Enzyme-controlled dissolution of MnO2 nanoflakes with enzyme cascade amplification for colorimetric immunoassay

Abstract

A new colorimetric immunosensing platform accompanying enzyme cascade amplification strategy was fabricated for quantitative screening of small-molecular mycotoxins (aflatoxin B, AFB used in this case) coupling with enzyme-controlled dissolution of MnO nanoflakes. The visual colored assay was executed by high-efficient MnO-3,3',5,5'-tetramethylbenzidine (TMB) system (blue). In the presence of ascorbic acid, MnO nanoflakes were dissolved into Mn ions, thus resulting in a perceptible color change from blue to colorless. The reaction could be weakened through ascorbate oxidase to catalyze ascorbic acid into dehydroascorbic acid, which indirectly depended on the concentration of ascorbate oxidase. By using ascorbate oxidase/ anti-AFB antibody-labeled gold nanoparticles, a novel competitive-type colorimetric enzyme immunoassay was developed for detection of AFB on AFB-bovine serum albumin (BSA)-conjugated magnetic beads. Upon addition of target AFB, the analyte competed with the conjugated AFB-BSA on the magnetic beads for the labeled anti-AFB antibody on the gold nanoparticles. Under optimal conditions, the absorbance decreased with increasing target AFB within the dynamic range of 0.05-150ngmL with a detection limit of 6.5pgmL at the 3S level. The precision and specificity of the MnO-TMB-based immunosensing system were acceptable. In addition, method accuracy was further validated for monitoring spiked peanut samples, giving results matched well with those obtained from commercialized AFB ELISA kit.

When Nanozymes Meet Single‐Atom Catalysis

“…To the best of our knowledge,t he complex protein scaffold is responsible for the high selectivity and efficiency of natural enzymes.However,nanozymes are intrinsically deficient in their fine structure and thus lack the finesse of enzyme-catalyzed reactions,t hereby resulting in unsatisfactory selectivity and activity.I na ddition, the atomic composition and structural complexity of nanomaterials endow ad iverse range of nanozyme catalytic mechanisms.F or example,m any transitionmetal-based nanozymes,such as Fe 3 O 4 , MnO 2 ,V 2 O 5 ,M oS 2 ,a nd so on, with intrinsic peroxidase,o xidase,c atalase,a nd superoxide dismutase activity,h ave been discovered. [4,[19][20][21][22][23] TheF enton or Fenton-like reactions are widely used to explain the catalytic mechanism of peroxidase mimics.T he generated COH can be used for the degradation of organic pollutants and in the treatment of cancer, as well as in biosensing applications. [24] Another catalytic mechanism of peroxidase mimics,w hich occurs in Prussian blue and its cyanometalate structural analogues,i st he electron transfer effects.…”

Development of Nanozymes for Food Quality and Safety Detection: Principles and Recent Applications

“…In addition to the above‐mentioned functional features, nanozymes have also made use of the stimulated degradation (Ji et al., ; Lai, Wei, Xu, Zhuang, & Tang, ), response to surface‐enhanced Raman scattering (SERS) (Hu et al., ; Wu, Li, & Wei, ), and other capacities to fabricate detection platforms of versatility. Meanwhile, a number of extraordinary functions of nanozymes remain to be discovered and put into practice.…”

A Multi‐crosslinking Nanocapsule‐Based Serial‐Stimuli‐Responsive Leakage‐Free Drug‐Delivery System In Vitro

“…Given its facile biological production,a bundantf unctional groups,a nd ideal biocompatibility,B SA has been widely used in various fields of biochemical research. [38,39] Gallica cid (GA, Figure S1) is ap olyphenolicc ompound that can be found in variousn atural foods and fruits [40] and has been utilized in various biological experiments because of its antiviral anda nti-inflammatory properties. [41] Recently,i ncreasinga ttention have been paid to GA with respect to its antitumora ctivity.…”