Issue 24, 2024

Imaging of intracellular protein aggregates through plasmon-assisted clusteroluminescence

Abstract

The formation of clusters in non-aromatic molecules can give rise to unconventional luminescence or clusteroluminescence. Typically containing heteroatoms without extended conjugation or aromatic rings, these molecules have drawn much attention owing to the prospects of label-free biological imaging. However, their applications have been limited due to the lack of knowledge of the underlying mechanism. Herein, we have elucidated the mechanism of clusteroluminescence from proteins, which were explicitly aggregated using plasmonic silver nanoparticles. The nanoparticles promoted protein aggregation and induced nitrile formation on the surface, which, along with other lone-pair-containing heteroatoms, contributed to enhanced emission in the visible range. Remarkably, this makes imaging of proteins possible with visible excitations, as co-factor-lacking proteins generally undergo electronic transitions only in the ultraviolet range. Furthermore, the inherent protein-aggregating behaviour of plasmonic nanoparticles was harnessed for imaging of intracellular Huntingtin protein aggregates overexpressed in HeLa cells through clusteroluminescence. Significant plasmon-enhanced and red-shifted fluorescence emission was observed, which helped in the imaging and localization of the intracellular aggregates. Density functional theory calculations and transient absorbance spectroscopy were used to probe the molecular interactions at the protein–nanoparticle interface and the charge transfer states, further elucidating the role of nanoparticles and the emission mechanism. This technique thus opens alternate avenues for label-free fluorescence bioimaging.

Graphical abstract: Imaging of intracellular protein aggregates through plasmon-assisted clusteroluminescence

Supplementary files

Article information

Article type
Paper
Submitted
25 এপ্রিল 2024
Accepted
16 মে 2024
First published
24 মে 2024

Nanoscale, 2024,16, 11749-11761

Imaging of intracellular protein aggregates through plasmon-assisted clusteroluminescence

A. K. Dhillon, P. E. Dudhe, S. Majumdar, S. Barman, D. Ghosh, K. Dhanasekaran and S. Siddhanta, Nanoscale, 2024, 16, 11749 DOI: 10.1039/D4NR01803F

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