Fluorescence aptasensor for Ochratoxin A in food samples based on hyperbranched rolling circle amplification

Abstract

A fluorescent aptasensor for Ochratoxin A(OTA) assay which combines high efficiency of hyperbranched rolling circle amplification(HRCA) and the specific recognition of aptamer has been developed. OTA can bind with the aptamer with high affinity, which hinders the hybridization between the aptamer and the capture probe DNA (CDNA). Then the free CDNA hybridizes with the padlock probe and initiates the HRCA reaction. Since the HRCA products contain large amounts of double strand DNA (dsDNA), which 10 can combine with SYBR Green I to produce fluorescence signal. The fluorescence intensity of the system has a linear relationship with the logarithm of OTA concentration in the range of 4fg/mL~400pg/mL and the limit of detection (LOD) of 1.2fg/mL was obtained. The fluorescent aptasensor has been applied to detect OTA in corn and oat samples with satisfied results. 65 80

Functional nucleic acid biosensors utilizing rolling circle amplification

“…Some assays opt to use Bst DP instead of phi29 DP for H-RCA as this DP shows excellent strand displacement and processivity but does not exhibit 3′ exonuclease activity. 194,195 H-RCA has been paired with a number of FNAs, including both aptamers 128,141,145,194–198 and DNAzymes. 164 Typically, H-RCA methods can improve amplicon production, and hence LOD, by as much as 10 4 -fold relative to linear RCA, 128 with the LOD being several orders of magnitude below the affinity constants for the MRE.…”

Target‐Mediated 5’‐Exonuclease Digestion of DNA Aptamers with RecJ to Modulate Rolling Circle Amplification for Biosensing

“…As with the T-AP system, the O-AP system exhibited a linear range of 5 orders of magnitude, which was competitive with other OTA-targeting linear RCA assays (Table S4). [33][34][35]…”

The rate-limiting procedure of 3D DNA walkers and their applications in tandem technology

“…HRCA, an evolution of linear RCA, with simple processes, isothermal conditions, and much higher amplification efficiency (10 9 -fold), has been proposed to develop biosensors for diverse analytes. 80 However, the selectivity of HRCA is insufficient, and it is necessary to integrate other technologies to make up for this deficiency. Given that 3D walkers offer negligible background signals and facile operation capabilities, one promising approach, introduced by Zhang et al , is the combination of HRCA with 3D walkers to develop a methyltransferase biosensor (Fig.…”