A Single-Tube Carbon Dot-based LAMP assay for rapid and visual detection of Group B Streptococcus

Group B Streptococcus (GBS) poses a significant health risk to mothers and newborns, requiring rapid and accurate detection for effective treatment. Traditional methods, such as bacterial culture and PCR, are time-consuming and procedurally complex. Herein, we developed a visual nucleic acid assay platform by combining loop-mediated isothermal amplification (LAMP) with LAMP-responsive carbon dots—polyethyleneimine carbon dots (PEI-CDs)—for GBS detection. In a positive LAMP reaction (with target DNA), the negatively charged amplification products (DNA and magnesium pyrophosphate) interact with positively charged fluorescence PEI-CDs via electrostatic adsorption to form a large fluorescent precipitate, while in a negative reaction, PEI-CDs remain dispersed. This visual distinction allows for the straightforward identification of GBS presence. To prevent contamination, PEI-CDs are integrated into the reaction tube lid. This visual detection platform achieves a detection limit of 10 2 copies/μL for GBS within 31 min, demonstrating high sensitivity and rapid visual readout. The platform shows significant potential for clinical practice in nucleic acid diagnostics, with versatility to detect other pathogens through primer substitution.