Preparation and brain delivery property of biodegradable polymersomes conjugated with OX26

A novel drug carrier for brain delivery, poly(ethyleneglycol)-poly(epsilon-caprolactone) (PEG-PCL) polymersomes conjugated with mouse-anti-rat monoclonal antibody OX26 (OX26-PO), was developed and its brain delivery property was evaluated. The diblock copolymers of methoxy-PEG-PCL and Maleimide-PEG-PCL were synthesized and applied to prepare polymersomes (PO) which were verified by direct cryogenic temperature transmission electron micrograph (Cryo-TEM) imaging. The TEM examination and dynamic light scattering results showed that OX26-PO had a round and vesicle-like shape with a mean diameter around 100 nm. Coupling of OX26 with PO was confirmed by immuno-gold labeling of OX26 visualized under the TEM and X-ray photoelectron spectroscopy test. The surface OX26 densities were obtained from enzyme-linked immunosorbant assay. The result of brain delivery in rats proved that the increase of surface OX26 density of OX26-PO decreased blood AUC. The optimized OX26 number conjugated per polymersome was 34, which can acquire the greatest blood-brain barrier (BBB) permeability surface area product and percentage of injected dose per gram brain (%ID/g brain). Furthermore, NC-1900, as a model peptide, was encapsulated into OX26(34)-PO and improved the scopolamine-induced learning and memory impairments in a water maze task via i.v. administration. These results indicated that OX26(34)-PO is a promising carrier for peptide brain delivery.