Size-controlled synthesis and sensing properties of anthracene-based metal-organic frameworks for detection of singlet oxygen in photodynamic therapy

Developing fluorescent probes to detect singlet oxygen (¹O₂) is essential to understanding the critical role of ¹O₂ in immunological and pathological processes in various organs. In this study, size-controlled DPA-MOF (X) with good biocompatibility and excellent optical stability was used as a nanoprobe for real-time imaging and monitoring of ¹O₂ in photodynamic therapy (PDT). The experimentally synthesized DPA-MOF (X), which can be adjusted in particle size by dilution, exhibits blue fluorescence signals. The results show that smaller-sized DPA-MOF (60) has a faster response to ¹O₂ and higher cell uptake ability. The ratio of fluorescence intensity (F₀/F_i) of DPA-MOF (60) showed a linear correlation with the concentration of ¹O₂ in the range of 0–7 mM, with a detection limit of 88 μM. DPA-MOF has a distinct advantage over most carrier loading sensors in that it effectively avoids the issue of fluorophore leakage from the nanomaterial matrix, thereby improving its stability. Additionally, the controlled synthesis of DPA-MOF can potentially improve probe accumulation in tumors and lower the uptake by the body system. This study presents a luminescent metal-organic framework (LMOF) sensor that utilizes a ¹O₂ capture unit as a measuring ligand. This sensor has been shown to have exceptional biocompatibility and can be utilized for highly specific and efficient detection of ¹O₂ in vivo or living cells.