A reduction-triggered nanocarrier based on host–guest interaction between pillar[5]arene derivative and viologen on MSN for intracellular delivery

Due to the difference of intracellular microenvironment between tumour and normal cells, stimuli-responsive supramolecular assemblies have been widely designed for accurate drug delivery and controlled release. This study introduces a reduction-triggered drug delivery system that encapsulates drugs in mesoporous silica nanomaterials (MSNs) pores using a supramolecular nanovalve based on host–guest interactions between pillar[5]arene and viologen groups. PEGylated pillar[5]arene (the host) can encircle viologen stalks (the guest), which have been grafted onto the MSNs surface in advance, and separate from viologen when it encounters a reducing agent. In vitro drug release experiments were conducted under various pH conditions and reducing environments to control drug release. Furthermore, cytotoxicity studies revealed that the drug-loaded nanoparticles exhibited low cytotoxicity to LO2 cells but effectively induced apoptosis in HepG2 cells. This work contributes to the development of targeted intracellular drug delivery in tumour clinical therapy.