1. Red pitaya peels-based carbon dots for real-time fluorometric and colorimetric assay of Au3+, cellular imaging, and antioxidant activity.
- Author
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Guo, Ying, Li, Te, Xie, Lianwu, Tong, Xia, Tang, Cui, and Shi, Shuyun
- Subjects
CELL imaging ,COLORIMETRY ,FLUORESCENCE quenching ,GOLD nanoparticles ,CHEMICAL properties ,RED - Abstract
The synthesis of fascinating multifunctional carbon dots (CDs) attracted immense attention. Here, a facile solvothermal treatment of red pitaya peels in acetic acid produced CDs (designated as ACDs, excitation/emission wavelengths at 357/432 nm). ACDs with high sp
2 -hybridized carbon and carboxylic group contents can rapidly and selectively reduce Au3+ to Au0 , and stabilize produced Au nanoparticles (AuNPs). The synergetic effect of electron transfer from ACDs to Au3+ and inner filter effect (IFE) from ACDs to AuNPs quenches the fluorescence within 30 s. Simultaneously, the resulting AuNPs have a purple color with a maximum absorption at 545 nm for visual detection. Therefore, for the first time, we reported a fluorometric and colorimetric dual-mode sensing system for real-time, highly sensitive and selective detection of Au3+ . The fluorescence quenching ratio and absorbance change linearly with the increase of Au3+ concentration in the range of 0.3–8.0 μM and 3.3–60.0 μM with limits of detection (LODs) at 0.072 μM and 2.2 μM, respectively. The assay was applied for Au3+ determination in spiked real water samples with recoveries from 95.5 to 105.0%, and relative standard deviation (RSD) of less than 6.5%. Furthermore, ACDs with good photostability, low cytotoxicity, and excellent biocompatibility were successfully applied for intracellular Au3+ sensing and imaging. In addition, ACDs exhibited an extraordinarily high antioxidant activity, with an IC50 value for DPPH radical scavenging (0.70 μg mL−1 ) much lower than that of ascorbic acid (4.34 μg mL−1 ). The proposed strategy demonstrates the outstanding properties of ACDs in chemical and biomedical analysis. [ABSTRACT FROM AUTHOR]- Published
- 2021
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