Antimicrobial resistance (AMR) is one of the most significant global health threats of the 21st century, driving the urgent search for alternatives to conventional antibiotics. Copper nanoparticles (CuNPs) have gained attention due to their broad antimicrobial spectrum, cost-effectiveness, and versatile applications in medicine, agriculture, and the food industry. This review provides a systematic overview of the advances in CuNP synthesis, mechanisms of antimicrobial action, biomedical and industrial applications, and associated toxicity issues. A comprehensive literature review was conducted, covering chemical, physical, and biological synthesis strategies; mechanistic studies on microbial inhibition; and experimental reports on biomedical and environmental applications. A comparative analysis revealed opportunities, limitations, and knowledge gaps, with particular emphasis on cytotoxic and ecotoxicological aspects. CuNPs show strong antimicrobial activity against bacteria, fungi, viruses, and multidrug-resistant strains through mechanisms such as reactive oxygen species (ROS) generation, membrane disruption, and DNA/protein interactions. Their use in medical devices, wound dressings, textiles, and packaging materials underlines their application potential. However, cytotoxicity to mammalian cells, ecological risks, and the lack of standardized safety protocols remain critical challenges. Particle size, morphology, and surface chemistry strongly influence both efficacy and toxicity, underlining the importance of controlled synthesis and functionalization. Overall, CuNPs represent a promising strategy to tackle the AMR crisis. Future research should focus on environmentally friendly and surface-modified synthesis approaches, standardized toxicity assessments, and robust regulatory frameworks. By balancing antimicrobial efficacy with biosafety and sustainability, CuNPs could become a transformative platform for clinical, industrial, and environmental applications.

A biobased material, polythymol (PTF), was prepared using thymol, a monoterpene obtained from the essential oil of Thymus vulgaris (Lamiaceae), as a starting material with the aim of enhancing the antimicrobial properties of this natural product. Initially, different processes were performed in order to optimize the reaction conditions to obtain a macromolecule with a high purity and yield. PTF was characterized using different techniques, such as NMR, infrared, UV-Vis, and thermogravimetric analyses. The antimicrobial activity of both PTF and thymol was evaluated against different microorganisms, including S. aureus, E. coli, P. aeruginosa, and C. albicans. The obtained MIC values showed a higher potential for PTF than the monomer thymol—for example, against S. aureus (500 and 31.5 µg·mL⁻¹ for thymol and PTF, respectively). Therefore, the obtained results show that the polymerization of thymol afforded more active biomaterial than the starting monomeric antimicrobial compound (thymol), suggesting that PTF is an important biomaterial.

The use of copper as an antimicrobial agent has a long history and has gained renewed interest in the context of the COVID-19 pandemic. In this study, the authors investigated the antimicrobial properties of an alloy composed of copper with a small percentage of silver (Cu-0.03% wt.Ag). The alloy was tested against various pathogens, including Escherichia coli, Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and the H1N1 virus, using contact exposure tests. Results showed that the alloy was capable of inactivating these pathogens in two hours or less, indicating its strong antimicrobial activity. Electrochemical measurements were also performed, revealing that the small addition of silver to copper promoted a higher resistance to corrosion and shifted the formation of copper ions to higher potentials. This shift led to a slow but continuous release of Cu²⁺ ions, which have high biocidal activity. These findings show that the addition of small amounts of silver to copper can enhance its biocidal properties and improve its effectiveness as an antimicrobial material.