Tecnai g20 tem

The dissected maxillae and mandibles of mice at P5 were immersed in a fixative containing 3% glutaraldehyde and 0.1 M cacodylate buffer (pH 7.2) at 4 °C for 28 h and decalcified in 10% ethylenediaminetetraacetic acid (EDTA) at 4 °C for 5 d. The samples were washed in 0.1 M sodium cacodylate buffer for 48 h at 4 °C, post-fixed with 1% OsO₄ (osmium tetroxide), dehydrated through acetone and embedded in araldite CY212 (Durcupan ACM, Fluka). The semithin sections were cut at a thickness of 1 µm and stained with methylene blue. The ultrathin sections were cut at 70 nm using an ultra-microtome (Reichert-Nissei, Unterschleißheim, Germany) with a diamond knife, mounted on copper grids, and contrasted 10 min with saturated 2% uranyl acetate in 70% ethanol followed by 5 min with 0.2% aqueous lead citrate, pH 11.8. The stained grids were examined using a FEI Tecnai G20 TEM (Hillsboro, OR).

The TEM measurements of AuNCs were performed by using a Talos F200S TEM (Thermo Fisher, USA) with an accelerating voltage of 200 kV. The TEM images of the brain slices were performed by using a FEI Tecnai G20 TEM (FEI, USA) with an accelerating voltage of 200 kV. Blinded observation of samples with random selection of grid areas was implemented to reduce bias during imaging.

The micro-morphology and elemental distribution were tested using a Zeiss Sigma 300-SEM (Carl Zeiss AG, Oberkochen, Germany) and a Tecnai G20-TEM (FEI, Hillsborough, OR, USA). The crystal structure and chemical composition of the as-prepared catalysts was recorded using an X-ray diffractometer with Cu Kα radiation (XRD, Bede Scientific Ltd., Centennial, CO, USA; Operated at 45 mA and 40 KV; Bruker Corporation, Waltham, MA, USA) and X-ray photoelectron spectroscopy with Al-K radiation (XPS, ESCALAB, 250Xi; Thermo Fisher Scientific, Waltham, MA, USA).