Fig. 4.

Different sensor surfaces for sandwich immunoassays, usable with electrochemical detection. (a) Carbon fiber microelectrode, modified with AuNP and protein A to capture a high density of primary antibodies. Adapted with permission from reference.⁴⁵ (b) SWCNT forest assembly developed on a pyrolytic graphite (PG) surface. Adapted with permission from reference.⁵⁰ (c) AuNP-modified pyrolytic graphite surface using layer-by-layer (LBL) approach. Adapted with permission from reference.⁴³ (d) Glassy carbon electrode modified with silver-MWCNT composite. Adapted with permission from reference.⁶⁵ (e) SWCNT-modified Pt substrate used for label-free detection. Adapted with permission from reference.⁶⁷