Targeted drug delivery system using nanoparticles is a promising strategy for efficient Photodynamic therapy (PDT) as they have the potential to overcome the problems of photosensitizer and enhance the effectiveness and specificity of PDT. In this study, Protoporphyrin IX (PpIX) conjugated gold nanoparticles were synthesized using electrostatic and covalent conjugation scheme. Folic acid (FA) was also conjugated suitably to the covalent complex to vectorize the complex. Optical characterizations of the complex prove the formation of the complex. The size of the synthesized nanocomplexes was studied using light scattering measurements. The photo-toxicity of the free PpIX and PpIX-nanoparticle complexes were studied using MTT assay technique against Vero and HeLa cell lines. These In-vitro results of this study indicates that, the nanoparticle complexes are more phototoxic compared to free PpIX, with the covalent complex being the better of the two complexes and the folate-mediated nanocomplex is the superior of the studied complexes. These results ensures that nanoparticle conjugated photosensitizers equipped with FA may be an effective drug delivery mechanism for PDT.

in).Cancer is of various kinds, so are the treatment modalities. Worldwide, cancer is the second leading cause of death, accounting for a whopping 9.6 million deaths in 2018. Globally, approximately one in six deaths is attributed to cancer. Photodynamic therapy (PDT) is a therapeutic strategy for the treatment of superficial lesions, warts, Barrett's esophagus, premalignant lesions, malignant tumors, and ophthalmic diseases. The literature on PDT is approximately one-third of that in radiation therapy, yet the clinical implementation of PDT in cancer is relatively less. Despite substantial research, the clinical application of photodynamic strategy in cancer therapy is still in its infancy with only a limited number of case studies reported so far. The limitations of the photosensitizer and the shallow depth of penetration of light source are the key technical impediments. However, the use of nanomedicine in PDT can overcome these obstacles. Thus, it is necessary to gain knowledge on how nanomaterials can be merged with PDT and how it can be utilized in cancer theranostics. In this article, the focus is to understand how PDT works and how it can be utilized in improving the sensitivity of the existing diagnostic and therapeutic techniques. The article also addresses the current challenges for PDT and the future prospects of this technique, particularly in the area of diagnosis and treatment of cancer. AbstractKeywords ► cancer ► photodynamic therapy ► nanoparticles ► theranostics