Ratiometric nanoprobe for circulating tumor cell detection and intracellular hydrogen peroxide evaluation in colorectal cancer patients

The application of intensity-based H2O2-responsive fluorescence nanoprobe for circulating tumor cell detection was limited by the complex background and the nanoprobe uptake in each CTC. In this context, we developed a ratiometric fluorescence nanoprobe, on which a H2O2-responsive subunit and a stable subunit grafted working as a H2O2 detector and a reference, respectively. When responding to intracellular H2O2, the reference fluorescence (580 nm) maintained as a correction background while the detector fluorescence (450 nm) was turned on to conduct CTC enumeration and intracellular H2O2 evaluation. Two normal cells and three colon cancer cells were examined to evaluate their endogenous H2O2 with the ratiometric nanoprobe by flow cytometry and confocal laser scanning microscopy. CTC sample from colorectal cancer patients was used to validate the performance of the nanoprobe for CTC enumeration and H2O2 evaluation. The results indicated that not only CTC could be effectively identified based on the turn on fluorescence, but also the viability of the identified CTCs could be assessed with the intensity of the reference fluorescence to avoid the false-positive number. Moreover, the clinical results demonstrated that the viability CTC count combined with intracellular H2O2 content (described as I-450/(580))were related to the tumor TNM stage, which might provide significant guidance for clinical treatments.

Automated summary

A ratiometric fluorescence nanoprobe was developed for CTC enumeration and H2O2 evaluation, effectively identifying CTCs and assessing their viability, providing significant guidance for clinical treatments. The combination of viability CTC count and intracellular H2O2 content was related to the tumor TNM stage, showing promise for clinical applications.