A New pH and Thermo-Responsive Chiral Hydrogel for Stimulated Release

Abstract

Chirality of the amphiphile to promote gelation in the given solvent medium is narrated in a new catanionic surfactant mixture from a twin-chiral, twin-tailed surfactant derived from tartaric acid and cetyltrimethylammonium bromide (CTAB). The surfactant bis(decyloxy) succinic acid (BDSA), a chiral Gemini-type surfactant with a rigid spacer, in association with CTAB formed pH and temperature responsive vesicles and hydrogels. Molecular chirality gave rise to supertwisted fibrillar hydrogels at a BDSA:CTAB molar ratio of 1:2 and in 31% water content. The hydrogels from enantiomeric BDSA were reversibly pH and irreversibly temperature responsive at pH<6.2 and at 55 degrees C, respectively, whereas the corresponding sodium succinates formed transparent clear gels reversible to both pH and temperature. The hydrogels were able to entrap and release model dye molecules, Rhodamine B, and Congo red, responding to thermal and pH stimuli. Circular dichroism unraveled the chiro-optical behavior of the assembled fibers, allowing monitoring of aggregation and packing. The presence and the relative configuration of the stereogenic centers in the structure of this low molecular weight gelator have been observed to be critical to form gels. The high curvature Gaussian gel network was modeled based on the chiral elastic membrane approach and the pitch angle of the Gaussian twist was estimated to be 45 degrees.

Contractive Polymeric Complex Micelles as Thermo‐Sensitive Nanopumps

“…Compared with traditional controlled release systems in which drug release was governed by diffusion, [21,22] our nanopump had a special driving force that the drug could be fast released (Figure 1(F)). While at 25 8C, only a small quantity of ibuprofen was released.…”

Chiral, pH responsive hydrogels constructed by N -Acryloyl-alanine and PEGDA/α -CD inclusion complex: preparation and chiral release ability

“…The slow release in the pH 1.2 solution and the quick release in the pH 7.4 solution could be explained by the swelling controlled mechanism. [20,50] The electrostatic repulsion between COO -in NAA and COO -in HP (LHP and DHP) in the pH 7.4 solution may also contribute to the quick release.…”

“…Chiral hydrogels can be fabricated by physically or chemically crosslinking amino acids, [10,11] collagen, [12] cholesterol, [13] peptide, [14][15][16] sugar, [17,18] and cellulose [19] derivatives. In particular, chiral hydrogels also hold the potentials in chiral recognition and enantioselective release materials [20] and advanced biomaterials. [21] The investigations dealing with chiral recognition and enantioselective release may provide alternatives for using chiral drugs and other chiral compounds.…”

Localized delivery of growth factors for periodontal tissue regeneration: Role, strategies, and perspectives

“…186 In recent years, environmentally responsive systems have been fabricated to combine temperature and pH stimuli-response capabilities. 184,185,[187][188][189] PNIPAAm/dextran-maleic acid (Dex-MA) hydrogels, for such a purpose, for example, were successfully synthesized by UV cross linking over a wide range of mixed solvent ratios of dimethyl formamide to water. PNIPAAm and Dex-MA precursors were chosen as thermo-sensitive and pH-sensitive components, respectively, and the latter was also used as a cross-linking agent.…”