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 × 103–3.01 ×
107 copies/μL) and a limit of detection (LOD) of
2.29 × 103 copies/μL. Using 4,4′,4″,4″′-(porphine-5,10,15,20-tetrayl)
tetrakis (benzenesulfonic acid) (tpps)-β-cyclodextrin (tpps-β-CD)
as a T1 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
× 104–6.02 × 106 copies/μL)
and an LOD of 2.6 × 104 copies/μL. 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 101–106 copies/mL
and LOD of 101 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.