212
J. A. Elegbede and A. Lateef
utilized for ascertaining human immunoglobulin G in serum with positive results.
Also, a facile and low-cost electrochemical biosensor for glucose detection was established using TiO 2 nanotube arrays produced by means of potentiostatic anodization
(Zhang et al. 2013). The TiO 2 nanotube arrays were observed to have an inherent
peroxidase-like activity. The electrochemical and colorimetric assays both revealed
their outstanding catalytic potential toward H 2 O 2 reduction.
Metal sulfide nanoparticles have also been revealed to portray peroxidase activities. Dutta et al. (2012) reported the production of iron sulfide (FeS) and iron selenide
(FeSe) nanoparticles (NPs) via solvothermal decomposition of precursor complex
[Fe 3 (μ 3 -O)(μ 2 -O 2 CCH 2 Cl) 6 (H 2 O) 3 ]NO 3 ·H 2 O in the co-presence of thiourea and
sodium selenite, correspondingly. Structural analyzes of the fabricated nanoparticles via TEM showed that the FeSNPs and FeSeNPs were composed of needle-like
and spherical-shaped particles, respectively. It was observed that the FeSNPs and
FeSeNPs displayed photocatalytic activity for the degradation of both rose bengal and
methylene blue dyes under illumination of white light. They also showed outstanding
catalytic potency in the oxidation of 3,3
,5,5
-tetramethylbenzidine (TMB) in the
coexistence with H 2 O 2 which was in line with the Michaelis–Menten kinetics. Additionally, both FeSNPs and FeSeNPs displayed electrocatalytic potency in the reduction of H 2 O 2 , which on immobilized on glass-carbon (GC) electrodes operated as
amperometric sensors for H 2 O 2 detection. Also, the catalytic action of uncapped
nanobranch-based copper sulfide (CuS) clews synthesized via a simple one-pot
hydrothermal technique as a peroxidase was studied by Niu et al. (2016). The synthesized CuS catalytically oxidized 3,3
,5,5
-tetramethylbenzidine by H 2 O 2 to create a
visible color reaction with quick response (having maximum change within 5 min).
The CuS nanozyme exhibited catalytic kinetics preferred over normal horseradish
peroxidase (HRP). Also, when incorporated with glucose oxidase (GOD), the
system displayed capability to monitor glucose in blood samples with exceptional
performance.
3.1.2 Oxidase-Like Nanomaterials
Liu et al. (2015) demonstrated that platinum nanoparticles (PtNPs) displayed catechol oxidase-like potentials while oxidizing polyphenols resulting in o-quinones.
Four unique approaches were employed to confirm the catechol oxidase-like potential
of the PtNPs. Firstly, UV–vis spectroscopy was firstly used to observe polyphenols
oxidation catalyzed by PtNPs. Also, the oxidized polyphenols products were detected
via ultrahigh-performance liquid chromatography (UHPLC) separation, after which
identification by high-resolution mass spectrometry (HRMS). In the third method,
the O 2 consumption during the oxidation was confirmed using the electron spin resonance (ESR) oximetry. And finally, semiquinone radicals (an intermediate product)
produced during the polyphenols oxidation were identified via ESR using spin stabilization. The oxidizing potential of polyphenols by the PtNPs was found very useful
because polyphenols and related bioactives have been examined as potent antioxidants that could be of great use in the impediment of cardiovascular diseases and
J. A. Elegbede and A. Lateef
utilized for ascertaining human immunoglobulin G in serum with positive results.
Also, a facile and low-cost electrochemical biosensor for glucose detection was established using TiO 2 nanotube arrays produced by means of potentiostatic anodization
(Zhang et al. 2013). The TiO 2 nanotube arrays were observed to have an inherent
peroxidase-like activity. The electrochemical and colorimetric assays both revealed
their outstanding catalytic potential toward H 2 O 2 reduction.
Metal sulfide nanoparticles have also been revealed to portray peroxidase activities. Dutta et al. (2012) reported the production of iron sulfide (FeS) and iron selenide
(FeSe) nanoparticles (NPs) via solvothermal decomposition of precursor complex
[Fe 3 (μ 3 -O)(μ 2 -O 2 CCH 2 Cl) 6 (H 2 O) 3 ]NO 3 ·H 2 O in the co-presence of thiourea and
sodium selenite, correspondingly. Structural analyzes of the fabricated nanoparticles via TEM showed that the FeSNPs and FeSeNPs were composed of needle-like
and spherical-shaped particles, respectively. It was observed that the FeSNPs and
FeSeNPs displayed photocatalytic activity for the degradation of both rose bengal and
methylene blue dyes under illumination of white light. They also showed outstanding
catalytic potency in the oxidation of 3,3
,5,5
-tetramethylbenzidine (TMB) in the
coexistence with H 2 O 2 which was in line with the Michaelis–Menten kinetics. Additionally, both FeSNPs and FeSeNPs displayed electrocatalytic potency in the reduction of H 2 O 2 , which on immobilized on glass-carbon (GC) electrodes operated as
amperometric sensors for H 2 O 2 detection. Also, the catalytic action of uncapped
nanobranch-based copper sulfide (CuS) clews synthesized via a simple one-pot
hydrothermal technique as a peroxidase was studied by Niu et al. (2016). The synthesized CuS catalytically oxidized 3,3
,5,5
-tetramethylbenzidine by H 2 O 2 to create a
visible color reaction with quick response (having maximum change within 5 min).
The CuS nanozyme exhibited catalytic kinetics preferred over normal horseradish
peroxidase (HRP). Also, when incorporated with glucose oxidase (GOD), the
system displayed capability to monitor glucose in blood samples with exceptional
performance.
3.1.2 Oxidase-Like Nanomaterials
Liu et al. (2015) demonstrated that platinum nanoparticles (PtNPs) displayed catechol oxidase-like potentials while oxidizing polyphenols resulting in o-quinones.
Four unique approaches were employed to confirm the catechol oxidase-like potential
of the PtNPs. Firstly, UV–vis spectroscopy was firstly used to observe polyphenols
oxidation catalyzed by PtNPs. Also, the oxidized polyphenols products were detected
via ultrahigh-performance liquid chromatography (UHPLC) separation, after which
identification by high-resolution mass spectrometry (HRMS). In the third method,
the O 2 consumption during the oxidation was confirmed using the electron spin resonance (ESR) oximetry. And finally, semiquinone radicals (an intermediate product)
produced during the polyphenols oxidation were identified via ESR using spin stabilization. The oxidizing potential of polyphenols by the PtNPs was found very useful
because polyphenols and related bioactives have been examined as potent antioxidants that could be of great use in the impediment of cardiovascular diseases and