Shodex gpc 101

¹H NMR (400 MHz) and ¹³C NMR (100 MHz) were measured in CDCl₃ using a JNM-ESC400 instrument (JEOL Ltd., Akishima, Japan) at ambient temperature. SEC was performed at 40 °C in THF (flow rate, 1.0 mL/min), using a Shodex GPC-101 (Showa Denko K.K., Tokyo, Japan) gel permeation chromatography system (Shodex DU-2130 dual pump, Shodex RI-71 reflective index detector, and Shodex ERC-3125SN degasser) equipped with a Shodex KF-G guard column (4.6 mm × 10 mm; pore size, 8 μm) and two Shodex KF-804L columns (8 mm × 300 mm) in series. TEM measurements were performed with a JEM-2010 (JEOL Ltd., Akishima, Japan) operated at 200 kV. The size distribution of AgNPs was determined by the average of 150–200 observed particles. UV–Vis absorption spectra were recorded on a JASCO 4100 spectrophotometer (JASCO Co., Tokyo, Japan) at 25 °C. Relative UV–Vis absorption intensity (A/A₀ × 100%) of AgNPs without and with NaCl was compared at λ_max (409, 405, and 420 nm for HO–PEG_5k–OH, c-PEG_5k, and MeO–PEG_5k–Ome, respectively). MALDI–TOF mass spectrometry was carried out using a Bruker Daltonics Ultraflex-S at the Open Facility, Hokkaido University, Hokkaido, Japan.