Red emissive N-S co-doped carbon dots for live imaging of tumor spheroid in the microfluidic device

Abstract Here, we present a one-pot, water‐based synthesis of red emissive biocompatible carbon dots (R-CDs) for live bioimaging of U87 microglia tumor spheroids produced in a microwell-based microfluidic device. R-CDs were synthesized by the hydrothermal method, using thiourea and para-phenylenediamine as the starting precursors. The mold of the microfluidic platform was produced by a lab-made high-resolution optical 3D printer and CNC micro-milling. The optical and physical properties of synthesized R-CDs were validated by different analytical methods such as fluorescent and absorption spectroscopy, FT‐IR, DLS, and TEM. The prepared R-CDs emit red light with a maximum fluorescent wavelength of 584 nm. The prepared R-CD has low cytotoxicity and has been successfully applied for staining the glioblastoma spheroid without any fixation step. Therefore, it is a promising fluorescent probe in live 3D cell imaging.