A self-assembly/disassembly two-photo ratiometric fluorogenic probe for bacteria imaging

Fluorescence imaging has facilitated fluorescent probes to analyze the subcellular localization and dynamics of biological targets. In this paper, we reported a fluorogenic probe for bacteria imaging. The probe was an imidazolium-derived pyrene compound, which self-assembled to form nano-particles and the pyrene fluorescence was quenched by the aggregation effects. When the self-assembly nanoparticles interacted with anionic bacteria surfaces, synergistic effects of electrostatic interaction and hydrophobic force caused competing binding between bacteria surfaces and imidazoliums. This binding resulted in the disassembly of the aggregates to give fluorescence turn-on signal. Meanwhile, the probe bound bacteria surfaces and displayed both pyrene-excimer and pyrene-monomer fluorescence, which gave ratiometric signal. Then, fluorescent labeling by the probe enabled the two-photo ratiometric imaging of bacteria.

Surfactant-regulated acetylpyrene assemblies as fluorescent probes for identifying heme proteins in an aqueous solution

Heme proteins play various important roles in a variety of physiological and pathological processes.Surfactant assemblies have drawn great attention in fabricating fluorescent sensors to detect and identify proteins.In this study,an acetylpyrene fluorophore containing imidazole HP-1 was synthesized,and it could be well modulated by an anionic surfactant sodium dodecyl sulfate(SDS).The selected ensemble based on HP-1/SDS assemblies exhibited selective fluorescence sensing performance towards the heme proteins,including neuroglobin(Ngb),myoglobin(Mb)and cytochrome c(Cyt c).Besides,phospholipid DMPC vesicles as membrane models were particularly explored the association process between the heme protein Mb and membrane.The present work showed that Mb induced the lysis of DMPC liposomes visualized by transmission electron microscopy and optical microscope.

Strong π-π stacking interactions led to the mis-assignment of dimer emissions to the monomers of 1-acetylpyrene

Understanding relationships between molecular structures and fluorescent properties is critical to enable rational deployment of fluorophores. 1-Acetyl pyrene is an important pyrene-derivative, used extensively as an environment-sensitive probe. In the past, the fluorescence of 1-acetylpyrene was considered to be polarity-sensitive with a large positive solvatochromism, and its monomer emissions were believed in the range of 410-470 nm. In this paper, our experimental and theoretical studies showed that the monomer fluorescence of 1-acetylpyrene is centered at ～390 nm,which is similar to that of pyrene dyes and not polarity-sensitive. Previously observed "monomer emission" has been re-assigned to that of dimers, which represent the dominant existence form of 1-acetylpyrene in the solution phase,as a result of strong intermolecular π-π stacking interactions.