Ratiometric Photoacoustic Chemical Sensor for Pd²⁺ Ion

Recently, small molecule photoacoustic sensors have emerged prominently in chem/biosensing owing to their excellent performance of high contrast, high resolution, and deep penetration depth. However, there has been little report on a photoacoustic sensor for Pd²⁺ detection so far. Herein, a ratiometric photoacoustic Pd²⁺ sensor, Cy-DPA, based on cyanine fluorophore has been developed. The absorbance peak of Cy-DPA shifts from 710 to 770 nm after the interaction with Pd²⁺, thus producing a strong PA signal output at 770 nm. As-prepared Cy-DPA could sensing palladium with high sensitivity (27 nM) and selectivity in a fast response (<30 s), which opened new avenue for Pd²⁺ real-time detection in vivo.