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One-dimensional (1D) supramolecular polymers are commonly found in natural and synthetic systems to prompt functional responses that capitalise on hierarchical molecular ordering. Despite amphiphilic self-assembly being significantly studied in the context of aqueous encapsulation and autopoiesis, very little is currently known about the physico-chemical consequences and functional role of 1D supramolecular polymerisation confined in aqueous compartments. Here, we describe the different phenomena that resulted from the chemically triggered supramolecular fibrillation of synthetic peptide amphiphiles inside water microdroplets. The confined connection of suitable dormant precursors triggered a physically autocatalysed chemical reaction that resulted in functional environmental responses such as molecular uptake, fusion and chemical exchange. These results demonstrate the potential of minimalistic 1D supramolecular polymerisation to modulate the behaviour of individual aqueous entities with their environment and within communities. One-dimensional (1D) supramolecular polymers are commonly found in natural and synthetic systems but very little is currently known about the physico-chemical consequences and functional role of 1D supramolecular polymerisation confined in aqueous compartments. Here, the authors describe the different phenomena that resulted from the chemically triggered supramolecular fibrillation of synthetic peptide amphiphiles inside water microdroplets. [ABSTRACT FROM AUTHOR]

A lysine based peptide amphiphile(PA) is designed and synthesizedfor efficient water immobilization. The PA with a minimum gelationconcentration (MGC) of 1% w/v in water shows prolonged stability andcan also efficiently immobilize aqueous mixtures of some other organicsolvents. The presence of a free amine induced pH dependency of thegelation as the PA could form hydrogel at a pH range of 1–8but failed to do so above that pH. Various spectroscopic and microscopicexperiments such as steady state fluorescence, NMR, IR, CD, and FESEMreveal the presence of hydrophobic interaction, hydrogen bond, andπ–π stacking interaction in the self-assembly process.The self-aggregation has been correlated with the design of the moleculeto show the involvement of supramolecular forces and the hierarchicalpathway. While the L analogue formed left-handed helical nanofibers,the other enantiomer showed opposite helicity. Interestingly the equimolarmixture of the isomers failed to form any fibrous aggregate. Althoughfibers formed at a subgel concentration, no helical nature was observedat this stage. The length and thickness of the fibers increased withincrease in the gelator concentration. The nanofibers formed by thegelator are used as a template to prepare mesoporous single wall silicananotubes (SWSNTs) in situ in plain water without the requirementof any organic solvent as well as any external hydrolyzing agent.The SWSNTs formed are open at both ends, are few micrometers in length,and have an average diameter of ∼10 nm. The BET isotherm showeda type IV hysteresis loop suggesting mesoporous nature of the nanotubes. [ABSTRACT FROM AUTHOR]

This study reports the self-assembly and application of a naphthalene diimide (NDI)-appended peptide amphiphile (PA). H-bonding among the peptide moiety in conjunction with p-stacking between NDI and hydrophobic interactions within the alkyl chain are the major driving forces behind the stepwise aggregation of the PA to form hydrogels. The PA produced efficient self-assemblies in water, forming a nanofibrous network that further formed a self-supportive hydrogel. The molecule followed a three-step self-assembly mechanism. At a lower concentration (50 µM), it forms extremely small aggregates with a very low population of the molecules. With an increase in concentration, spherical aggregates are formed above 450 µM concentration. Importantly, this water-soluble conjugate was found to be nontoxic, cell permeable, and usable for cell imaging. Moreover, the aggregation process and consequently the emission behavior are highly responsive to the pH of the medium. Thus, the pH responsive aggregation and emission behavior has an extended biological application for assessing intracellular pH. The biocompatibility and intracellular pH determining capability suggest it is a promising candidate for use as a supramolecular material in biomedical applications. [ABSTRACT FROM AUTHOR]