Control of the gastrointestinal digestion of solid lipid nanoparticles using PEGylated emulsifiers

- Saturation of PEGylated emulsifiers onto SLNs was determined by the lipophilic tail.
- Larger and denser PEG molecules on SLNs better inhibit the adsorption of bile acids.
- Lipolysable degree of small PEGylated SLNs was inversely proportional to the size.
- Lipolysable degree of highly PEGylated SLNs was proportional to the PEG density.

We prepared solid lipid nanoparticles (SLNs) with tristearin and various emulsifiers which had different chain length PEGs (10-100 times-repetition of ethylene glycol) to control their digestion fate in the gastrointestinal tract. Fabricated SLNs after acidic/high-ionic-strength media treatment were stable regardless of the ζ-potential (ZP) disappearance. Additionally, highly PEGylated SLNs successfully hindered the adsorption of both bile acid (BA) and lipase on the SLN surface, while lowly PEGylated SLNs interrupted that of only lipase. In simulated small intestinal fluid, lipolysis of highly PEGylated SLNs increased with decrease of the emulsifier density on the SLNs, whereas lipolysis of lowly PEGylated SLNs increased with decrease of the particle size. These results suggested that high PEGylation was more efficient than low PEGylation to hinder the lipolysis initiated from the competitive replacement of the SLN-covering emulsifiers with BAs. Consequently, the SLN digestion could be controlled by choosing the length and concentration of PEGylated emulsifiers.