A swarm of slippery micropropellers penetrates the vitreous body of the eye

TLDR

Intravitreal delivery of therapeutic agents offers major benefits, yet traditional passive diffusion cannot rapidly concentrate cargo at the posterior pole, and although particle-based approaches promise targeted delivery, the vitreous’s tight macromolecular matrix hinders penetration. The study demonstrates slippery micropropellers that can be actively propelled through the vitreous humor to reach the retina. The micropropellers are helical magnetic devices coated with a liquid layer to reduce adhesion, and their motion is tracked by clinical optical coherence tomography to confirm arrival near the optic disc. The submicrometer propellers penetrate the vitreous matrix and propel over centimeter distances, demonstrating that overcoming adhesion forces and navigating a swarm can enable practical ophthalmic applications.

Abstract

The intravitreal delivery of therapeutic agents promises major benefits in the field of ocular medicine. Traditional delivery methods rely on the random, passive diffusion of molecules, which do not allow for the rapid delivery of a concentrated cargo to a defined region at the posterior pole of the eye. The use of particles promises targeted delivery but faces the challenge that most tissues including the vitreous have a tight macromolecular matrix that acts as a barrier and prevents its penetration. Here, we demonstrate novel intravitreal delivery microvehicles-slippery micropropellers-that can be actively propelled through the vitreous humor to reach the retina. The propulsion is achieved by helical magnetic micropropellers that have a liquid layer coating to minimize adhesion to the surrounding biopolymeric network. The submicrometer diameter of the propellers enables the penetration of the biopolymeric network and the propulsion through the porcine vitreous body of the eye over centimeter distances. Clinical optical coherence tomography is used to monitor the movement of the propellers and confirm their arrival on the retina near the optic disc. Overcoming the adhesion forces and actively navigating a swarm of micropropellers in the dense vitreous humor promise practical applications in ophthalmology.