Monomeric state of photosensitizer (PS) molecules can induce biological responses in a variety of neoplastic tissues in photodynamic therapy (PDT), but the self-aggregate forms are mostly inactive. Although verteporfin has showed a history of success as a photosensitizer, its self-aggregation inside cancer cells has not been fully described. This study aims to elucidate the self-aggregation of verteporfin in glioblastoma multiforme cells at various concentrations, using steady-state/time-resolved fluorescence and fluorescence lifetime imaging microscopy. According to our findings, low internalization mainly led to the monomeric state of verteporfin inside cells, with a fluorescence lifetime of ∼6.0 ns. J-type fluorescent self-aggregates of verteporfin were found in intermediate conditions, in coexistence with monomers, presenting a lower fluorescence lifetime of ∼2.5 ns. At high internalization of verteporfin, the amount of self-aggregates increased and the monomer's lifetime decreased, showing the dependence of the aggregation of verteporfin on concentration. The findings suggest that the amount of monomers of verteporfin inside cells reaches a saturation limit. This limitation could be a critical factor in PDT that uses poor intracellular soluble PS.

光敏剂（PS）分子的单体状态可以在光动力疗法（PDT）中诱导多种赘生组织中的生物学反应，但自聚集形式大多无效。尽管维替泊芬已显示出成功用作光敏剂的历史，但尚未完全描述其在癌细胞内部的自聚集。本研究旨在通过稳态/时间分辨荧光和荧光寿命成像显微镜，阐明不同浓度下维替泊芬在多形胶质母细胞瘤细胞中的自聚集。根据我们的发现，低内在化主要导致细胞内Verteporfin的单体状态，荧光寿命约为6.0 ns。在中间条件下发现Verteporfin的J型荧光自聚集体与单体共存，荧光寿命较低，约为2.5 ns。在Verteporfin的高度内在化作用下，自聚集体的数量增加，单体的寿命缩短，这表明Verteporfin聚集体对浓度的依赖性。该发现表明细胞内维替泊芬的单体数量达到饱和极限。该限制可能是使用不良细胞内可溶性PS的PDT中的关键因素。