Based on specific homo-A/T DNA binding properties, a strategy for coralyne and mercury ions detection was realised by exonuclease-aided signal amplification . Coralyne could specifically bind homo-A DNA and protect it from the hydrolysis of exonuclease I. The coralyne-protected DNA was subsequently used as a trigger strand to hydrolyze DNA2 in exonuclease-aided signal amplification process. Thiazole orange was used to quantify the remainder DNA2. Under the optimal condition, the fluorescence intensity was linearly proportional to the concentration of coralyne in the range of 0.2–100 nM with a limit of detection (LOD) of 0.31 nM, which presented the lowest LOD for coralyne among all reported. With homo-T and Hg 2+ taking the place of homo-A DNA and coralyne, respectively, the system could also be used for Hg 2+ detection. The experiments in real samples also showed good results. This method was label-free, low-cost, easy-operating and highly repeatable for the detection of coralyne and mercury ions. It could also be extended to detect various analytes, such as other metal ions, proteins and small molecules by using appropriate aptamers.
The p53 gene is a known cancer marker. We report a novel protocol for the SERS tandem strategy to detect the p53 gene with high sensitivity. Herein, the click reaction between azide and alkyne was catalyzed by utilizing copper oxide nanoparticles (CuONPs), which were enriched by a T-DNA-triggered hybridization chain reaction (HCR). The T-DNA signal was amplified by establishing the correlation between the T-DNA signal and the concentration of CuONPs in a nonenzymatic isothermal environment. In contrast to other Raman reporters, we used alkynyl compounds as Raman reporters, which showed excellent characteristics in the Raman-silent region (1800–2800 cm −1 ). Therefore, the highly sensitive and highly selective SERS signals could be obtained in complex biological matrices. Due to utilizing multistep amplification strategies, including the nanoparticle-modified HCR polymer and “click” reaction, the limit of detection (LOD) and the limit of quantification (LOQ) of this sensor could be as low as 0.0174 pM and 0.0583 pM, respectively. The accuracy of the strategy expressed as the RSD was in the range of 3.14%–6.21%. The results indicated that the constructed sensor has excellent performance for the detection of the p53 gene in serum samples in a low concentration range, which suggests that the proposed enzyme-free SERS analytical sensor has good clinical application prospects.
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