In the first part of the project, experiments were conducted to design and optimize LLC formulations to obtain applicable coatings for implant surface. In this context, amphiphilic lipids including, GMO and docosahexaenoic acid monoglyceride (MAG-DHA) have been investigated with and without antibiotic loaded. The structural features of the designed LLC phases and effects of parameters on structural features have been investigated by using SAXS (or GISAXS) characterizations. To obtained LLC coatings were loaded with commercially available antibiotics (such as colistin, vancomycin, rifampicin, tobramycin, and daptomycin), and their antibacterial efficacy was tested against both gram-positive and gram-negative bacteria. The significant antibacterial properties of LLC coatings suggest that lipid-based self-assembled nanocoatings could be effectively used to prevent biofilm formation on orthopedic implants.
The second goal of WP1 was to develop novel antibiotic-free LLC coatings based ω-3 PUFA monoglyceride of MAG-DHA. This objective was achieved by designing and formation of MAG-DHA and GMO binary LLC coatings at various compositions, testing their antibacterial efficiencies to prevent implant infections. The produced self-assembled coatings, particularly at a high content of MAG-DHA, demonstrated unique inherent antibacterial activities against gram-positive Staphylococcus aureus and Staphylococcus epidermidis strains, without the use of antibiotics.
The third objective of the project was to structurally investigate the topological surface coating with desired durability and stability through advanced characterization techniques. Various metallic substrates including, stainless steel discs, titanium plates, 3D printed porous titanium substrates, and silicon wafers were used as representative surfaces. Spin coating, dip (layer-by-layer) coating and polpolydopamine-assistedating have been employed to generate LLC coatings on various surfaces. The structural properties of the coatings on the surface have been investigated by advanced modalities, including SAXS and GISAXS. It is demonstrated that, depending on lipid composition and relative humidity, the directed self-assembly of MAG-DHA and GMO on solid interfaces led to the generation of different self-assemblies (including swollen micelles, and hexagonal (H2) and bicontinuous cubic (Q2) phases). These studies were important to gain insight into the hydration-induced formation of different inverse non-lamellar liquid crystalline self-assemblies.
