In Vivo Chemoselective Photoacoustic Imaging of Copper(II) in Plant and Animal Subjects

The detection of Cu²⁺ in living plants and animals is of great importance for environment monitoring and disease diagnosis. Here, a near-infrared (NIR) turn-on photoacoustic (PA) probe (denoted as LET-2) is developed for Cu²⁺ detection in living subjects, such as soybean sprouts and mice. The absorbance band of LET-2 shifts from 625 to 715 nm after the interaction with Cu²⁺ , thus producing strong PA signal output at 715 nm (PA₇₁₅ ) as an indicator. The PA₇₁₅ value is increased as a function of the concentration of Cu²⁺ (0 × 10^-6 -20 × 10^-6 m), with a calculated limit of detection of 10.8 × 10^-9 m. More importantly, both in vitro and in vivo studies in soybean sprouts and mice indicate that the as-prepared LET-2 PA probe is highly sensitive and selective for Cu²⁺ detection. These findings provide a solution for in vivo detection of metal ions by using chemoselective PA probes.