Tecnai g2 spirit tem microscope

Conventional TEM imaging was performed using an FEI Tecnai G2 Spirit TEM microscope at 80 kV equipped with an Orius SC1000 camera. The polymersomes were stained using a PTA solution at 0.75% (w/v). PTA at 10% (w/v), supplied by Sigma-Aldrich, was used. The solution was prepared by dissolving 37.5 mg of PTA in boiling distilled water (5 ml). The pH was adjusted to 7.0 by adding a few drops of 5 M NaOH under continuous stirring. The PTA solution was then filtered through a 0.2-μm filter.
Copper grids were glow-discharged for 40 s to render them hydrophilic. Then, 5 μl of polymersome/PBS dispersion (diluted 10-fold; concentration, 0.5 mg/ml) was deposited onto the grids for 1 min. Then, the grids were blotted with filter paper and immersed in the PTA staining solution for 5 s for negative staining. The grids were blotted again and dried under vacuum for 1 min.

Transmission electron microscopy was used to measure the number-average particle diameter (D_n) and the particle size distribution (dispersity Ð) using a Fei Tecnai G2 Spirit TEM microscope (Brno, Czech Republic). The size of mag.SLPs was evaluated using a MAIA3 scanning electron microscope (Tescan; Brno, Czech Republic). Dynamic light scattering (DLS) of aqueous SLP dispersions (25°C) on a Zen 3600 Zetasizer (Malvern Instruments; Malvern, UK) was used to determine ζ-potential, hydrodynamic diameter (D_h), and polydispersity index (PDI) from the intensity distribution curve. Iron content was determined using a Perkin Elmer 3110 atomic absorption spectrometer (AAS; Waltham, MA, USA), content of C was measured on a FlashSmart^TM elemental analyzer (Thermo Fisher Scientific; Waltham, MA, USA), and thermogravimetric analysis was performed in air flow with 10°C/min heating rate on a Perkin Elmer TGA 7 thermogravimetric analyzer (Waltham, MA, USA) equipped with Pyris software. The heat effect of the mag.SLPs was tested under an alternating magnetic field (AMF) by homemade AC system and temperature changes were monitored by a fiber optic temperature sensor (FISO Technologies; Québec, Canada) (Skumiel et al., 2016 (link)). Magnetization of dry particles was determined using an EV9 vibrating sample magnetometer (DSM Magnetics, ADE Corp.; Lowell, MA, USA) at RT.