SKM 2023 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 56: Focus: Self-Assembly of Plasmonic Nanostructures (joint session CPP/HL)

CPP 56.3: Talk

Friday, March 31, 2023, 10:15–10:30, GÖR 226

What happens to bovine serum albumin in-between two gold nanoparticles and how this biomolecule defines the plasmonic effect? — Nina Tverdokhleb, •Olga Guskova, Ziwei Zhou, Holger Merlitz, and Vladyslav Savchenko — Leibniz-Institut für Polymerforschung Dresden e. V.

In experiments, spherical gold nanoparticles (NPs) covered by bovine serum albumin (BSA) create 1D Au-BSA nanoarrays on a polymer film. The external mechanical strain applied to the film leads to plasmon-coupled circular dichroism (PCCD) enhancement. To explain this phenomenon, we perform all-atom MD simulations of plasmonic nanostructures, representing BSA in-between two gold NPs. The following steps were undertaken: (1) BSA was adsorbed on the gold wall (a model of NP) in implicit water with optimization of its geometry; (2) the second mobile gold wall was approaching adsorbed protein until the distance between NPs reaches the experimentally measured value; (3) mimicking mechanical stretching mentioned above, an external tensile force applied on the second wall has induced the backbone stretching of the initially compressed BSA. This process is accompanied by the crucial growth of BSA dipole moment along the directional deformation, restructuring of the protein secondary structure from helices to coils upon compression (2), the reorientation of the charged amino-acid residues, and subsequent partial back-folding of the secondary structure elements upon stretching (3). We correlate an observed plasmonic effect in the 1D Au-BSA arrays to the changes in dipole moment and chirality of BSA.