Fabrication of Yellow-Emitting Chiral Silicon Nanoparticles and Fluorescence/Colorimetric Dual-Mode Recognition of Lysine Enantiomers together with Nanobioimaging

Long-wavelength emission fluorescent chiral silicon nanoparticles (c-SiNPs) hold significant potential for biological imaging and complex sample analysis due to their superior optical properties. However, the synthesis of these materials remains a considerable challenge. The activity of lysine is intrinsically linked to its configuration, making it crucial to develop a rapid, sensitive, and selective method for differentiating lysine enantiomers in biochemical and biomedical fields. In this study, N-[3-(trimethoxysilyl)propyl]ethylenediamine and chlorogenic acid were innovatively employed as precursors, and the yellow-emitting c-SiNPs with an emission wavelength of 572 nm were synthesized at room temperature for the first time by adjusting experimental parameters. The obtained c-SiNPs exhibited excellent optical properties, stability, and cell compatibility. Furthermore, the c-SiNPs demonstrated outstanding fluorescence and colorimetric recognition capabilities for lysine enantiomers. Consequently, fluorescence/colorimetric dual-mode sensing methods with high selectivity and sensitivity for the recognition of lysine enantiomers were established, and the linear ranges of these methods for d-lysine were 0.050–20 and 0.10–30 mM, with detection limits of 7.5 and 17 μM, respectively. Additionally, the c-SiNPs demonstrated an ability to bioimaging d-lysine within HeLa cells. Using density functional theory to calculate the recognition mechanism and correlating this with fluorescence and ultraviolet–visible (UV–vis) absorption spectra data, it was confirmed that the recognition mechanism was associated with the Gibbs free energy, binding energy, and hydrogen bond number difference between the c-SiNPs and lysine enantiomers. The method developed in this study for preparing c-SiNPs provided a reference for synthesizing fluorescent c-SiNPs with longer emission wavelengths. Moreover, the established method for identifying lysine enantiomers holds significant guiding implications for the use of high-purity lysine.