A simple surface modification process that conjugates a photosensitizer, photoporphyrin IX (PpIX), with mesoporous silica nanoparticles (MSNs) through covalent bonding to yield PpIX-modified for photodynamic therapy (PDT) study, was reported. In-vitro tests performed with HeLa cells revealed high cellular uptake efficiency and the phototoxicity was found to be both irradiation time and dosage dependent. Well-dispersed MSNs were synthesized in ammonium solution containing dilute tetraethyl orthosilicate (TEOS) and a low surfactant concentration. The surfactant templates were removed by the extraction in acidic ethanol to obtain surfactant-free MSNs. Amine-functionalized MSNs were obtained by post-modification of Ext-MSNs with 3-aminopropyl-trimethoxysilane (APTMS). The amine group then conjugated with activated PpIX to form PpIX-MSNs. Elemental analysis and the UV/Vis absorption spectrum were used to estimate the concentration of PpIX on PpIX-MSNs. The surface area, pore size, and pore volume were all decreased with APTMS and PpIX.
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