Xuemei Xu,Ying Gao,Shixi Zhang,Shuzhen Li,Ting Bai,Yue Zhang,Xiaorong Hu,Rui Liu
Electro-thermal atomic absorption spectrometry (ETAAS) is a powerful element detector, thanks to its low cost, high sensitivity, multiple element detectability, and low sample consumption. In this work, a simple and sensitive DNA assay utilizing ETAAS detection was demonstrated with Au nanoparticles (NPs) tag. Ebola Virus (EV)-related DNA was detected by sandwich hybridization assay, using Au NPs-labeled reporter probes and magnetic microparticle (MMP)-labeled capture probes. The sandwich hybridization reaction conditions were optimized. After hybridization reaction, aqua regia was added to dissolve Au NPs and release Au ions , which were subsequently detected by ETAAS. A good linearity was obtained between the concentration of target DNA and the atomic absorbance signal intensity. The limit of detection (LOD) was 3 pM (LOD, 3σ), with the linear range of 10–200 pM (R = 0.9933). The relative standard deviation (RSD) for 20 pM target DNA was 1.07%. The target DNA results obtained by the proposed method correlated well with those obtained by inductively coupled plasma-based hybridization assay.
Cao Xiaodong,Zhang Chenlu,Gao Yu,Yu Weina,Liu Chao,He Shudong,Sun Hanju,Ye Yongkang
Foodborne pathogens are a leading cause of food safety incidents. Here, we developed a highly sensitive dual-channel biosensor for the parallel electrochemical detection of Salmonella typhimurium ( S. typhimurium ) and Escherichia coli ( E. coli ) O157:H7 using bimetallic metal–organic framework (BMOF)-based signal nanotags. The BMOF-based nanotags were synthesized by functionalizing gold nanoparticle-doped CuZr-MOF with signal DNA sequences sDNA1 (forming sDNA1-AuNPs@CuZr-MOF nanotag) and PbZr-MOF with signal DNA sequence sDNA2 (forming sDNA2-AuNPs@PbZr-MOF nanotag). The biosensing platform was constructed using two glassy carbon electrodes (GCEs). Each GCE was sequentially modified, first with electrodeposited gold nanoparticles (depAu) and then with the corresponding capture DNA sequences (cDNA1 for channel 1 or cDNA2 for channel 2). Target detection was achieved on the sensing interface via sandwich hybridization: in channel 1, the invA gene of S. typhimurium (tDNA1) was recognized by both cDNA1 on the sDNA1-AuNPs@CuZr-MOF nanotag; similarly, in channel 2, the eaeA gene of E. coli O157:H7 (tDNA2) was recognized by both cDNA2 and sDNA2 on the sDNA2-AuNPs@PbZr-MOF nanotag. Leveraging the high stability and ease of surface modification of UiO-66 (Zr-MOF), along with the enhanced electrochemical oxidation signals from the introduced secondary metal ions (Cu 2+ and Pb 2+ ) in Zr-MOF framework, the biosensor achieved parallel detection with wide linear ranges (3.5 to 3.5 × 10 5 CFU mL −1 for S. typhimurium , and 2.2 to 2.2 × 10 5 CFU mL −1 for E. coli O157:H7) and low detection limit (LODs of 0.54 CFU mL −1 and 0.80 CFU mL −1 , respectively). Furthermore, the fabricated biosensor demonstrated excellent reproducibility, selectivity, and stability, highlighting great potential for practical use in monitoring foodborne pathogens. Graphical
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