Photothermal Transport for Guiding Nanoparticles Through the Vitreous Humor

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Nanotechnology

Background:

• Visual impairments affect billions globally, with drug delivery to the posterior eye segment being a significant hurdle.
• Current intravitreal injections offer limited drug diffusion through the vitreous, restricting retinal access.
• Existing methods lack guided transport for ocular drug delivery systems.

Purpose of the Study:

• To investigate photothermal transport for guided nanoparticle delivery in the eye's vitreous.
• To establish a novel, clinically relevant method for light-controlled ocular drug delivery.

Main Methods:

• Utilized a pulsed laser and indocyanine green (clinically approved) for photothermal transport.
• Employed multiple-particle tracking and numerical simulations to analyze nanoparticle motion.
• Identified key parameters influencing transport, including dye concentration, particle size, laser focus distance, and fluence.

Main Results:

• Demonstrated successful guided transport of nanoparticles towards laser-illuminated areas within the vitreous.
• Confirmed that thermal convection is the primary driver of nanoparticle motion, with thermophoresis playing a secondary role.
• Established optimal parameters for efficient photothermal transport in the vitreous.

Conclusions:

• Photothermal transport offers a novel, light-guided approach for enhanced ocular drug delivery.
• This method overcomes limitations of conventional intravitreal injections for posterior segment diseases.
• This is the first demonstration of guided light-controlled particle transport in the vitreous using ophthalmology-approved modalities.