Protoporphyrin IX (PpIX) conjugated gold nanoparticle (GNP) was synthesized, characterized, and used for the delivery of a hydrophobic photosensitizer to a cervical cancer cell line. The GNP conjugates have an average diameter of 7 nm. The conjugated GNPs were made by a single coupling reaction. Protoporphyrin absorbs radiation at 630 nm and catalytically produces the reactive oxygen species in high efficiency. These properties indicate that PpIX-GNP conjugates could be used as a photosensitizer in photodynamic therapy (PDT) through the formulation of singlet oxygen. The conjugates were tested on Hela cells. PDT efficacy of the system was evaluated with the MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. The effect of photon-induced toxicity was assesed by comparing it with control experiments. Our findings suggest that the PpIX-GNP conjugate is an excellent carrier for the delivery of surface bound hydrophobic protoporphyrin molecule into the cell which makes PpIX- GNP conjugates potential candidates for PDT.

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