Fluorescent-colorimetric dual signal ratio sensor with AuNRs@UCNPs superstructure nanoprobe for accurate hypochlorite detection

There is a significant need for sensitive and selective hypochlorite (ClO - ) detection in rheumatoid arthritis, especially at the site of inflammation. However, the traditional single signal strategy based on visible emission cannot meet sensitive and accurate analysis requirements in practical applications. In this work, a novel fluorescent-colorimetric dual-signal ratio luminescent nanoprobe (superstructure AuNRs@UCNPs) was developed based on Förster resonance energy transfer (FRET) between the ClO - responsive gold nanorods (AuNRs) and lanthanide doped up-conversion nanoparticles (UCNPs). ClO - gradually etched AuNRs to produce corresponding color changes and plasmon resonance absorption peak shifts. The luminescence at 650 nm of UCNPs gradually recovered, while the luminescence at 540 nm gradually weakened. It allows for the sensitive and accurate detection of ClO - with excellent limits of detection (0.156 μM for the fluorescent ratio method and 0.231 μM for the colorimetric method). It provides a powerful dual guarantee for ClO - detection. The detection in serum of actual samples shows that the probe has reasonable accuracy and precision.