Real-Time <i>In Situ</i> Sequential Fluorescence Activation Imaging of Cyt <i>c</i> and Caspase-9 with a Gold–Selenium-Bonded Nanoprobe
Bo Liu, Jingjing Li, Ping Zhou, Wei Pan, Na Li, Bo Tang
Abstract
Apoptosis, as a very important mode of programmed death, is closely associated with many diseases. Real-time in situ monitoring of the dynamic change of the apoptotic process remains a great challenge. Herein, a nanoprobe based on the gold–selenium (Au–Se) bond was developed for a sequential fluorescence activation imaging of cytochrome c (Cyt c) and caspase-9, two important apoptotic signaling molecules, to monitor the progression of apoptosis. The Cyt c aptamer and caspase-9-cleavable peptide chains labeled with two dyes were modified onto the surface of gold nanoparticles (Au NPs) by the Au–Se bond, which can be activated by upstream Cyt c and downstream caspase-9 to trigger fluorescence recovery. The Au–Se nanoprobe exhibited good specificity and stability. Compared with the traditional nanoprobe based on the gold–sulfur (Au–S) bond, the interference of biological thiols on the Au–Se nanoprobe can be effectively avoided. Importantly, the Au–Se nanoprobe can image the sequential changes of the two markers in situ in real time during cell apoptosis. This work provides an effective tool for the accurate and real-time detection of apoptosis and is conducive to the in-depth study of the relationship between apoptosis and disease.