Figure 7. Quick-freeze deep etch negative replica immunoelectron microscopic images of soluble Aβ aggregates from human AD brain.

(A,B) Exemplar images of soluble high molecular weight Aβ aggregates immunoprecipitated from the sucrose cushion after 475,000× g ultracentrifugation spotted onto glass and stained with N-terminal Aβ antibody HJ3.4 followed by anti-mouse secondary conjugated to 6 nm diameter gold beads. Replicas were produced by platinum deposition and mounted for imaging. Red arrows indicate aggregates with multiple gold bead (white) labeling. Scale bars 100 nm: (C) Images with no primary antibody indicating absence of nonspecific binding of gold-labeled secondary antibody. (D,E) Expanded view of aggregates from panels A and B with contrast inverted to make the gold bead labels (black) more apparent.