Biomedical Engineering Reference
In-Depth Information
they contacted with the bacteria. Liu et al. discovered fascinating antibac-
terial properties of various graphene derivatives (i.e., graphite, graphite
oxide, GO, and reduced GO) toward Escherichia coli are regulated through
the cell membrane, and oxidative stress similar to that for the carbon
nanotubes [26]. Due to low cost and the ability to mass produce graphene-
based materials, it is hoped that graphene-based antibacterial products
will fi nd wide clinical and environmental applications in the near future.
GO is considered an ideal nanocarrier for drugs/genes due to unique
structural and physicochemical properties, such as planar and high sur-
face area, oxygen-containing functional groups, solubility in the physi-
ological conditions, biocompatibility, and capability of carrying drugs/
genes through both physisorption and chemical approaches. In particu-
lar, -COOH and -OH functional groups of GO facilitate its conjugation
with various targets ranging from biomolecules [27], nanoparticles [28],
to quantum dots [29]. For instance, nanographene oxide has been dem-
onstrated to effi ciently deliver high amounts of gentamicin sulfate (i.e.,
2.57 mg/mL) as an antibiotic and water insoluble drug into cells [30].
The drug was bound to the GO nanosheets through the hydrophobic
interactions and π-π stacking between the GO and aromatic parts of the
drug. This study revealed the potential applications of GO to deliver a
whole class of aromatic and water insoluble drugs. The pH-responsive
drug release has also been observed using GO sheets [31]. Pan et al. also
created a thermo-responsive drug delivery system using poly(N-isopro-
pylacrylamide) attached to the graphene sheets [32]. GO derivatives have
also shown great promise in gene delivery and therapy [33]. Gene therapy
needs a gene vector to avoid the nuclease degradation of DNA and to
ensure high transfection effi ciency of DNA by cells [34]. A major obstacle
in developing the gene therapy approach is in fi nding safe and highly
effi cient gene vectors [35]. GO derivatives, such as polyethylenimine-
modifi ed GO [21] and chitosan-functionalized GO [36], have shown great
potential for effi cient gene delivery.
Graphene-based materials have been extensively employed for bio-
sensing and detection [37, 38] mainly based on the following principles:
(i) high yield in fl uorescence quenching [39], (ii) unique electrical proper-
ties [40], (iii) ease of self-assembling with biomolecules [41], (iv) high sur-
face area, and (v) capability to load various biomolecules through physical
or chemical bindings [42]. For instance, graphene-based electrochemical
devices have been largely used for biomarker detection. These devices
rely on the ballistic electron transport properties of graphene that facilitate
the electron transfer between the electrode and underlying sample and
thus improve the electrochemical feedback. Lin et al. fabricated an electro-
chemical biosensor for ultra-highly sensitive detection of phosphorylated
p53 using the GO as a carrier [43]. Application of nanomaterials for bio-
sensing and detection in vivo has always been restricted because of their
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