Figure 7.

(A) Schematic of the mechanism for multicolor visual detection of exosomes based on HCR and enzyme-catalyzed metallization of Au NRs. Reprinted with permission from Zhang Y, Wang D, Yue S, et al. Sensitive multicolor visual detection of exosomes via dual signal amplification strategy of enzyme-catalyzed metallization of Au nanorods and hybridization chain reaction. ACS Sens. 2019;4:3210–3218. Copyright 2019 American Chemical Society.¹²⁷ (B) Schematic of the visible detection of exosomes based on ssDNA-enhanced Fe₃O₄ NPs nanozyme activity. Reprinted with permission from Chen J, Xu Y, Lu Y, Xing W. Isolation and visible detection of tumor-derived exosomes from plasma. Anal Chem. 2018;90:14207–14215. Copyright 2018 American Chemical Society.¹³¹ (C) Schematic of DNA aptamer accelerating the intrinsic peroxidase-like activity of g-C₃N₄ NSs for the detection of exosomes. Reprinted with permission from Wang YM, Liu JW, Adkins GB, et al. Enhancement of the intrinsic peroxidase-like activity of graphitic carbon nitride nanosheets by ssDNAs and its application for detection of exosomes. Anal Chem. 2017;89:12327–12333. Copyright 2017 American Chemical Society.¹³² (D) Schematic of the detection mechanism for the visible detection of exosomes based on ssDNA-enhanced Fe₃O₄ NPs nanozyme activity. Reprinted with permission from Zhang Y, Su Q, Song D, Fan J, Xu Z. Label-free detection of exosomes based on ssDNA-modulated oxidase-mimicking activity of CuCo₂O₄ nanorods. Anal Chim Acta. 2021;1145:9–16. Copyright 2021 Elsevier B.V.¹³⁴