Multiple signal-enhanced electrochemiluminescence aptamer sensors based on carboxylated ruthenium (II) complexes for acetamiprid detection.

Rapid and sensitive detection for acetamiprid, a kind of widely used neonicotinoid insecticide, is very meaningful for the development of modern agriculture and the protection of human health. Highly stable electrochemiluminescence (ECL) materials are one of the key factors in ECL sensing technology. ECL materials prepared by porous materials (e.g., MOFs) coated with chromophores have been used for ECL sensing detection, but these materials have poor stability because the chromophores escape when they are in aqueous solution. Therefore, the development of highly stable ECL materials is of great significance to improve the sensitivity of ECL sensing technology. In this work, by combining etched metal-organic frameworks (E-UIO-66-NH 2) as carrier with Tris(4,4′-dicarboxylic acid-2,2′-bipyridine)Ru(II) chloride (Ru(dcbpy) 3 2+) as signal probe via amide bonds, highly stable nanocomposites (E-UIO-66-NH 2 -Ru) with excellent ECL performance were firstly prepared. Then, using MoS 2 loaded with AuNPs as substrate material and co-reactant promoter, a signal off-on-off ECL aptamer sensor was prepared for sensitive detection of acetamiprid. Due to the excellent catalytic activity of E-UIO-66-NH 2 -Ru and MoS 2 @Au towards K 2 S 2 O 8 , the ECL signals can be enhanced by multiple signal enhancement pathways, the prepared ECL aptamer sensor could achieve sensitive detection of acetamiprid in the linear range of 10−13 to10−7 mol L−1, with the limit of detection (LOD) of 2.78ⅹ10−15 mol L−1 (S/N = 3). After the evaluation of actual sample testing, this sensing platform was proven to be an effective method for the detection of acetamiprid in food and agricultural products. The E-UIO-66-NH 2 -Ru prepared by linking Ru(dcbpy) 3 2+ to E-UIO-66-NH 2 via amide bonding has very high stability. The synergistic catalytic effect of MoS 2 and AuNPs enhanced the ECL signal. By exploring the sensing mechanism and evaluating the actual sample tests, the proposed signal "on-off" ECL sensing strategy was proved to be an effective and excellent ECL sensing method for sensitive and stable detection of acetamiprid. The conventional cathodic ECL response uses K 2 S 2 O 8 as co-reactant. Generally, K 2 S 2 O 8 can only be activated by participating in redox reactions on the electrode surface, and then the reactive intermediate SO 4 •− is produced to participate in the subsequent luminescence process (Route 1). However, since the amount of the active intermediate SO 4 •− limits the luminescence efficiency of the luminophore, increasing the production rate of the active intermediate SO 4 •− is an effective way to improve the efficiency of ECL. In this study we used MOFs material (E-UIO-66-NH 2) etched by thermal treatment as the carrier of the luminophore Ru(dcbpy) 3 2+, and the etched E-UIO-66-NH 2 exposed more amino groups, which can effectively catalyze the activation process of K 2 S 2 O 8 and produce more SO 4 •− (Route 4). Not only that, the Mo4+/Mo6+ active sites produced by 3D MoS 2 nanoflowers involved in the redox reaction on the electrode surface can also effectively catalyze the activation process of K 2 S 2 O 8 (Route 2). AuNPs grown in situ on the MoS 2 surface can also effectively catalyze the activation process of K 2 S 2 O 8 (Route 3). Therefore, we constructed a sandwich-type ECL sensor based on multiple signal enhancement strategy to achieve efficient and sensitive detection of acetamiprid in the range of 10−13 to 10−7 mol L−1 with a detection limit of 2.78ⅹ10−15 mol L−1. This provides an effective method for the sensitive detection of acetamiprid in food and agricultural products. [Display omitted] • The synergistic effect of Ru(dcbpy) 3 2+ and –NH 2 showed more excellent ECL response. • MoS 2 , AuNPs and E-UIO-66-NH 2 promote catalysis co-reactants and enhance ECL response. • Ru(dcbpy) 3 2+ can enter larger pore diameter inside E-UIO-66NH 2 to increase the load. • E-UIO-66-NH 2 exposes more amino groups, which enhances the catalytic of co-reactant. [ABSTRACT FROM AUTHOR]