Evaluación del efecto antimicrobial de amplio espectro de los nanocompósitos magnéticos a base de óxido de grafeno y nanotubos de carbono de pared múltiple basados en la acción bimodal fotodinámico/fototérmico.

Abstract

Throughout history, microbial diseases caused by microorganisms such as bacteria, viruses, fungi, and protozoa, have had a significant impact on humanity, causing millions of deaths and affecting entire communities. For this reason, in recent years there has been a great interest in the development of antimicrobial nanocomposites that can combat this threat. In the present research, magnetic nanocomposites based on multi-walled carbon nanotubes (MWCNT) and graphene oxide (GO) were obtained. These magnetic nanocomposites were synthesized in three steps: first, the coprecipitation synthesis of magnetic nanoparticles in graphene oxide and magnetic nanoparticles in multi-walled carbon nanotubes, obtaining the first two nanocomposites MNPs-GO and MNPs-MWCNTs, respectively; second, functionalization with the photosensitizer Menthol-Zinc Phthalocyanine (ZnMintPc); and finally, the magnetic nanocomposites MNPs-GO and MNPs-MWCNTs carrying ZnMintPc (MNPs-MWCNTs-ZnMintPc and MNPs-GO-ZnMintPc) were dispersed in the biocompatible hydrogel poly(N-vinyl caprolactam-co-poly(ethylene glycol) diacrylate) poly(VCL-co-PEGDA) abbreviated as VCL/PEGDA, thus obtaining the third and fourth magnetic nanocomposite: VCL/PEGDA-MNPs-GO-ZnMintPc and VCL/PEGDA-MNPs-MWCNTs-ZnMintPc. This study addressed the optical, morphological, magnetic, and photophysical properties of nanocomposites. The in vitro antimicrobial effect of the four magnetic nanocomposites obtained on the bacteria Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and the yeast Candida albicans (C. albicans) was evaluated based on the photodynamic/photothermal effect (PTT/PDT) applying a wavelength of 630 nm and a light dose of 65.5 mW·cm−2. The results obtained in the study of the antimicrobial effect showed that the colonies of C. albicans were completely eliminated by the MNPs-GO (MNP=93,3 μg·mL-1, GO=3.47 μg·mL-1) and MNPs-MWCNTs (MNP=93,3 μg·mL-1, MWCNT=3.47 μg·mL-1) nanocomposites based on the bimodal PTT/PDT strategy. Additionally, by the PDT strategy, the E. coli and S. aureus colonies were completely eliminated by the nanocomposite VCL/PEGDA-MNPs-GO-ZnMintPc (MNP=93,3 μg·mL -1, ZnMintPc=8,1 μM, GO=3.47 μg·mL -1), while the three microorganisms were completely eliminated by the nanocomposite VCL/PEGDA-MNPs-MWCNTs-ZnMintPc (MNP=93,3 μg·mL -1, ZnMintPc=8,1 μM MWCNT=3.47 μg·mL -1), therefore, this last magnetic nanocomposite is considered a broad-spectrum antimicrobial agent for PDT.