This talk will focus of the computational investigation of the change in the optical properties of the CdSe quantum dots due to their binding with firefly Luciferase enzyme. Semiconductor quantum dots and nanocrystals can be used as nanoscale probes for analyzing the local pH and electrostatic environment in proteins and biomolecules. However, computational investigation of protein-quantum dot complex continues to be challenging because of the large number of atoms in the system. In the present work, we address this challenge by developing a QM/MM approach where the electronic excitation in the quantum dot is treated using quantum mechanics and the protein environment is treated using molecular mechanics force field. The CdSe quantum dots studies in this work are in the range of 5-10 nm in diameter with a protein corona of the firefly Luciferase enzyme on the surface of the nanoparticle. Starting with the bare quantum dot, the change in the optical gap (of the quantum dot) due to addition of each enzyme molecule was computed. This process was continued until the formation of the protein corona was complete and binding with addition enzyme was sterically unfavorable. We find that the change in the local electrostatic environment of the quantum dot due to the formation of the protein corona has a significant impact on the optical properties of the bare quantum dot. The consequence of introducing mutation in Luciferase on the optical properties of the protein-quantum dot complex will be presented. These results indicate that it is possible to spectroscopically monitor the formation of protein corona on the quantum dot.

Optical signature of formation of protein corona in the firefly Luciferase-CdSe quantum dot complex

248th National Meeting (2014)

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