Microbial Enzymes in Nanotechnology …
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the protein model of BSA-stabilized AuNCs. The limit of detection for trypsin was
0.6 μg/ml much beneath the average level of trypsin in urine or serum of patient.
Wei et al. (2015) investigated the mimetic enzyme activities of twodimensional (2D) palladium-based nanostructures (Pd nanosheets, Pd@Au and
Pd@Pt nanoplates) and found out that they had inherent oxidase-, peroxidase-, and
catalase-like activities. For production of Pd nanosheets (PdNSs), a known weight
of Pd(acac) 2 , PVP and tetrabutylammonium bromide (TBAB) were mixed together
with N, N-dimethylformamide (DMF) and distilled water in a glass pressure vessel
which was then stimulated with CO to 1 bar and heated from ambient temperature to
90 °C in 1 h, then maintained for an added 3 h before being cooled to ambient temperature resulting in a dark blue product precipitated by acetone. While for synthesis
of Pd@Au bimetallic nanoplates, the synthesized PdNSs stock solution (1.2 mg/ml)
and varying mass of AuPPh 3 Cl (2 mg/ml prepared in DMF) were mixed in DMF,
then 100 μL hydrazine was added dropwise while the mixture was vigorously stirred.
The solution was left untouched at ambient temperature in excess of 12 h, then the
products obtained were precipitated by acetone. For Pd@Pt bimetallic nanoplates,
the similar procedure was applied except that Pt(acac) 2 (2 mg/ml prepared in DMF)
was employed to replace AuPPh 3 Cl. The nanostructures synthesized were capable
of activating H 2 O 2 or dissolved oxygen (DO) to enable catalysis of the oxidation
of organic substrates and breakdown hydrogen peroxide to produce oxygen. The
Pd-based nanostructures were employed for detection of glucose and H 2 O 2 via
colorimetry, in addition to electrocatalytic reduction of H 2 O 2 .
3.1.3 Catalase-Like Nanomaterials
He et al. (2013) investigated the catalytic activity of AuNPs in biologically reactions through the electron spin resonance spectroscopy (ESR). The AuNPs with
spherical morphology had sizes which ranged from 10–100 nm and were coated
with either tannic acid or polyvinylpyrrolidone (PVP). It was reported that the
AuNPs facilitated the rapid decomposition of H 2 O 2 which occurred in conjunction with the development of oxygen at higher pH and hydroxyl radicals at lower
pH. In addition, it was noticed that the AuNPs proficiently catalyzed the breakdown of superoxide, thus mimicking superoxide dismutase. These results revealed
that AuNPs can function as catalase and superoxide dismutase mimetics. Ren et al.
(2018) described the effectiveness of graphene oxide quantum dots (GOQDs) as
nanozymes which competently diminish reactive oxygen species (ROS) and H 2 O 2 in
1-methyl-4-phenyl-pyridinium ion (MPP
+ )-induced PC12 cells. Besides, the GOQDs
exercised neuroprotective impacts in a neuronal cell model by reducing α-synuclein
and apoptosis. GOQDs also proficiently reduce ROS, mitochondrial impairment
and apoptosis in zebrafish treated with MPP
+ . Furthermore, the GOQDs-pretreated
zebrafish displayed improved locomotive activity in Nissl bodies in the brain, thus
establishing that GOQDs can amend MPP
+ -induced neurotoxicity. The Fenton reactions and H 2 O 2 decomposition suggested the catalase-like potential of the GOQDs.
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the protein model of BSA-stabilized AuNCs. The limit of detection for trypsin was
0.6 μg/ml much beneath the average level of trypsin in urine or serum of patient.
Wei et al. (2015) investigated the mimetic enzyme activities of twodimensional (2D) palladium-based nanostructures (Pd nanosheets, Pd@Au and
Pd@Pt nanoplates) and found out that they had inherent oxidase-, peroxidase-, and
catalase-like activities. For production of Pd nanosheets (PdNSs), a known weight
of Pd(acac) 2 , PVP and tetrabutylammonium bromide (TBAB) were mixed together
with N, N-dimethylformamide (DMF) and distilled water in a glass pressure vessel
which was then stimulated with CO to 1 bar and heated from ambient temperature to
90 °C in 1 h, then maintained for an added 3 h before being cooled to ambient temperature resulting in a dark blue product precipitated by acetone. While for synthesis
of Pd@Au bimetallic nanoplates, the synthesized PdNSs stock solution (1.2 mg/ml)
and varying mass of AuPPh 3 Cl (2 mg/ml prepared in DMF) were mixed in DMF,
then 100 μL hydrazine was added dropwise while the mixture was vigorously stirred.
The solution was left untouched at ambient temperature in excess of 12 h, then the
products obtained were precipitated by acetone. For Pd@Pt bimetallic nanoplates,
the similar procedure was applied except that Pt(acac) 2 (2 mg/ml prepared in DMF)
was employed to replace AuPPh 3 Cl. The nanostructures synthesized were capable
of activating H 2 O 2 or dissolved oxygen (DO) to enable catalysis of the oxidation
of organic substrates and breakdown hydrogen peroxide to produce oxygen. The
Pd-based nanostructures were employed for detection of glucose and H 2 O 2 via
colorimetry, in addition to electrocatalytic reduction of H 2 O 2 .
3.1.3 Catalase-Like Nanomaterials
He et al. (2013) investigated the catalytic activity of AuNPs in biologically reactions through the electron spin resonance spectroscopy (ESR). The AuNPs with
spherical morphology had sizes which ranged from 10–100 nm and were coated
with either tannic acid or polyvinylpyrrolidone (PVP). It was reported that the
AuNPs facilitated the rapid decomposition of H 2 O 2 which occurred in conjunction with the development of oxygen at higher pH and hydroxyl radicals at lower
pH. In addition, it was noticed that the AuNPs proficiently catalyzed the breakdown of superoxide, thus mimicking superoxide dismutase. These results revealed
that AuNPs can function as catalase and superoxide dismutase mimetics. Ren et al.
(2018) described the effectiveness of graphene oxide quantum dots (GOQDs) as
nanozymes which competently diminish reactive oxygen species (ROS) and H 2 O 2 in
1-methyl-4-phenyl-pyridinium ion (MPP
+ )-induced PC12 cells. Besides, the GOQDs
exercised neuroprotective impacts in a neuronal cell model by reducing α-synuclein
and apoptosis. GOQDs also proficiently reduce ROS, mitochondrial impairment
and apoptosis in zebrafish treated with MPP
+ . Furthermore, the GOQDs-pretreated
zebrafish displayed improved locomotive activity in Nissl bodies in the brain, thus
establishing that GOQDs can amend MPP
+ -induced neurotoxicity. The Fenton reactions and H 2 O 2 decomposition suggested the catalase-like potential of the GOQDs.