A catalytic hairpin self-assembly (CHA) amplification method was developed for CAP detection based on cross-shaped DNA and UiO-66. MOF was used to quench the fluorescent signal of FAM labeled DNA. Cross-shaped DNA with four fluorophore group (FAM) was utilized to enhance the fluorescent intensity. CAP could open hairpin structure of H-apt and induce CHA reaction. The product of CHA hybridized with cross-shaped DNA, resulting its leaving from the surface of UiO-66 and recovery of fluorescent signal. The limit of detection (LOD) was low to 0.87 pM. This method had been successfully applied for the detection of CAP in actual samples. Importantly, the high sensitivity was attributed to the great amplification efficiency of CHA, strong fluorescent intensity of cross-shaped DNA structure and great fluorescent quenched efficiency of UiO-66.
Fu-Ting Wang,Yi-Han Wang,Jing Xu,Ke-Jing Huang,Zhen-hua Liu,Yun-fei Lu,Shu-yu Wang,Zi-wei Han
A self-powered microRNA (miRNA) biosensing device is fabricated with high-energy enzymatic biofuel cell (EBFC) and cruciform DNA (cDNA). Sulfur-selenium co-doped graphene/gold nanoparticles (S–Se-GR/AuNPs) is synthesized and used as supporting substrate of biocathode and bioanode . The glucose oxidase (GOD) molecules are bonded to carboxyl-functionalized AuNPs through the condensation reaction between the amino groups in enzyme and carboxyl groups on the AuNPs to form the bioanode. The ultra-thin porous carbon shell/AuNPs-complementary strand of cDNA (UPCS/AuNPs-cDNA) is meticulously designed. The potassium ferricyanides are then inserted in mesoporous UPCS/AuNPs as the biocathode electron acceptor , and the cruciform DNA bioconjugate is synthesized as signal amplifier. When target miRNA is added, the hybridization reaction happens between miRNA and capture probe DNA on the biocathode to open the capture probe DNA chain. Cruciform DNA bioconjugate is immobilized onto the biocathode through base pairing with the capture DNA on the biocathode, which can release electron acceptor [Fe(CN) 6 ] 3- , resulting in the dramatically increase of the open circuit voltage of the EBFCs. The self-powered biosensor responds linearly in the miRNA level range of 0.5–10000 fM with a detection limit of 1.5 × 10 −16 mol L −1 . Detection of miRNA in spiked serum samples is also realized with the self-powered biosensor, demonstrating its great potential in the clinical applications.
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