Effect of Silver Nanoparticles on the Photophysics of Riboflavin: Consequences on the ROS Generation

Abstract

Fluorescence lifetimes of Rf in the absence and presence of Pec.AgNP (Table S1)…………………………………….S3Emission spectra of Rf in the absence and presence of Pec.AgNP (Figure S2)…………………………………………….S4 Calculation of the diffusion-controlled rate constant with the Smoluchowski equation……………………………….S5

Photodynamic Therapy in HeLa Cells Incubated with Riboflavin and Pectin‐coated Silver Nanoparticles

“…This result is in line with the increase of O 2 ( 1 Δ g ) yield produced by Rf in the presence of Pec@AgNP, which was previously demonstrated in time‐resolved phosphorescence experiments. According to the phosphorescence assays, a larger increment in rate of oxygen uptake is expected for concentrations of Pec@AgNP higher than those employed in the present work .…”

“…In this paper, we proved that incubation of HeLa cells with normal cell medium containing additionally Rf and Pec@AgNP lead to the incorporation of both the dye and the nanomaterial. We have previously demonstrated that a 1:1 complex (Rf‐Pec@AgNP) between Rf and Pec@AgNP is formed . While it is not possible for us to determine directly, that is, by spectroscopic means, whether and to which extent the complex exists, when incorporated into the cells, we have here given evidence for the synergistic photodamage effect by the nanoparticles and Rf (see Figs.…”

“…We have prepared pectin‐coated silver nanoparticles according to the reported procedure . A typical TEM image and its corresponding histogram are shown in Fig.…”

“…This is interpreted as a consequence of the presence of Rf and Pec@AgNP in the same intracellular microenvironment. According to a previous publication of our laboratory, the enhancement of the amount of ROS (O 2 ( 1 Δ g ) and ) generated by Rf in the presence of Pec@AgNP is a consequence of the decay of the excited state of the complex Rf‐Pec@AgNP*, which feeds the triplet state of Rf ( 3 Rf*) (Scheme ). Thus, we here propose that the uptake of the complex is the responsible for the increased photodamage effect observed when Pec@AgNP and Rf are present (see MTT in Fig.…”

“…More recently, we have shown by time‐resolved absorption spectroscopy that the decay of the excited state of the complex formed by Rf with pectin‐coated Ag nanoparticles (Pec@AgNP) in aqueous solution feeds 3 Rf* excited state. As a result, the amounts of 3 Rf*, O 2 ( 1 Δ g ), and superoxide radical anion, , generated by Rf are enhanced in the presence of the nanoparticles .…”