Structure-switching fluorescence aptasensor for sensitive detection of chloramphenicol

Fluorescent Aptasensors: Design Strategies and Applications in Analyzing Chemical Contamination of Food

“…When the aptamer is designed as hairpin DNA containing the HCR initiator sequence, the target-aptamer binding can open the hairpin and expose the initiator DNA, which then triggers HCR of H1 and H2 (Figure A­(a)) . Another approach is the target-dependent release of cDNA from an aptamer-cDNA duplex, such that the cDNA serves as the DNA initiator for HCR (Figure A­(b)) …”

“…Structure-switching fluorescent aptasensors using HCR for signal amplification were applied in the detection of CAP to improve the sensitivity. Ma et al designed a separation-based dual amplification strategy to detect CAP with Exo I-assisted target recycling and HCR amplification . The binding thermodynamics, structure switching, and binding domain of CAP-aptamer binding were explored by isothermal titration calorimetry, circular dichroism, and molecular docking.…”

“…126 Another approach is the target-dependent release of cDNA from an aptamer-cDNA duplex, such that the cDNA serves as the DNA initiator for HCR (Figure 4A(b)). 127 Signal transduction in HCR-based fluorescence aptasensors can be performed label-free, via dsDNA specific dyes that may emit strong fluorescence in response to the long dsDNA structure in the HCR products (Figure 4B(a)), 128 via G4specific dyes inserted into the G4 structure generated in the HCR products by incorporating the G4 sequence into one of the hairpins (Figure 4B(b)), 129 or via G4/hemin DNAzymes that catalyze the reaction between substrate and H 2 O 2 to generate fluorescent products using G4 structures formed in the HCR products by linking split G4 sequences to the ends of both hairpins (Figure 4B(c)). 130 HCR aptasensors can also be carried out via functionalized hairpins, in which H1 and H2 are F-Q labeled (low fluorescence), and the HCR product displaces F away from Q, thereby leading to fluorescence recovery (Figure 4B(d)), 119 or Nano-Q adsorbs and quenches the free F-H1 and F-H2 hairpins but not the F-containing HCR product (Figure 4B(e)), 126 or Q and F are labeled to the hairpins and an additional DNA probe, respectively, and a triplex DNA structure formed by the HCR product and the additional F-DNA probe brings F and Q in close proximity, such that the fluorescence of F is quenched (Figure 4B(f)).…”

Fluorescence Polarization-Based Bioassays: New Horizons

“…Combining the advantages of aptamers as receptor agents and FA, this method allows the detection of small molecules with higher sensitivity and removes some of the limitations inherent in traditional immune assay formats. Aptamer structure switching FA assays for detecting low molecular weight compounds are based on changes in anisotropy caused by competition between aptamer-target binding and a conformationally altered aptamer-complementary DNA (cDNA) complex [ 112 ]. A significant increase in the FP change is due to the large difference in the rates of rotation of the free aptamer and the aptamer-cDNA complex ( Figure 9 ).…”

Cu Nanoparticle-Decorated Boron–Carbon–Nitrogen Nanosheets for Electrochemical Determination of Chloramphenicol

“…Residues of pollutants such as CAP in medical wastewater adversely affect human health . CAP is often used in pharmaceutical and aquaculture industries as a broad-spectrum antibacterial antibiotic. , The increasing use of CAP , has resulted in CAP residues being found in aquatic environments and animals. CAP is banned in many countries because it can cause aplastic anemia and leukemia after entering the human body .…”