Multisignal Biosensors Based on Mn Paramagnetic Relaxation and Nanocatalysis for Norovirus Detection

A multisignal method for the sensitive detection of norovirus based on Mn paramagnetic relaxation and nanocatalysis was developed. This dual-modality sensing platform was based on the strong relaxation generated by cracked Au@MnO2 nanoparticles (NPs) and their intrinsic enzyme-like activity. Ascorbic acid rapidly cracked the MnO2 layer of Au@MnO2 NPs to release Mn(II), resulting in the relaxation modality being in a "switch-on" state. Under the optimal conditions, the relaxation modality exhibited a wide working range (6.02 x 10(3)-3.01 x 10(7) copies/mu L) and a limit of detection (LOD) of 2.29 x 10(3) copies/mu L. Using 4,4 ',4 '',4 '''-(porphine-5,10,15,20-tetrayl) tetrakis (benzenesulfonic acid) (tpps)-beta-cyclodextrin (tpps-beta-CD) as a T-1 relaxation signal amplification reagent, a lower LOD was obtained. The colorimetric modality exploited the "peroxidase/oxidase-like" activity of Au@MnO2 NPs, which catalyzed the oxidation of colorless 3,3 ',5,5 '-tetramethylbenzidine (TMB) to blue oxidized TMB, which exhibited a working range (6.02 x 10(4)-6.02 x 10(6) copies/mu L) and an LOD of 2.6 x 10(4) copies/mu L. In addition, the rapid amplification reaction of recombinase polymerase enabled the detection of low norovirus levels in food samples and obtained a working range of 10(1)-10(6) copies/mL and LOD of 10(1) copies/mL (relaxation modality). The accuracy of the sensor in the analysis of spiked samples was consistent with that of the real-time quantitative reverse transcription polymerase chain reaction, demonstrating the high accuracy and practical utility of the sensor.