Hypoxia-responsive Azocalixarene-doxycycline host-guest complex for synergistic myopia control

Myopia is one of the most common visual impairments worldwide. Recent studies suggest that scleral hypoxia may act as an early trigger for myopia, initiating oxidative stress (OS) that disrupts extracellular matrix (ECM) remodeling and, in turn, drives axial elongation. In this study, we constructed a novel hypoxia-responsive host-guest complex, DOX@SAC4A, by encapsulating doxycycline (DOX) within sulfonated azocalix[4]arene (SAC4A). In vitro, this system significantly reduced DOX cytotoxicity and enabled efficient hypoxia-triggered drug release. Moreover, the intrinsic activity of SAC4A synergistically enhanced the antioxidant and anti-apoptotic effects of DOX, helping to maintain ECM homeostasis. In vivo studies further confirmed that DOX@SAC4A selectively targeted hypoxic sclera and markedly increased local drug accumulation. Consequently, it effectively suppressed myopia progression in guinea pigs by delaying axial elongation and alleviating myopic refractive shift. In conclusion, DOX@SAC4A is a multifunctional drug delivery system that offers both therapeutic effects and targeted delivery. These results present a promising candidate and an improved delivery strategy for myopia prevention and control.