A fluorescent aptasensor for Staphylococcus aureus (S. aureus) was constructed by integrating the mechanisms of fluorescence signal regulation and exonucleases-assisted two-step signal amplification into a navigable DNA walker. After the recognition of S. aureus, the first signal amplification step converts the aptamer-cDNA1 duplex to the hydrolysate of cDNA1 by exonuclease I (Exo I). Then the second signal amplification step converts the hydrolysate to the fuel chain of the navigable DNA walker by exonuclease III (Exo III) reaction system containing hairpin probe and cDNA2. Driven by the fuel chain, the movement of the DNA walker triggers the fluorescence resonance energy transfer (FRET) to obtain an amplified fluorescent signal that correlates to the target concentration. The movement track is ingeniously designed and constructed by DNA self-assembly technology, which controls the motion direction and stride of the DNA walker. In addition, the movement triggers FRET, which effectively enhances the detection signal. The biosensor has a wide detection concentration range of 1×102-2×107 CFU/mL with the detection limit of 9 CFU/mL. This biosensor provides a reference method for customization of signal amplification strategy in DNA circuit machinery. The biosensor exhibits good specificity, and has potential applications in the fields of environmental and food safety monitoring.
A novel electrochemical aptasensor for ATP was developed based on an aptamer-embedded configuration-switchable tetrahedral DNA nanostructure (TDN) and the formation of a G-quadruplex.
Abstract For sensitive analysis of cancer biomarker carcinoembryonic antigen (CEA), an amperometric sandwich‐type aptasensor is proposed based on a signal amplification strategy of Au@Pt bimetallic nanoprobes. As the excellent catalytic activity to hydrogen peroxide (H 2 O 2 ), core‐shell Au@Pt nanoparticles are employed as nanoprobes by conjugating directly with the secondary aptamer of CEA (Apt‐II). Due to the synergic recognition effect of dual aptamers and the excellent catalytic activity of nanoprobes, this amperometric sandwich‐type aptasensor for CEA exhibits high specificity and good sensitivity with a limit of detection of 0.31 ng/mL, along with a wide linear range from 0.1 ng/mL to 100 ng/mL.
DNA-templated silver nanoclusters (DNA-AgNCs) are novel nanomaterials with unique fluorescence characteristics. DNAzyme is a functional oligonucleotide which can catalyze the disruption of nucleic acid substrates. In this research, the manipulation...
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