Mucopenetration and biocompatibility of polydopamine surfaces for delivery in an Ex Vivo porcine bladder.

Urine voiding and the presence of a mucus layer on the apical surface of the urothelium are two major challenges towards an effective intravesical drug delivery for bladder malignancies. Improved bioavailability to the underlying bladder tissue could be achieved with delivery vectors that diffuse efficiently through the bladder mucus. Pegylation of delivery vectors remains the existing "gold standard" to enhance mucosal delivery despite known poor cell uptake and reported PEG sensitivity. Here, we showed improved mucopenetration of carboxylated polystyrene (PS) nanoparticles (NPs) passivated with a polydopamine (PDA) surface, at similar level as PEG. While the diffusion of PS NPs in mucus was retarded by ~1000-fold, PS-PDA diffused only 6-fold slower in mucus than water. This enabled faster and deeper penetration of PS-PDA into porcine bladder tissue beneath the mucus layer. The same PDA surface also conferred biocompatibility and enabled photothermal therapy (PTT) with significant surface disruption on an ex vivo porcine bladder model upon localized laser irradiation, which was not possible with PEG. Our outcomes suggested the facile and versatile PDA surface passivation of nanoparticles as an enabler for dual purposes of enhancing mucopenetration and allowing photothermal therapy on bladder tissue, which has not been demonstrated to date.