Fe-doped Tryptophan-derived Carbon Dots as pH-sensitive Platforms for Kidney Cell Imaging

Abstract

Iron-doped carbon dots (Fe-TrypCDs) were synthesized via a one-step hydrothermal method using tryptophan as the carbon precursor. The obtained nanoparticles exhibited uniform size distribution, good water solubility, and high fluorescence quantum yield. Fe doping effectively modulated the surface electronic structure, enabling reversible and stable pH-responsive fluorescence within the range of 2.0–8.0. This switching behavior is primarily attributed to the protonation/deprotonation of surface functional groups and Fe–ligand coordination, which alter electron density and charge transfer pathways. Cellular experiments demonstrated that Fe-TrypCDs were efficiently internalized by HK-2 cells, produced bright fluorescence imaging, and showed low cytotoxicity. This study provides a facile strategy for constructing pH-responsive fluorescent probes, offering promising potential for real-time monitoring of renal cellular microenvironments and related pathological processes.

Keywords

Fe-doped carbon dots / pH-responsive fluorescence / protonation/deprotonation / HK-2 cell / bioimaging

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