Received 00th January 20xx, Accepted 00th January 20xx DOI: 10.1039/x0xx00000x A dendritically amplified fluorescence signal probe on SiO2 microspheres for ultrasensitive detection of mercury ions
In this work, a new kind of dendritically amplified fluorescence signal probe on SiO2 microspheres were controllably fabricated by terminal deoxynucleotidyl transferase (TdT)-catalyzed incorporation of nucleotides combined with bio-bar-code (BBC) amplification for ultrasensitive detection of Hg2+. The thymine T-Hg2+-T hairpin structure was firstly formed and further initiated the strand-displacement-amplification (SDA) reaction, generating mimic target (MT). MT hybridized with capture probe 1 (c1) on SiO2 microspheres, and the 3′-hydroxyl (OH) termini of MT initiated TdT-based DNA extension, producing abundant poly-Guanine sequence (G1). Then G1 hybridized with capture probes (C2) with poly-Cytosine (C) to assemble multiple C2/reporter probe-AuNPs onto the SiO2 microspheres. The reporter DNA further initiated TdT-based extension with poly T sequence (T1) to link large numbers of signal probes, which generated very high fluorescence signal for ultrasensitive detection of target Hg2+. This TdT-based signal amplification method coupled with SDA exhibits extraordinary sensitivity for Hg2+ assay with a limit down to 1.0 aM. The proposed highly sensitive fluorescence strategy holds great potential for detecting targets in environmental and biological fields.