Green Synthesis of Glabridin-Loaded Zeolitic Imidazolate Framework-8 Drug Delivery System: Characterization, Synergistic Antibacterial Efficacy, and pH-Dependent Drug Release Kinetics

This study reports a green one-pot synthesis of glabridin-loaded Zeolitic Imidazolate Framework-8 (Glab@ZIF-8) drug delivery system (DDS) with exceptional drug loading encapsulation (DLE) of ≈ 98.7% and drug loading capacity (DLC) of 32%, surpassing values reported in previous ZIF-8-based DDS. Characterizations using Fourier-transform infrared (FTIR), UV–Visible spectroscopy, dynamic light scattering (DLS), and X-ray diffraction (XRD) confirmed successful encapsulation of Glab within ZIF-8 while preserving its crystallinity. Glab@ZIF-8 exhibited a hexagonal morphology with increased particle size (138.6 ± 5.4 nm) and a higher zeta potential (+41.9 mV), suggesting enhanced colloidal stability and efficient drug entrapment. Thermogravimetric analysis (TGA) demonstrated a total of 32.1% decomposition of Glab@ZIF-8 up to 644 °C. Antibacterial assays revealed that Glab@ZIF-8 exhibited superior activity against Staphylococcus aureus (inhibition zone: 26.2 ± 0.3 mm) and Escherichia coli (23.3 ± 0.2), comparable to that of ampicillin. The minimum inhibitory concentration (MIC) was determined to be 32.5 μg/100 μL. Furthermore, the time-kill studies confirmed a dose- and time-dependent antibacterial effects of Glab@ZIF-8. In vitro drug release studies showed strong pH- and temperature-responsive behavior, with a cumulative release of 93.7% ± 2.4% release at pH 5 (at 37°C) over 72 h. The Glab@ZIF-8 system thus combines high drug loading efficiency, excellent antibacterial activity, and tuneable release characteristics, highlighting its potential as a promising DDS for combating drug-resistant infections.