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Highlights • Structure-switching aptamer probe was designed to achieve enzyme-free amplification. • Detection process for AFB 1 could be finished within 1 min. • All detection process could be conducted in one test-tube at a constant temperature. • AFB 1 contamination in fluid or liquid food samples were accurately detected. Abstract Aptamer probes provide an opportunity for achieving rapid and on-site detection of food contaminants. Herein, we proposed a general design strategy for aptamer probes enabling enzyme-free amplified, ultrafast and one-test tube homogeneous detection of aflatoxin B 1 (AFB 1). The key feature of the aptamer probe is designed with dual-terminal proximity structures, allowing the binding of one molecule to light up two fluorophores, leading to enzyme-free amplification and a remarkable improvement of signal to background ratio and sensitivity for AFB 1 detection. This aptamer probe could accommodate quick response to AFB 1 , and the detection process could be finished within 1 min, ranking one of the quickest assays for AFB 1. AFB 1 detection of broad bean paste and peanut oil conferred satisfactory recoveries ranging from 90.3% to 114.8%. Contributed to the generality and simplicity of the design strategy, this structure-switching probe could potentially act as a general platform of on-site detection for food safety. [ABSTRACT FROM AUTHOR]

Aggregation-induced emission (AIE) dyes are promising for labeling nucleic acid probes. Aptamer is one of the most appealing nucleic acid probes, and may enable to output signal response to target molecules by the direct use of single aptamer sequence. However, the concise sensing platform is often suffered from low sensitivity. In response, by the adoption of AIE dyes, we propose an intrinsic conformation response-leveraged aptamer probe (iconAptamer) for aflatoxin B 1 (AFB 1) detection. The design strategy lies in the synergetic utilization of AIE and fluorescence resonance energy transfer (FRET) effects. AIE dyes confer a much higher sensitivity for monitoring the response of aptamer towards AFB 1 compared to traditional DNA intercalation dyes. FRET process between AIE dyes and the terminal-labeled fluorophore would induce a distance effect in the structure-switching process, further leveraging the response signal. Consequently, the sensitivity of the aptamer probe was dramatically improved by over 2 orders. IconAptamer allowed to mix-to-read detection of AFB 1 contaminations at room temperature. The application of iconAptamer for AFB 1 detection in food and environmental samples has been demonstrated, with recovery rates of 91.8%–111.1%. IconAptamer would provide a simple, fast, convenient, and cost-effective platform for food safety control and environmental monitoring by broadening the target species. Based on aggregation-induced emission dye and FRET process for leveraging the Intrinsic conformation response of aptamer toward targets, a single-aptamer sequence-based assay was established, which enables sensitive and mix-to-read detection of aflatoxin B 1. Image 1 • A sensitive single-strand aptamer probe was built using AIE dye and FRET process. • Achieving mix-to-read analysis of aflatoxin B 1 , thus well fit for on-site detection. • Potential application for food safety control and environmental monitoring. [ABSTRACT FROM AUTHOR]