Highly sensitive fluorescent aptasensor for Salmonella paratyphi A via DNase I-mediated cyclic signal amplification

Abstract

An elegant aptasensor was developed for dual fluorimetric determination of Salmonella paratyphi A through DNase I-assisted target recycling enlargement.

Ultrasensitive fluorescent aptasensor for CRP detection based on the RNase H assisted DNA recycling signal amplification strategy

“…Aptamers are single-stranded nucleic acids isolated from random-sequence DNA or RNA libraries by an in vitro SELEX, 19 which can bind to various kinds of targets, including ions, proteins, whole cells and small molecules, with high specicity, sensitivity and affinity. 20 They have attracted lot of interest because of their several advantages similar to antibodies, 10 as well as their relative ease of isolation, modication, tailored binding affinity, chemical synthesis and resistance against denaturation. 3 Aptamers belong to the group of so-called "functional nucleic acids" possessing catalytic or receptor properties.…”

“…RNase H is a ribonuclease, 34 which cleaves RNA phosphodiester bonds only when they present in an RNA-DNA heteroduplex; it does not digest the DNA in the heteroduplex, nor does it digest single-or double-stranded RNA or DNA. 35 Members of the RNase H family can be found virtually in all organisms, from archaea and prokaryotes to eukaryotes, as well as in many important biological processes, such as DNA replication, DNA repair, and transcription. 36 RNase H is also tightly associated with the retroviral reverse transcription process and drug resistance.…”

Aptamer-Based Biosensors for Environmental Monitoring

“…Based on this principle, Liang et al developed a rapid and ultrasensitive FRET-based aptasensor using Phi29-DNA polymeraseassisted signal amplification for the detection of Salmonella paratyphi A (Liang et al, 2019). The aptamer used in this work was originally selected by Yan et al (2015), and had an evaluated affinity for S. paratyphi A of 27 ± 5 nM. In Liang et al's design ( Figure 1B), an arched probe consisting of an aptamer specific for S. paratyphi A (blue) and a primer (red) is disassembled in the presence of S. paratyphi A (purple) as the aptamer is bound to the target resulting in the release of the primer sequence.…”

Aptamers used for biosensors and targeted therapy

“…7 A) [ 128 ]. Using a dye-labeled probe/GO quenching model, various targets, including IgE [ 129 ], aflatoxin B-1 [ 130 ], platelet-derived growth factor-BB (PDGF-BB) [ 131 ], and Salmonella [ 132 ], have been successfully detected. Ning et al fabricated a label-free fluorescent aptasensor for the determination of ATP.…”

“…Enzyme-assisted target recycling and signal amplification designs have attracted significant attention owing to their high sensitivity [ 134 ]. To date, different types of nucleases, such as polymerases [ 123 , 135 ], exonucleases [ 136 , 137 ], deoxyribonucleases [ 132 , 138 ], and endonucleases [ 139 , 140 ], have been frequently employed to construct aptasensors for many target assays. The different properties of these nucleases can trigger several rounds of target recycling by implementing their endonuclease reaction or polymerization reaction.…”