Squamous cell carcinoma is the second most abundant form of skin cancer. Till this day, the most effective treatment strategy for squamous cell carcinoma is surgical removal of the tumor. Photodynamic therapy (PDT) is a localized, non-invasive treatment modality. PDT can be used as an alternative treatment strategy against skin cancers like squamous cell carcinoma. PDT utilizes the combination of a photosensitizer, tissue oxygen and a light source. For the first part of this study, ferrous chlorophyllin (Fe-CHL), the selected photosensitizer, was encapsulated into ethosomes and phosphatidyl choline coated chitosan (PC/CHI) carriers. The aim was to improve topical delivery of Fe-CHL deep in the skin for the potential treatment of squamous cell carcinoma by PDT. The carriers were characterized for size, surface charge and shape. In addition, skin retention and penetration depth of the Fe-CHL carriers across mice skin were assessed using confocal microscopy and high performance liquid chromatography (HPLC). In comparison to PC/CHI, ethosomes showed deeper penetration across mouse skin (down to dermis) via confocal microscope images. While PC/CHI was confined only in the epidermis of the mouse skin. For skin retention studies, ethosomes had higher retention but in comparison to PC/CHI, there was no significant difference. Immunohistochemistry (IHC) staining with TUNEL and Ki67 show no cytotoxicity from the gel formulations of the carriers and maintained skin structure. The PDT effect of the carriers against squamous cell carcinoma monolayer and 3D spheroids were studied. PC/CHI showed a higher cytotoxic effect than ethosomes using MTT assay. Higher cell disintegration was also observed for PC/CHI after laser exposure using live confocal microscopy. In addition, in 3D spheroids, PC/CHI showed higher cytotoxic effects and a higher decrease in spheroid size was observed using acid phosphatase assay and light microscopy respectively. Depending on tumor skin localization, it was concluded that both carriers can be used for the potential treatment of squamous cell carcinoma using PDT. For the second part of this study, the photosensitizer selected was chlorin e6 (Ce6), an FDA approved and natural chlorophyll derivative. Ce6 was loaded into ethosomes and upon laser exposure, it was found that singlet oxygen production was not significantly affected. The PDT effect of Ce6 ethosomes against squamous cell carcinoma resulted in enhanced caspase 3/7 activity and mitochondrial superoxide levels – light dose and concentration dependent cytotoxic effects. Deep penetration was observed into 3D spheroids and when exposed to laser irradiation, a reduction in size, viability and proliferation was observed. When compared to normal skin fibroblast spheroids, PDT effect of Ce6 loaded ethosomes showed enhanced and specific cytotoxic effects against squamous cell carcinoma 3D spheroids. Finally, PDT effect of Ce6 carrier was evaluated in xenografts of squamous cell carcinoma grown on chorioallantoic membranes of chick eggs (CAM). An increase in terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining and a reduction in expression of Ki-67 proliferation marker was observed, indication activation of apoptosis and reduced proliferation respectively. The results show that Ce6-loaded ethosomes can be used as a formulation of choice for the PDT of squamous cell carcinoma.