Terpyridine Zn(II) Complexes with Azide Units for Visualization of Histone Deacetylation in Living Cells under STED Nanoscopy

Histones are the alkali proteins in eukaryotic somatic chromatin cells which constitute the nucleosome structure together with DNA. Their abnormality is often associated with multiple tumorigenesis and other human diseases. Nevertheless, a simple and efficient super-resolution method to visualize histone distribution at the subcellular level is still unavailable. Herein, a Zn­(II) terpyridine complex with rich-electronic azide units, namely, TpZnA–His, was designed and synthesized. The initial <i>in vitro</i> and <i>in silico</i> studies suggested that this complex is able to detect histones rapidly and selectively <i>via</i> charge–charge interactions with the histone H3 subunit. Its live cell nuclear localization, red-emission tail, and large Stokes shift allowed super-resolution evaluation of histone distributions with a clear distinction against nuclear DNA. We were able to quantitatively conclude three histone morphology alternations in live cells including condensation, aggregation, and cavity during activating histone acetylation. This work offers a better understanding as well as a versatile tool to study histone-involved gene transcription, signal transduction, and differentiation in cells.