Colorimetric determination of ascorbic acid using a polyallylamine-stabilized IrO2/graphene oxide nanozyme as a peroxidase mimic

Synthesis, Catalytic Properties and Application in Biosensorics of Nanozymes and Electronanocatalysts: A Review

“…These include different material types, such as Nafion-cytochrome c [ 85 ], supramolecular complexes of hydrogel [ 86 ], nanocomplexes of lanthanides [ 87 , 88 , 89 , 90 , 91 , 92 ], Co 3 O 4 @CeO 2 hybrid microspheres [ 93 ], transition metal oxides and their composites [ 71 , 94 , 95 , 96 , 97 , 98 , 99 ], as well as noble metals: Au [ 100 ], Fe/Au [ 101 ], Au/Pt [ 102 ], Pt [ 103 , 104 ], Ru [ 105 ], Pt/Ru [ 60 ], Pd, Pd@Pt [ 106 ], Pd/Pt [ 107 ], Pd@γ-Fe 2 O 3 [ 108 ], etc. In the last decade, special interest in bionanotechnology has focused on the use of NZs based on carbon materials such as fullerenes [ 109 ], Prussian blue [ 110 ], TiO 2 [ 111 ] or Fe 2 O 3 /Pt-modified [ 112 ] multi-walled carbon nanotubes, hemin-graphene hybrid nanosheets [ 113 ], Pt/Ru/3D graphene foam [ 114 ], graphene oxide [ 115 ], Au/Pt/Au-graphene oxide nanosheets [ 116 ], Pd-magnetic graphene nanosheets [ 117 ], hemin-graphene-Au hybrid [ 118 ], IrO 2 [ 119 ], Cu-Ag [ 120 ] or Fe 2 O 3 -modified graphene oxide [ 121 ] ( Figure 4 ), Co-modified magnetic carbon [ 122 ], Co 3 O 4 graphene composite [ 123 ], carbon nanofibers […”

Two-Dimensional Nanomaterials With Enzyme-Like Properties for Biomedical Applications

“…In recent studies, the in-situ growth method was also adopted by different groups for the synthesis of Pt/h-BN (Ivanova et al, 2019) and "naked" Au NPs on g-C 3 N 4 NSs (Wu et al, 2019), via the reduction of metal precursors on NSs with various reducing agents like NaBH 4 , ascorbic acid, etc. Our group also constructed a variety of 0D/2D heterostructures, including PtAg NPs-decorated MoS 2 NSs through the hydrothermal process (Cai et al, 2016), Pt NPs-covered CuO NSs by NaBH 4 reduction (Wang X. H. et al, 2017), and IrO 2 NPs-modified GO (Sun et al, 2020) and reduced GO (rGO) (Liu X. L. et al, 2019) NSs by electrostatic adsorption/hydrothermal treatment. The modification of NPs onto 2D NMs could not only prevent NPs from aggregation but inhibit the restacking of NSs, which could facilitate practical applications.…”

“…PODs and ODs are a class of known oxidative enzymes in biosystems, which activate H 2 O 2 and O 2 to catalyze the oxidation of respective substrates under mild conditions (Wei and Wang, 2013;Huang et al, 2019;Jiang D. W. et al, 2019). To evaluate the POD-/OD-like activity of 2D NMs, catalytic oxidations of enzymatic chromogenic substrates like 3,3' ,5,5'tetramethylbenzidine (TMB), which are often carried out in acidic media and produce colored products (Equation 1), are chosen as a probe reaction by most researchers (Gao et al, 2007;Song et al, 2010;Tao et al, 2013;Cai et al, 2016Cai et al, , 2018aCai et al, , 2019Huang et al, 2017a;Wang X. H. et al, 2017;Ouyang et al, 2018;Ivanova et al, 2019;Liu X. L. et al, 2019;Wu et al, 2019;Sun et al, 2020). The reaction process is tracked by UV-Vis spectroscopy and the color variation of the reaction solution can be easily observed by naked eyes.…”

“…The constant K m characterizes the binding affinity of a substrate to the enzyme, in which a lower K m value means the higher affinity. Table 1 lists the kinetic parameters of typical 2D NMs as POD-mimics based on GO (Zhang L. N. et al, 2014;Sun et al, 2020) or rGO (Liu X. L. et al, 2019), TMDs (Lin et al, 2014a,b;Huang et al, 2018;Wu et al, 2018;Feng et al, 2020), LDHs (Zhan et al, 2018;Yang et al, 2020), g-C 3 N 4 (Darabdhara et al, 2019), MOF NSs (Chen J. Y. et al, 2018), h-BN (Ivanova et al, 2019), metal oxides (Wang X. H. et al, 2017;Li et al, 2019), and metallic NSs (Wei et al, 2015;Cai et al, 2018b.…”

Recent Progress of Nanozymes in the Detection of Pathogenic Microorganisms

“…Due to their remarkable biocompatibility and intrinsic catalytic performance, Fe 3 O 4 NPs and many other metal oxide-based nanozymes were greatly explored and applied for biosensing, environmental treatment, antioxidation, antibiosis and cancer treatment. [4,[62][63][64][65][66][67][68][69][70][71][72][73][74] Among nanozymes applied for detecting pathogenic microorganisms, Fe 3 O 4 is a widely studied material due to the magnetic and peroxidase-like properties. For instance, the Ebola virus (EBOV) that broke out in West Africa in 2014 caused plenty of deaths.…”