Figure 19.

Semiconducting polymer nanoparticles for protease sensing. A) Protease-triggered “turn on” sensing scheme. The cross-linking effectively strains the nanoparticles into a more tightly aggregated and quenched state. The protease cleaves the peptide cross-linkers and releases the strain, resulting in a “turn-on” fluorescence response. B) Fluorescence spectra of shell cross-linked nanoparticle suspensions before (red) and after (blue) incubation with trypsin. Reproduced from Ref. [74] with permission.