Simple 1,3-diphenylureas are capable of transporting carboxylic acid-based drugs across phospholipid bilayers without affecting the permeability of other physiological anions such as chloride.

Herein, we introduce a new method to optimize the properties of optical sensors, coined the Transporter-Liposome-Fluorophore (TLF) approach. It is shown that this approach can greatly improve the selectivity of...

Lipids fulfill a variety of important physiological functions, such as energy storage, providing a hydrophobic barrier, and signal transduction. Despite this plethora of biological roles, lipids are rarely considered a...

An arginine derivative with a fluorescent side-chain, Boc-Arg(Nap)-OH, was prepared by palladium(0)-catalyzed coupling of Boc-Arg-OH with a 4-bromonaphthalimide. The presence of the fluorophore lowers the pK a of the side-chain guanidinium group by several orders of magnitude, to 9.0 (±0.1), allowing the derivative to access an electrically neutral protonation state that is not generally available to arginine itself. Computational modeling (DFT) predicts that protonation takes place at the side-chain CN atom that bears the fluorophore. Calculated electronic absorptions for the protonated (356 nm) and neutral species (440 nm) are in good agreement with experiment. When irradiated with light, excited-state proton transfer (ESPT) occurs from cationic side-chains to suitably basic solvents, resulting in fluorescence emission from the neutral species. Arg(Nap) can be incorporated into peptides with sterically accessible N-termini using specially adapted conditions of solid-phase peptide synthesis.