Magnetic Hyperthermia Method Synthesis of Water-Soluble Silicon–Carbon Dots: Excitation-Independent Fluorescence Materials

Carbon dots (CDs) have attracted widespread attention in recent years due to their synthetic simplicity, biocompatibility, and unique photoluminescent behavior. In this work, water-soluble silicon-carbon dots (SiCDs) were synthesized, and their properties were evaluated. First, a series of SiCDs was prepared by using a novel magnetic hyperthermia method from citric acid (CA) and 3-(2-aminoethylamino) propyldimethoxymethylsilane (AEAMPS). Then, based on the Stöber method, silica (SiO₂) was loaded onto the SiCDs in a one-pot reaction to obtain SiCDs@SiO₂ microspheres. This synthesis strategy is safe, efficient, and simple, allowing gram-scale production in a short time. The resulting SiCDs@SiO₂ microspheres exhibited excellent fluorescent performance, along with high water solubility and independence of excitation fluorescence. The SiCDs@SiO₂ microspheres possessed good thermal resistance and acid-base stability. The influence of storage time and different metal ions on the microsphere suspension was minimal. The SiCDs@SiO₂ microspheres show potential applications for water detection in horizontal wells as fluorescent markers.