Induced chirality of previously achiral quantum confined CdE (E=S, Se, Te) nanocrystals has been demonstrated through post-synthetic ligand exchange using chiral ligands. The emergence of chirality is manifested through circular dichroism (CD) absorbance and photoluminescence corresponding to the electronic transitions of the CdE nanocrystal. Most of these works have investigated induced chirality in these nanocrystals using biphasic exchanges where the chiral ligand is in excess in polar solvent and pH≥12  while the native CdE nanocrystals are suspended in hydrophobic solvents. This traditional method is not feasible for proteins due to the harsh pH conditions and reagents required. Additionally, understanding how the concentration of the chiral ligand impacts the intensity of the CD spectra (g-factor) is challenging due to the excess amount of ligand required for the exchange process.

     In this work, we first demonstrate a novel approach of direct post-synthetic attachment of CdS quantum dots (QDs) to proteins by first solubilizing hydrophobic QDs using glycine as the hydrophilic ligand followed by exchanging glycine for C-terminal cysteine on thermoresponsive elastin-like polypeptides (ELPs). ELPs are attractive organic components in inorganic-organic hybrid materials due to their water solubility, low sequence and structural complexity, and ability to reversibly phase-separate (coacervate) above their intrinsic transition temperature. For the first time, we demonstrate that chirality can be induced in the QDs by coordinating ligands as large as proteins. Successful conjugation of the ELPs onto QDs is confirmed by the characteristic CD response corresponding to the QD electronic transitions in the visible spectrum. Additionally, we demonstrate the reversible coacervation of ELP:CdS conjugates, as observed through dynamic light scattering, small-angle X-ray scattering, and electron microscopy.

     Building off this work, we are now using a similar approach to understand the conditions under which the CD response is maximized by cysteine and its derivatives on CdS nanorods (NRs). Using an aqueous titration method, we can achieve a maximum g-factor of 1.4x10-3 with less than 50 µM concentration of cysteine derivatives. In future work, we look to investigate how varying the NR aspect ratio impacts both the maximum achievable g-factor and the concentration of thiol needed to achieve this value.