Abstract
In this work, we report the synthesis of copper nanoparticles (Cu NPs), employing the chemical reduction method in an aqueous medium. We used copper sulfate pentahydrate (CuSO4·5H2O) as a metallic precursor; polyethylenimine (PEI), allylamine (AAM), and 4-aminobutyric acid (AABT) as stabilizing agents; and hydrated hydrazine as a reducing agent. The characterization of the obtained nanoparticles consisted of X-ray, TEM, FTIR, and TGA analyses. Through these techniques, it was possible to detect the presence of the used stabilizing agents on the surface of the NPs. Finally, a zeta potential analysis was performed to differentiate the stability of the nanoparticles with a different type of stabilizing agent, from which it was determined that the most stable nanoparticles were the Cu NPs synthesized in the presence of the PEI/AAM mixture. The antimicrobial activity of Cu/PEI/AABT toward P. aeruginosa and S. aureus bacteria was high, inhibiting both bacteria with low contact times and copper concentrations of 50–200 ppm. The synthesis method allowed us to obtain Cu NPs free of oxides, stable to oxidation, and with high yields. The newly functionalized Cu NPs are potential candidates for antimicrobial applications.
Highlights
The synthesis of Cu NPs was performed at a constant pH of 12.0, a condition that favors the formation of CuO and Cu2 O
The presence of the organic coating was confirmed by the Fourier-transform infrared spectroscopy (FTIR), Transmission Electron Microscopy Analysis (TEM), and Thermogravimetric analysis (TGA) analyses
The colloidal solution obtained with Cu-polyethylenimine and allylamine (PEI/AAM) NPs showed the highest stability with a zeta potential of −82.8 mV
Summary
Copper has been identified as a material with excellent antimicrobial properties, as it can efficiently eliminate fungi, bacteria, and viruses [1]. The antimicrobial activity of copper was demonstrated with the emergence of the COVID-19 pandemic, since copper was able to inactivate the novel coronavirus (SARS-CoV-2) in shorter times compared to other materials [2]. Regarding Cu NPs, several papers have recently highlighted their importance in priority areas for humankind, for instance, in medical (the COVID-19 pandemic) [3,4], farming [5,6,7,8], and environmental applications [9,10], among others. As with other metallic nanoparticles (M NPs), Cu NPs have been widely studied due to their antimicrobial, electrical, thermal conductivity, catalytic, and optical properties [11]
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