A β-Cyclodextrin-Eugenol Complex as a Modifier of Methacrylate Bone Cement

The work is devoted to research on the influence of β-cyclodextrin/eugenol complex (CP-EU) on the properties of methacrylic bone cement. Eugenol (4-allyl-2-methoxyphenol) is an essential oil that exhibits antimicrobial properties against pathogenic bacteria, and these properties are desirable in bone cements. This may allow the replacement of antibiotics currently used in bone cements. However, since eugenol causes a decrease in the polymerization rate, it was decided to modify it with sulfobutylether-β-cyclodextrin (Captisol). The use of CP-EU complex in the amount of 0.5 wt% (calculated on EU amount) eliminated this unfavorable effect of eugenol on the polymerization process and influenced its release from bone cement. Properties of modified bone cements were examined, including doughing time, maximum temperature (T_max), setting temperature (T_set), setting time (t_set), compressive strength, and antibacterial properties. The CP-EU complex does not affect the maximum curing temperature of bone cement, which remained within the clinically acceptable range (58.7°C-69.8°C), and all formulations meet ISO 5833:2002 standards. Importantly, it causes an increase in compressive strength of up to 33.5% and Young's modulus of up to 454.1%, demonstrating a beneficial enhancement in the mechanical performance of the tested materials. The release of eugenol was very high, ranging from 84.5% to 86.9%. Furthermore, antibacterial studies show that the tested materials, the CP-EU complex and modified bone cements, have antibacterial properties for Escherichia coli strains. The cell viability in the presence of the CP-EU complex was 39.9% after 72 h of incubation. Cytotoxicity assays conducted on osteoblasts demonstrated that free eugenol induces both acute and persistent cytotoxic effects, whereas its complexation with Captisol restores biocompatibility and enhances osteoblast viability. Consequently, Captisol serves as an effective carrier for modulating eugenol release and improving the biological performance of modified acrylic cements. In summary, the modified bone cements meet all standard requirements and are characterized by good mechanical properties, high eugenol release, and antibacterial properties. Thus, the incorporation of eugenol into β-cyclodextrin allowed obtaining a CP-EU complex for bone cement modification, exhibiting the desired properties.