Recent research has focused on developing electromagnetic wave absorbers that exhibit high absorption performance, thin thickness, low density, light weight, low cost, and a broad absorption bandwidth. In this study, a virtual model of a polycaprolactone (PCL)-based composite reinforced with varying proportions of nano zinc oxide (ZnO) and silicon dioxide (SiO₂) was developed using COMSOL Multiphysics. A rectangular waveguide structure was designed to simulate a Network Analyser (NWA) setup used for wave transmission measurements. The complex permittivity of the composites was calculated for different ZnO andSiO₂ contents. The results revealed that the dielectric constant increased from 2.893 to 3.833, and the dielectric loss factor rose from 0.253 to 0.369 with higher filler loading. Consequently, the reflection loss (RL) decreased to 3.718 dB, while the absorption coefficient increased to 0.110, and the attenuation coefficient reached 3.2393dB at 10 GHz for an absorber thickness of 0.003 m. These findings demonstrate the potential of PCL/ZnO/SiO₂composites as lightweight and efficient microwave absorbing materials.

Biological synthesis of nanoparticles is a promising approach that is comparatively inexpensive and eco-friendly. Among various microorganisms, actinobacteria have been found to be efficient in the synthesis of nanomaterials. In this study, extracellular biosynthesis of silver nanoparticles (Ag-NPs) was investigated by mixing silver nitrate with culture filtrate of Streptomyces rochei strain MFA-37. The biosynthesized Ag-NPs were characterized by UV–Vis spectrophotometric analysis, and showed a peak of absorbance at 440 nm. Fourier transform infrared (FTIR) analysis showed amines and amides that are responsible for the stabilization of Ag-NPs. The morphology and size of nanoparticles were determined using high-resolution transmission electron microscopy, XRD and DLS techniques which indicated well dispersed, spherical Ag-NPs sized 2–20 nm, and the zeta potential of AgNPs reached -20.5 mV. Enhancement of antibacterial activity of fourteen antibiotics was conducted by combining antibiotics with synthesized AgNPs. The synergistic activities of AgNPs combination with antibiotics were determined using disc diffusion against two multi-drug resistant Staphylococcus aureus SA-185 and SA-325 recovered from Libya. The highest synergistic effects were 6.11 and 6.37 folds for Penicillin followed by 6.11 and 4.44 folds for Ciprofloxacin and 6.11 and 3.69 folds for Erythromycin for MRSA-185 and MRSA-325, respectively. This activity of AgNPs and antibiotics could be valuable for the manufacture of hybrid drugs to kill or inhibit the MRSA infection especially in case of superficial injuries.