Multifunctional lignin-gum Arabic nanocomposites: Green nanoarchitectonics via ultrasonic-assisted laccase catalysis for antimicrobial, antioxidant, and antidiabetic therapies.

Nanotechnology leveraging natural materials offers sustainable and cost-effective solutions for therapeutic advancements. Lignin and gum Arabic (GA), as biocompatible natural polymers, possess significant bioactive properties; however, their synergistic potential in nanocomposite form remains underexplored. This study synthesized and characterized Lignin-GA nanocomposites (LGA-NPs) through ultrasonic-assisted laccase catalysis, a green synthesis method. The resulting nanocomposites exhibited an average size of 67 ± 18.9 nm and a zeta potential of -32 ± 0.3 mV. Structural analysis via XRD, FTIR, and XPS confirmed the introduction of new functional groups and enhanced oxygen functionalities driven by enzymatic oxidative coupling and ultrasonic treatments. LGA-NPs demonstrated potent antimicrobial activity, with MIC values of 156 μg/mL for S. aureus and C. albicans and 312 μg/mL for E. coli, significantly outperforming lignin, GA, and lignin nanoparticles. Mechanistic studies revealed that LGA-NPs interact with microbial surfaces, disrupting membranes, inhibiting respiratory chains, generating ROS, and reducing ATP and metabolic activity, ultimately impairing microbial growth. Antioxidant evaluations showed superior radical scavenging activity (IC50 at 50 μg/mL), while α-amylase inhibition assays confirmed antidiabetic potential (IC50 of 75.0 μg/mL). Hemolysis tests demonstrated biocompatibility, with hemolysis rates below 5 %, reflecting safety for biomedical applications. The incorporation of GA into lignin not only improved bioactivity but also enhanced safety, emphasizing the synergistic effects of composite formation. These nanocomposites present a novel, sustainable, and economically viable therapeutic platform, addressing complex conditions like diabetic septic foot that demand effective glycemic control, robust antimicrobial action, and potent antioxidant capabilities.