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Hydrogels of Superlong Helices to Synthesize Hybrid Ag-Helical Nanomaterials

Li, Guihua, Wang, Yitong, Wang, Ling, Song, Aixin, Hao, Jingcheng
Langmuir 2016 v.32 no.46 pp. 12100-12109
Fourier transform infrared spectroscopy, circular dichroism spectroscopy, deoxycholic acid, gelation, glutathione, hydrogels, ions, nanofibers, nanosilver, silver, silver nitrate, strength (mechanics)
The gelation behavior of mixtures of sodium deoxycholate (NaDC) and glutathione (GSH) in water is investigated. The system exhibits a structural transition of self-assembled hydrogels from nanofibers to nanohelix structures, and then to helical ribbons with increasing GSH concentration. Superlong helical nanofibers with left- and right-handed orientations are produced by tuning the concentration of GSH at a fixed concentration of NaDC. Random coil and β-sheet structures are significant for the formation of the helical structures, and are indicated by circular dichroism (CD) and Fourier transform infrared (FT-IR) spectra. The mechanical strength of the “weak” hydrogels is enhanced by the introduction of appropriate suitable amount of AgNO₃. Furthermore, the controlled growth of Ag nanoparticles at spatially arranged locations along the nanohelices (hybrid Ag-helical nanomaterial) is readily achieved by UV reduction of Ag (I) ions on the supramolecular helical templates.