Tailored lipid crystallization in confined microparticle domains through alkyl chains infiltration from cellulose nanofiber surfactants

Through this study, we show that hydrophobically modified cellulose nanofibers can substantially influence the subcell crystallization of ceramide-based lipids within confined particle domains. We demonstrate that C18 alkyl chain-conjugated bacterial cellulose nanofibers (BCNF_C18) can armor ceramide (Cer)/stearyl alcohol (SA) lipid crystal phases to form ceramide-based lipid microparticles (CerMPs). X-ray diffraction measurements revealed that by armoring CerMPs with BCNF_C18, lipid crystal structures could be changed from the β subcell to β’ subcell. Less generation of β subcells within a densely packed lipid crystal structure is critically important to confine the growth of Cer/SA lipid crystals within a microparticle domain. By performing energy calculations and interfacial rheology analysis, we found that the alkyl chains of BCNF_C18 infiltrated the CerMP peripheries. We demonstrate through this study that the alkyl chains of BCNF_C18 can associate with the highly crystalline Cer/SA crystal phase of a lipid, thereby strengthening the interface between the lipid and the BCNF_C18. The study findings highlight the importance of engineering nanoscale fiber surfactants capable of alkyl chain infiltration. These surfactants can be used to prepare crystallizable active ingredients in a feasible and diverse manner for applications in the pharmaceutical, food, and cosmetic industries.