Biomedical Applications of Carbon-Based Nanomaterials
169
Gene therapy is the deletion/replacement of defective genes through the delivery
and expression of the exogenous gene. CQDs have shown great potential in delivering
genes with their electrostatic interaction between positively charged functionalized
CDs and negatively charged nucleic acids. Plasmid DNA loaded-CQDs can be used
in bioimaging, gene delivery and tissue engineering due to their superior capacity
to condense plasmid DNA [71]. They are used as a gene vector for chondrogenesis
from fibroblasts. By using CDs, the plasmid SOX9 was used to form nanoparticles
with size ranging from 10 to 30 nm with excellent properties with low toxicity and
high fluorescence [72].
The turn on-off theranostic application of CQDs were reported against
hyaluronidase in cancer cells for self-targeted drug delivery. The CDs were coated
with polyethyleneimine (PEI) via electrostatic interaction and functionalized with
hyaluronic acid-Doxocubicin conjugate (p-CDs-HA-Dox). This conjugate was able
to penetrate the cells with the target site on the cancer cells and successfully targeted
bio-imaging and delivery vehicles for cancer therapy [73].
5.3 Bio-imaging
Carbon dots (CDs) with optical properties have been extensively used as fluorophores
in the bio-imaging of cells and tissues for in vivo and in vitro applications. They
have excellent biocompatibility, small size, broad absorption and narrow emission
spectra with multicolored fluorescence properties suitable for biomedical applications. Several kinds of research have used CQDs over organic dyes and fluorescent
proteins because of the imaging sensitivity, stability, and brightness. Earlier, semiconductor QDs have been used for in vitro and in vivo imaging; however, it caused
aggregation in the tissues leading to toxicity. To overcome the toxicity of conventional QDs, these carbon dots have been used in live-cell imaging due to their small
size with strong fluorescent and non-blinking activity compared to the commercial
QDs. The smaller size of CDs provides efficient probing of biological structures and
it reduces the in vivo injection volume [74]. Plant cells have a rigid cell wall, so it
is more complicated than animal cells for in vivo imaging of cells. In a study, N and
S heterodoped CDs were prepared for in vivo imaging of plant cells and the results
indicated the successful penetration inside the cells, which suggested that CDs can
be used for in vivo cell imaging for plants [70].
6 Carbon Nanohorns
Carbon nanohorns are one form of carbon nanomaterials closely related to nanotubes
with narrowest opening and five pentagonal rings in its apex. Their average diameter size is 100 nm with a peculiar geometry similar to sponge with high porosity
large surface area [71–75]. They have high affinity and absorbing capacity for
169
Gene therapy is the deletion/replacement of defective genes through the delivery
and expression of the exogenous gene. CQDs have shown great potential in delivering
genes with their electrostatic interaction between positively charged functionalized
CDs and negatively charged nucleic acids. Plasmid DNA loaded-CQDs can be used
in bioimaging, gene delivery and tissue engineering due to their superior capacity
to condense plasmid DNA [71]. They are used as a gene vector for chondrogenesis
from fibroblasts. By using CDs, the plasmid SOX9 was used to form nanoparticles
with size ranging from 10 to 30 nm with excellent properties with low toxicity and
high fluorescence [72].
The turn on-off theranostic application of CQDs were reported against
hyaluronidase in cancer cells for self-targeted drug delivery. The CDs were coated
with polyethyleneimine (PEI) via electrostatic interaction and functionalized with
hyaluronic acid-Doxocubicin conjugate (p-CDs-HA-Dox). This conjugate was able
to penetrate the cells with the target site on the cancer cells and successfully targeted
bio-imaging and delivery vehicles for cancer therapy [73].
5.3 Bio-imaging
Carbon dots (CDs) with optical properties have been extensively used as fluorophores
in the bio-imaging of cells and tissues for in vivo and in vitro applications. They
have excellent biocompatibility, small size, broad absorption and narrow emission
spectra with multicolored fluorescence properties suitable for biomedical applications. Several kinds of research have used CQDs over organic dyes and fluorescent
proteins because of the imaging sensitivity, stability, and brightness. Earlier, semiconductor QDs have been used for in vitro and in vivo imaging; however, it caused
aggregation in the tissues leading to toxicity. To overcome the toxicity of conventional QDs, these carbon dots have been used in live-cell imaging due to their small
size with strong fluorescent and non-blinking activity compared to the commercial
QDs. The smaller size of CDs provides efficient probing of biological structures and
it reduces the in vivo injection volume [74]. Plant cells have a rigid cell wall, so it
is more complicated than animal cells for in vivo imaging of cells. In a study, N and
S heterodoped CDs were prepared for in vivo imaging of plant cells and the results
indicated the successful penetration inside the cells, which suggested that CDs can
be used for in vivo cell imaging for plants [70].
6 Carbon Nanohorns
Carbon nanohorns are one form of carbon nanomaterials closely related to nanotubes
with narrowest opening and five pentagonal rings in its apex. Their average diameter size is 100 nm with a peculiar geometry similar to sponge with high porosity
large surface area [71–75]. They have high affinity and absorbing capacity for