Peptide nanotubes are promising materials for a variety of biomedical applications
with ultrashort (<= 7 amino acids) forms providing particular promise for clinical
translation. The manufacture of peptide nanotubes has, however, been associated with
toxic organic solvents restricting clinical use. The purpose of this work is to formulate
dipeptide nanotubes using mild techniques easily translated to industrial upscale
and to characterize their physiochemical and biological properties. Phenylalanine-phenylalanine
variants can be successfully formulated using distilled water as demonstrated here.
Formulations are homogenous in shape (tubular), with apparent size (50-260 nm) and
a zeta potential of up to +30 mV. L-(H2N-FF-COOH), and D-enantiomers (H2N-ff-COOH)
demonstrate no toxicity against glioblastoma cells and are explored for ability to
deliver a model hydrophilic molecule, sodium fluorescein, at pH 5.5 (tumor) and 7.4
(physiological). Peptide nanotubes loaded with >85% sodium fluorescein, demonstrate
burst release characteristics, fitting the Weibull model of drug release. This research
provides important data contributing to the pharmaceutical formulation of peptide
nanotubes as drug delivery platforms for hydrophilic drugs.