Mechanically Stable C2-Phenylalanine Hybrid Hydrogels for Manipulating Cell Adhesion

Tuning of the viscoelastic properties of supramolecular hydrogels to be used as biological material substrates in tissue engineering has become significantly relevant in recent years due to their ability to influence cell fate. In the quest to enhance the stability and mechanical properties of a derived C2-phenylalanine gelator (LPF), derivatives of the polysaccharide dextran were incorporated as additives to promote hydrogen bonding and π-π stacking with the gelator. Dextran was esterified to yield carboxymethyl dextran (CMDH), which was subsequently amidated to furnish amino dextran (AD), the resulting hybrid hydrogels were denoted as LPF-AD_x and LPF-CMDH_x, where x represents the amount of AD and CMDH (mg). The LPF gelator interacted with the carboxyl and amino functional groups of the CMDH and AD, respectively, through hydrogen bonding and π-π stacking, resulting in mechanically stable hydrogels. Morphological studies revealed that the hybrid hydrogels were formed as a result of dense highly branched thin and broad fibers for LPF-AD and LPF-CMDH, respectively. Rheological studies confirmed the superiority of the hybrid hydrogels over the neat hydrogel, where LPF-CMDH₃ exhibited the best mechanical properties with an improved elastic modulus of 11 654 Pa over 1518 and 140 Pa for LPF-AD_4.5 and LPF, respectively. The adhesion and spreading behavior of NIH 3T3 fibroblast cells were significantly improved on the LPF-CMDH₃ substrate owing to their enhanced mechanical properties. The tuning of the mechanical properties of the therein hydrogels via the facile incorporation of biodegradable and biocompatible functionalized additives opens up avenues for strengthening the supposed weak supramolecular gelators and hence increasing their potential of being employed largely in the field of tissue engineering.