Microbial Enzymes in Nanotechnology …
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was sonicated for 8 h, then centrifuged, after which the sample was dehydrated at
−50 °C in a vacuum. The results actualized in the experiments showed that the MoS 2
nanosheets displayed peroxidase-like activity by transferring electrons as against
generating ROS. Nanozymatic antioxidant system (NAS) (which is similar to enzymatic antioxidant system (EAS)) was developed by MoS 2 nanosheets for oxidative stress management. Interestingly, the NAS could efficiently scavenge other free
radicals which include nitrogen-centered free radicals (DPPH), hydroxyl radicals
(OH) and nitric oxide (NO). Applying the MoS 2 -based NAS in vivo, in Staphylococcus aureus and Escherichia coli, and A549 cell models showed that MoS 2
nanosheets superiorly protected these bacteria and cells against oxidative injury that
could be instigated by H 2 O 2 , and this reinforces the NAS unique characteristics of the
MoS 2 nanosheets. In a study reported by Wang et al. (2013), silicon nanowire arrays
(SiNWAs) synthesized via chemical etching technique which involved cleaning of
silicon wafers in a freshly piranha solution (7:3 v/v H 2 SO 4 / H 2 O 2 ) at 90 °C for
30 min, then rinsing with deionized water and dried in nitrogen stream. The cleaned
silicon wafers were submerged in an etching solution (5.0 mol/l hydrogen floride and
20 mmol/l AgNO 3 ) at 50 °C for 5, 10 and 30 min resulting in silicon nanowire arrays
with 4, 9 and 24 μm nanowire lengths, respectively. The SiNWAs were observed
to produce catalytic activities comparable to those of biological enzymes (catalase
and peroxidase). It was reported that the SiNWAs facilitated H 2 O 2 decomposition
reaction into oxygen and water, in addition to the oxidation of o-phenylenediamine
(OPD), a general substrate for peroxidases. The morphology of the SiNWAs and
existence of Si–H bonds were said to be crucial to the incidence of such catalytic
activity.
3.1.4 Superoxide Dismutase-Like Nanomaterials
Superoxide radicals are connected with the incident of many severe diseases, cancer
inclusive. In non-pathogenic conditions, the natural enzyme superoxide dismutase
(SOD) controls and normalizes the concentrations of superoxide in intracellular
environments; in fact, nearly all tumor tissues display reduced SOD levels (Ragg
et al. 2016). Moglianetti et al. (2016) showed the potentials of biocompatible platinum
nanoparticles (PtNPs) as antioxidant nanozymes with strong and broad properties
which include acting as catalase, superoxide dismutase and peroxidase enzymes,
which showed similar and even superior activities than natural enzymes, with higher
adaptability to changing environmental conditions. Two varieties of PtNPs were
synthesized; Pt5 and Pt20. Pt5 was fabricated by mixing 0.5 M H 2 PtCl 6 (160 μl) to
79.65 ml of MilliQ water together with 192 μl of 0.5 M sodium citrate. A solution
0.06 M of NaBH 4 was added dropwisely while vigorously stirred; the heat was then
raised to 75 °C and sustained for 30 min. Pt20 was synthesized by utilizing the
seed-growth method (Bigall et al. 2008). The PtNPs synthesized were revealed to
be monodispersed, with Pt5 being quasi-spherical-shaped having mean size of 5 nm
while Pt20 was flower shaped with mean size of 20 nm. The activities of the PtNPs
as radical scavenging agents in a cellular prototype of an oxidative stress-associated
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was sonicated for 8 h, then centrifuged, after which the sample was dehydrated at
−50 °C in a vacuum. The results actualized in the experiments showed that the MoS 2
nanosheets displayed peroxidase-like activity by transferring electrons as against
generating ROS. Nanozymatic antioxidant system (NAS) (which is similar to enzymatic antioxidant system (EAS)) was developed by MoS 2 nanosheets for oxidative stress management. Interestingly, the NAS could efficiently scavenge other free
radicals which include nitrogen-centered free radicals (DPPH), hydroxyl radicals
(OH) and nitric oxide (NO). Applying the MoS 2 -based NAS in vivo, in Staphylococcus aureus and Escherichia coli, and A549 cell models showed that MoS 2
nanosheets superiorly protected these bacteria and cells against oxidative injury that
could be instigated by H 2 O 2 , and this reinforces the NAS unique characteristics of the
MoS 2 nanosheets. In a study reported by Wang et al. (2013), silicon nanowire arrays
(SiNWAs) synthesized via chemical etching technique which involved cleaning of
silicon wafers in a freshly piranha solution (7:3 v/v H 2 SO 4 / H 2 O 2 ) at 90 °C for
30 min, then rinsing with deionized water and dried in nitrogen stream. The cleaned
silicon wafers were submerged in an etching solution (5.0 mol/l hydrogen floride and
20 mmol/l AgNO 3 ) at 50 °C for 5, 10 and 30 min resulting in silicon nanowire arrays
with 4, 9 and 24 μm nanowire lengths, respectively. The SiNWAs were observed
to produce catalytic activities comparable to those of biological enzymes (catalase
and peroxidase). It was reported that the SiNWAs facilitated H 2 O 2 decomposition
reaction into oxygen and water, in addition to the oxidation of o-phenylenediamine
(OPD), a general substrate for peroxidases. The morphology of the SiNWAs and
existence of Si–H bonds were said to be crucial to the incidence of such catalytic
activity.
3.1.4 Superoxide Dismutase-Like Nanomaterials
Superoxide radicals are connected with the incident of many severe diseases, cancer
inclusive. In non-pathogenic conditions, the natural enzyme superoxide dismutase
(SOD) controls and normalizes the concentrations of superoxide in intracellular
environments; in fact, nearly all tumor tissues display reduced SOD levels (Ragg
et al. 2016). Moglianetti et al. (2016) showed the potentials of biocompatible platinum
nanoparticles (PtNPs) as antioxidant nanozymes with strong and broad properties
which include acting as catalase, superoxide dismutase and peroxidase enzymes,
which showed similar and even superior activities than natural enzymes, with higher
adaptability to changing environmental conditions. Two varieties of PtNPs were
synthesized; Pt5 and Pt20. Pt5 was fabricated by mixing 0.5 M H 2 PtCl 6 (160 μl) to
79.65 ml of MilliQ water together with 192 μl of 0.5 M sodium citrate. A solution
0.06 M of NaBH 4 was added dropwisely while vigorously stirred; the heat was then
raised to 75 °C and sustained for 30 min. Pt20 was synthesized by utilizing the
seed-growth method (Bigall et al. 2008). The PtNPs synthesized were revealed to
be monodispersed, with Pt5 being quasi-spherical-shaped having mean size of 5 nm
while Pt20 was flower shaped with mean size of 20 nm. The activities of the PtNPs
as radical scavenging agents in a cellular prototype of an oxidative stress-associated