Figure 4.

Colorimetric sensing strategy based on the aggregation of NPs. (A) Detection of Vibrio parahemolyticus based on Mn²⁺-mediated aggregation of AuNPs. Reprinted with permission from [51]. Copyright 2018, American Chemical Society. (B) Detection of Escherichia coli, Vibrio cholerae, Pseudomonas aeruginosa, and Xanthomonas campestris based on engineered bacteriophage-mediated aggregation of AuNPs. Reprinted with permission from [52]. Copyright 2018, American Chemical Society. (C) Detection of E. coli O157:H7 through pH-responsive concanavalin A-mediated aggregation of AuNPs. Reprinted with permission from [54]. Copyright 2017, Springer Nature. (D) Detection of Staphylococcus aureus using DNA dual-walker signal amplification combined with colorimetric systems. Reprinted with permission from [56]. Copyright 2020, American Chemical Society. (E) Detection of Salmonella typhimurium using colorimetric systems in combination with the aptamer-catalytic hairpin assembly (CHA) method. Reprinted with permission from [57]. Copyright 2021, MDPI. GNP, gold nanoparticle; AA, ascorbic acid; RBP, receptor-binding protein; EDC, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide; ConA, concanavalin A; MNP, magnetic nanoparticle; ExoIII, exonuclease III; MRSA, methicillin-resistant S. aureus; SMB, streptavidin-coated MNP; Bapt, biotinylated aptamer; Tapt, non-labelled aptamer; Y-CHA, Y-shaped catalytic hairpin assembly.