Induced Chirality\nin QDs Using Thermoresponsive Elastin-like\nPolypeptides

Circular dichroism (CD) spectroscopy\nhas emerged as a potent tool\nfor probing chiral small-molecule ligand exchange on natively achiral\nquantum dots (QDs). In this study, we report a novel approach to identifying\nQD–biomolecule interactions by inducing chirality in CdS QDs\nusing thermoresponsive elastin-like polypeptides (ELPs) engineered\nwith C-terminal cysteine residues. Our method is based on a versatile\ntwo-step ligand exchange process starting from monodisperse oleate-capped\nQDs in nonpolar media and proceeding through an easily accessed achiral\nglycine-capped QD intermediate. Successful conjugation of the ELPs\nonto the QDs is confirmed by the diagnostic CD response corresponding\nto the QD electronic transitions in the visible range. The resulting\nELP:CdS conjugates demonstrate thermally reversible coacervation,\nas observed through dynamic light scattering, small-angle X-ray scattering,\nand electron microscopy. This research provides a foundation for using\ninduced chirality in QD electronic transitions to probe QD conjugation\nto complex peptides and proteins, opening pathways for designing dynamic,\nstimuli-responsive hybrid nanomaterials.