Optical oxygen sensor based on luminescence quenching for dissolved oxygen (DO) detection: Metalloporphyrin embedded in fluorinated acrylate nanospheres and their biological application

Optical oxygen sensors based on the luminescence quenching mechanism were developed by encapsulating platinum octaethylporphyrin (PtOEP) into fluoropolymer nanospheres of Poly(methyl methacrylate-co-trifluoroethyl methacrylate) (Poly(MMA-co-TFEMA)) and Poly(methyl methacrylate-co-trifluoroethyl methacrylate-co‑butyl acrylate) (Poly(MMA-co-TFEMA-co-BA)) via miniemulsion polymerization for dissolved oxygen (DO) detection. The luminescence intensity of the oxygen-sensing nanospheres decreases significantly with increasing DO concentration, with maximum quenching ratios ( I ₀/ I ₁₀₀) estimated to be 6.19±0.15, and 8.92±0.26 for Poly(MMA-co-TFEMA) and Poly(MMA-co-TFEMA-co-BA) nanospheres, respectively. The response times to DO were 28 s and 24 s for Poly(MMA-co-TFEMA) and Poly(MMA-co-TFEMA-co-BA) nanospheres. After 1 h of continuous light irradiation, the decay ratios of luminescence intensity for both remained below 0.1%. Experimental results demonstrate that both nanosphere-based oxygen sensors exhibit high sensitivity and accuracy, fast response time, and excellent photostability. Finally, PtOEP@Poly(MMA-co-TFEMA-co-BA) nanospheres were used as a photosensitizer, and their photodynamic therapy (PDT) efficacy was evaluated in human A431 cells. In vitro studies indicate that cancer cells are effectively destroyed at a low dose of PtOEP@Poly(MMA-co-TFEMA-co-BA) nanospheres under light irradiation, suggesting the potential of these oxygen-sensing nanospheres for photodynamic therapy applications.