Cells from a human fibroblast cell line (HeLa) were used to explore the role of photothermal and photodynamic effects of laser irradiation using plasmonic gold nanoparticles. The two types of spherical gold nanoparticles used were (i) citrate- stabilised and (ii) peptide stabilised particles. These particles were prepared following standard protocols and characterised by a range of methods including TEM, UV-vis spectroscopy and dynamic centrugal sedimentation. Different sizes of particles were prepared and the effect of size was investigated. Cellular uptake of the nanoparticles prior to exposure to laser light was quantified by TEM and by ICP-AES. Cell cultures were exposed to a laser of a wavelength within the plasmon band of the gold nanoparticles (520 nm), and cell death was monitored by optical microscopy using the standard Trypan blue exclusion assay. The total energy transfer from the laser to the cell culture was estimated based on the extinction coefficient of the nanoparticles and also measured directly by UV-vis spectroscopy. Heating profiles for a range of laser intensities and exposure times were calculated. The temperature at which thermal cell death occurs was estimated by exposing the cells to a heated water bath and monitoring viability. Conditions were established to demarcate photothermal from photodynamic cell death, and a photodynamic mechanism was suggested based on the photochemical production of singlet oxygen. The plausibility of this mechanism was demonstrated by quantitative studies of singlet oxygen formation by laser irradiation of gold nanoparticles dispersed in water.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:677605 |
| Date | January 2015 |
| Creators | Chadwick, Samantha |
| Publisher | University of Liverpool |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://livrepository.liverpool.ac.uk/2038139/ |
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