Pathogenic bacteria are pathogens widely spread that are capable of causing mild to life-threatening diseases in human beings or other organisms. Rationally organizing the simple helical motif of double-stranded DNA (dsDNA) tiles into designed ensemble structures with architecturally defined collective properties could lead to promising biosensing applications for pathogen detection. In this work, we facilely engineered multivalent hairpin aptamer probe-tethered DNA monolayers (MHAP-DNA monolayers) and applied them to build a fluorescence polarization-responsive circular isothermal strand displacement amplification (FP-CSDA) for Salmonella assay. In this system, the MHAP-DNA monolayers were constructed based on a dsDNA tile-directed selfassembly. A FAM-labeled reporting probe (RP FAM ) with an inherent low FP signal serves as the signaling unit. The presence of target Salmonella leads to the trapping of F RP FAM into the super DNA monolayers via a target-triggered CSDA to peel off the tethered hairpin-structured aptamer probes (HAPs) responsible for the binding of RP FAM . As a result, the FP signal of the FAM fluorophore can be remarkably amplified due to the recycling of target Salmonella and the capacity of structural DNA materials to strongly restrict the free rotation of the FAM fluorophore but without a fluorescence quenching effect. Experimental results demonstrate that the FP assay is able to detect Salmonella with a low limit of detection (LOD) of 7.2 × 10 0 CFU/mL and high specificity. As a proof-ofconcept study, we envision our study using DNA nanoarchitecture as the foundation to modulate CSDA-based FP assays, promising to open up a new avenue for disease diagnosis, food safety detection, and biochemical studies.
BACKGROUND:
The nervous system senses and transmits information through the firing behavior of neurons, and this process is affected by various noises. However, in the previous study of the influence of noise on nerve discharge, the channel of some noise effects is not clear, and the difference from other noises was not examined.
OBJECTIVE:
To construct ion channel noise which is more biologically significant, and to clarify the basic characteristics of the random firing rhythm of neurons generated by different types of noise acting on ion channels.
Method:
Based on the dynamics of the ion channel, we constructed ion channel noise. We simulated the nerve discharge based on the Chay model of potassium ion channel noise, and used the nonlinear time series analysis method to measure the certainty and randomness of nerve discharge.
RESULTS:
In the Chay model with potassium ion noise, the chaotic rhythm defined by the original model could be effectively unified with the random rhythm simulated by the previous random Chay model into a periodic bifurcation process.
CONCLUSION:
This method clarified the influence of ion channel noise on nerve discharge, better understood the randomness of nerve discharge and provided a more reasonable explanation for the mechanism of nerve discharge.
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