Insights into the co-assemblies formed by different aromatic short-peptide amphiphiles

Abstract

The mechanism of co-assembly of different aromatic dipeptides has been studied using a combination of microscopy and spectroscopy techniques. At an equimolar ratio, the kinetics of the process is favored giving rise to alternate copolymers.

Macroscopic volume phase transitions in supramolecular gels directed by covalent crosslinking

“…Moreover, a decrease in intensity of the negative peak at 305 nm suggests a modulation of aromatic stacking involving the fluorenyl groups after crosslinking. 37 By fluorescence, a decrease in intensity of the fluorenyl excimer peaks in the region of 425-500 nm further agrees with the CD data (Figure S27). From PXRD, the broad peak centred at 2θ=19.48 o (before crosslinking) almost disappeared after EDC coupling and a broad band near 2θ = 9.93 o became predominant (Figure 3h).…”

“…On increasing the pH of the multicomponent gel from pH 3.3 to 10.8, the monomer emission of 2 at 323 nm gradually disappeared and the intensity of the excimer emission peaks in the region 425-500 nm increased considerably (Figure S8). The negative CD signal at 305 nm derived from the fluorenyl group 37 of 2 was also intensified on increasing the pH to 10.8 suggesting aromatic stacking plays a pivotal role in maintaining the assembled structures at high pH (Figure 2h). Moreover, different CD signals in the region 218-284 nm for the system (1+2) at different pH signify a change in the underlying molecular packing of the gels.…”

Organic/inorganic hydrogels by simultaneous self-assembly and mineralization of aromatic short-peptides

“…Since self-assembly of Fmoc-FF is triggered by Ca 2+ , both processes (self-assembly and mineralization) are interconnected maximizing the interactions and interplay between the organic/inorganic phases and favoring the formation of more homogeneous hybrid hydrogels. Furthermore, Fmoc-AA (Fmoc-dialanine) a known peptide able to form weak hydrogels 26,38,39 have also been used to further shed light about the influence of peptide's self-assembly in the biomineralization process. Previous reports on mineralization of self-assembled supramolecular peptides studied the growth of the mineral from a preexisting supramolecular polymeric network, [40][41][42][43][44] similar to works carried out in polymeric hydrogels.…”

Single-atom substitution enables supramolecular diversity from dipeptide building blocks

“…Prediction of the self-assembly behaviour of dipeptides is remarkably difficult in light of their richness in diverse functional groups and conformational flexibility, so that even subtle structural variations could potentially lead to very divergent outcomes through the cooperative process of self-organization. 14–16 The most popular approach for their design includes the use of polyaromatic N-caps, which facilitate hydrophobically driven self-aggregation and ordered stacking. 14,17 Derivatization can be extended to both termini, introducing non-ionizable groups to reduce the hydrophilic character and, thus, the minimal concentration required for assembly and/or gelation.…”

“…14–16 The most popular approach for their design includes the use of polyaromatic N-caps, which facilitate hydrophobically driven self-aggregation and ordered stacking. 14,17 Derivatization can be extended to both termini, introducing non-ionizable groups to reduce the hydrophilic character and, thus, the minimal concentration required for assembly and/or gelation. 18–21 Halogenation is another useful strategy, which has the additional advantage of enabling further non-covalent interactions.…”