In recent years, microbial diseases have been declared one of the main threats to humanity, which has generated significant interest in the development of nanocomposites with antimicrobial capabilities. The study conducted by our researcher Miryan Rosita Rivera, in collaboration with the Escuela Politécnica Nacional (EPN), focused on two magnetic nanocomposites based on graphene oxide (GO) and multiwall carbon nanotubes (MWCNTs). The synthesis of these magnetic nanocomposites consisted of three phases: firstly, the synthesis of iron magnetic nanoparticles (MNPs); secondly, the adsorption of the photosensitizer menthol-zinc phthalocyanine (ZnMintPc) onto MWCNTs and GO; and the third phase involved encapsulation in a biocompatible poly (N-vinylcaprolactam-co-poly(ethylene glycol diacrylate)) (VCL-co-PEGDA) polymer hydrogel to obtain the magnetic nanocomposites VCL/PEGDA-MNPs-MWCNTs-ZnMintPc and VCL/PEGDA-MNPs-GO-ZnMintPc.

In vitro, studies were conducted using Escherichia coli and Staphylococcus aureus bacteria, as well as Candida albicans yeast, based on the photodynamic/photothermal (PDT/PTT) effect. This research describes the optical, morphological, magnetic, and photophysical characteristics of the nanocomposites, as well as their application as antimicrobial agents. The antimicrobial effect of the magnetic nanocomposites was evaluated based on the PDT/PTT effect. For this purpose, doses of 65 mW·cm-2 with 630 nm light were used.

The VCL/PEGDA-MNPs-GO-ZnMintPc nanocomposite eliminated E. coli and S. aureus colonies, while the VCL/PEGDA-MNPs-MWCNTs-ZnMintPc nanocomposite was able to eradicate all three types of microorganisms. Consequently, the latter is considered a broad-spectrum antimicrobial agent in PDT and PTT.

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