Zeta potential changing nanoemulsions based on phosphate moiety cleavage of a PEGylated surfactant
Markus Kurpiers, Julian Dominik Wolf, Christian Steinbring, Sergey Zaichik, Andreas Bernkop‐Schnürch
Abstract
The aim of this study was to develop and evaluate a zeta potential changing nanoemulsion (NE) containing polyoxyethylene (9) nonylphenol monophosphate ester (PNPP) as emulsifier. 2% (v/v) of PNPP and 0.18% (5 μM) of cetyltrimethylammonium bromide (CTAB) were incorporated into the lipophilic NE preconcentrate (PEG-40 castor oil, glyceryl tricaprylate/tricaprate, propylene glycol dicaprylocaprate, propylene glycol monolaurate, highly purified diethylene glycol monoethyl ether; 20/20/10/30/20, v/v). After diluting the lipophilic preconcentrate, resulting NE was analyzed regarding droplet size, polydispersity index (PDI), storage stability and zeta potential change after incubation with intestinal alkaline phosphatase (IAP). Phosphate release due to cleavage by IAP was quantified by malachite green assay and toxicity as well as cellular uptake behavior on Caco-2 cells was determined. The NE containing PNPP and CTAB displayed a droplet size of 113 nm and a PDI of 0.20. It was stable over 4 h. A zeta potential change from −33.7 to +8.2 mV was observed due to cleavage of phosphate groups by isolated IAP. PNPP could be identified as non-toxic up to concentrations of 0.01% (v/v). Furthermore, an enhanced cellular uptake of the NE changing its zeta potential on Caco-2 cells was determined. Therefore, PNPP seems to be a promising tool for the development of zeta potential changing NE.