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Global Translational Medicine Graphene oxide in cancer drug delivery applications

Table 2. Advantages and disadvantages of different reduced graphene oxide (rGO) synthesis methods
Methods Advantages Disadvantages
Chemical route i. Yields high-quality rGO with desired properties. i. The chemical reduction process is notably slow.
ii. rGO can be readily dispersed in a range of solvents. ii. The use of reducing agents poses significant health hazards.
iii. The resulting rGOs are either nitrogen-doped or
iodine-doped.
Biological route i. Environmentally friendly method. i. The method can involve a long reduction time.
ii. Provides rGO with extended colloidal stability and ii. Prone to contamination, leading to impure rGO.
biocompatibility utilizing plant extracts.
Thermal reduction i. Yield rGO with excellent barrier characteristics. The rGO produced can be brittle due to the high temperatures
ii. Produces rGO with improved electrical properties. used during the process.
Photoreduction i. A cost-effective method with rapid response time and minimal The requirement for sophisticated equipment such as plasma
waste generation. sources and lasers presents certain limitations.
ii. The process can be conducted at room temperature.

groups of GO, facilitating the production of rGO while oxygenated functional groups. In this process, photon
simultaneously releasing water as a by-product. Utilizing energy is converted into thermal energy, resulting in a
plant extracts not only guarantees the extended colloidal decrease in temperature. Reduction can occur through
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stability and biocompatibility of rGO but also promotes either photochemical or photothermal reactions. This
a more environmentally friendly approach compared to technique offers several advantages: it can be performed at
conventional methods. In addition, proteins and sugars, room temperature, allows material patterning without the
such as d-fructose and glycine, have been utilized, with need for masks, and enables contact-free treatment with
improvements in effectiveness achieved through pH controlled reduction, eliminating the need for chemical
adjustment or the use of catalysts. Furthermore, several agents. In some cases, photoreduction is enhanced by
microorganisms are being studied for their capacity the use of inorganic catalysts. Additional benefits include
to reduce GO by utilizing their metabolic activities, cost-effectiveness, rapid response time, and minimal waste
enhancing the reduction process. However, this method generation. Nonetheless, limitations such as the availability
sometimes requires extended reduction times and may of plasma sources and lasers, among other factors, must be
lead to contaminated rGO. 42 considered. 37
3.3. Thermal reduction 4. Roles in cancer drug delivery

Thermal reduction is a widely used method for synthesizing applications
rGO, typically performed in vacuum or inert atmospheres, GO and rGO possess distinct properties that make them
and sometimes in the presence of reducing agents. This suitable for cancer drug delivery applications. 46,47 Graphene
method is often more effective than traditional chemical offers several distinctive characteristics, such as a high
reduction for restoring sp² carbon domains and improving surface area, chemical purity, and the presence of free
the electrical properties of rGO. The thermal treatment π-electrons, making it an effective carrier for therapeutic
entails the annealing of GO, which eliminates functional 48
groups and induces defects. The specific reduction agents. The polyaromatic architecture of graphene,
temperature is determined by the desired properties and coupled with its high surface-to-volume ratio, allows
application of rGO. For instance, heating GO at around for the efficient loading and delivery of drugs to specific
200°C in an argon atmosphere eliminates hydroxyl groups tissues. Furthermore, graphene’s surface can exhibit both
and partially eliminates carboxyl and epoxy groups. After hydrophilic and hydrophobic properties, making its
complete reduction, by-products such as molecular oxygen, physicochemical properties highly flexible, allowing for
CO, and CO₂ are generated. While thermal reduction can functionalization and conjugation with various functional
43
48,49
produce rGO with excellent barrier characteristics, the groups.
process requires high temperatures, and the resulting rGO One study demonstrated the use of a nanosystem
may exhibit brittleness. 44 for targeted drug delivery to cancer cells, utilizing GO
conjugated with methotrexate (MTX) as the therapeutic
3.4. Photoreduction agent and folic acid (FA) as the targeting ligand
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The photoreduction of GO involves the use of lasers, (Figure 1). The drug release kinetics revealed a 96%
plasma, or ultraviolet radiation to partially eliminate release of MTX. The MTX/FA/GO drug delivery system

Volume 3 Issue 3 (2024) 4 doi: 10.36922/gtm.4602