Design of a serum albumin sensitive probe for cell imaging and drug delivery by modifying a fluorescent agent

Abstract

Protein-ligand interaction serves as a critical foundation for intramolecular charge transfer (ICT) probes to bind and recognize proteins. Many fluorescent agents are reported to have favorable protein binding abilities but lack protein sensitivity. Herein, a new serum albumin sensitive ICT probe (named MBD) was synthesized by modifying an existing fluorescent agent MPM. MBD not only inherited the favorable human serum albumin (HSA) binding ability of MPM but also newly obtained favorable serum albumin responsiveness. These properties were maintained after MBD formed a complex with water-soluble pillar[5]arene (WP5). Typical commercial drugs, fluorescent amino acids, fatty acids, and metal ions had negligible effects on the HSA responsiveness of the complex. The WP5-MBD complex possessed strong anti-interference ability in binding and recognizing HSA. Moreover, the WP5-MBD complex self-assembled into supramolecular fluorescent nanoparticles in solution. Such nanoparticles possessed good cell imaging and traceable drug delivery properties, which hold great potential for cancer treatment and diagnosis.