An electrochemiluminescence aptasensor based on highly luminescent silver-based MOF and biotin-streptavidin system for mercury ion detection

• Published in: Analyst (London) 2023-02, Vol.148 (4), p.772-779
• Main Authors: Liu, Si-Qi, Chen, Jing-Shuai, Liu, Xing-Pei, Mao, Chang-Jie, Jin, Bao-Kang
• Format: Article
• Language: English
• Subjects: Aptamers, Nucleotide - chemistry; Biosensing Techniques - methods; Biosensors; Biotin; Biotin - chemistry; Chitosan; DNA, Complementary; Electrochemical Techniques - methods; Electrochemiluminescence; Electrodes; Emitters; Gold; Gold - chemistry; Ion detectors; Ions; Limit of Detection; Luminescent Measurements - methods; Mercury; Mercury (metal); Metal Nanoparticles - chemistry; Metal-organic frameworks; Nanoparticles; Sensors; Silver; Streptavidin - chemistry
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/d2an02036j

In this study, for the first time, a silver-based metal-organic framework (Ag-MOF) was synthesized and used as the electrochemiluminescence (ECL) emitter for building an ECL sensor. After modification with chitosan (CS) and gold nanoparticles (Au NPs), the ECL stability of Ag-MOF was improved. To detect mercury ions, a biosensor was constructed using the mercury ion aptamer and steric effect of streptavidin. First, the capture strand (cDNA) with terminal-modified sulfhydryl group was attached to the electrode surface by the Au-S bond. Then, the mercury-ion aptamer (Apt-Hg) modified with biotin was anchored to the electrode by complementary pairing with cDNA. Streptavidin (SA) could be fixed on the electrode by linking with biotin, thereby reducing the ECL signal. However, in the presence of mercury ions, the aptamer was removed and streptavidin could not be immobilized on the electrode. Hence, the ECL signal of the sensor increased with the concentration of mercury ions, which was linear in the range from 1 μM to 300 fM. The detection limit could reach 66 fM (S/N = 3). The sensor provided a new method for the detection of mercury ions. Silver-based organic frameworks with high ECL activity were synthesized and applied for the first time to construct an ECL sensor. The detection limit was as low as 66 fM for mercury ion concentration in water.