Fabrication and Characterization of Nerolidol-Based Invasomes: Loading, Stability and Antimicrobial Applications

Background/Objectives: Nerolidol (NER) is a sesquiterpene alcohol with recognized antimicrobial potential, whose applications as a pure substance are limited by hydrophobicity, instability, and cytotoxicity. Invasomes, i.e., liposomes with terpene ingredients, offer a strategy to improve their delivery; however, the NER loading limits compatible with vesicle integrity are still unclear. Here, Nerolidol-loaded invasomes were produced using a controlled simil-microfluidic coaxial injection process. Methods and Results: As a preliminary step, unloaded liposomes were fabricated to consolidate operating conditions and ensure their reproducible colloidal properties. Thereafter, formulations with progressively decreasing nominal NER loads were investigated to evaluate vesicle size, polydispersity, ζ-potential, encapsulation efficiency, effective loading, and stability. High nominal loads promoted turbidity, size increase (by agglomeration coalescence phenomena), and structural instability, whereas formulations containing approximately 1-2% NER achieved nearly complete encapsulation, Z-average ≈ 300 nm, |ζ| > 30 mV, and satisfactory physical stability. Antimicrobial and cytotoxic profiles of representative formulations, previously evaluated in an independent study are here reported only to contextualize the practical relevance of the optimized systems, while the present work primarily focuses on process-formulation aspects and loading/stability limitations. Conclusions: Overall, the present work identifies a realistic loading window for Nerolidol invasomes and highlights the suitability of the simil-microfluidic approach to obtain scalable, well-controlled formulations, providing a rational basis for their future biological assessment. Nerolidol invasome systems indeed can be considered a promising, versatile platform for antimicrobial applications, including prospective use in animal feed.