with GOs; the fluorescence of fluorophore-labeled single-stranded DNA is quenched by GOs, where it can be instantly recovered by adding its complementary
sequence [58]. With further surface modifications on GOs, other groups also
reported the detection of other small biological molecules including protein kinases,
neurotransmitters, and metabolites with phosphates [59–62]. Rationally designed
GOs were also employed in the discrimination of Fe
2+ and Fe
3+ in living cells based
on the level of fluorescence quenching [63].
A number of studies focused on the graphene-based nanomaterials’ outstanding
optical properties for various imaging applications. As mentioned, GQDs exhibit
respectably high photoluminescence without the issue of serious toxicity or photobleaching, which can also be tuned by appropriate size/edge modifications.
Recently, many groups exploited these properties in various photothermal therapy
and drug delivery systems to yield in situ imaging upon therapies. Nahain et al.
used 20 nm-sized GQDs to track the successful targeting of overexpressed CD44
receptors in cancer cells [64]. The authors prepared GQDs-hyaluronic acid
(HA) conjugate to target the receptors, where their localization in the tumor tissue
could be monitored with GQDs’ intrinsic fluorescence both in vitro and in vivo
(Fig. 4.4). Anti-cancer treatment was subsequently achieved by loading doxorubicin on the plane of GQDs, which was immediately released under acidic conditions. In 2014, Ge et al. demonstrated more advanced photodynamic anti-cancer
therapy with a few nanometer-sized GQDs [65]. Notably, the synthesized GQDs
exhibited a broad absorption range with distinct emission at 680 nm. The authors
exploited these optical properties and utilized them as novel photodynamic agents,
which can generate singlet oxygen with respectable pH-and photostability in both
in vivo and in vitro trials. Moreover, they could simultaneously track the whole
process with fluorescence imaging.
In 2013, Zheng et al. utilized GQDs as a novel fluorophore to reveal unknown
biological functions [66]. In this study, the authors specifically labeled and tracked
the dynamic movements of insulin receptors in adipocytes with GQDs’ fluorescence to confirm the specific biological roles of a few neighboring proteins
(Fig. 4.5). Through the dynamic tracking, they found that two distinct proteins
regulate insulin receptor’s internalization and recycling in an opposite manner:
while TNF a improves the insulin resistance, apelin enhances the insulin sensitivity.
Although this study alone cannot bring momentous changes in diabetes treatments,
the report is remarkable as they utilized GQDs’ fluorescence to divulge unknown
cellular functions while previous researchers exploited GQDs’ fluorescence merely
on tracking drug delivery by monitoring successful targeting.
90
J. M. Yoo et al.
sequence [58]. With further surface modifications on GOs, other groups also
reported the detection of other small biological molecules including protein kinases,
neurotransmitters, and metabolites with phosphates [59–62]. Rationally designed
GOs were also employed in the discrimination of Fe
2+ and Fe
3+ in living cells based
on the level of fluorescence quenching [63].
A number of studies focused on the graphene-based nanomaterials’ outstanding
optical properties for various imaging applications. As mentioned, GQDs exhibit
respectably high photoluminescence without the issue of serious toxicity or photobleaching, which can also be tuned by appropriate size/edge modifications.
Recently, many groups exploited these properties in various photothermal therapy
and drug delivery systems to yield in situ imaging upon therapies. Nahain et al.
used 20 nm-sized GQDs to track the successful targeting of overexpressed CD44
receptors in cancer cells [64]. The authors prepared GQDs-hyaluronic acid
(HA) conjugate to target the receptors, where their localization in the tumor tissue
could be monitored with GQDs’ intrinsic fluorescence both in vitro and in vivo
(Fig. 4.4). Anti-cancer treatment was subsequently achieved by loading doxorubicin on the plane of GQDs, which was immediately released under acidic conditions. In 2014, Ge et al. demonstrated more advanced photodynamic anti-cancer
therapy with a few nanometer-sized GQDs [65]. Notably, the synthesized GQDs
exhibited a broad absorption range with distinct emission at 680 nm. The authors
exploited these optical properties and utilized them as novel photodynamic agents,
which can generate singlet oxygen with respectable pH-and photostability in both
in vivo and in vitro trials. Moreover, they could simultaneously track the whole
process with fluorescence imaging.
In 2013, Zheng et al. utilized GQDs as a novel fluorophore to reveal unknown
biological functions [66]. In this study, the authors specifically labeled and tracked
the dynamic movements of insulin receptors in adipocytes with GQDs’ fluorescence to confirm the specific biological roles of a few neighboring proteins
(Fig. 4.5). Through the dynamic tracking, they found that two distinct proteins
regulate insulin receptor’s internalization and recycling in an opposite manner:
while TNF a improves the insulin resistance, apelin enhances the insulin sensitivity.
Although this study alone cannot bring momentous changes in diabetes treatments,
the report is remarkable as they utilized GQDs’ fluorescence to divulge unknown
cellular functions while previous researchers exploited GQDs’ fluorescence merely
on tracking drug delivery by monitoring successful targeting.
90
J. M. Yoo et al.