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Ultrasensitive Electrochemiluminescent Sensor for MicroRNA with Multinary Zn–Ag–In–S/ZnS Nanocrystals as Tags

Zhang, Bin, Zhang, Fang, Zhang, Ping, Shen, Dazhong, Gao, Xuwen, Zou, Guizheng
Analytical chemistry 2019 v.91 no.5 pp. 3754-3758
coatings, detection limit, electrochemiluminescence, electrochemistry, microRNA, models, nanocrystals, screening, zinc sulfide
For the screening of novel toxic-element-free and biocompatible electrochemiluminophores, electrochemiluminescence (ECL) of multinary nanocrystals (NCs) was investigated for the first time with Zn–Ag–In–S (ZAIS) NCs as model. Aqueous soluble ZAIS NCs could bring out efficient reductive-oxidation ECL with tri-n-propylamine as coreactant, while coating the ZAIS NCs with a ZnS shell could reduce the surface defects of ZAIS NCs, and enable 6.7-fold enhanced ECL of ZAIS/ZnS NCs as compared to ZAIS NCs. ECL of ZAIS/ZnS NCs was about 4.2-fold that of ternary CuInS₂/ZnS NCs, spectrally similar to that of Ru(bpy)₃²⁺ with maximum emission around 605 nm, and favorable for less electrochemical interference with a lowered triggering potential (∼0.95 V) than that of Ru(bpy)₃²⁺. An ultrasensitive ECL microRNA sensor was fabricated with ZAIS/ZnS NCs as tags, which could sensitively and selectively determine microRNA-141 with a wide linearity range from 0.1 fmol/L to 20 pmol/L and a low limit of detection at 50 amol/L (S/N = 3). Multinary NCs might provide a promising alternative to the traditional binary NCs for both electrochemiluminophore screening and NC ECL modulating.