The Effect of Ligand Reactivity and Carrier Mechanics on Thiol-Mediated Cellular Uptake for miRNA Nano-Drugs

Thiol-mediated uptake (TMU) is a powerful strategy for promoting the cellular uptake of nano-drugs; however, the mechanochemical principles that coupled ligand reactivity, carrier mechanics, and receptor clustering remain poorly understood. Herein, the effect of carrier rigidity and cyclic disulfide reactivity on the thiol-mediated cellular uptake of miRNA nano-drugs was revealed. Compared with lipoic acid (LA), the higher enhancing effect of asparagusic acid (AspA) is identified with the greater affinity, higher binding stability, and more double-disulfide binding. The greater association of AspA-TFRC was also visualized by super-resolution microscopy imaging. Molecular dynamics simulation further verified the superior membrane disruption and deeper insertion induced by AspA. However, both LA and AspA display concentration-dependent self-activation and self-inhibition effects on exchanging with thiols. Furthermore, we provided direct evidence that thiolation can significantly accelerate endocytosis of rigid mesoporous silica nano-drugs, whereas thiolation will shift the entry cell pathway of soft lipid nano-drugs from endocytosis to membrane fusion, and AspA is more efficient. This work establishes a mechanochemical framework that links ligand reactivity, carrier mechanics, and receptor engagement to predict the cellular uptake mechanism of a thiol-mediated nano-drug delivery system.