Pickering emulsion stabilized by amphiphilic pH-sensitive starch nanoparticles as therapeutic containers

In this paper, we report the use of amphiphilic crosslinked starch nanoparticles (CSTNs) as biocompatible, biodegradable and effective stabilizer for Pickering emulsion formulation. The nearly monodispersed CSTNs (˜140 nm) were synthesized through alkali-freezing method followed by crosslinking using citric acid. The prepared nanoparticles were characterized by field emission scanning electron microscopy, zeta-potential measurements, dynamic light scattering, and Fourier transform infrared spectroscopy. The efficacy of the CSTNs toward the stability, the oil droplet size distribution and the surface area moment mean diameter (d_3,2) of sunflower oil-in-water emulsions were then assessed as a function of pH. Increase in pH from 3 to 5 and 7.4 led to an enhance in the emulsion stability, decrease in d_3,2 and narrowing of the size distribution of emulsions droplets. Moreover, the abundance of nanoparticles increased with pH so that the surface coverage for pH 3, 5 and 7.4 were calculated 10.6, 14.8 and 22.2%, respectively. In vitro controlled release studies showed that the encapsulated curcumin, as a lipophilic and therapeutic compound, into the Pickering emulsion can be tuned by pH of the release media; drug release increases with pH. Collectively, the facile preparation of emulsions stabilized by solid particles derived from biocompatible and renewable resources along with the pH responsivity of these emulsions make them promising drug carriers to treat gastrointestinal tissue disorders via oral drug delivery.