Abstract
M.Sc. (Biochemistry)
Cancer, defined as the uncontrollable proliferation of cells, is one of the most challenging
diseases worldwide to effectively control and treat. Several consequences, such as the
diversity of a tumour, potential side effects and the resistance to favourable drugs have
hindered any success towards an effective and reliable form of treatment (Bradbury, et al.,
2007). Melanoma has a high proliferative index, a high metastatic potential and is
exceedingly invasive. Therefore, it is one of the most defiant types of cancer to treat as it
inherently resists traditional forms of modern therapeutics such chemotherapy and ionizing
radiation. The development of an alternative and enhanced therapeutic modality is
therefore supported (Davids, et al., 2011 and Zbytek, et al., 2008).
Photodynamic therapy (PDT) is an invasive therapeutic modality, which relies on the basis
of light and the production of reactive oxygen species (ROS) to damage a cell. It has been
presented as a successful type of treatment for several types of superficial cancers (Sung
and Kim, 2017), whereby the cancer cells are limited to the submucosa or are non-muscle
invasive, such as oesophageal, bladder and colon cancer (Murata, et al., 2006 and Stecco,
et al., 2015).
This study was formerly established with the idea that the novel photosensitizer free base
5, 10, 15, 20 – Tetrakis (4-hydroxyphenyl) – 21H, 23H-porphine (H2THPP) encapsulated
within PEG2000-DSPE polymers had the potential for application in PDT. H2THPP-PDT
could then be utilized as an alternative therapeutic modality, either alone or with the aid of
modern therapeutics, to effectively treat melanoma. However, during practical application,
H2THPP (PEG2000-DSPE) was insoluble and presented unwanted dark toxicity, without
irradiation activation.
As a result, to increase efficiency as an effective photosensitizer and to decrease unwanted
toxicity presented by H2THPP; silver ions (Ag+) and palladium ions (Pd2+) were coordinated
to THPP. Both Ag(I)- and Pd(II)THPP required encapsulation in PEG2000-DSPE polymers,
as both derivatives were similar in solubility profiles to its parent (H2THPP). Therefore, it
was essential to investigate whether Ag(I) and Pd(II) metal coordinated derivatives of the
free base H2THPP-PDT, enhanced phototoxicity and was an effective treatment for in vitro
melanoma cancer cells...