Fluorescence “turn-on” determination of H2O2 using multilayer porous SiO2/NGQDs and PdAu mimetics enzymatic/oxidative cleavage of single-stranded DNA

• A novel 3D microfluidic paper-based fluorescence analytical device with hollow channels was developed.
• Green environment-friendly FA-pPdAu/GO nanocatalysts were prepared.
• NGQDs as fluorescence report element, which also presented peroxidase-like activity.
• The DNA could be cleaved by hydroxyl radical produced, and this assay was easy to implement for visual detection.

A 3D microfluidic paper-based fluorescence analytical device with hollow channels based on the turn-on switching of a resonance energy transfer triggered by the
• OH induced cleavage of a DNA strand was successfully constructed. And this fluorescent nanoplatform was first designed to achieve in situ and real-time determination of H2O2 released from cancer cells to obtain an accurate determination. With optimal conditions, the proposed method displayed excellent analytical performance for the detection of H2O2 ranging from 0.3 to 1.0 mM with a detection limit of 0.1 nM. The favorable performances of this sensor were due to the peroxidase-like activity of nitrogen-doped graphene quantum dots (multilayer porous SiO2 act as stabilizer to load more nitrogen-doped graphene quantum dots for signal amplification) and folic acid-pPdAu/GO (which also could act as an efficient fluorescence quencher and a recognition element of cancer cells by folic acid). It was worth noting that it could be used for visually determined the flux of H2O2 from the cells. Therefore, the developed biosensor holds potential for ultrasensitive quantitative analysis of H2O2 and supplies valuable information for diabetes mellitus research and clinical diagnosis.