Microgels Based on Carboxymethylpullulan Grafted with Ferulic Acid Obtained by Enzymatic Crosslinking in Emulsion for Drug Delivery Systems

Carboxymethylpullulan (CMP) grafted with ferulic acid (FA) is crosslinked with laccase by the reverse water-in-oil emulsion technique (with sunflower oil) to obtain microgels with size from 40 to 200 mu m. It is demonstrated that laccase activity and dispersion time have an impact on microgels' size. Fluorescence spectroscopy of different probes (e.g., pyrene, Nile red, and curcumin) shows the nonpolar characteristics of hydrophobic microdomains formed by the FA moieties and its dimers forming the crosslinking nodes. Encapsulation and release of curcumin or lidocaine used as drug models are studied in different buffers. Curcumin is well encapsulated but retained in microgels, while lidocaine is released at 65-70% in 2 h and 30 min in buffer simulating the gastrointestinal tract and at 75-85% in 1 h in acetate buffer pH 5.6 or phosphate-buffered saline (PBS) pH 6.9.

Automated summary

The size of microgels is influenced by the laccase activity and dispersion time. The hydrophobic microdomains formed by ferulic acid moieties play a key role in the encapsulation of curcumin, while lidocaine release rate depends on the type of buffer solution.