Lipids contain
hydrocarbons and are the building blocks of cells.
Lipids can naturally form themselves into nano-films and nano-structures,
micelles, reverse
micelles, and
liposomes.
Micelles or reverse
micelles are monolayer structures, whereas
liposomes are bilayer structures.
Liposomes have been recognized as carriers for
drug delivery. Solid
lipid nanoparticles and lipoplex (
liposome-polycation-
DNA complex), also called
lipid nanoparticles, are currently used to deliver drugs and genes to ocular tissues. A solid
lipid nanoparticle (SLN) is typically spherical, and possesses a solid
lipid core matrix that can solubilize lipophilic molecules. The
lipid nanoparticle, called the
liposome protamine/
DNA lipoplex (LPD), is electrostatically assembled from cationic
liposomes and an anionic
protamine-
DNA complex. The LPD nanoparticles contain a highly condensed
DNA core surrounded by
lipid bilayers. SLNs are extensively used to deliver drugs to the cornea. LPD nanoparticles are used to target the retina.
Age-related macular degeneration,
retinitis pigmentosa, and
diabetic retinopathy are the most common
retinal diseases in humans. There have also been promising results achieved recently with LPD nanoparticles to deliver functional genes and
micro RNA to treat
retinal diseases. Here, we review recent advances in ocular
drug and gene delivery employing
lipid nanoparticles.