Since the discovery of carbon nanotubes (CNTs), they have gained much
interest in many science and engineering fields. The modification of CNTs by
introducing different functional groups to their surface is important for CNTs to be
tailored to fit the need of specific applications. This dissertation presents several
CNT-based systems that can provide biomedical and environmental advantages.
In this research, polyethylenimine (PEI) and polyvinyl alcohol (PVA) were used
to coat CNTs through hydrogen bonding. The release of doxorubicin (DOX, an anticancer
drug) from this system was controlled by temperature. This system represents
a promising method for incorporating stimuli triggered polymer-gated CNTs in
controlled release applications.
To create an acid responsive system CNTs were coated with 1,2-Distearoyl-snglycero-
3-Phosphoethanolamine-N-[Amino(Polyethylene glycol)2000]-(PE-PEG) and
Poly(acrylic acid) modified dioleoy lphosphatidyl-ethanolamine (PE-PAA). An acidlabile
linker was used to cross-link PAA, forming ALP@CNTs, thus making the
system acid sensitive. The release of DOX from ALP@CNTs was found to be higher
in an acidic environment. Moreover, near infrared (NIR) light was used to enhance
the release of DOX from ALP@CNTs. A CNT-based membrane with controlled diffusion was prepared in the next
study. CNTs were used as a component of a cellulose/gel membrane due to their
optical property, which allows them to convert NIR light into heat. Poly(Nisopropylacrylamide)
(PNIPAm) was used due to its thermo-sensitivity. The
properties of both the CNTs and PNIPAm’s were used to control the diffusion of the
cargo from the system, under the influence of NIR.
CNTs were also used to fabricate an antibacterial agent, for which they were
coated with polydopamine (PDA) and decorated with silver particles (Ag). Galactose
(Gal) terminated with thiol groups conjugated with the above system was used to
strengthen the bacterial targeting ability. The antibacterial activity of
Ag/Gal@PDA@CNTs was examined on Escherichia coli. NIR was used to enhance
the antibacterial activity of Ag/Gal@PDA@CNTs.
Finally, CNTs were used as a support for methyl orange (MO) and palladium
catalysts (Pd). MO was used due to its ability to enhance the catalyst activity.
Pd@CNTs composites were used to test the reduction rate of nitrite with and without
the addition MO. The results showed that over repeated cycles of nitrite reduction, the
activity enhancement was lost.
In summary, CNTs are promising building blocks for preparation of smart and
stimuli responsive systems that have potential for a wide range of applications. The
methods presented are simple and can be scaled up for industrial processing purposes.
|Date of Award||May 2015|
- Biological, Environmental Science and Engineering
|Supervisor||Niveen Khashab (Supervisor)|
- Carbon Nanotubes
- Surface Modification
- Drug Delivery
- Near Infrared