A dual-functional dendrimer-based system integrating recombinant endolysin and cinnamic acid for enhanced endolysin stability and antibacterial activity against Acinetobacter baumannii.

The application of recombinant endolysins against Gram-negative bacteria is often limited by their stability and the protective barrier presented by the outer membrane. In this study, we developed a dual-component magnetic nanoplatform to address these challenges. Third-generation poly(amidoamine) (PAMAM)-functionalized superparamagnetic iron oxide nanoparticles (SPIONs) were employed for PlyF307 immobilization (PlyF307-immobilized G3 PAMAM-SPIONs, G3E), while an analogous cinnamic acid-functionalized G3 PAMAM-SPION platform (G3Cin) was prepared to provide additional antimicrobial activity and potentially influence interactions with the bacterial envelope. Immobilized PlyF307 retained 92.7% of its initial activity, with optimal performance at pH 8 and 30 °C. The combined G3E + G3Cin system reduced the viability of Acinetobacter baumannii by approximately 2 log₁₀ from an initial concentration of 1.0 × 10⁶ CFU/mL and exhibited greater antibacterial activity than the individual treatments. Physicochemical characterization (VSM, FTIR, DLS, zeta potential, and SEM) confirmed successful functionalization and provided complementary information on the nanoparticle properties. Overall, the dual-component SPION-based platform improved the functional stability and antibacterial performance of immobilized PlyF307, highlighting its potential for antimicrobial nanobiotechnology applications.