UM-DAE Centre for Excellence in Basic Sciences , University of Mumbai , Kalina, Santacruz (E), Mumbai 400 098 , India.
Radiation & Photochemistry Division , Bhabha Atomic Research Centre , Mumbai 400 085 , India.
Langmuir. 2019 Nov 12;35(45):14628-14638. doi: 10.1021/acs.langmuir.9b03083. Epub 2019 Oct 28.
In general, aggregation-prone organic molecules are prevented from self-aggregation in the presence of macrocyclic hosts like β-cyclodextrin because of their preference for the formation of inclusion complex with guest molecules. On the contrary, sulfate-laced β-cyclodextrin has been recently reported to induce the aggregation of some of the non-aggregation-prone organic dyes, which have been subsequently utilized for biosensing applications. In the present contribution, we report the interaction of a cationic organic probe molecule, 1-pyrene methyl amine (PMA), which belongs to one of the most useful families of organic fluorescent probes, that is, pyrene, with a sulfated β-cyclodextrin derivative (SCD). Interaction of a cationic probe with a β-cyclodextrin derivative was studied using a variety of photophysical methods such as ground-state absorption, steady-state emission, and time-resolved emission techniques. Detailed photophysical investigations have revealed that SCD induces the ground-state association of PMA molecules. This SCD-induced aggregation of PMA molecules has been attributed to the charge neutralization of the cationic probe by negatively charged sulfate groups, which subsequently lead to their association because of the close proximity on the rims of cyclodextrin. This monomer-dimer equilibrium of the PMA-SCD system is found to be extremely responsive to external chemical stimuli like temperature, pH, ionic strength of the medium, and organic solvent (dimethyl sulfoxide), which projects them as potential platforms for various sensing applications including bioanalytes. The supramolecular assembly has been demonstrated to sense arginine.
一般来说，在大环主体如β-环糊精的存在下，聚集倾向的有机分子由于它们优先与客体分子形成包合复合物，因此不会发生自聚集。相反，最近有报道称，带有硫酸盐的β-环糊精会诱导一些不易聚集的有机染料聚集，这些染料随后被用于生物传感应用。在本研究中，我们报告了一种阳离子有机探针分子 1-芘甲胺（PMA）与硫酸化β-环糊精衍生物（SCD）的相互作用。PMA 属于最有用的有机荧光探针家族之一，即芘。我们使用各种光物理方法研究了阳离子探针与β-环糊精衍生物的相互作用，如基态吸收、稳态发射和时间分辨发射技术。详细的光物理研究表明，SCD 诱导 PMA 分子的基态缔合。这种 SCD 诱导的 PMA 分子聚集归因于带负电荷的硫酸盐基团中和阳离子探针的电荷，随后由于环糊精边缘的紧密接近，导致它们发生缔合。PMA-SCD 系统的这种单体-二聚体平衡对外部化学刺激（如温度、pH 值、介质的离子强度和有机溶剂（二甲亚砜））非常敏感，这使它们成为各种传感应用的潜在平台，包括生物分析物。已经证明超分子组装可以检测精氨酸。
