Topics in Current Chemistry (2020) 378:15
1 3
local accumulation in the desired site and reducing the toxic effect of chemotherapy
[165].
Relevant achievements in the field of nanotechnology to improve cancer treatment include carbon nanotubes loaded with classical therapeutic drugs and other
anticancer agents like siRNA, chemosensitizers, radiosensitizers, and antiangiogenic compounds [166]. Liu et al. [167] developed hyaluronic acid (HA)-modified amino SWVCNTs to target breast cancer cells overexpressing CD44, improving doxorubicin (DOX) deliver. In vitro studies in MDA-MB-231 breast cancer
cells showed an increased intracellular DOX delivery, higher inhibition of proliferation and induction of apoptosis, and decreased cell migration.
The tubular structure of nanotubes is also optimal to attach DNA or RNA molecules to modulate the expression of specific genes [168]. In this sense, Taghavi
et al. [169] functionalized SWCNTs with AS1411 aptamer as ligand to target
tumor cells and with DOX and small interfering RNA (siRNA) molecules to perform chemotherapy and gene therapy, respectively. This nanoplatform increased
cell death in a model of human gastric cancer measured in vitro when compared
to the individual CNT-based treatments or with free DOX. Chang Guo et al. [170]
prepared cationic MWCNT-NH 3
+
to deliver siRNA against polo-like kinase 1
(PLK1) in a lung carcinoma model in vivo. CNTs were injected directly in the
tumoral mass, finding higher efficiency of PLK1 silencing compared to liposomes
due to a higher CNT cell penetration.
The possibilities that carbon nanotubes offers as drug carriers in the treatment of malignant tumors is very large [171–173], but they afford other potential approaches in cancer treatment, like photothermal therapy (PTT) [174]. CNTs
can be used as external agents in PTT because they absorb NIR radiation and
efficiently convert it into heat energy, allowing the ablation of the cells in the
CNT surroundings. Virani et al. used this phenomenon to target bladder cancer
cells [175]. They conjugated SWCNTs with annexin V, which specifically binds
to bladder cancer cells and tested the method in vivo. Once the CNTs reached the
cancer, the tumor was heated using NIR light, inducing cell death and preserving
the healthy bladder wall. They founded no damage on the bladder 24 h after treatment and no tumors were visible. To date, the main approach for PTT with CNTs
has been based on the irradiation by laser or infrared light, limiting the application to superficial tissues due to low penetration capacity, but CNTs can also
be exposed to external electromagnetic fields in a non-contact manner, achieving
higher penetration while obtaining the desired thermal effects [176].
Nowadays, chemoresistant tumors with a high tumor load and in advanced
stages require the combination of different therapies for effective treatment. CNTs
are well suited for this, with carbon-based nanoparticles being used for combining thermal therapy with other therapeutic approaches based on drug delivery
[177]. Wang et al. reported the use of NIR photothermal therapy and RNAi to
enhanced tumor cells death in a prostate cancer model [178]. They synthesized
SWCNTs functionalized with polyethylenimine to allow siRNA complexation,
and decorated the CNT with a peptide motif that specifically binds to tumor cells.
The cancer therapy effect of these CNTs was tested in vitro and in vivo using
PC-3 tumor cells. The CNTs silenced the target gen, causing significant inhibition
198
Reprinted from the journal
1 3
local accumulation in the desired site and reducing the toxic effect of chemotherapy
[165].
Relevant achievements in the field of nanotechnology to improve cancer treatment include carbon nanotubes loaded with classical therapeutic drugs and other
anticancer agents like siRNA, chemosensitizers, radiosensitizers, and antiangiogenic compounds [166]. Liu et al. [167] developed hyaluronic acid (HA)-modified amino SWVCNTs to target breast cancer cells overexpressing CD44, improving doxorubicin (DOX) deliver. In vitro studies in MDA-MB-231 breast cancer
cells showed an increased intracellular DOX delivery, higher inhibition of proliferation and induction of apoptosis, and decreased cell migration.
The tubular structure of nanotubes is also optimal to attach DNA or RNA molecules to modulate the expression of specific genes [168]. In this sense, Taghavi
et al. [169] functionalized SWCNTs with AS1411 aptamer as ligand to target
tumor cells and with DOX and small interfering RNA (siRNA) molecules to perform chemotherapy and gene therapy, respectively. This nanoplatform increased
cell death in a model of human gastric cancer measured in vitro when compared
to the individual CNT-based treatments or with free DOX. Chang Guo et al. [170]
prepared cationic MWCNT-NH 3
+
to deliver siRNA against polo-like kinase 1
(PLK1) in a lung carcinoma model in vivo. CNTs were injected directly in the
tumoral mass, finding higher efficiency of PLK1 silencing compared to liposomes
due to a higher CNT cell penetration.
The possibilities that carbon nanotubes offers as drug carriers in the treatment of malignant tumors is very large [171–173], but they afford other potential approaches in cancer treatment, like photothermal therapy (PTT) [174]. CNTs
can be used as external agents in PTT because they absorb NIR radiation and
efficiently convert it into heat energy, allowing the ablation of the cells in the
CNT surroundings. Virani et al. used this phenomenon to target bladder cancer
cells [175]. They conjugated SWCNTs with annexin V, which specifically binds
to bladder cancer cells and tested the method in vivo. Once the CNTs reached the
cancer, the tumor was heated using NIR light, inducing cell death and preserving
the healthy bladder wall. They founded no damage on the bladder 24 h after treatment and no tumors were visible. To date, the main approach for PTT with CNTs
has been based on the irradiation by laser or infrared light, limiting the application to superficial tissues due to low penetration capacity, but CNTs can also
be exposed to external electromagnetic fields in a non-contact manner, achieving
higher penetration while obtaining the desired thermal effects [176].
Nowadays, chemoresistant tumors with a high tumor load and in advanced
stages require the combination of different therapies for effective treatment. CNTs
are well suited for this, with carbon-based nanoparticles being used for combining thermal therapy with other therapeutic approaches based on drug delivery
[177]. Wang et al. reported the use of NIR photothermal therapy and RNAi to
enhanced tumor cells death in a prostate cancer model [178]. They synthesized
SWCNTs functionalized with polyethylenimine to allow siRNA complexation,
and decorated the CNT with a peptide motif that specifically binds to tumor cells.
The cancer therapy effect of these CNTs was tested in vitro and in vivo using
PC-3 tumor cells. The CNTs silenced the target gen, causing significant inhibition
198
Reprinted from the journal