[Retracted] Fluorescent Carbon Dot-Supported Imaging-Based Biomedicine: A Comprehensive Review

Figure 4

Fluorescence imaging-supported sensing of various metal ions and biomolecules. (a) Intracellular silver ions detection in HEK 293T cells and B16F10 cells without (-), and with (+) Ag⁺, through obvious quenching phenomenon. Adapted with permission from Ref. [162]. (b) In vivo semiquantitative detection of Fe³⁺ through CLSM images of zebrafish treated with CDs and quenching FL effect after treatment with different concentrations of Fe³⁺ and corresponding FL intensity. Adapted with permission from Ref. [126]. (c) Action mechanism of AS1411–CQDs–Ce6 nanoprobe for the intracellular detection of endogenous CTSB through specific binding of AS1411 aptamer with nucleolins. Adapted with permission from Ref. [137]. (d) Strong FL imaging of living HeLa cells under different treatments with AS1411–CQDs–Ce6 and no FL signal of nucleolin-deficient HEK293 cells under treatment with AS1411–CQDs–Ce6 indicated the feasibility of nanoprobes for the detection of CTSB. Adapted with permission from Ref. [137]. (e) In vivo detection of Cyt (c) in zebrafish. CLSM images of zebrafish (A) untreated NCDs, (B) incubated with NCDs for 30 min; and subsequent treatment with (C) Cyt (c), or (D) etoposide for 20 min showed a significant FL quenching effect of Cyt (c). Adapted with permission from Ref. [142]. (f) Selective detection of superoxide anion in mice through the FL enhancement of O₂−to CDs. FL imaging of O₂−levels in the tumor tissues (A)–(C) and normal tissue (D)–(F) after treatment with Te-CDs, FO-PTe, and Se-CDs-treated mice, respectively, acquired using 800 nm two-photon excitation. (G) Corresponding FL intensity revealed the significant increase of O₂−level between normal and tumor tissues. Adapted with permission from Ref. [143].