Search

The development and performance of a DNA probe adsorbing Mn2+-modified black phosphorus (BP@Mn2+/DNA) hybrid nanosensor is reported that enables rapid detection of cancer-derived exosomal microRNAs (miRNAs) and exosomes. This two-dimensional (2D) nanosensor can spontaneously penetrate the lipid bilayer of exosome membranes owing to its ultra-thin geometry. Subsequently, the adsorbed probe specifically hybridizes with the target miRNA and then dissociates from the nanosensor surface, generating fluorescent signals. Therefore, the BP@Mn2+/DNA nanosensor can differentiate between colorectal cancer (CRC) cell-derived exosomes and those derived from intestinal epithelial cells through sensing of exosomal miRNAs. Furthermore, when the epithelial cell adhesion molecule (EpCAM) aptamer is adsorbed onto BP@Mn2+ instead of the miRNA probe, the nanosensor is able to distinguish exosomes derived from the plasma of CRC patients from those of healthy controls by the recognition ability of the EpCAM aptamer. By utilizing this nanosensor, we were able to effectively differentiate cancer-derived exosomes through the direct detection of miRNA-21 within the exosomes, as well as the identification of specific exosomal membrane proteins. This nanosensor design paves the way for the development of rapid and efficient cancer-derived exosomal miRNA and exosome biosensing nanoplatforms. [ABSTRACT FROM AUTHOR]

A simple fluorescence resonance energy transfer (FRET) sensing platform (termed as USP), comprised of upconversion nanoparticles (UCNPs) as the energy donor and Cy5 as the energy acceptor, has been synthesized for cathepsin B (CTSB) activity detection in vitro and in vivo. When Cy5-modified peptide substrate (peptide-Cy5) of CTSB is covalently linked on the surface of UCNPs, the FRET between the UCNPs (excitation: 980 nm; emission: 541 nm/655 nm) and Cy5 (excitation: 645 nm) leads to a reduction in the red upconversion luminescence (UCL) signal intensity of UCNPs. Cy5 can be liberated from UCNPs in the presence of CTSB through the cleavage of peptide-Cy5 by CTSB, leading to the recovery of the red UCL signal of UCNPs. Because the green UCL signal of UCNPs remains constant during the CTSB digestion, it can be considered as an internal reference. The findings demonstrate the ability of USP to detect CTSB with the linear detection ranges of 1 to 100 ng·mL−1 in buffer and 2 × 103 to 1 × 105 cells in 0.2 mL cell lysates. The limits of detection (LODs) are 0.30 ng·mL−1 in buffer and 887 cells in 0.2 mL of cell lysates (S/N = 3). The viability of USP to detect CTSB activity in tumor-bearing mice is has further been investigated using in vivo fluorescent imaging. [ABSTRACT FROM AUTHOR]