The combination of different components such as carbon nanostructures and organic gels into composite nanostructured hydrogels is of great interest to a wide variety of applications, including sensors and biomaterials. In particular, supramolecular hydrogels formed from D-, L-Tripetides unprotected with the Phe-Phe pattern and nitrogen carbon nanodots (NCND) are promising materials for biological use. In this work, they were combined to obtain luminescent supramolecular hydrogels under physiological conditions. Self-assembly of a tripeptide when using a pH-trigger was studied in the presence of non-indications to assess the effects at the supramolecular level. Luminescent hydrogels were obtained, the addition of NCND refining rheological properties and resulting in an overall more homogeneous system composed of finer fibrils with a narrow diameter distribution. For secondary products [a3], [a2], [y2 – 2H – CO], and tertiary products, [a2 – CO] and [y1 – 2H], ET, there is at least one theoretical value in experimental uncertainty. Taking into account all 11 fragments of H-GGG, MADs are increased to 13-29 kJ/mol, Table 2. Obviously, the M06-2X level of the theory gives the best agreement with the experience, if the primary products and if all products are taken into account, even if the deviations are reasonable for all levels of the theory. Overall, the good consistency between experience and theory, particularly for primary products, confirms the reaction mechanisms described above. Transmission echronic microscopy (RPT) was used to evaluate the hydrogel nanostructure (Figure 6). Once composed, tripeptid formed obese fibrils that grouped into thicker fibers and formed a three-dimensional network that inserts water. Typical hydrogel samples, composed solely of GFT-imaging peptides, have emerged as highly heterogeneous fiber networks, with a wide distribution ranging from individual fibrils to thick bundles that, over time, grow in thickness .
TFT imaging in this study confirmed in all cases the presence of anisotropic structures, regardless of the diameter of fibrils when adding NNN (i.e. 9 ± 3 nm for the peptide alone and 10 ± 2 nm for the addition of NCND, regardless of the protocol used). In all cases, there was a high density of fibrils greater than the field of view of several microns, which hindered the ability to quantify minor differences in fibrian number or length. However, the number of parallel fibrils reflecting their tendency to concentrate appeared higher in the absence of noncommunicable areas, which could play a role in explaining the thioflavin fluorescence data. Indeed, the presence of a higher number of thinner and less grouped fibrils could lead to a more accessible surface for the thioflavinte-T bond. In the presence of the dye, NCNs showed negligible fluorescence on the wavelength studied, unlike the self-composed peptide that is consistent with the literature . Unexpectedly, the addition of noncommunicable NDs to hydrogel resulted in an increase of twice as much as thioflavinte-T fluorescence, regardless of the protocol used (Figure 5). Since the addition of noncommunicable ANCs reduced the overall viscosity of hydrogel systems, as shown by rheometry, it is unlikely that the observed increase in fluorescence could be attributed to viscosity variations.
Overall, while NNNs do not alter peptide conformation, they appeared to prefer the formation of enlarged supramolecular beta sheets that could bind thioflavin T. This led to more intense CD minima at 216 and 219 nm and more intense thioflavin T fluorescence.