Hydrothermal synthesis of fluorescent carbon dots from myrrh residue for Fe3+ detection and antioxidant application.

In current work, myrrh residue, a special type of natural biomass, was used as the feedstock for carbon dots (CDs) preparation for the first time. The effect of synthesis conditions including ethylenediamine addition, reaction temperature, and reaction time on the CDs fluorescence intensity was investigated to construct a proper synthesis system. Under the suitable condition, CDs with an average particle size of 6.35 ± 1.07 nm and excitation wavelength dependence were prepared, and the CDs yield and the CDs quantum yield were 3.78% and 10.63%, respectively. The CDs obtained were used for the detection of various metal ions, and Fe³⁺ could be detected most sensitively due to its significant quenching effect. For low Fe³⁺ concentrations (0.2–1 mM), it had a good linear relationship with F₀/F (the relative fluorescence intensity) that a standard curve (y = 0.3553x + 0.926) was built with R² of 0.997 and the limit of detection (LOD) of 24.62 μM. While for high Fe³⁺ concentrations (1–15 mM), it also had a good linear relationship with F₀/F that a standard curve (y = 0.3232x + 0.7636) was built with R² of 0.991 and LOD of 27.06 μM. The CDs was used for the real samples detection with the recoveries ranged from 92.71 to 103.84%. The fluorescence quenching mechanism of CDs by Fe³⁺ was learned and the static quenching was the possible mechanism. In addition, based on the antioxidant properties of myrrh itself, the myrrh residue derived CDs also had antioxidant activities and thus had potential for antioxidant application. On the whole, this work can provide an attractive technology for chemical conversion from low-cost myrrh residue to functional CDs which can be applied for Fe³⁺ detection and antioxidation. [ABSTRACT FROM AUTHOR]