To date, Ag-based nanomaterials have demonstrated a high potential to overcome antibiotic resistance issues. However, bare Ag nanomaterials are prone to agglomeration in the biological environment, which results in a loss of antibacterial activity over time. Furthermore, it is still challenging to collect small-sized Ag nanomaterials right after the synthesis process. In this study, spherical-shaped Ag nanoparticles (NPs) (~6–10 nm) were attached on the surface of cetyltrimethylammonium bromide (CTAB)-loaded mesoporous silica nanoparticles (MSNs) (~100–110 nm). Antibacterial activity tests suggested that the obtained nanocomposite can be used as a highly efficient antibacterial agent against both Gram-negative and Gram-positive bacterial strains. The minimum inhibitory concentration (MIC) recalculated to pure Ag weight in nanocomposite was found to be ~1.84 µg/mL (for Escherichia coli) and ~0.92 µg/mL (for Staphylococcus aureus)—significantly smaller compared to values reported to date. The improved antibacterial activity of the prepared nanocomposite can be attributed to the even distribution of non-aggregated Ag NPs per volume unit and the presence of CTAB in the nanocomposite pores.

Regeneration of damaged tissues or organs is one of the significant challenges in tissue engineering and regenerative medicine. Many researchers have fabricated various scaffolds to accelerate the tissue regeneration process. However, most of the scaffolds are limited in clinical trials due to scaffold inconsistency, non-biodegradability, and lack of non-invasive techniques to monitor tissue regeneration after implantation. Recently, carbon dots (CDs) mediated fluorescent scaffolds are widely explored for the application of image-guided tissue engineering due to their controlled architecture, light-emitting ability, higher chemical and photostability, excellent biocompatibility, and biodegradability. In this review, we provide an overview of the recent advancement of CDs in terms of their different synthesis methods, tunable physicochemical, mechanical, and optical properties, and their application in tissue engineering. Finally, this review concludes the further research directions that can be explored to apply CDs in tissue engineering.

In this study, magnetic Fe₃O₄ particles and Fe₃O₄-Ag⁰ nanocomposites were prepared by a facile and green method, fully characterized and used for the removal of Hg²⁺ from water. Characterizations showed that the Fe₃O₄ particles are quasi-spherical with an average diameter of 217 nm and metallic silver nanoparticles formed on the surface with a size of 23–41 nm. The initial Hg²⁺ removal rate was very fast followed by a slow increase and the maximum solid phase loading was 71.3 mg/g for the Fe₃O₄-Ag⁰ and 28 mg/g for the bare Fe₃O₄. The removal mechanism is complex, involving Hg²⁺ adsorption and reduction, Fe²⁺ and Ag⁰ oxidation accompanied with reactions of Cl⁻ with Hg⁺ and Ag⁺. The facile and green synthesis process, the fast kinetics and high removal capacity and the possibility of magnetic separation make Fe₃O₄-Ag⁰ nanocomposites attractive materials for the removal of Hg²⁺ from water.