High-Performance Oxygen Sensing Films with Enhanced Quenching Efficiency and Fluorescence Stability via FITC–PtOEP FRET and Imidazole Modification

HighlightsA FRET system (FITC-PtOEP) was integrated into a photonic crystal film for oxygen sensing.Imidazole modification boosted fluorescence intensity by 52.4% under 100% O2atmosphere.Imidazole also provided excellent photostability with a 99.77% fluorescence retention rate.Fluorescence resonance energy transfer (FRET) was implemented in a photonic crystal-structured oxygen sensing film by incorporating fluorescein isothiocyanate (FITC) with platinum octaethylporphyrin (PtOEP). The highest Stern-Volmer quenching constant (KSV= 20.20 ± 0.25) and maximum quenching ratio (21.81 ± 0.21) were achieved at a PtOEP:FITC molar ratio of 1:1. Compared to the control, theKSVand maximum quenching ratio increased by 56.8% and 48.4%, respectively. Additionally, imidazole was introduced into the oxygen-sensing film via a casting method. The results demonstrated that imidazole effectively modulates the energy transfer efficiency between oxygen molecules and PtOEP. Under 20% O2and 100% O2atmospheres, the fluorescence intensity of the imidazole-modified film increased by 18.4% and 52.4%, respectively. Furthermore, imidazole provided excellent protection for PtOEP, yielding a fluorescence retention rate of 99.77% ± 0.18%.