Use of nanoparticles of copper with plant extracts as an alternative against multidrug-resistant bacteria causing urinary tract infections

Abstract

There is increasing concern due to the high incidence of multi-resistant bacteria. The importance of these microorganisms is in the economic and health impact that cause at global level in different countries. Many efforts have been made to improve drugs to attack these bacteria, however in the long term this only aggravates the situation. Due to this, alternatives that allow to reverse this situation are necessary. Thanks to the development of nanotechnology, the importance of nanoparticles has increased in the last years to fight infections. The green synthesis process is particularly appealing. It has been reported the use of plant extracts as reducing agents allows obtaining metallic nanoparticles with antibacterial activity. That is why in this project copper nanoparticles (CuNPs) with green synthesis were obtained. For this, extracts of Azadiractha Indica (Neem) and Eysenhardtia Polystachia (Palo Azul) were used given a previously reported medicinal properties in urinary tract infections and their high content of metabolites as reducing agents for the formation of nanoparticles (NPs). The extracts were characterized at different conditions of time and temperature, by IFTR (Fourier transform infrared) and UV-vis. Following this, mixtures of the selected extract with solutions of copper precursor salt at a specific concentration were heated under constant stirring for 20 h, taking samples at 4-hour intervals. The obtained nanoparticles were analyzed in terms of distribution, size, morphology, and concentration through dynamic light scattering (DLS) and scanning electron microscopy (SEM). Meanwhile, the characterization of its antimicrobial effect was determined thanks to absorbance analysis in liquid culture and plate reader. It was observed that as the synthesis time passes, the size of the nanoparticle tends to reduce. On the other hand, its morphology shows signs of being colloidal, although not uniformly. Meanwhile, when comparing the nanoparticles made with both extracts and different precursor salts, a different size trend was observed in nanoparticles. in terms of antibacterial activity, it was observed that the synthesis time at 20 h of the process shows an insight of bacteriostatic activity compared to a shorter stirring time. Meanwhile an indication of concentration-dependent inhibition was observed. On the other hand, it was observed that the combination of Neem extract with copper nitrate precursor salt is the best option for inhibition of bacteria. However, it is necessary to carry out more studies of antibacterial effects to guarantee its effectiveness to be an alternative to conventional antibiotic treatments.