Singlet oxygen imaging in polymeric nanofibers by delayed fluorescence

Area of Science:

• Materials Science
• Photochemistry
• Biomedical Engineering

Background:

• Polymeric nanofibers loaded with photosensitizers show promise for antibacterial applications.
• Photosensitizers generate cytotoxic singlet oxygen upon light activation, crucial for antimicrobial effects.

Purpose of the Study:

• To monitor photosensitized processes in polystyrene (PS) and gelatin (GE) nanofibers.
• To investigate the generation and localization of singlet oxygen within these nanofiber systems.

Main Methods:

• Time-gated fluorescence imaging was employed to study tetraphenylporphyrin (TPP) loaded PS and GE nanofibers.
• Singlet oxygen-sensitized delayed fluorescence (SODF) imaging was used to visualize singlet oxygen activity.
• Time-resolved phosphorescence measurements at 1270 nm confirmed the findings.

Main Results:

• TPP fluorescence decay in PS nanofibers showed single exponential kinetics at the periphery.
• Increased fluorescence quenching and a shorter lifetime component were observed in TPP-rich domains within PS nanofibers.
• Significant singlet oxygen production was detected in PS nanofibers, but limited production occurred in GE nanofibers.

Conclusions:

• Polystyrene nanofibers facilitate efficient singlet oxygen generation for potential antibacterial applications.
• Gelatin nanofibers exhibit limited capacity for singlet oxygen production under the tested conditions.
• The study highlights the importance of material properties in photosensitizer-mediated antimicrobial strategies.