Open AccessEffect of pH and Au Nanoparticles on Cytochrome c Investigated by Electrochemistry and UV-Vis Absorption Spectroscopy
Author(s) -
Yanyan Wang,
Yu Jiang,
Andrei S. Susha,
Andrey L. Rogach,
ShiGang Sun,
孙世刚
Publication year - 2012
Publication title -
wuli huaxue xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.396
H-Index - 37
ISSN - 1000-6818
DOI - 10.3866/pku.whxb201203073
Subject(s) - spectroscopy , electrochemistry , absorption spectroscopy , absorption (acoustics) , ultraviolet visible spectroscopy , chemistry , nanoparticle , photochemistry , analytical chemistry (journal) , nuclear chemistry , materials science , nanotechnology , electrode , optics , environmental chemistry , physics , organic chemistry , quantum mechanics , composite material
In this paper, gold nanoparticles (NPs) with an average size of (4.7 +/- 0.6) nm, capped with mercaptopropionic acid (MPA) ligand, are prepared. The effect of pH and Au NPs on cytochrome c (Cyt c) is investigated by electrochemistry and UV-Vis absorption spectroscopy. UV-Vis absorption spectra indicate that the structures of Cyt c and Cyt c-Au NPs complex do not change appreciably between pH=7.5 and pH=3.0, but their Soret band positions change markedly at pH=2.0, indicating that low pH value induces a conformational change in Cyt c. Cyclic voltammetry (CV) result shows that Au NPs capped with MPA enhance electron transfer between Cyt c and the electrode. The data also reveals that the biocompatibility of Au NPs is improved when citric acid ligand is replaced with MPA. The change in pH value causes a change of peak currents in CV and a shift of peak potential. When pH value deviates from 7.0, levels of electroactive Cyt c decrease. Significant pH change induces irreversible denaturing of Cyt c. The pH at which Cyt c-Au NPs complex denatures completely is one unit higher than that of Cyt c. Combining the results from UV-Vis spectroscopy and CV, we find that addition of Au NPs makes adsorbing state Cyt c more vulnerable to pH.National Natural Science Foundation of China [20833005, 20873116, 60936003, 21021002