity towards fibroblast cells at pH 7.4. The minimum inhibition concentration of Au@AgNPs for bacterial growth was found similar to that of AgNO3 in terms of released Ag amount. Thus, stabilized Au@AgNPs not only allow the in-situ monitoring of Ag dissolution via LSPR sensing but also constitute an effective antibacterial agent with controlled toxicity, holding great potential for future biomedical and healthcare applications.

Autoclavable Albumin-Based Cryogels with Uncompromising Properties.

The development of autoclavable hydrogels has been driven by the need for materials that can withstand the rigors of sterilization without compromising their properties or functionality. Many conventional hydrogels cannot withstand autoclave treatment owing to the breakdown of their composition or structure under the high-temperature and high-pressure environment of autoclaving. Here, the effect of autoclaving on the physical, mechanical, and biological properties of bovine serum albumin methacryloyl (BSAMA) cryogels at three protein concentrations (3, 5, and 10%) was extensively studied. We found that BSAMA cryogels at three concentrations remained little changed after autoclaving in terms of gross shape, pore structure, and protein secondary structure. Young's modulus of autoclaved BSAMA cryogels (BSAMAA) at low concentrations (3 and 5%) was similar to that of BSAMA cryogels, whereas 10% BSAMAA exhibited a higher Young's modulus value, compared with 10% BSAMA. Interestingly, BSAMAA cryogels prolonged degradation. Importantly, cell viability, drug release, and hemolytic behaviors were found to be similar among the pre- and post-autoclaved cryogels. Above all, autoclaving proved to be more effective in sterilizing BSAMA cryogels from bacteria contamination than UV and ethanol treatments. Thus, autoclavable BSAMA cryogels with uncompromising properties would be useful for biomedical applications.