Aztectem

The surface morphology of the coating was observed via the SEM (SSX-550, SHIMADZU from Tsushima, Japan). The elements on the surface of coating were detected via the EDS (AZtecTEM, Oxford Instruments from Oxford, UK) surface scanning method, and the elements in the thickness direction of the coating section were detected via the EDS line scanning method. XRD (D8-FOCUS, BRUKER from Brook, Germany) using a Cu Kα radiation was used to detect the phase composition of the coating before and after corrosion. The grazing angle was 2°, the scanning range was 10~90°, and the scanning speed was 5°/min. The corrosion of the damaged coating was observed using a confocal microscope (KH-8700, HIROX from Shanghai, China). LEIS (AMETEK, VersaSCAN^TM, Princeton, NJ, USA)was used to test the three-dimensional micropore distribution and local electrochemical behavior with a test area of 2 × 2 mm².

Transmission
electron microscopy (TEM) characterization was performed using a JEOL
JEM-2100F field emission S/TEM equipped with an Oxford X-MaxN 80 mm2
SDD detector for elemental analysis. TEM images were acquired at a
200 kV accelerating voltage and 116 μA emission current. DigitalMicrograph
GMS3 (Gatan) and Aztec TEM (Oxford Instruments) software packages
were used for the TEM data and energy dispersive X-ray (EDX) spectral
analysis and interpretation, respectively. Briefly, for the immunogold
labeling with antibodies, GPC-1 antibodies (pa5–51290, Thermo
Scientific) were attached on 10 nm gold particles (AURION) according
to the manufacturer’s instructions at room temperature. Healthy
plasma and PDAC plasma sample pools were prepared. 200 μL from
each of 5 healthy or 5 PDAC plasma samples was taken to form a healthy
plasma or PDAC plasma sample pool. Exosomes were isolated as previously
described. Then isolated exosome samples were conjugated with the
gold-particles attached GPC-1 antibodies at the appropriate dilution
overnight at 4 °C. Samples for TEM characterization were drop-cast
from dilute aqueous suspensions onto amorphous carbon coated (200
nm) Cu grids (Agar Scientific) and dried naturally overnight.