Fluorescent nanohybrid of conjugated polymer dots on mesoporous silica particles for protease sensing via Förster resonance energy transfer

We prepared anthracence-embedded mesoporous silica nanoparticles (Anth-MSNs) to be used as substrates for decoration with polymer dots (Pdot) via electrostatic interaction. To accomplish this, polyarginine (Parg) was encapsulated to induce positive charges on the surface of the Anth-MSNs, which provided a fluorescent Pdotimmobilized Parg@Anth-MSNs nanohybrid. The nanohybrid showed Förster resonance energy transfer (FRET) from anthracene to Pdot, which were located inside and on the same MSN substrate, respectively. Trypsin is an enzymatic protein that is capable of selectively degrading peptide bonds, such as lysine and arginine. Thus, in the presence of trypsin, the FRET between anthracene and Pdot would no longer be possible, because the Parg linker between anthracence and Pdot would disappear due to the catalytic action of trypsin, leading to the release of Pdot from Anth-MSNs. Finally, the FRET would be retarded and the fluorescence intensity of Pdot would thus decrease in line with the concentration of trypsin, which can be used as an efficient sensing protocol for various proteases.