Ultrastable gold nanoparticles-based nanoplatform with mitochondria targeting and high-fidelity intracellular bioimaging enterokinase levels

Mitochondria are key organelles in mammalian cells whose dysfunctions are linked to various diseases. Numerous gold nanoparticles functionalized with lipophilic cation categories via Au-S bond for mitochondria targeting have been reported. However, cleavage of the Au-S bond by biothiols and other chemicals is a long-standing problem hindering practical applications, especially for intracellular detection and bioimaging. Herein, we report a mitochondria-targeting AuNP-based nanosensor with negatively charged peptide modification. Furthermore, we directly introduce the peptide motif via diselenide-modified AuNPs instead of traditional Au-S bonds. In vitro and living cell-based assays show that our designed strategy is simple to prepare, but ultrastable under thiol-rich physiological conditions. Furthermore, we have demonstrated that the nanosensor AuNP@DSe-P_linkerTMR can monitor enterokinase (ENTK) levels in the mitochondria of HeLa cells with a high-fidelity fluorescent signal under physiological conditions, thus providing a new idea for the design and preparation of ultrastable AuNP-based nanosystem.