In Silico Study of Low Molecular Weight Hydrogelators used as Biomaterials

Dafna Knani
Braude College, Israel

Low molecular weight gelators (LMWG) are molecules capable of forming gels in which they are self-assembled into a physical 3D network of fibers, held together by noncovalent interactions like hydrogen bonds, van der Waals forces, and π−π-interactions. The organic gelator 1,3(R):2,4(S)-dibenzylidene-D-sorbitol (DBS) self-organizes to form a 3-D network at relatively low concentrations in a variety of nonpolar organic solvents and polymer melt. DBS could be transformed into a hydrogelator by introduction of hydrophilic groups, which facilitate its self-assembly in aqueous medium. In order to obtain effective hydrogelators, fine-tuning of the balance between the hydrophilic (soluble) and hydrophobic (insoluble) parts is essential. In this work, the self- and co-assembly of DBS and its derivatives was investigated by dynamic molecular simulation. Various properties (Cohesive Energy Density, Mixing energy, Radial Distribution Function) were calculated to illustrate the interactions that govern the self-and co-assembly of the examined compounds. The results of the simulation indicate that intermolecular H-bonding interactions are formed between the gelator molecules as pure substances, and they dramatically decrease in the presence of water. In contrast, the intramolecular interactions increase in water. This result indicates that in aqueous environment the molecular structure tends to be more rigid and fixed in the preferred conformation. Due to H-bonds, DBS and its derivatives form a rigid structure which might explain their tendency to create nanofibrils. The co-assembly of the hydrogelator DBSCOOH with Amphiphilic Peptides (PAs) was examined as well. It was found that the two components mix well and that as the PAs are less hydrophobic, they mix better with DBSCOOH. Intramolecular interactions are formed between the PA molecules and DBSCOOH, which supports their co-assembly.

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