Biomass-derived carbon nanodots with pH-operated LAMP switching for ultrasensitive DNA detection

Loop-mediated isothermal amplification (LAMP) has been used as one of the tools for nucleic acid detection. The pyrophosphoric acid (PPi) produced by LAMP leads to a change in the pH value of the solution, and acid-base indicators can be used to distinguish positive from negative. However, the microliter reaction system and low concentration target cause small changes in pH, sensitive pH indicators are urgently needed. Herein, we developed a one-step solvothermal approach to synthesize biomass-derived carbon dots named FA-bioCDs. Compared with hydrothermal synthesis, the solvothermal approach red-shifted the emission maximum to 535 nm, and made FA-CDs pH-sensitive in the range of 8.16–9.12, so it can be used for LAMP endpoint detection. The relatively alkaline LAMP buffer reduces the fluorescence of FA-bioCDs. Rapid LAMP accumulates hydrogen ions, lowering the pH and “turning on” FA-bioCDs fluorescence. Thus, LAMP acts as a pH-mediated fluorescence switch for FA-bioCDs. The strategy was used for human papillomavirus DNA detection, and the detection limit was as low as 2.450 copies·μL −1 in about 30 min. LAMP ensures rapid and sensitive detection, and the relatively long emission wavelength of FA-bioCDs may reduce interference in practical detection scenarios. The development of LAMP-FA-bioCDs not only offers a rapid and environmentally friendly tool for nucleic acid detection in clinical settings but also bridges the gap between agriculture and medicine.