Das Shrabanti, Purkayastha Pradipta
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, WB, India.
ACS Omega. 2017 Aug 28;2(8):5036-5043. doi: 10.1021/acsomega.7b00899. eCollection 2017 Aug 31.
Thiazole orange (TO) exists mainly as a monomer in aqueous medium, where its fluorescence is negligibly small due to intramolecular movements. In the present study, it has been shown that in presence of giant unilamellar vesicles, produced from anionic lipid molecules, TO prefers to form H-dimer and H-aggregates at low lipid concentrations. The nonfluorescent form of TO (monomer) starts fluorescing in the aggregated or dimeric forms. At higher 1,2-dimyristoyl--glycero-3-phospho-(1'-rac-glycerol) concentration, the TO aggregates disintegrate to the monomeric variants. This is principally due to generation of more surface of residence for the TO molecules. The dye molecules/aggregates reside on the outer surface as well as percolate inside the lipid vesicles toward the inner water pool due to the presence of anionic charges at the interface. We adopted fluorescence lifetime imaging to find out the heterogeneity in photophysics of the different forms of TO inside the lipid vesicles supported by fluorescence correlation spectroscopy to characterize the formation or disintegration of the TO aggregates.
噻唑橙（TO）在水性介质中主要以单体形式存在，由于分子内运动，其荧光非常微弱。在本研究中，已表明在由阴离子脂质分子产生的巨型单层囊泡存在下，TO在低脂质浓度下倾向于形成H-二聚体和H-聚集体。TO的非荧光形式（单体）开始以聚集或二聚体形式发出荧光。在较高的1,2-二肉豆蔻酰-sn-甘油-3-磷酸-（1'-rac-甘油）浓度下，TO聚集体分解为单体变体。这主要是由于为TO分子产生了更多的驻留表面。由于界面处存在阴离子电荷，染料分子/聚集体既存在于外表面，也会向脂质囊泡内部的水池渗透。我们采用荧光寿命成像来发现脂质囊泡内不同形式的TO在光物理性质上的异质性，并通过荧光相关光谱对TO聚集体的形成或分解进行表征。
