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, <i>N</i>-[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.