Biomedical Engineering Reference
In-Depth Information
into zero-dimensional fullerenes, rolled into one-dimensional nanotubes, or stacked into
three-dimensional graphite. Electrons in graphene were found to obey a linear dispersion
relation; since they behave like massless relativistic particles, they form the base for all of
graphene's peculiar electronic property. These electrons move ballistically in the graphene
layer without scattering, with mobility exceeding 15,000 m
2
V
−1
s
−1
at room temperature.
Graphene can be synthesized via chemical reduction of exfoliated graphitic oxide (GO) as
described by Stankovich et al. [65]. GO can be produced by any of the oxidative treatments
of graphite reported by Brodie [66], Hummers and Offeman [67], and Staudenmaier [68].
According to Wang et al. [69], few-layered substrate-free graphene can also be synthesized
by the CVD of methane over cobalt supported on magnesium oxide at 1000°C in a gas flow
of argon. Approximately 50 mg of few-layered graphene can be obtained under the experi-
mental conditions set up by Wang et al. [69].
BiomedicalApplicationsofCarbon-BasedMaterials
Biomedical Utility of CNTs
CNTs possess important characteristics such as high aspect ratio, ultralight weight, high
mechanical strength, high electrical conductivity, high thermal conductivity, metallic or
semimetallic behavior, and high surface area. The combination of all these characteristics
makes CNTs an appropriate and unique material that holds potential for diverse applica-
tions [70-75]. To date, there has been an increasing interest among biomedical scientists in
exploring all of the foretold properties that CNTs possess for nanobiotechnology applica-
tions. For instance, at present, CNTs are considered a suitable substrate for the growth of
cells for tissue regeneration, as delivery systems for a variety of diagnostic or therapeutic
agents, or as vectors for gene transfection [75]. Here we describe a few potential biomedical
applications of CNTs that has been well established
CNTs for Therapeutic Applications
Initially, the application of CNTs as a template for targeting bioactive peptides to the
immune system was studied in detail by Guiseppi-Elie et al. [76]. These peptide-modified
CNTs bioconstructs were found to mimic the appropriate secondary structure for recogni-
tion by specific monoclonal and polyclonal antibodies. After this, the immunogenic fea-
tures of peptide-based CNTs conjugates were subsequently assessed in vivo. Immunization
of mice with peptide-CNTs conjugates provided high antibody responses than the free
peptide upon comparison. Moreover, the antibodies displayed virus-neutralizing ability.
The use of CNTs as a potential and novel vaccine delivery tools was further confirmed by
studying the interaction with complement factors [77]. Surfactant proteins A and D are
collectin proteins that are secreted by airway epithelial cells present in the lung, and they
play an important role in first-line defense against infection within the lung. Furthermore,
the interaction between CNTs and proteins contained in lung surfactant by using sodium
dodecyl sulfate-polyacrylamide gel electrophoresis was demonstrated by Salvador-
Morales et al.
[78] (by using a novel technique known as affinity chromatography based
on CNTs—Sepharose matrix and electron microscopy data), which showed that surfactant
proteins selectively bind to CNTs. The study of CNTs mediated oligonucleotide transport
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