For the past few decades, the popularity of graphene oxide (GO) nanomaterials
(NMs) has increased exceedingly due to their biomedical applications in drug
delivery of anti-cancer drugs. Their unique physicochemical properties such as
high surface area and good surface chemistry with unbound surface functional
groups (e.g. hydroxyl - OH, carboxyl /ketone C=O, epoxy/alkoxy C-O, aromatic
group C=C, etc) which enable covalent bonding with organic molecules (e.g.
RNA, DNA) make GO NMs as excellent candidates in drug delivery nanocarriers.
Despite the overwhelming biomedical applications, there are concerns about their
genotoxicity on human DNA. Published genotoxicity studies on GO NMs were
performed using non-commercial GO with 2-3 layers of GO sheets, synthesized
in various laboratories with the potential for inter-laboratory variabilities. However,
what has not been studied before is the effects of the commercial GO (15-20
sheets; 4-10% edge-oxidized; 1 mg/mL) in vitro on DNA damage in human whole
blood and peripheral blood lymphocytes (PBL) from real-life patients diagnosed
with chronic pulmonary diseases [asthma, chronic obstructive pulmonary disease
(COPD), and lung cancer], and genotoxic endpoints compared with those from
healthy control individuals to determine whether there are any differences in GO
sensitivity. Thus, in the present study, we had characterized GO NMs using
Zetasizer Nano for Dynamic Light Scattering (DLS) and zeta potential (ZP) in the
aqueous solution, and electron microscopy using the Scanning Electron
Microscope (SEM) and Transmission Electron Microscope (TEM) in the dry state,
respectively. Cytotoxicity studies were conducted on human PBL from healthy
individuals and patients (asthma, COPD, and lung cancer) using the
Methylthiazolyldiphenyl-tetrazolium bromide (MTT) and Neutral Red Uptake
(NRU) assays, respectively. The genotoxicity (DNA damage) and cytogenetic
effects (chromosome aberration parameters) induced by GO NMs on human
whole blood from healthy individuals and patients were studied using the Alkaline
Comet Assay and Cytokinesis-blocked Micronucleus (CBMN) assay,
respectively. Our results showed concentration-dependent increases in
cytotoxicity, genotoxicity, and chromosome aberrations, with blood samples from
COPD and lung cancer patients being more sensitive to DNA damage insults
compared with asthma patients and healthy control individuals. Furthermore, the
relative gene and protein expressions of TP53, CDKN1A/p21, and BCL-2 relative
to GAPDH on human PBL were studied using the Reverse Transcription
Quantitative Polymerase Chain Reaction (RT-qPCR) and Western Blot
techniques, respectively. Our results have shown altered gene and protein
expression levels. Specifically, GO-induced cytotoxicity, genotoxicity, and
micronuclei aberrations were associated with TP53 upregulation - a biomarker of
DNA damage - in both patients and healthy individuals. These effects show that
GO NMs have promising roles in drug delivery applications when formulated to
deliver drug payload to COPD and cancer cells. However, the fact that cytotoxicity, genotoxicity, chromosome instability, and gene/protein expressions
- biomarkers of cancer risk - were observed in healthy individuals are of concern
to public health, especially in occupational exposures at micro levels at the
workplace.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/18685 |
| Date | January 2019 |
| Creators | Amadi, Emmanuel E. |
| Contributors | Anderson, Diana, Najafzadeh, Mojgan |
| Publisher | University of Bradford, Faculty of Life Sciences |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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