Tecnai g2 20 transmission electron microscope

Transmission electron microscopy (TEM) images of the Fe₃O₄@MPS@PMAC nanoparticles were obtained by an FEI Tecnai G2 20 transmission electron microscope operating at 200 kV. Field-emission scanning electron (FE-SEM) images were recorded on a Hitachi S-4800 cold field-emission scanning electron microscope (Hitachi, Tokyo, Japan) equipped with an energy-dispersive X-ray spectrometer (EDX). Fourier transform infrared spectroscopy (FT-IR) characterization was performed using a Fourier spectrophotometer with KBr pellets (Nicolet, Wisconsin, USA). Thermogravimetric analysis (TGA) was carried out under nitrogen flow at a heating rate of 10 °C/min from 25 °C to 700 °C on a Pyris 1 TGA instrument (Perkin Elmer, Massachusetts, USA). All nanoparticles were dried at 60 °C prior to each TGA measurement to remove the solution attached to the surface. The saturation magnetization curves were measured at room temperature with a Physical Property Measurement System 9 T (Quantum Design, San Diego, USA).

The formation of fibrils by PrPs was confirmed by electron microscopy of negatively stained samples. The preparation for negatively stained samples was described in detail previously [28] (link), [33] (link)–[35] (link). Briefly, the incubation time was chosen within a time range of the plateau of each kinetic curve of ThT fluorescence shown in Fig. 1. Sample aliquots of 10 µl were placed on copper grids and left at room temperature for 1–2 min, rinsed twice with H₂O, and then stained with 2% (w/v) uranyl acetate for another 1–2 min. The stained samples were examined using an FEI Tecnai G2 20 transmission electron microscope (Hillsboro, OR) operating at 200 kV or an H-8100 transmission electron microscope (Hitachi, Tokyo, Japan) operating at 100 kV.