Modern medicine has been searching for new and more efficient strategies for diagnostics and therapeutics applications. Considering this, porphyrin molecules have received great interest for applications in photodiagnostics and phototherapies, even as magnetic nanoparticles for drug-delivery systems and magnetic-hyperthermia therapy. Aiming to obtain a multifunctional system, which combines diagnostics with therapeutic functions on the same platform, the present study employed UV/vis absorption and fluorescence spectroscopies to evaluate the interaction between meso-tetrakis(p-sulfonatofenyl)porphyrin (TPPS) and maghemite nanoparticles (γ-FeO). These spectroscopic techniques allowed us to describe the dynamics of coupling porphyrins on nanoparticles and estimate the number of 21 porphyrins per nanoparticle. Also, the binding parameters, such as the association constants (K = 8.89 × 10 M) and bimolecular quenching rate constant (k = 2.54 × 10 M s) were obtained. These results suggest a static quenching process where the electrostatic attraction plays an essential role. The work shows that spectroscopic techniques are powerful tools to evaluate the coupling of organic molecules and nanoparticles. Besides, the system studied provides a relevant background for potential applications in bionanotechnology and nanomedicine, such as (1) nanodrug delivery system, (2) photodiagnostics/theranostics, and/or (3) a combined action of photodynamic and hyperthermia therapies, working in a synergetic way.

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In this work, the photodynamic efficiency of anionic meso-tetrakis sulfonophenyl (TPPS4), cationic meso-tetrakis methylpyridiniumyl (TMPyP) and their zinc complexes (ZnTPPS4 and ZnTMPyP) in the inactivation of Bovine herpesvirus type 1 (BoHV-1) was evaluated. At a non-cytotoxic concentration, all porphyrins showed significant antiviral activity after irradiation using a halogen lamp. The efficiency of the cationic porphyrins was higher than that of the anionic ones. Porphyrin complexation with zinc increases its lipophilicity and the number of absorbed photons, dramatically reducing the time for complete virus inactivation. The high superposition of the compound optical absorption and light source emission spectra played a key role in the virus inactivation efficiency. The results demonstrated the high effectivity of the photodynamic inactivation of BoHV-1. This method can be used as an auxiliary in the treatment of disorders attributed to BoHV-1 infection, and the porphyrins are promising photosensitizers for this application.

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