Preparation and characterization of polyethylene glycol/sodium alginate aerogel beads loaded with biogenic zinc oxide nanoparticles: potential therapeutic option for treating multidrug-resistant bacteria and cytotoxic activity

We present a novel 3D nanocomposite aerogel that combines the benefits of polyethylene glycol (PEG), sodium alginate (SA) and zinc oxide nanoparticles (ZnO NPs). PEG serves as the primary component of the aerogel, while SA acts as a filler to enhance its mechanical properties. Both PEG and SA contribute to the aerogel’s adsorption capabilities, while the incorporation of ZnO NPs enhances its antibacterial properties. The ZnO NPs were synthesized using a green method with the assistance of Atriplex halimus (A. halimus) extract. The biosynthesized ZnO NPs were added to a mixture of PEG and SA, and the resulting mixture was subjected to freeze-drying to obtain a porous aerogel beads with a distinctive 3D microstructure. The aerogel composite exhibited a highly porous and sheet-like surface as indicated by scanning electron microscope (SEM). Also, the physicochemical properties of the PEG/SA/ ZnO NPs aerogels composite were estimated such as crystallinity, chemical structure and optical properties. The PEG/SA/ZnO NPs aerogels beads exhibited a swelling rate exceeding 200%. The MIC of the ZnO NPs against E. coli, A. baumannii, K. pneumonia, P. aeruginosa, S. aureus and S. epidermidis were 12.5, 12.5, 25, 25, 6.25 and 6.25 U/ml, respectively. The aerogel demonstrated remarkable antibacterial activities, as evidenced by inhibition zones ranging between 15 and 22 mm² against multidrug-resistant bacteria (MDR). Moreover, the aerogels exhibited significant inhibition efficacy on the MDR bacterial growth with complete inhibition for all strains. These findings highlight the highly effective bactericidal properties of the aerogels. The cytotoxicity of both ZnO NPs and PEG/SA/ZnO NPs was evaluated using HeLa cell lines. The results showed that the ZnO NPs and PEG/SA/ZnO NPs exhibited reasonable anticancer activity against this cell line. The newly developed 3D composite PEG/SA/ZnO NPs aerogels exhibits broad-spectrum antibacterial capabilities against MDR bacterial strains for medical and pharmaceutical applications.