Photodynamic therapy (PDT) is an emerging treatment modality that employs the photochemical interaction of three components. These are light of suitable wavelength, photosensitizer, and singlet oxygen. The main objective of this work is the determination of pharmacokinetics of different photosensitizers after laser irradiation in different biological samples like cell lines and tissues to improve the efficacy of PDT. Present study investigates the dynamic behaviour of different photosensitizers under laser irradiation e.g. (a) biodistribution of Photofrin® (b) laser induced effects (c) depth of necrosis under exposure of different wavelengths of light sources (d) synergistic effect of toxicity of ZnO nanostructures bare and conjugated with photosensitizers like Aminolevulinic acid (5-ALA), Photofrin® and protoporphyrin dimethyl ester (PPDME) determined for the treatment of localized cancer cells.