Red, green, and blue fluorescent folate-receptor-targeting carbon dots for cervical cancer cellular and tissue imaging

Folate receptor targeted photo-luminescent quantum carbon dots (Fr-CDs) were successfully prepared from folic acid and phenylenediamine isomers through hydrothermal approaches. Fr-CDs were spherical particles smaller than 10 nm, and emit stable green, blue and red luminescence under ultraviolet region excitation (λex = 365 nm) with maximum emissive lengths at 530, 429, and 612 nm. And the corresponding photoluminescence quantum yield as 15.4%, 12.6% and 16.2% respectively. Up-converted photoluminescent properties in near infrared 800 nm spectral region located in green, blue and yellow region. In-vitro studies showed Fr-CDs had almost none cytotoxicity (cell viability over 80%) and high affinitive to the Hela celline highly-expressed-folate-receptor membranes, and lighted on cytoplasm as the fluorescent marker. It displayed long luminescent-stability with PL intensity above 90% in ultraviolet illuminant exposure over 24 h. In in-vivo studies, Fr-CDs were internalized and accumulated in targeted cancer tissues of cervical carcinoma and the emitting fluorescence maintains over 30 min.