Reversibly unlocking the blood-brain barrier: A study on microtubule dynamics modulation using gold nanoparticle-modified reduced graphene oxide.

The blood-brain barrier (BBB) is a crucial biological interface between the central nervous system and circulation, playing a key role in maintaining the brain's homeostasis and function, but presenting a challenge for drug delivery. Although enhancing the paracellular permeability of the BBB using graphene-based materials (GBMs) is a promising strategy, detailed biological effects and molecular mechanisms remain poorly understood and understudied. In this study, we prepared gold nanoparticle-modified reduced graphene oxide (Au-rGO) sheets as representative GBMs to enhance BBB paracellular permeability transiently. Remarkably, the induced permeability modulation exhibited both significant efficacy and complete reversibility. Biological experiments and molecular dynamics simulations provided full insights into the molecular mechanism of this process, confirming that Au-rGO influences the dynamic equilibrium of MTs by adsorbing soluble tubulins to hinder MT polymerization, and disassembling MTs to promote depolymerization, thus mediating the unlocking of the BBB. Moreover, the subsequent closure of the BBB is mediated by increased MT polymerization, regulated by the activation of the ERK-stathmin pathway. Collectively, this present study comprehensively elucidates the phenomenon of reversible BBB opening induced by Au-rGO and its intricate molecular mechanism, and supports the safety and efficacy of Au-rGO as a paracellular penetration enhancer for enhancing BBB drug delivery efficiency.