Microbial Enzymes in Nanotechnology …
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rGO/CuS/Au composite nanosheets were deemed to be exceptional (Jin et al. 2016;
Ma et al. 2016; Song et al. 2016; Hu et al. 2017a).
3.1 Fabrication of Nanozymes and Their Enzyme-Like
Activities
3.1.1 Peroxidase-Like Nanomaterials
Carbon nanotubes (CNTs) and carbon nanomaterials have become known as a leading
nanomaterial in biomedical applications as a consequence of their unusual properties,
which make them valuable as delivery vehicles for proteins, drugs, in addition to
DNA into cells (Shin et al. 2017). Zeng et al. (2017) reported that an economical
and easy synthesis of water-soluble carbon nanomaterials obtained from graphite and
polypropylene carbon fibers. Commercially obtainable graphite powder or pulverized
carbon fiber powder was added into a mix of concentrated H 2 SO 4 (95%) and HNO 3
(65%), after which this was sonicated and refluxed. The pH of the solution was
adjusted to 8 using Na 2 CO 3 , and then the solution was filtered and dialyzed in a
dialysis bag for seven days. The carbon nanomaterials powder was hereafter obtained
via freeze drying. It was detected that the prepared carbon nanomaterials (with sizes
varying from 1–8 nm) could instigate the production of hydroxyl radicals during
hydrogen peroxide degradation, thus own inherent peroxidase-like potential for both
colorimetric and UV–Vis absorption detection of hydrogen peroxide. These carbon
nanomaterials exhibited outstanding hydrogen peroxide sensitivity with the threshold
of detection reported as low as 0.014 mM. Shin et al. (2017) demonstrated a selfdegradation means for single-wall carbon nanotubes (SWNT) facilitated by the inbuilt peroxidase-like potentials of biocompatible bacterial magnetic nanoparticles
(BMPs) which was biosynthesized using Magnetospirillum sp. AMB-1. The resulting
SWNT–BMP hybrid was established to demonstrate highly synergetic peroxidaselike activity, and BMPs acted as a proficient intrinsic peroxidase in effecting the selfdegradation of BMP-coated SWNTs. Moreover, the result obtained reported that the
SWNT–BMP hybrid could offer an innovative approach for prevention and treatment
of neurodegenerative diseases as it was revealed that they exercised neuroprotective
effects against β-amyloid (Aβ) fibrillation-induced neurotoxicity in SH-SY5Y human
neuroblastoma cells by decreasing the growth of β-amyloid (Aβ) fibrils considered
as a key element in Alzheimer’s disease.
Graphene-based nanomaterials have also been said to have peroxidase-like potentials. As a result of their high diffusion, high catalytic potential and outstanding
biocompatibility, graphene dots are probable to be applied in various fields, such
as biotechnology, environmental monitoring and medical diagnostics (Zheng et al.
2013). According to Hosseini et al. (2017), cobalt-doped magnetite/graphene
207
rGO/CuS/Au composite nanosheets were deemed to be exceptional (Jin et al. 2016;
Ma et al. 2016; Song et al. 2016; Hu et al. 2017a).
3.1 Fabrication of Nanozymes and Their Enzyme-Like
Activities
3.1.1 Peroxidase-Like Nanomaterials
Carbon nanotubes (CNTs) and carbon nanomaterials have become known as a leading
nanomaterial in biomedical applications as a consequence of their unusual properties,
which make them valuable as delivery vehicles for proteins, drugs, in addition to
DNA into cells (Shin et al. 2017). Zeng et al. (2017) reported that an economical
and easy synthesis of water-soluble carbon nanomaterials obtained from graphite and
polypropylene carbon fibers. Commercially obtainable graphite powder or pulverized
carbon fiber powder was added into a mix of concentrated H 2 SO 4 (95%) and HNO 3
(65%), after which this was sonicated and refluxed. The pH of the solution was
adjusted to 8 using Na 2 CO 3 , and then the solution was filtered and dialyzed in a
dialysis bag for seven days. The carbon nanomaterials powder was hereafter obtained
via freeze drying. It was detected that the prepared carbon nanomaterials (with sizes
varying from 1–8 nm) could instigate the production of hydroxyl radicals during
hydrogen peroxide degradation, thus own inherent peroxidase-like potential for both
colorimetric and UV–Vis absorption detection of hydrogen peroxide. These carbon
nanomaterials exhibited outstanding hydrogen peroxide sensitivity with the threshold
of detection reported as low as 0.014 mM. Shin et al. (2017) demonstrated a selfdegradation means for single-wall carbon nanotubes (SWNT) facilitated by the inbuilt peroxidase-like potentials of biocompatible bacterial magnetic nanoparticles
(BMPs) which was biosynthesized using Magnetospirillum sp. AMB-1. The resulting
SWNT–BMP hybrid was established to demonstrate highly synergetic peroxidaselike activity, and BMPs acted as a proficient intrinsic peroxidase in effecting the selfdegradation of BMP-coated SWNTs. Moreover, the result obtained reported that the
SWNT–BMP hybrid could offer an innovative approach for prevention and treatment
of neurodegenerative diseases as it was revealed that they exercised neuroprotective
effects against β-amyloid (Aβ) fibrillation-induced neurotoxicity in SH-SY5Y human
neuroblastoma cells by decreasing the growth of β-amyloid (Aβ) fibrils considered
as a key element in Alzheimer’s disease.
Graphene-based nanomaterials have also been said to have peroxidase-like potentials. As a result of their high diffusion, high catalytic potential and outstanding
biocompatibility, graphene dots are probable to be applied in various fields, such
as biotechnology, environmental monitoring and medical diagnostics (Zheng et al.
2013). According to Hosseini et al. (2017), cobalt-doped magnetite/graphene