Electrochemical analysis of gold nanoparticles multifunctionalised withCytochrome c and a zinc Porphyrin

Abstract

<p>Cytochrome c (Cyt c), known for its functional redox capabilities, plays a pivotal role in biological</p><p>processes such as the electron transport chain and apoptosis. However, understanding how different</p><p>conjugation strategies impact its structural and redox characteristics is limited. To fill this gap, we</p><p>investigated the effects of conjugating Cyt c and a zinc(II) porphyrin (Zn Porph) to gold nanoparticles</p><p>(AuNPs). We used circular dichroism (CD) spectroscopy to detect structural conformational changes</p><p>in Cyt c upon conjugation and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to</p><p>identify protein orientation. Cyt c was predicted to have different orientations depending on the size</p><p>of AuNPs and methods used to conjugate the protein, it was hypothesised that the orientation of Cyt</p><p>https://doi.org/10.26434/chemrxiv-2023-rsrwv ORCID: https://orcid.org/0000-0002-4872-8928 Content not peer-reviewed by ChemRxiv. License: CC BY 4.0</p><p>2</p><p>c may influence the redox properties of the protein. The electrochemical properties of Cyt c were</p><p>assessed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). We used DPVbased</p><p>to determine the heterogeneous rate constant (k0). The results show a lower k0 for conjugated</p><p>Cyt c than free Cyt c, likely due to structural changes in the protein. The spatial orientation of Cyt c</p><p>had minimal influence on k0, while ligand density and AuNP size had an effect. The k0 value of Zn</p><p>Porph did not decrease on conjugation. Despite these changes, Cyt c and Zn Porph maintained their</p><p>electrochemical capabilities after conjugation.</p>