Preparation of chiral red-emitting carbon dots by isocyanate post-synthetic treatment with specific interaction with bio-objects.

A post-synthetic modification strategy is presented to induce a chirality in red-emissive carbon dots (CDs) by covalent bonding with chiral isocyanates. The resulting chiral CDs exhibit circular dichroism signals in the 300-500 nm range with a dissymmetry factor of 8 × 10- 5 at 345 nm, distinct from their chiral precursors. These chiral CDs maintain photoluminescence in the red spectral range (615-640 nm) and reasonably high quantum yield of 12-13%. Cytotoxicity assays reveal differential biocompatibility, with the R-enantiomer showing higher toxicity across multiple cell lines (H9c2, 4T1, HeLa, B16) compared to the S-enantiomer. The enantioselective interactions are modeled on example of dynamic system of CDs and tryptophan enantiomers, monitored by changes in CD spectra and molecular dynamics simulations. These findings highlight the potential of chiral CDs for applications in biosensing, chiral separation, and targeted therapy, providing a scalable and controllable synthesis route for red-emissive chiral nanomaterials.