Recent Advances in Excimer-Based Fluorescence Probes for Biological Applications

Abstract

The fluorescent probe is a powerful tool for biological sensing and optical imaging, which can directly display analytes at the molecular level. It provides not only direct visualization of biological structures and processes, but also the capability of drug delivery systems regarding the target therapy. Conventional fluorescent probes are mainly based on monomer emission which has two distinguishing shortcomings in practice: small Stokes shifts and short lifetimes. Compared with monomer-based emission, excimer-based fluorescent probes have large Stokes shifts and long lifetimes which benefit biological applications. Recent progress in excimer-based fluorescent sensors (organic small molecules only) for biological applications are highlighted in this review, including materials and mechanisms as well as their representative applications. The progress suggests that excimer-based fluorescent probes have advantages and potential for bioanalytical applications.

1,6-Naphthyridin-7(6H)-ones: synthesis and optical properties

“…The intrinsic mechanism associated with dual emission can originate from several factors. [32][33][34] However, a photoinduced tautomerization or excited state intramolecular transfer (ESIPT) has been reported to be responsible for dual emission in similar systems. 35 Indeed, compounds with enolizable protons possessing an intramolecular hydrogen bond could undergo an ESIPT which often gives excited state enol tautomer and excited state keto tautomer emissions.…”

Enzyme-Instructed CBT-Cys-like Click Cyclization Reactions for Bioimaging

“…50 Meanwhile, because of various wavelength emissions of excimer and monomer, this strategy can significantly improve contrast after activation. 51 Kim and co-workers used cysteinyl aspartate-specific proteinase-3 (caspase-3, a reliable biomarker for assessing cell apoptosis 52,53 ), recognition peptide sequence (DEVD), and a benzothiazole-based reference molecule (CV-NH 2 ) to construct an excimer-based molecular fluorescent probe Ac-DEVD-NH−CV for the detection of caspase-3. 54 Upon enzymatic cleavage of the DEVD peptide by caspase-3, the solubility of the obtained probe significantly decreased, which 4a).…”

“…This large Stokes red shift can also avoid interference from biological background signals . Meanwhile, because of various wavelength emissions of excimer and monomer, this strategy can significantly improve contrast after activation . Kim and co-workers used cysteinyl aspartate-specific proteinase-3 (caspase-3, a reliable biomarker for assessing cell apoptosis , ), recognition peptide sequence (DEVD), and a benzothiazole-based reference molecule ( CV-NH 2 ) to construct an excimer-based molecular fluorescent probe Ac-DEVD- NH–CV for the detection of caspase-3 .…”

Fluorescent Sensor Based on 1H-Pyrazolo[3,4-b]quinoline Derivative for Detecting Zn2+ Cations

“…It forms complexes both in ratio SENS-6:M n+ and (SENS-6) 2 :M n+ . Apart from the previously described sensing mechanisms, in the literature one can find many others that take advantage of physical phenomena like fluorescence resonance energy transfer [ 23 ], excited-state proton transfer [ 24 , 25 ], aggregation-induced emission [ 26 ], and excimer/exciplex formation [ 27 , 28 ]. The mentioned earlier fluorescent probes are depicted in Figure 1 .…”