groups was the key for enzymatic oxidation. Indeed, the authors discussed that
GOs’ oxygenated functional groups promote weaker binding with HRP and thus
enabled it to be more dynamic, which ultimately brought its catalytic heme site in
proximity of GOs to induce oxidative degradation (Fig. 4.3). In 2012, the authors
performed similar studies with similar outcomes using myeloperoxidase (MPO),
which has a human analogue as human MPO [48]. The report encourages the use of
functionalized graphene-based nanomaterials for in vivo studies as they can be
readily degraded by peroxidase-related intracellular enzymes. However, experiments must be carried out in a cautious manner as these in vitro outcomes may turn
out to be entirely irrelevant to the actual biodegradation processes in the body.
Besides the fact that oxidative debris of GOs can also be lethal to cells, the levels of
intracellular enzymes may be more dilute in physiological milieu in vivo.
4.4 Graphene-Based Nanomaterials for Biomedical
Applications
4.4.1 Therapeutic Applications
Graphene-based nanomaterials are known to exhibit high absorbance in the NIR
region, which gave rise to novel approaches for NIR laser-triggered selective
ablation of cancer cells [49, 50]. With appropriate modifications with targeting
moieties, graphene-based nanomaterials can specifically target malignant tumor
cells without damaging the healthy ones. Interestingly, graphene-based nanomaterials’ hydrophobic basal plane can be exploited for various synergistic therapies.
Some groups attended to the fact that hydrophobic anti-cancer drugs and photodynamic agents could be easily loaded onto the basal plane of graphene-based
materials through p–p interactions. By combining the photothermal ablation with
either chemotherapies or photodynamic therapies, therapeutic effects came to be
higher [51, 52]. NIR-responsive hyperthermia was not only utilized for the direct
ablation of cells, but also employed as an external cue for controlled drug/gene
delivery by disorganizing a drug-loading matrix or endocytosed vesicles by NIR
laser [53–55]. Moreover, some groups also discovered unusual stem cell growth
and differentiation patterns on graphene substrates, which can be possibly employed
in stem cell engineering and/or stem cell-based therapy [56, 57].
4.4.2 Fluorescence Sensing and Imaging
In addition to the therapeutic applications, people have utilized graphene oxides
(GOs) for bio-sensing studies by exploiting their ability to quench fluorescence. For
the first time in 2009, Lu et al. reported the detection of fluorophore-labeled DNA
88
J. M. Yoo et al.
GOs’ oxygenated functional groups promote weaker binding with HRP and thus
enabled it to be more dynamic, which ultimately brought its catalytic heme site in
proximity of GOs to induce oxidative degradation (Fig. 4.3). In 2012, the authors
performed similar studies with similar outcomes using myeloperoxidase (MPO),
which has a human analogue as human MPO [48]. The report encourages the use of
functionalized graphene-based nanomaterials for in vivo studies as they can be
readily degraded by peroxidase-related intracellular enzymes. However, experiments must be carried out in a cautious manner as these in vitro outcomes may turn
out to be entirely irrelevant to the actual biodegradation processes in the body.
Besides the fact that oxidative debris of GOs can also be lethal to cells, the levels of
intracellular enzymes may be more dilute in physiological milieu in vivo.
4.4 Graphene-Based Nanomaterials for Biomedical
Applications
4.4.1 Therapeutic Applications
Graphene-based nanomaterials are known to exhibit high absorbance in the NIR
region, which gave rise to novel approaches for NIR laser-triggered selective
ablation of cancer cells [49, 50]. With appropriate modifications with targeting
moieties, graphene-based nanomaterials can specifically target malignant tumor
cells without damaging the healthy ones. Interestingly, graphene-based nanomaterials’ hydrophobic basal plane can be exploited for various synergistic therapies.
Some groups attended to the fact that hydrophobic anti-cancer drugs and photodynamic agents could be easily loaded onto the basal plane of graphene-based
materials through p–p interactions. By combining the photothermal ablation with
either chemotherapies or photodynamic therapies, therapeutic effects came to be
higher [51, 52]. NIR-responsive hyperthermia was not only utilized for the direct
ablation of cells, but also employed as an external cue for controlled drug/gene
delivery by disorganizing a drug-loading matrix or endocytosed vesicles by NIR
laser [53–55]. Moreover, some groups also discovered unusual stem cell growth
and differentiation patterns on graphene substrates, which can be possibly employed
in stem cell engineering and/or stem cell-based therapy [56, 57].
4.4.2 Fluorescence Sensing and Imaging
In addition to the therapeutic applications, people have utilized graphene oxides
(GOs) for bio-sensing studies by exploiting their ability to quench fluorescence. For
the first time in 2009, Lu et al. reported the detection of fluorophore-labeled DNA
88
J. M. Yoo et al.