Fig. 4
From: Nanosensors based on polymer vesicles and planar membranes: a short review
a Preparation of the calcein-loaded PeptiSome with methoxy-poly(ethylene glycol)-block- poly(rac-leucine) (mPEG-b-pLeu) mixed with MT1-MMP antagonist peptide-b-pLeu, then with calcein. b Chemical structure of the peptide sequence in the PeptiSome bi-layer membranes. The cleavage site is located between Phe and Leu. c Schematic representation of calcein-loaded PeptiSome and enzyme-activatable nanoprobe. When the calcein is loaded into PeptiSomes, fluorescence is self-quenched. After PeptiSomes enter cancer cells by endocytosis, enzymatic cleavage of the peptide by MT1-MMP releases calcein, which is no longer quenched [25]