This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles againstEscherichia coli,Staphylococcus aureus, andEnterococcus faecalis. These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates overE. faecalis. Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used.

Nanomaterials obtained by green synthesis technologies have been widely studied in recent years owing to constitute cost-effective and environmental-friendly methods. In addition, there are several works that report the simultaneous performance of the reducer agent as a functionalizing agent, modifying the properties of the nanomaterial. As a simple and economical synthesis methodology, this work presents a method to synthesize silver nanoparticles (AgNPs) using Annona muricata aqueous extract and functionalized with 5-fluorouracil (5-FU). The processes of reduction, nucleation, and functionalization of the nanoparticles were analyzed by UV-Vis absorption spectroscopy, and it was found that they are the function of the contact time of the metal ions with the extract. The structural characterization was carried out by transmission electron microscopy (TEM) and X-ray diffraction patterns (XRD). The antibacterial properties of the synthetized nanomaterials were tested using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Enterococcus faecalis, Staphylococcus aureus, and Escherichia coli growth.

Due to the concern to find an alternative to reduce the colonization (microfouling and macrofouling) or the biocorrosion of surfaces submerged for long periods in water, we evaluated the antifouling activity of a commercial paint added with silver nanoparticles (AgNP’s) and copper nanoparticles (CuNP’s), beside copper‐soybean chelate, by electrolytic synthesis, using them in low concentrations (6.94E − 04 mg Ag g⁻¹ paint, 9.07E − 03 mg Cu g⁻¹ paint, and 1.14E − 02 mg Cu g⁻¹ paint, respectively). The test for paint samples was carried out by JIS Z2801‐ISO 22196 for periods of initial time, 6 months, and 12 months, against three bacterial strains of marine origin, Bacillus subtilis, Bacillus pumilus, and Bacillus altitudinis. It was possible to demonstrate, according to the standard, that the sample with the greatest antimicrobial activity was the copper‐soybean chelate against two of the three strains studied (B. pumilus with R = 2.11 and B. subtilis with R = 2.41), which represents more than 99% of bacterial inhibition. Therefore, we considered a novel option for inhibiting bacterial growth with nanoparticles as antifouling additives.

Nanoparticles (NPs) of magnesium hydroxide appear to be an exceptional nanomaterial due to its biocompatibility and low toxicity. However, the mechanism by which the NPs act in the organism has been very difficult to study. In order to contribute to that challenge, in this work magnesium hydroxide was functionalised with organic fluorophores allowing the material to be traced during an in-vivo experiment. Magnesium hydroxide NPs were obtained by the co-precipitation method and analysed by TEM (Transmission electron microscopy), XRD (x-ray diffraction), Raman spectroscopy (RS) and FTIR (Fourier transform infrared spectroscopy). The effects of reaction time, agitation and stoichiometric ratios of the reagents (MgCl ₂ :NaOH) on the NPs characteristics were studied. Mg(OH) ₂ NPs with average sizes below 65 ± 26 nm were obtained with hexagonal, circular or irregular platelet-shape. NPs with an average size of 41 ± 12 nm were functionalised with curcumin and rhodamine using (3-aminopropyl)-triethoxysilane (APTES) as a coupling agent. It was observed the positive effect of the addition of APTES keeping the Mg(OH) ₂ NPs dispersed. Moreover, it was found that incorporating APTES as a binding agent with curcumin quenched the fluorescence of curcumin on nanoparticles.