An Amino Acid‐Based Thixotropic Hydrogel: Tuning of Gel Recovery Time by Mechanical Shaking

Abstract

Fmoc-Trp-OH (Fmoc: N-fluorenylmethoxycarbonyl; Trp-OH: L-Tryptophan) undergone hydrogelation at 50 mM phosphate buffer saline of pH 7.4 with a minimum gelation concentration (MGC) of 0.25 % w/v after 12 to 15 hours. However, the hydrogel formation kinetics can be faster just by mechanical hand shaking of the hydrogelator solution during the hydrogel preparation procedure. The shake hydrogel is thermally and mechanically more stable than the non-shake hydrogel. These hydrogels have been characterized thoroughly by Tgel estimations, UV-Vis spectroscopy, Fluorescence spectroscopy, Fourier Transform-Infra Red (FT-IR) Spectroscopy, X-ray diffractions (XRD), Field Emission Scanning Electron Microscopy (FE-SEM) and rheology. This amino acid-based hydrogel is thixotropic in nature and interestingly without doping any foreign materials into the hydrogel, the gel reformation kinetics can be faster just by number of times breaking of the hydrogel by mechanical hand shaking followed by keeping the hydrogel glass vial at rest. This holds future promise to develop supramolecular mechanocatalyst for various functional group transformation reactions in water through green and sustainable chemistry pathways.

1-Naphthylacetic acid appended amino acids-based hydrogels: probing of the supramolecular catalysis of ester hydrolysis reaction

“…The blue shifts upon dilution were observed for all the hydrogels due to less scattering from their lower-order aggregates compared to the hydrogels. 4 The λ max peak at 303 nm for the native hydrogel Nap-F was red shifted to 315 nm/317 nm for the histidine-based two-component ( Nap-F H ), three-component ( Nap-F H–K and Nap-F H–R ) and four-component ( Nap-F H–K–R ) hydrogels. This could be due to the presence of π–π stacking interactions between the histidine aromatic imidazole side chain unit and phenyl aromatic moiety of the native gelator ( Nap-F ).…”

“…This motivates us to study the hydrogelation behaviour of 1-naphthaleneacetic acid-conjugated phenylalanine ( Nap-F ) and hydrogelation behavior of its two-, three- and four-component systems. These systems have designed and developed judiciously by selecting the basic amino acids and Nap-F at various combinations as phenylalanine 4,20 is well known for its assembly propensity and basic amino acids are well known for their esterase-like activity in various peptides and proteins. 32,33 , 38,39 No catalytic activity has been identified from the native hydrogel ( Nap-F ) nor its diluted self-assembled solution.…”

“…In this regard, amino acids and peptides are considered building blocks for constructing bioinspired, emerging, smart and functional advanced supramolecular biomaterials due to the ease of their synthesis, amino acid mutation and fantastic self-assembly/co-assembly behavior. [1][2][3][4][5][6][7][8][9][10][11] Systems chemistry investigates such emerging behaviour of moleculess that store energy in the form of chemical potential to form various supramolecular assemblies to attain life-like functions. [12][13][14][15][16] Simple biomolecular building blocks, which were present when life began on Earth, react to form complex molecules (biopolymers).…”

Bioinspired Amino Acid Based Materials in Bionanotechnology: From Minimalistic Building Blocks and Assembly Mechanism to Applications

“…Gour et al reported the self-assembly of the nonaromatic amino acids cysteine (Cys) and methionine (Met) into amyloid-like fibrils in neutral water . The formation of amyloid-like assembled structures was verified by binding assays of Thioflavin T (ThT) and Congo red (CR) as ThT exhibited significant fluorescence enhancement, while CR showed increased red-shifted light absorption intensity upon binding to the amyloid structures. , In addition, amino acids could self-assemble into 3D gels through molecular modification. ,− Typically, Fmoc-modified amino acids are able to trap solvent molecules to form hydrogels. ,− Among these, as a leading hydrogel promoter, Fmoc-Phe has excellent assembly capabilities and could self-assemble into efficient, stable, and transparent hydrogels with a minimum gelation concentration of 0.1% w/v. Hydrogels with 3D structures act as templates to complex with silver ions (Ag + ) and induce the formation of silver nanoclusters in the presence of diffuse sunlight at pH 7.46 and room temperature .…”

A stimuli-responsive l-DOPA-based supramolecular gel for the detection of fluoride ion

“…Such visual detection techniques are simple, convenient, and do not require major instruments. This gelation-based method has been utilised for the detection of different analytes such as metal ions, 26 sugars, 27,28 amino acids, 29,30 enzymes, 31,32 anions, 33,34 and others. 35,36 It is well known that anions play important roles in a wide range of chemical and biological processes.…”