Paper microfluidic device using carbon dots to detect glucose and lactate in saliva samples

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Point-of-Care Diagnostics

Background:

• Traditional bioanalyses rely on invasive blood or serum collection.
• Saliva offers a non-invasive alternative for clinical analysis due to its rich biomarker content.
• Saliva's low analyte concentrations and viscosity pose challenges for paper-based devices.

Purpose of the Study:

• To develop a simple, low-cost saliva pretreatment method for analysis on multilayer paper devices (3D-μPADs).
• To enable accurate detection of glucose and lactate in saliva using enzymatic reactions and carbon dot fluorescence quenching.

Main Methods:

• A cotton-paper-syringe filtration system was used for saliva sample pretreatment.
• Enzymatic oxidation of glucose and lactate produced hydrogen peroxide.
• Detection was achieved by monitoring the fluorescence quenching of carbon dots by hydrogen peroxide.

Main Results:

• Good linear correlations were observed between analyte concentrations and fluorescence quenching.
• Achieved low limits of detection (LODs) of 2.60 × 10⁻⁶ M for glucose and 8.14 × 10⁻⁷ M for lactate.
• Demonstrated satisfactory repeatability and specificity, with no significant matrix influence on results.

Conclusions:

• The developed filtration method effectively preprocesses saliva for analysis on 3D-μPADs.
• The methodology is suitable for accurate and reliable quantification of glucose and lactate in saliva and serum.
• This approach provides a promising non-invasive alternative for clinical diagnostics.