DNA-mediated Au@Ag@silica nanopopcorn fluorescent probe for in vivo near-infrared imaging of probiotic Lactobacillus Plantarum

Foodborne probiotics substantially impact human health. Thus, there is an urgent need for real-time and in situ detection of targeted probiotics. In this paper, a novel nanopopcorn fluorescent probe based on DNA-mediated Au@Ag@silica was designed and shown to display plasma resonance characteristics that generated more hot spots. This led to >18-fold greater fluorescence of indocyanine green dye with strong emission in the near-infrared (NIR-I and NIR-II) regions. Moreover, the new fluorescent probe exhibited high stability and low biotoxicity, having a strong linear relationship (R2 = 0.9615) with Lactobacillus Plantarum concentration over the range of 105-109 cfu/mL; it enabled in vivo tracing of exogenous probiotics. Compared with the traditional inductively coupled mass spectrometry (ICP-MS), the results are consistent (Correlation coefficient = 0.994), but the analysis time is much reduced by 89.6%. It is remarkable that the probe enabled real-time and in situ monitoring of target probiotic behavior in a simple, robust, and effective manner.