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. 2019 Jul 29;24(15):2745.
doi: 10.3390/molecules24152745.

Highly Selective, Aptamer-Based, Ultrasensitive Nanogold Colorimetric Smartphone Readout for Detection of Cd(II)

Lu Xu  1   2 , Jun Liang  2 , Yonghui Wang  1 , Shuyue Ren  1 , Jin Wu  1 , Huanying Zhou  3 , Zhixian Gao  4
Affiliations

Highly Selective, Aptamer-Based, Ultrasensitive Nanogold Colorimetric Smartphone Readout for Detection of Cd(II)

Lu Xu et al. Molecules. .

Abstract

A highly selective and sensitive method for Cd(II) detection was developed based on aptamer and gold nanoparticles (AuNPs) combined with a colorimetric smartphone readout. The experimental conditions such as reaction time of polydiene dimethyl ammonium chloride (PDDA) and AuNPs, PDDA dose, time of aptamer and PDDA incubation, and aptamer concentration were optimized. Under the optimized conditions, the color and red(R) value of the solution was concentration-dependent on Cd(II). The proposed method exhibited a linear range of 1-400 ng/mL (r2 = 0.9794) with a limit of detection (LOD) of 1 ng/mL. This method had been successfully applied to test and quantify Cd(II) in water and rice samples, and the results were in full agreement with those from the atomic absorption spectrometer. Therefore, low-cost colorimetry demonstrated its potential for practical application in visual or quantitative detection with a smartphone. This approach can be readily applied to other analytes.

Keywords: Cd(II); aptamer; colorimetry; nanogold; smartphone readout.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic illustration of the colorimetric method. (A) Gold nanoparticles (AuNPs) incubated with aptamer and polydiene dimethyl ammonium chloride (PDDA); the color of the free AuNP solution was wine red; (B) AuNPs incubated with the aptamer, PDDA, and few Cd(II); the color of partial aggregation of the AuNP solution changed to reddish; (C) AuNPs incubated with the aptamer, PDDA, and sufficient Cd(II); the color of aggregation of the AuNP solution changed to blue; and (D) The red(R) values of the solution recorded with a smart phone.
Figure 2
Figure 2
TEM images and particle size distribution of AuNPs added to different materials. (A) AuNPs, (B) added PDDA, (C) added aptamer, and (D) added Cd(II).
Figure 3
Figure 3
Effect of (A) incubation time after the addition of AuNPs, (B) PDDA dosage, (C) aptamer and PDDA incubation time, and (D) aptamer concentration (nM).
Figure 4
Figure 4
The standard curve and selectivity of the aptamer/nanogold-based colorimetric assay for detection of Cd(II). (A) The standard curve with different concentrations of Cd(II) using the proposed colorimetric method with UV−vis spectra. (B) Selectivity of the colorimetric detection of Cd(II). (C) Schematic illustration and the standard curve with different concentrations of Cd(II) using the proposed colorimetric method combined with a smartphone.
See this image and copyright information in PMC

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