Supramolecular Hydrogels Based on Silver Mercaptide. Self-Organization and Practical Application

L-Cysteine/AgNO2 low molecular weight gelators: self-assembly and suppression of MCF-7 breast cancer cells

We report a new supramolecular hydrogel based on simple amino acids and silver salt compounds with low molecular weights. The in situ formation of silver nanoparticles during the self-assembly process endows the hydrogel with high cytotoxicity towards adenocarcinoma breast cells but no toxic effects towards embryonic fibroblasts.

Mechanism of gelation in low-concentration aqueous solutions of silver nitrate with l-cysteine and its derivatives

We discuss the results of experimental studies of the processes of gelation in aqueous solutions of silver nitrate with l-cysteine and its derivatives. We focus on understanding what determines if these small molecules will self-assemble in water at their extremely low concentration to form a gel. A mechanism of gel formation in a cysteine-silver solution (CSS) is proposed. The analysis of the results indicates that filamentary aggregates of a gel network are formed via interaction of NH₃⁺ and C(O)O^- groups that belong to neighboring silver mercaptide (SM) aggregates. In turn, formation of sulphur-silver bonds between silver mercaptide molecules is responsible for self-assembling these molecules into SM aggregates which can be considered as supramonomers. Free polar groups located on the surfaces of the aggregates can form hydrogen bonds with water molecules, which explains the unique ability of CSS hydrogels to trap water at low concentrations of low-molecular-weight hydrogelators.

Self-Assembled Soft Nanomaterials Via Silver(I)-Coordination: Nanotube, Nanofiber, and Remarkably Enhanced Antibacterial Effect

Silver(I)-induced instant gelation of pyridine-containing Fmoc-l-glutamate and its concentration-dependent self-assembly from nanotubes to nanofibers are investigated. The formed metallogel with nanostructure has remarkably enhanced antibacterial activities. Interestingly, the nanotube and nanofiber exhibit different antibacterial activities, and a corresponding antimicrobial mechanism is proposed.

Thixotropic hydrogelators based on a cyclo(dipeptide) derivative

Thixotropic hydrogelators have great potential in biomedical and biotechnological applications. In this study, we report new hydrogelators and their behavior during gel-sol-gel transitions. In particular, cyclo(L-O-hydroxyhexylaspartyl-L-phenylalanyl), which was synthesized with 1,6-hexanediol, formed a thermally/isothermally reversible physical gel with several solvents, including pure water, saline, alcohols, as well as 1.0 M aqueous NaCl, KCl, CaCl2, and MgCl2 solutions. TEM observations showed self-assembled fibers with diameters of 10-100 nm. FT-IR results revealed that the gels were mainly formed by hydrogen bonding and van der Waals forces; thixotropic behavior resulted from the disruption of the van der Waals forces between the alkylene chains under shearing. These results were repeatedly and reproducibly observed at room temperature, even when measurements were repeated many times.