Figure 3.

Gold and silver enhancement of NM fibers. (a) Long NM^K184C fibers were assembled by seeding soluble NM^K184C with short NM^K184C fibers. Monomaleimido Nanogold was covalently cross-linked and the 1.4-nm Nanogold particles were subjected to gold toning. (b) Fibers were gold-toned on Si₃N₄ membrane substrates (33) by enhancing with LI Silver and GoldEnhance LM each for 5 min and imaged by TEM. (c) Gold toning is specific to labeled fibers. The resulting gold-toned fibers show a significant increase in height from 9–11 nm (bare fibers) to 80–200 nm (labeled fibers), imaged by AFM. (d) The height of the resulting fiber strictly depends on the length of exposure time of either the silver and/or the gold enhancement solution, imaged by AFM. (Left) Gold-labeled fibers on Si₃N₄ subjected to 3 min of silver enhancement and 5 min of gold enhancement, leading to a fiber diameter of 50 ± 5 nm. (Right) Fibers after 5 min of silver enhancement and 5 min of gold enhancement, leading to a fiber diameter of 100 ± 7 nm.