Zein nanocarriers for controlled maresin-1 delivery: A novel approach in biomaterial-based immunomodulation

In this research work, we report the development of a new immunoengineering approach of sustained drug delivery for regenerative medicine applications. We have produced an innovative nanobiomaterial that integrates the unique advantages of zein, as a protein-based delivery system, with maresin-1, a specialised pro- resolving mediator that plays a critical role in controlling inflammation and promoting its resolution. A microfluidic chip was used as a manufacturing platform to load maresin-1 into zein nanoparticles, by flow- focusing the organic central stream with the aqueous outer fluid. We were able to develop homogeneous nanoparticles presenting a mean diameter between 100 and 117 nm. Different drug loadings were tested: 10, 50, and 100 nM of maresin-1. The nanoparticles loaded with the highest concentration of maresin-1 presented a more controlled release profile throughout 72 h. The biocompatibility and immunomodulatory potential were assessed in primary human macrophages. Maresin-1-loaded zein nanoparticles were non-cytotoxic and, the nanoparticles loaded with 100 nM maresin-1 significantly enhanced macrophage polarisation towards an antiinflammatory M2-like phenotype, as evidenced by a pronounced increase in the M2/M1 ratio. This polarisation effect was higher than that obtained with free maresin-1 or empty zein nanoparticles, highlighting the synergistic potential of this nanocarrier system. This work emphasizes maresin-1-loaded zein nanoparticles as a safe and effective immunomodulatory platform, paving the way for novel therapeutic approaches in inflammation management and tissue repair and regeneration.