A nuclear-staining, water-soluble, polycationic two-photon DNA probe for identifying dead neuronal cells and monitoring traumatic brain injury

Neuronal cells are in most parts exempt from the daily flux of cell birth and death. The identification of dead neuronal cells is essential for facilitating our understanding of the types, mechanisms, and roles of neuronal cell death in physiology and pathology and for the investigation and treatment of neurodegenerative diseases. It is highly desirable to fabricate fluorescent probes with strong binding affinity, high brightness, and long-wavelength excitation to identify dead neuronal cells. In this study, we developed a water-soluble, polycationic two-photon fluorescent probe (BTD-V) for identifying dead neuronal cells. The hydrophilic nature and positive-charged polycation enabled BTD-V to selectively accumulate in the nuclei of dead cells. BTD-V also exhibited a large Stokes shift of 180 nm, enhanced high brightness of 13 251 M-1 cm-1 upon binding with DNA, and strong DNA-binding ability with an apparent dissociation constant of 0.75 nM. Based on these properties, this probe could be used to effectively monitor different types of neuronal cell death induced by hydrogen peroxide and glutamate due to differences in the nuclear morphologies. The BTD-V probe could also be used for two-photon brain imaging, enabling the monitoring of traumatic brain injury (TBI) in mice by staining the dead nuclei of paraffin sections and cryosections. This research provides a promising DNA probe for identifying the dead cells, discriminating the cell death type, and monitoring the neuronal-related diseases.