S 4160 microscope

The AFM analyses was done by an NT-MDT microscope in non-contact modes. TEM images were taken by a Philips CM30 microscope at an operating voltage of 150 kV. SEM analyses was obtained by a SEM, Hitachi, S-4160 microscope. Raman spectra were measured by Senterra Raman system with a laser source of 532 nm. The electrical characterizations were done by a Keithly K361 source measure unit.

Pure materials such as solvents, metallic salts and chemical compounds were procured from Merck companies. The FE-SEM images were taken by using a Hitachi S-4160 microscope. The FT-IR spectrum was acquired using a Shimadzu IR-470 spectrometer with a KBr pellet. X-ray diffraction (XRD) was performed by using a D8 Advance model made via Bruker. Numerix DXP-X10P reported the EDX analysis of the nanocatalyst.

Fmoc-FF (Chempep, USA) was synthesized through tert-butyl ester reaction chemistry, as reported elsewhere [25 (link)]. Briefly, 315 µl isobutyl chloroformate was added to the Fmoc-phenylalanine-OH (472 mg) solution in CHCl₃ under stirring. The mixture was then stirred overnight by adding 2.5 ml phenylalanine-OtBu (314 mg) to CHCl₃. Upon dissolving Fmoc-FF in a CHCl₃/TFA (1:1) mixture, the tert-butyl protecting groups were removed. The product was precipitated with cold tert-butyl methyl ether, centrifuged for 15 min at 3000 × g, and lyophilized (Christ alpha 1–2 LD, Germany).
To prepare the mixed peptide hydrogels, Fmoc-FF + Fmoc-RGD or Fmoc-FF + Fmoc-RGE, 20 mM Fmoc-FF (pH = 10) and 20 mM Fmoc-RGD (Fmoc-RGE) (pH = 3) were mixed in 15% and 30% volume ratios and vortexed until homogenization. The mixed solution was further neutralized to pH = 7 by dropwise addition of dilute HCl or NaOH. Field-emission scanning electron microscopy (FE-SEM) was carried out using a HITACHI S-4160 microscope (Japan) to investigate the nanoscale morphology of the mixed hydrogels.