Quenching of chlorophyll fluorescence induced by silver nanoparticles

• Interaction between chlorophyll and silver nanoparticles was investigated.
• Fluorescence spectroscopy was used for monitoring chlorophyll-nanoparticle interaction.
• Nanoparticles quenched the chlorophyll emission and reduced the fluorescence lifetime.
• Fluorescence suppression was caused by a dynamic quenching process.
• The Stern-Volmer constant was linearly nanoparticle size-dependent.

The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100 nm of diameter). UV–Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678 nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles.

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