Magnetic guidance of ferrofluidic nanoparticles in an in vitro model of intraocular retinal repair

Agarose gel at a concentration of 0.6% was used to simulate the vitreous body of the eye during the infusion of a ferrofluid and the subsequent magnetic concentration of it onto a surrogate retinal surface. The 10 nm Fe3O4 particles in the ferrofluid served to mimic the cobalt particles in a silicone magnetic fluid that is being developed for use as a tamponading agent in magnetic fluid therapies designed to alleviate retinal detachments and other types of retinopathy. Magnetically guided interstitial diffusion of the nanoparticles through up to 20 mm of the gel over periods of 72 h was shown to be possible, thus demonstrating that essentially all points on the retinal surface are reachable from elsewhere in the ocular interior. The nanodynamics of the magnetic and viscous forces at work on the particles during movement through the gel are discussed; in particular the diffusion speeds of the particles are estimated and compared with observations.