Intramolecular Charge Transfer Probe Induced Formation of α-Cyclodextrin Nanotubular Suprastructures: A Concentration Dependent Process

Abstract

A suitably sized charge transfer probe of an elongated geometry can induce the formation of R-cyclodextrin nanotubular suprastructures, a rare event because of size restriction of the host. The specific molecular structure is found to be responsible only for the 1:2 guest-host complex formations. No evidence of the formation of the 1:1 complex is found. Steady-state fluorescence anisotropy and atomic force microscopy show that the nanocomposites club with other such species very efficiently to form nanotubes and nanoclusters because of primary interactions through hydrogen bonding and develop nanotubular suprastructures due to secondary interactions. The degree of formation of the suprastructures is found to be very much controlled by the probe concentration. In aqueous environment, 2 µM is observed to be the best concentration for the fluorophore form of large rodlike aggregates. Concentrations as low as 1 µM and as high as 4 µM induce the formation of relatively smaller structures. The findings encourage the applications of cyclodextrin nanotubular clusters toward nanotechnology and pharmaceutical research. The concentration dependent phenomenon will dictate the drug dosage as also the extent of formation of the nanostructures in the formation of insulated nanowires. The work is purely indicating the anchoring capability of the used molecule to form nanotubular R-CD suprastructures which otherwise does not form so frequently.

Secondary assembly mechanism of cyclodextrin based on LiNTf2@β-CD system

“…The shapes roughly correspond to nanosheet structures after being fractured and replicated. This kind of nanosheet structure is apparently different from the nanotubes and their SA as reported before [23][24][25][26][27][28][29].…”

“…Later similar SA structures of CD nanotubes have also been reported by some other research groups [26][27][28][29][30][31][32][33]. Jaffer et al and Sowmiya et al found that trans-2-[4-(dimethylamino)styryl]benzothiazole (DMASBT) could induce the formation of CD nanotubes and their rodlike SA [26][27][28], although they suggested that the SA consisted of nanotubes filled with DMASBT only and no empty CD was involved [28].…”

“…Jaffer et al and Sowmiya et al found that trans-2-[4-(dimethylamino)styryl]benzothiazole (DMASBT) could induce the formation of CD nanotubes and their rodlike SA [26][27][28], although they suggested that the SA consisted of nanotubes filled with DMASBT only and no empty CD was involved [28]. Recently, they discovered rodlike SA in a hemicyanine dye, 4-[4-(dimethylamino)-styryl]-1-docosylpyridinium bromide (DASPC22) and b-CD system [29].…”

Fragmentation of molecule-induced γ-cyclodextrin nanotubular suprastructures due to drug dosage

“…Fluorescence spectroscopy coupled with atomic force microscopy can serve as a very effective tool to understand this effect. The steady state and time-resolved fluorescence can tell us about the encapsulation of the guest molecules through a well-established procedure (see later), whereas steady state fluorescence anisotropy can let us know about the orientation and the ordered arrangement of the fluorophore, and the atomic force microscopy can give us a clearer view of the whole system so as to confirm our propositions [25][26][27]. The drug concentration has been proved to have profound effect on the nanotubular suprastructures formed by a-CD where the space constraint is a major factor [27].…”

Supramolecular Interactions of Nonsteroidal Anti‐inflammatory Drug in Nanochannels of Molecular Containers: A Spectroscopic, Thermogravimetric and Microscopic Investigation

“…[61] Purakayastha and co-workers confirmed CD-based host-guest complex formation by using AFM analysis techniques. [62,63] From the AFM topography of the surface morphology, Dionisio et al demonstrated that host-guest interactions occur among the polymer chains in the polymeric blending. [64] Liu and co-workers also reported the hierarchical structure of IMC-loaded poly(amidoamine) hydroxyl-terminated dendrimers and the nature of IMCdendrimer interactions by studying high-resolution STM micrograph images.…”