Multiparametric Sensing of Membrane Bilayer Properties with a Highly Environment-Susceptible Fluorophore

Abstract

Push-pull type fluorophores are often exploited as a biological probe because of their high environment-sensitivity nature. Herein, we report the potentiality of a push-pull fluorophore, 2-formyl-5-(4'- N, N-dimethylaminophenyl)thiophene, as a membrane probe. This molecule exhibits strong absorbance in the violet region (∼400 nm) and a high emission quantum yield (≤0.6). The emission is highly sensitive to the surrounding environment, and a high Stokes shift (>7000 cm) appears in strong polar solvents. The molecule is highly susceptible to the fluorescence quenching by protic solvents. The neutral probe efficiently senses aprotic environments such as lipid bilayer membranes through all six fluorescence parameters: emission maxima, intensity, and anisotropy as well as the corresponding time-dependent parameters. The small and flat shape, nonemissive nature in the aqueous medium along with the high susceptibility to all six fluorescence parameters of the molecule strongly suggests a promising fluorescence probe for biological medium.

π‐Extended Push‐Pull‐Type Bicyclic Fluorophores Based on Quinoline and Naphthyridine Frameworks with an Iminophosphorane Fragment

“…To clarify the hydrogen-bonding effect, fluorescence quantum yield and decay measurements were conducted in deuterated methanol (MeOD). [25,26] As expected, the Φ f value and fluorescence decay of 1 in MeOD increased, and those of compound 2 also slightly improved.…”

“…Remarkably, in the case of 1 , decreased Φ f values in protic solvents, such as n ‐butanol and methanol, were obtained, indicating the possibility of emission quenching through hydrogen bonding via the strongly basic IPP. To clarify the hydrogen‐bonding effect, fluorescence quantum yield and decay measurements were conducted in deuterated methanol (MeOD) [25,26] . As expected, the Φ f value and fluorescence decay of 1 in MeOD increased, and those of compound 2 also slightly improved.…”

Exploring the Relationship between BODIPY Structure and Spectroscopic Properties to Design Fluorophores for Bioimaging

“…[5] Furthermore, to induce strong solvatochromism,w hichi se ssential for environmental sensing,t wo diethyl-amino groups were installed ( Figure 3). [28,29] Amino groupsc an render fluorophores highly sensitivet os olventp olarity [30] and also contribute to longer absorption wavelengths. [29] Thec ompact amphiphilic design of HiBO is aimed to counter commoni ssues of other long wavelength,y et lipophilic non-BODIPY probes, such as poor biological compatibility,c ompromised fluorescencee missiona nd limited retention within membranes.…”

Curcumin-Induced Membrane Property Changes in DMPC Multilamellar Vesicles and the Effects of Membrane-Destabilizing Molecules on Curcumin-Loaded Multilamellar Vesicles

“…Fluorescent molecular probe-based techniques have been used extensively to understand the microenvironment of organized media such as micelles, reverse micelles, solid lipid nanoparticles, niosomes, and lipid bilayer membranes. Our group has been studying the physical properties of lipid bilayer membranes using fluorescent probes for the last two decades. − If the drug molecule is fluorescent, then the drug–membrane interactions can be studied using its intrinsic fluorescence properties. − The use of intrinsic probes not only excludes the possibility of perturbation offered by the extrinsic probe but also provides additional information such as the partition coefficient, , location of the drug, and a molecular-level understanding of the interactions . Literature reports show that CUR can be used as a fluorescent probe to study various organized media such as micelles, , reversed micelles, nanoparticles, , niosomes, , and liposomes. , Patra et al have already established CUR as a fluorescent molecular probe to study lipid bilayer membranes. − Thus, in this work, our objective is to investigate CUR-induced change in the physical properties of DMPC multilamellar vesicles (MLVs) using the intrinsic fluorescent properties of CUR.…”