Evaluating Lanthanide-Doped Carbon Dots for Sensing Glucose and pH Within the Concentration Range of Clinical Interest

Monitoring glucose and pH levels is essential for tracking diabetes and preventing complications. Even though traditional sensing methods such as immunoassays, chromatog-raphy and wearables are effective, they still have limitations in the practicality, accessibility, and variability of fluid used for sensing. This research explores a different approach to developing a sensing platform for glucose and pH detection using carbon dots (CDs) doped with lanthanide ions (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Gd}^{3+}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Yb}^{3+}$</tex>). Comparing fluorescence responses of three different nanoplatforms (CDs, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{CDs}:\text{Gd}^{3+}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{CDs}: \text{Gd}^{3+}/\text{Yb}^{3+}$</tex>) at various pH and glucose concentrations within the concentration range of clinical interest of these analytes in biofluids such as blood serum, saliva, and urine, allows us to identify the most effective nanoplatforms: CDs for blood serum, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{CDs}:\text{Gd}^{3+}$</tex> for saliva, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{CDs}:\text{Gd}^{3+}/\text{Yb}^{3+}$</tex> for urine. Using a fixed excitation wavelength of 500 nm, significant fluorescence variations were evidenced within the control and variance between them. These early results are encouraging and allow for identifying potential new applications of CDs in the biomedical field, especially in the monitoring diseases such as diabetes and pH changes.