posted on 2023-12-26, 11:06authored byDavide Redolfi-Bristol, Alessandro Mangiameli, Kenta Yamamoto, Elia Marin, Wenliang Zhu, Osam Mazda, Pietro Riello, Giuseppe Pezzotti
Ammonia (NH3) is a commonly used industrial
chemical
to which exposure at high concentrations can result in severe skin
damage. Moreover, high levels of ammonia in the human body can lead
to hyperammonemia conditions and enhanced cancer metabolism. In this
work, the toxicity mechanism of NH3 has been studied against
human dermal fibroblast (HDF) cells using surface-enhanced Raman spectroscopy
(SERS). For this purpose, gold nanoparticles of size 50 nm have been
prepared and used as probes for Raman signal enhancement, after being
internalized inside HDF cells. Following the exposure to ammonia,
HDF cells showed a significant variation in the protein ternary structure’s
signals, demonstrating their denaturation and oxidation process, together
with early signs of apoptosis. Meaningful changes were observed especially
in the Raman vibrations of sulfur-containing amino acids (cysteine
and methionine) together with aromatic residues. Fluorescence microscopy
revealed the formation of reactive oxygen and nitrogen species in
cells, which confirmed their stressed condition and to whom the causes
of protein degradation can be attributed. These findings can provide
new insights into the mechanism of ammonia toxicity and protein oxidation
at a single-cell level, demonstrating the high potential of the SERS
technique in investigating the cellular response to toxic compounds.