Fig. 5: Real-time sensing of the stress-induced H₂O₂ signal in lettuce.

a Schematic of in vivo visualization of stress-induced H₂O₂ by AIE₁₀₃₅NPs@Mo/Cu-POM nanosensor. b Schematic of the response of the nanosensor to various stresses in vivo. c Schematic of the experimental setup for in vivo detection. The illustrations of (a–c) were created in BioRender. Hu, H. (2025) https://BioRender.com/h4u7ond. d Brightfield image and false-colored NIR images of lettuce leaf in the intact plant infiltrated with AIE₁₀₃₅NPs and AIE₁₀₃₅NPs@Mo/Cu-POM. White arrows and the red dashed line indicate the location of AIE₁₀₃₅NPs and AIE₁₀₃₅NPs@Cu-POM, respectively. The yellow dashed line represents the location of touching and wounding. Time denotes the time points after wounding. Laser excitation: 808 nm, 15 mW. Filter: 900 nm long-pass filter. e Average time response of normalized AIE₁₀₃₅NPs@Mo/Cu-POM fluorescence intensity in the lettuce leaf. The black arrow represents the time point (10 min) of touching and wounding. Shaded regions represent standard error across five independent measurements. f Brightfield image and NIR images of lettuce leaf infiltrated with AIE₁₀₃₅NPs@Mo/Cu-POM after multiple woundings. The yellow dashed lines represent wounding locations, and the numbers represent the order of the wounding process. The red dashed lines indicate the location of AIE₁₀₃₅NPs@Mo/Cu-POM. Time denotes the time points after the first wounding. Damage caused every 30 min. g Average time response of normalized AIE₁₀₃₅NPs@Mo/Cu-POM fluorescence intensity during multiple woundings. Black, red, and blue arrows represent the time points of the first (10 min), second (40 min), and third (70 min) injuries, respectively. Shaded regions represent standard error across three independent measurements. h NIR fluorescence intensity changes of AIE₁₀₃₅NPs@Mo/Cu-POM in the leaf upon the stress of pathogen-associated peptide stress (flg22). Inset: NIR fluorescence images of the leaf from the representative period. Red and blue dots indicate the flg22-treated and no-stress groups, respectively, with the center dotted line representing the mean value and the shaded regions indicating the standard deviation of five independent measurements.