Tunable Supramolecular Gel Properties by Varying Thermal History

Abstract

The possibility of using differential pre-heating prior to supramolecularg elation to control the balance between hydrogen-bonding and aromatic stacking interactions in supramolecular gels and obtain consequents ystematic regulation of structure and properties is demonstrated. Using am odel aromatic peptide amphiphile, Fmoc-tyrosylleucine (Fmoc-YL) and ac ombination of fluorescence, infrared, circular dichroism and NMR spectroscopy,i ti ss hown that the balance of these interactions can be adjusted by temporary exposure to elevated temperatures in the range 313-365 K, followed by supramolecular locking in the gel state by cooling to room temperature. Distinct regimes can be identified regarding the balance between H-bonding and aromatic stacking interactions, with at ransition point at 333 K. Consequently,g els can be obtained with customizable properties,i ncluding supramolecular chirality and gel stiffness. The differential supramolecular structures also result in changes in proteolytic stability, highlighting the possibility of obtaining ar ange of supramoleculara rchitectures from as ingle molecular structure by simply controlling the pre-assemblyt emperature.[a] Dr.

Spontaneous Aminolytic Cyclization and Self‐Assembly of Dipeptide Methyl Esters in Water

“…The approach shown here enables the reproducible self-assembly of insoluble materials by starting their assembly from soluble precursors and forming the self-assembling molecule in situ. Previously reported approaches to regulate assembly of poorly soluble molecules involves dissolution from organic solvents, [42] heat-cool cycles, [52] temporary deprotonation through controlled pH changes, [53] or in situ enzymatic condensation of precursors. [54,55] Cyclic dipeptides have been previously suggested as antimicrobial and antiviralagents [56,57] and this study might pave the way for spontaneous fabrication of peptide nanostructures with the desired structure and function.…”

Varying the hydrophobic spacer to influence multicomponent gelation

“…In all cases, a strong emission at 318 nm corresponding to the monomeric forms of 2-4 was recorded (Figure S12). 27 pH titration data reveal that the apparent pK a of the amphiphiles gradually increases from 8.6 to 9.1 on moving from compound 2 to 4 (Figure S10). At high pH, deprotonation of the terminal ammonium groups generates the corresponding amines (pH 11.1-11.3 in presence of 0.01 M NaOH, Figure 1).…”

Quantification of energy of activation to supramolecular nanofibre formation reveals enthalpic and entropic effects and morphological consequence

“…3 These selfassembly processes are oen dominated by the rate that they proceed at, where the system attains a particular energetic state (kinetically trapped, or metastable), whose formation can be strictly affected by experimental procedures and protocols, as a consequence of nucleation processes and multiple pathways of growth that can strongly depend on variables such as the mixing, 4 solvent composition 5,6 and temperature. 7 Understanding the fundamental processes of the nucleation and growth in these situations can lead to controlling aggregation, such as that occurring in nature including in certain illnesses. For example, the formation of actin laments, 8 collagen 9 and amyloid brils [10][11][12] show self-assembly kinetics that comprise an initial induction period, where the formation of "critical seeds" or "nuclei" occurs and is the rate limiting step of the aggregation process, followed by growth.…”