Delivery of polymeric particles into skin using needle-free liquid jet injectors.

Needle-free liquid jet injectors have been developed for the delivery of several drugs including insulin and growth hormone. Here, we assess the ability of liquid jet injectors to deliver polymeric nanoparticles into skin. As a first step, polystyrene particles of several sizes and two shapes were injected into skin using a jet injector. The dispersion area of particles, measured in the cross section of the skin, was found to inversely relate to the particle size and directly proportional to the injection volume. Environmental scanning electron microscopy studies confirmed that particles indeed penetrate into the skin and are generally located around the injection site. Next, poly lactide co-glycolide (PLGA) particles, containing a model solute, coumarin-6, were synthesized and delivered into the skin using the jet injector. PLGA particles were effectively delivered into the skin and released coumarin-6 into the skin.