Supramolecular Hydrogels from a Tripeptide and Carbon Nano-Onions for Biological Applications

Abstract

Nanocomposite hydrogels have attracted researchers’ attention in recent years to achieve superior performances in a variety of materials applications. In this work, we describe the outcome of three different strategies to combine a self-assembling tripeptide and carbon nano-onions (CNOs), through covalent and non-covalent approaches, into supramolecular and nanostructured hydrogels. Importantly, the tripeptide coated the nano-onions and extended their aqueous dispersions’ stability by several hours. Furthermore, CNOs could be loaded in the tripeptide hydrogels at the highest level ever reported for nanocarbons, indicating high compatibility between the components. The materials were formed in phosphate-buffered solutions, thus paving the way for biological applications, and were characterized by several spectroscopic, microscopic, thermogravimetric, and rheological techniques. In vitro experiments demonstrated excellent cytocompatibility.

Nanocomposite Hydrogels with Self‐Assembling Peptide‐Functionalized Carbon Nanostructures

“…The tripeptide Fmoc‐ L‐Leu‐D‐Phe‐D‐Phe was prepared according to a typical procedure in solid phase, followed by purification by trituration [22] . To covalently attach Fmoc‐ L‐Leu‐D‐Phe‐D‐Phe onto the CNSs, the short linker 2,2’‐(ethylenedioxy)bis(ethylamine) was employed as shown in Scheme 1.…”

“…All CNS filtrations during washes were performed in a Millipore pyrex apparatus with a Millipore membrane filter (JHWP, 0.45 μm). TGA, TEM, Raman spectroscopy, and oscillatory rheometry were carried out as previously described [22] …”

“…Washes were performed thrice with water, thrice with methanol, and once with diethyl ether. Peptide coupling was performed by dissolving Fmoc‐L‐Leu‐D‐Phe‐D‐Phe [22] (3 eq. ), HBTU (2.5 eq.)…”

“…TGA, TEM, Raman spectroscopy, and oscillatory rheometry were carried out as previously described. [22]…”

“…The tripeptide Fmoc-L-Leu-D-Phe-D-Phe was prepared according to a typical procedure in solid phase, followed by purification by trituration. [22] To covalently attach Fmoc-L-Leu-D-Phe-D-Phe onto the CNSs, the short linker 2,2'-(ethylenedioxy)bis(ethylamine) was employed as shown in Scheme 1. Briefly, each CNS was first oxidized to the same level of oxygen content as confirmed by thermogravimetric analysis (TGA), with a weight loss of ~10 % at 600 °C, using previously optimized protocols in acidic solutions.…”