Alginate/Cucurbit[7]uril/Dequalinium-Based Supramolecular Carbohydrates: Modulation of FRET Signals by Temperature Control

Abstract

Herein, we describe the synthesis of a bioactive, inexpensive, and easy-to-handle supramolecular carbohydrate polymer by grafting of cucurbit[7]­uril macrocycle (CB7)-encapsulated dequalinium chloride hydrate (DCH) onto alginic acid carbohydrates (ALG) via amide linkage formation and show that light energy transfer based on energy migration can be controlled by altering polymer temperature without changing polymer composition. DCH (donor) and 2-anilinonaphthalene-6-sulfonic acid (acceptor) were used to generate Förster resonance energy transfer (FRET) signals. Stationary and time-resolved photoluminescence spectra of the modified carbohydrate platform revealed that FRET resulted in a color change from violet (∼387 nm) to blue (∼429 nm), which could be repeatedly switched on and off in response to temperature stimuli at 298–368 K. Temperature-dependent NMR measurements suggested that the responsiveness of DCH/CB7ALG to thermal stimuli was due to the threading of CB7 onto the DCH backbone in solution and upon grafting onto ALG polymers.

Chemically Modified Biopolymers for the Formation of Biomedical Hydrogels

“…154 Furthermore, Sohail et al engineered a tunable photoluminescent guest−host hydrogel consisting of CB [7] derivatives and alginate modified with dequalinium chloride hydrate guest moieties. 333 CB [8] host molecules can accommodate two guest molecules due to the relatively large cavity size. Toward hydrogel formation, biopolymers can be chemically modified with guest moieties and subsequently mixed with free CB [8] compounds to form shear-thinning, self-healing hydrogels (Figure 13b).…”

Mini review Applications of FRET-based supramolecular architectures for temperature sensing and Cancer diagnosis: A mini-review

“…The supramolecular assembly was shown to have the capability of light energy transfer which can be controlled by varying polymer temperature without changing the polymer. (4) To validate energy transfer, DCHALG and DCH/CB7ALG polymer was titrated with ANS. No FRET signals were observed as no significant decrease in the excited lifetime was recorded while titrating DCHALG with ANS as shown in Figure 2a and 2c.…”

“…(3) This binding of host and guest molecules leads to the formation of host-guest complex. (1,3,4) More importantly, the guest molecules should fit in the cavity of host molecules, emphasizing on selective and spontaneous binding of host and guest, and thus realizing the molecular recognition. (5-7) Host−guest molecular recognition has brought revolutions in the development of more sophisticated supramolecular systems or materials because of their good selectivity and stimuli responsiveness.…”

“…Taking advantage of weaker non-covalent host-guest interactions, the host-guest complexes are more suitable for reversibility and responsiveness towards various factors in the confined surrounding environment such as pH, light radiation, temperature, competitive factors, chemical signals, and biological interfering, etc. (3,4,(6)(7)(8) The stimuli-responsive property of host-guest systems provide a favorable platform for the developing of new advanced artificial molecular machines and nanoscale smart materials. (9)(10)(11) In the past decades, many FRET-based supramolecular system has been reported with extended applications such as optical sensor, photo-switches, artificial light harvesting system etc.…”

Polymeric self-assembled cucurbit[n]urils: Synthesis, structures and applications

“…This response to temperature was attributed to the increased ability of Q [7] to shuttle along the dequalinium chloride hydrate backbone as the temperature increased. This temperature control negated the need to adjust the ratio of donor:acceptor, which is the usual method of FRET control in other systems [48] .…”