Zinc Oxide-Loaded Recycled PET Nanofibers for Applications in Healthcare and Biomedical Devices

Abstract

Polyethylene terephthalate (PET) is a widely utilized synthetic polymer, favored in various applications for its desirable physicochemical characteristics and widespread accessibility. However, its extensive utilization, coupled with improper waste disposal, has led to the alarming pollution of the environment. Thus, recycling PET products is essential for diminishing global pollution and turning waste into meaningful materials. Therefore, this study proposes the fabrication of electrospun membranes made of recycled PET nanofibers as a cost-effective valorization method for PET waste. ZnO nanoparticles were coated onto polymeric materials to enhance the antimicrobial properties of the PET fibers. Morphostructural investigations revealed the formation of fibrillar membranes made of unordered nanofibers (i.e., 40-100 nm in diameter), on the surface of which zinc oxide nanoparticles of 10-20 nm were attached. PET@ZnO membranes demonstrated effective antimicrobial and antibiofilm activity against Gram-positive and Gram-negative bacteria, yeasts, and molds, while imparting no toxicity to amniotic fluid stem cells. In vivo tests confirmed the materials' biocompatibility, as no side effects were observed in mice following membrane implantation. Altogether, these findings highlight the potential of integrating ZnO nanoparticles into recycled PET to develop multifunctional materials suitable for healthcare facilities (such as antimicrobial textiles) and biomedical devices, including applications such as textiles, meshes, and sutures.

Keywords: antimicrobial activity; biocompatibility; electrospun membranes; polyethylene terephthalate nanofibers; recycling; zinc oxide nanoparticles.

Figure 1

SEM images recorded for PET@ZnO at various deposition rates, where (a1,2)—2.5 mL/h; (b1,2)—5 mL/h; (c1,2)—7.5 mL/h; (d1,2)—10 mL/h.

Figure 1

SEM images recorded for PET@ZnO at various deposition rates, where (a1,2)—2.5 mL/h; (b1,2)—5 mL/h; (c1,2)—7.5 mL/h; (d1,2)—10 mL/h.

Figure 2

TEM images recorded for the nanostructured PET@ZnO membranes, with a deposition rate of 2.5 mL/h.

Figure 3

FT-IR spectra recorded for the PET@ZnO-type membranes.

Figure 4

X-ray diffraction (XRD) patterns of PET@ZnO membranes, where (a) 2.5 mL/h, (b) 5 mL/h, (c) 7.5 mL/h, (d) 10 mL/h deposition rate.

Figure 5

Absorbance values for Ps. aeruginosa, S. aureus, and C. albicans cultures, showing cell growth after 24 h in the presence of recycled PET@ZnO membranes.

Figure 6

CFU/mL values showing the number of S. aureus cells in monospecific biofilms formed on the material surfaces after 24, 48, and 72 h at 37 °C.

Figure 7

CFU/mL values showing the number of Ps. aeruginosa cells in monospecific biofilms formed on the material surfaces after 24, 48, and 72 h at 37 °C.

Figure 8

CFU/mL values showing the number of C. albicans cells in monospecific biofilms formed on the material surfaces after 24, 48, and 72 h at 37 °C.

Figure 9

Appearance of A. niger cultures developed in the presence of the nanostructured PET@ZnO membranes, deposition rate 5 mL/h, over 1, 2, or 3 weeks.

Figure 10

Graphical representation of the MTT technique results, represented by absorbance values at 570 nm, which suggest the optical density of the formazan released following the reduction reaction of the MTT reagent by the mitochondrial oxidoreductases of metabolically active cells in the presence of the tested PET materials.

Figure 11

Luminescence values, expressed in arbitrary units, indicating glutathione S-transferase activity, which reflects oxidative stress levels in cultured diploid cells exposed to the obtained materials.

Figure 12

Histopathological analysis of PET@ZnO at 24 h and 7 days post-implantation in H&E stain. * Implanted material; arrow (a)—neutrophils; arrow (b)—macrophages; Scale bar 50 μm and 20 μm.

Figure 13

Collagen proliferation analysis after PET@ZnO subcutaneous implantation at 24 h and 14 days by Masson-Goldner trichrome stain; Scale bar 50 μm.