Peptide-Conjugated Aggregation-Induced Emission Fluorogen: Precise and Firm Cell Membrane Labeling by Multiple Weak Interactions

Abstract

The cell membrane is a vital barrier that protects the cell from external damage and is involved in many biochemical processes. Thus, it is of great significance to label the cell membrane to explore its function. However, due to its complex and dynamic nature, precise and firm cell membrane labeling simultaneously is still a challenge. Herein, we report the fabrication of a peptide-conjugated aggregation-induced emission fluorogen (AIEgen), RTP, consisting of three main components: (1) An integrin-targeting peptide (RGD, R), which could bind specifically to integrin αvβ3 on cell membranes through ligand-receptor interaction. (2) An AIE-active tetraphenylethene derivative (T-MY, T) for fluorescent imaging. (3) Palmitic acid-modified peptide (Pal-RRRR, P), in which Pal is inserted into the lipid on the cell membrane by hydrophobic interaction, and RRRR interacted with the negatively charged cell membrane components (proteins and lipids) through electrostatic forces. RTP could precisely label tumor cells with high integrin αvβ3 expression and firmly trace the cell membrane for up to 4 h; it also has a strong resistance to photobleaching. Moreover, RTP achieved in vivo tumor-specific imaging via cell membrane labeling. Thereby, utilizing multiple weak interactions between the fluorescent probe and the cell membrane provided a new strategy for precise and firm imaging of the cell membrane simultaneously.