Colorimetric Detection of Hg²⁺ Based on the Growth of Aptamer‐Coated AuNPs: The Effect of Prolonging Aptamer Strands

Abstract

Herein, a versatile and sensitive colorimetric sensor for Hg based on aptamer-target specific binding and target-mediated growth of AuNPs is reported. The 15 T bases are first designed to detect Hg through T-Hg -T coordination. Aptamer-target binding results in the desorption of the aptamer from AuNP surface, the remaining aptamers adsorbed on AuNP surface trigger the growth of AuNPs with morphologically varied nanostructures, and then different colored solutions are formed. On this occasion, the limit of detection (LOD) of 9.6 × 10 m is obtained. The other two aptamer strands (25- and 59-mer) are designed by increasing A bases on either side and both sides of 15 T, respectively. The interaction of the binding domain and Hg makes desorption of 15 T from AuNP surface, whereas excess bases not committed to the binding domain still adsorbed on AuNP surface. These excess bases control the growth of AuNPs, and enhance the sensitivity. The LODs are 4.05 and 3 × 10 m for 25- and 59-mer aptamers, respectively. In addition, the 59-mer aptamer system is applied to identify Hg in real river samples, the LOD of 6.2 × 10 m is obtained.

Poly(adenine)-mediated DNA-functionalized gold nanoparticles for sensitive detection of mercury ions in aqueous media

“…The detection limit of this method was found to be 3.75 nM, and was estimated based on the 3d/slope rule. Compared to other colorimetric methods for the assay of Hg 2+ ions, 10,36,37 this proposed strategy was shown to have a comfortable limit of detection based on a very facile experimental process. In addition, the selectivity of the designed assay was also evaluated for the determination of other metal ions, including Zn 2+ , Mn 2+ , Cd 2+ , Cr 3+ , Mg 2+ , Al 3+ , Cu 2+ , Ni 2+ , Fe 3+ , Ca 2+ , and Pb 2+ ions instead of Hg 2+ ions in the solution.…”

“…[2][3][4][5] These serious health problems have encouraged researchers to develop efficient, facile and fast methods for detection of Hg 2+ in the environment with high selectivity and sensitivity to reduce the conversion of organic mercury. [6][7][8][9][10][11] The World Health Organization has established a maximum permissible Hg 2+ level of 5 nM in drinking water. 12 At present, the conventional analysis methods for Hg 2+ ions with responsive sensitivity include absorption spectrometry, inductively coupled plasma-mass spectrometry and so on.…”

“…30 Recently, Chen and co-workers developed a colorimetric sensor for Hg 2+ based on "T-Hg 2+ -T" coordination to grow Au NPs furtherly. 10 Up to now, most DNA-functionalized Au NPs are usually thiolate-modied DNA probes on the surface of Au NPs, and it is a multi-step and time-consuming chemical process to construct them. 31,32 Fortunately, it has been reported that poly-A as an effective anchoring block could bind tightly to the surface of Au NPs, which is a facile and label-free process.…”

Anti-Agglomeration Behavior and Sensing Assay of Chlorsulfuron Based on Acetamiprid-Gold Nanoparticles

“…Gold nanoparticles (AuNPs) have attracted attention in many research areas because of their unique chemical, optical, and electronic properties [ 14 , 15 ]. Their strong surface plasmon resonance endows them with good signal generation and transduction.…”

Equipment-Free Quantitative Aptamer-Based Colorimetric Assay Based on Target-Mediated Viscosity Change

“…It integrates SiO 2 microparticles labeled with glucoamylase molecules for efficient yet robust signal amplification with naked-eye measurement of diffusion distance of a colored reporting reagent (i.e., red ink) in the reaction solution for simple equipment-free quantitative readout. In our initial proof-of-concept study, adenosine, a key cofactor in numerous biochemical processes, 37 is chosen as a model analyte. The working principle and analytical procedures of this adenosine assay are illustrated in Figure 1 .…”