A Review of Gold and Silver Nanoparticle‐Based Colorimetric Sensing Assays

TLDR: In this article, the main parameters that influence colorimetric-based methods and provides a rational classification of the current approaches, by focusing particularly on gold nanoparticles and silver nanoparticles (AgNPs).

Abstract: The nanoparticle colorimetric-based methods have been extensively used for rapid detection, however there are few limitations which can be kept under control or avoided by understanding the crucial parameters involved in these reactions. This review addresses the main parameters that influence colorimetric-based methods and provides a rational classification of the current approaches, by focusing particularly on gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs). The AgNP and AuNP-based colorimetric assays can be very efficient and sensitive especially for biomolecule identification and for metal ion detection in environmental screening. Specifically, this review highlights the detection of metal ions through their coordination with nanoparticle stabilizing ligands. The review also addresses various approaches based on label-free aptasensors to better understand their role as smart colorimetric sensing devices.

Figures

Table 2: Biomolecule-sensing based on AuNPs or AgNPs aggregation. 209

Fig. 10. Schematic representation of Type I colorimetric aptasensors for detection (A) small [4q, 4aa] 485 and (b) large molecular targets [5g] 486 487

Fig. 18. (A) Schematic representation of the assay to assess endonuclease and methyltransferase 744 activity and inhibition. (B) Sequences of the DNA probe, DNA-1 (recognition site for the 745 DpnII/Dam MTase) and DNA-2 (recognition site for the EcoRI/EcoRI MTase). The arrows show 746 the cleavage sites, and the red letters indicate the methylation sites [7k]. 747 748

Table 3: DNA/protein sensing based on AuNP aggregation 432

Fig. 8. Amplified thrombin detection on surfaces by catalytic enlargement of thrombin-aptamer-354 functionalized Au-NPs [5a]. As the concentration of thrombin increases, the surface loading of bound 355 thrombin is higher, resulting in a number of Au NP seeds for enlargement. 356

Fig. 13. Schematic of the approach by Xie et al. A synthetic RNA–DNA duplex substrate is first 583 incubated or not with HIV-1 RT. HIV-1 RT should cleave the RNA into fragments, resulting in the 584 dissociation of ssDNA and ssRNA probes at room temperature (≈ 28 °C). Reproduced with 585 permission from [7o]. GNPs, AuNPs. 586 587 Wang et. al [3e] used K+ as a target because it stabilizes ssDNA, thus facilitating the formation of 588

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28 The nanoparticle colorimetric-based methods have been extensively used for rapid detection, 29 however there are few limitations which can be kept under control or avoided by understanding 30 the crucial parameters involved in these reactions. This review addresses the main parameters 31