Detection and imaging of cathepsin L in cancer cells using the aggregation of conjugated polymer dots and magnetic nanoparticles

• Published in: Sensors and actuators. B, Chemical Vol. 307; p. 127641
• Main Authors: Kim, Daigeun, Lee, Yong-Deok, Jo, Seonyoung, Kim, Sehoon, Lee, Taek Seung
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.03.2020; Elsevier Science Ltd
• Subjects: Agglomeration; Cancer; Cathepsin L; Conjugated polymer dots; Fluorescence; Fluoroscopic imaging; Imaging; Lysine; Magnetic induction; Magnetic nanoparticles; Magnetic resonance imaging; Medical imaging; Nanoparticles; Polymers; Quenching; Selectivity; Sensors; Signal generators; Fluorescence; Cathepsin L; Sensors; Conjugated polymer dots; Imaging; Magnetic nanoparticles
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2019.127641

•A nanohybridized probe composed of magnetic particles and conjugated polymer dots was prepared.•The selectivity was realized by specific interaction between cathepsin L and poly(L-lysine).•A nanohybridized probe exhibited an excellent performance in vivo tumor imaging. New technique for cathepsin L detection and imaging was developed via controlling an aggregation between magnetic nanoparticles (MNPs) and conjugated polymer dots (CPdots). By changing the electrostatic surface charges of MNPs, the techniques provided two protocols: 1) fluorescence quenching and spin-spin relaxation (T2)-based magnetic resonance imaging (MRI); 2) fluorescence recovery for fluorescent imaging. By adding cathepsin L, the fluorescence and MRI relaxivity were altered by the formation of aggregates of CPdots and MNPs, inducing fluorescence quenching by MNP as well as a change in T2 relaxation. In addition, nonfluorescent, pre-aggregated nanohybrid (CPdots and MNPs) can be dissolved in the presence of cathepsin L, resulting in turn-on fluorescent detection and the imaging of cathepsin L in cancer cells and in mice with tumors. In all cases, the MNPs played important roles as the fluorescence quencher and as the MRI-signal generator. The surface of CPdots was covered with poly(L-lysine) (pLys) for the aggregation of CPdots and MNPs, in which pLys was specifically degraded by the enzymatic action of cathepsin L. The CPdots systems showed high sensitivity and selectivity toward cathepsin L, by which these systems can be considered as potential candidates for cathepsin L detection and imaging.