Dynamics of Bound Dyes in a Nonpolymeric Aqueous Gel Derived from a Tripodal Bile Salt

Abstract

Rotational dynamics of polarity sensitive fluorescent dyes (ANS and DPH) in a nonpolymeric aqueous gel derived from tripodal cholamide 1 was studied using ultrafast time-resolved fluorescence technique. Results were compared with that of naturally occurring di- and trihydroxy bile salts. ANS in the gel showed two rotational correlation time (φ) components, 13.2 ns (bound to the hydrophobic region of the gel) and 1.0 ns (free aqueous ANS), whereas DPH showed only one component (4.8 ns). In the sol state, faster rotational motion was observed, both for ANS and DPH. Our data revealed that dyes get encapsulated more tightly in the gel network when compared to the micellar aggregates. ANS has more restrained rotation compared to DPH. This was attributed to the interaction of the sulfonate group of ANS with water molecules and hydrophilic parts of the gelator molecule. No restricted rotation was observed for DPH in the gel state unlike when it is in the gel phase of lipid bilayer.

Supramolecular Gelation of Europium and Calcium Cholates through the Nucleation‐Elongation Growth Mechanism

“…Where, R h is the mean hydrodynamic radius of the aggregate, k is Boltzmann's constant, η is microviscosity and T is absolute temperature (298.15 K). The calculated [50] R h of 0.8 nm was in good agreement to that observed (0.9 nm) from dynamic light scattering (DLS; Figure SI 5). This observation further proves that the correlation time of 8.2 ns was due to the global rotation (CaCh aggregates) and not due to independent rotation of ANS.…”

“…The global rotational correlation time of the aggregates (φ a ) is given by [Eq. ]: …”

“…In the sol (Figure 7a), the fluorescence anisotropy decayed completely with two rotational correlation times, � 1 = 1.3 ns (49 %) and � 2 = 8.2 ns (51 %). The � 1 (smaller value) was expected to be from ANS in bulk solvent [50] and � 2 from ANS bound to cholate. However, once the gel was formed, ANS anisotropy showed a 'dip-and-rise' pattern and did not decay to zero in the timescale of its fluorescence emission (Figure 7b).…”

Hydrophobic End‐Modulated Amino‐Acid‐Based Neutral Hydrogelators: Structure‐Specific Inclusion of Carbon Nanomaterials

“…The most common probe used to measure fluorescence anisotropy is 1,6‐diphenyl‐1,3,5‐hexatriene (DPH), which intercalates between the hydrophobic interior of the aggregates thanks to its rod‐like shape and hydrophobic nature . The higher steady‐state anisotropy ( r ) value indicates the restricted movement of DPH in various aggregated structures . We used this technique to understand the gelation mechanism of 1 .…”

Sensitization effects of supramolecular assemblies on the luminescence of terbium-ion prulifloxacin complexes

“…For instance, Friggeri and co-workers reported that fluorescent energy transfer occurred between host matrices and guest molecules when the fluorescent propyldansylamide was added into supramolecular hydrogels [14]. Maitra and co-workers prepared luminescent hydrogels by entrapment of the organic fluorescent dyes 8-anilino-1-naphtalene sulfonic acid (ANS) and found that the fluorescence lifetime of ANS in supramolecular hydrogels was longer than that in corresponding aqueous solutions [15]. Chang and co-workers found that the fluorescence intensity of norfloxacin in supramolecular hydrogels was ten times larger in comparison with that in corresponding aqueous solutions [16].…”