Pressure-Responsive Polymer Chemosensors for Hydrostatic Pressure-Signal Detection: Poly-L-Lysine-Pyrene Conjugates

Stimulus-responsive polymer materials are an attractive alternative to conventional supramolecular and polymer assemblies for applications in sensing, imaging, and drug-delivery systems. Herein, we synthesized a series of pyrene-labeled- and -poly-L-lysine conjugates with varying degrees of substitution (DSs). Hydrostatic pressure-UV/vis, fluorescence, excitation spectroscopies, and fluorescence lifetime measurements revealed ground-state conformers and excited-state ensembles emitting fluorescence with variable intensities. The polylysine-based chemosensors demonstrated diverse ratiometric responses to hydrostatic pressure through adjustments in polar solvents, DSs, and polymer backbones. Additionally, the fluorescence chemosensor exhibited a promising glum value of 3.2 × 10-3, indicating potential applications in chiral fluorescent materials. This study offers valuable insights for the development of smart hydrostatic pressure-responsive polymer materials.