Self-assembled amphiphilic fluorescent probe: detecting pH-fluctuations within cancer cells and tumour tissues.

Abnormal anaerobic metabolism leads to a lowering of the pH of many tumours, both within specific intracellular organelles and in the surrounding extracellular regions. Information relating to pH-fluctuations in cells and tissues could aid in the identification of neoplastic lesions and in understanding the determinants of carcinogenesis. Here we report an amphiphilic fluorescent pH probe () that, as a result of its temporal motion, provides pH-related information in cancer cell membranes and selected intracellular organelles without the need for specific tumour targeting. Time-dependent cell imaging studies reveal that localizes within the cancer cell-membrane about 20 min post-incubation. This is followed by migration to the lysosomes at 30 min before being taken up in the mitochondria after about 60 min. Probe can selectively label cancer cells and 3D cancer spheroids and be readily observed using the green fluorescence channel ( = 532 nm). In contrast, only labels normal cells marginally, with relatively low Pearson's correlation coefficients being found when co-incubated with standard intracellular organelle probes. Both and experiments provide support for the suggestion that acts as a fluorescent label for the periphery of tumours, an effect ascribed to proton-induced aggregation. A much lower response is seen for muscle and liver. Based on the present results, we propose that sensors such as may have a role to play in the clinical and pathological detection of tumour tissues or serve as guiding aids for surgery.