Egyptian propolis 14: Potential antibacterial activity of propolis-encapsulated alginate nanoparticles against different pathogenic bacteria strains

The present study evaluates the synergistic antimicrobial effect of the propolis-encapsulated alginate nanoparticles (propolis-ALg NPs) against different pathogenic bacteria. The prepared samples were characterised by transimissin electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), zeta potential and dielectric spectroscopy. The morphological analysis using TEM revealed that, the propolis-ALg NPs are spherical, discrete and have a small particle size (13 nm) in the nanometer scale. FTIR studies showed a spectral change of the characteristic absorption bands of ALg NPs after being encapsulated with propolis. A high negative zeta potential value is obtained for propolis-ALg NPs which indicates a high suspension stability of the prepared formulation. The dielectric study showed a decrease in the dielectric constant (epsilon'), dielectric loss (epsilon'') and conductivity (sigma) values after the incorporation of the propolis into ALg NPs. All these investigations confirm the successful encapsulation of propolis within ALg NPs. On the other hand, the propolis-ALg NPs sample showed the highest antimicrobial activity against all examined pathogens in comparison with pure propolis and/or antibiotic (clindamycin). So, it can be concluded that the propolis-ALg NPs exhibited a synergistic antibacterial activity against different bacterial strains.