We demonstrate that to predict the diffusion of multiple electrolytes treating each electrolyte as an individual electroneutral species leads to an inaccurate prediction of ion fluxes, especially for large concentration and diffusivity ratios.

Urinary tract infections (UTIs) are a major public health problem affecting millions of individuals each year. Recurrent UTIs are managed by long-term antibiotic use, making the alarming rise of antibiotic resistance a substantial threat to future UTI treatment. Extended antibiotic regimens may also have adverse effects on the microbiome. Here, we report the use of a supramolecular vaccine to provide long-term protection against uropathogenic Escherichia coli , which cause 80% of uncomplicated UTIs. We designed mucus-penetrating peptide-polymer nanofibers to enable sublingual (under the tongue) vaccine delivery and elicit antibody responses systemically and in the urogenital tract. In a mouse model of UTI, we demonstrate equivalent efficacy to high-dose oral antibiotics but with significantly less perturbation of the gut microbiome. We also formulate our vaccine as a rapid-dissolving sublingual tablet that raises response in mice and rabbits. Our approach represents a promising alternative to antibiotics for the treatment and prevention of UTIs.

Nanoformulating poorly water-soluble drugs is attractive for improving oral dissolution kinetics, but concentrating and drying dilute nanoparticle (NP) suspensions is a barrier to translation. This work describes a reversible, pH-driven flocculation technique for concentrating NPs stabilized with a carboxylic acid-bearing cellulose polymer. Lumefantrine NPs 150 nm in diameter stabilized by anionic hydroxypropylmethylcellulose acetate succinate, a Food and Drug Administration-approved pharmaceutical polymer excipient, are prepared using flash nanoprecipitation. Particles are then concentrated 50-fold by acid-induced flocculation at pH 2.0, separation (either filtration or centrifugation), and base-induced redispersion at pH 6.9, reducing the drying time 50-fold. Dried powders retain enhanced lumefantrine dissolution kinetics. Filtration efficiency is assessed, and flocculation is found to improve NP retention from 3 to 85% on a 2.5 μm filter. The kinetics of flocculation and the fractal nature of the flocs are studied using confocal microscopy and agree closely with a diffusionlimited aggregation model. These results demonstrate a proof of concept that reversible flocculation is a facile method for separating amphiphilic polyelectrolyte-coated NPs from suspension for advanced processing.