Nanoparticles for New Pharmaceuticals: Metabolites from Actinobacteria

DAVILA COSTA JOSE; ROMERO CINTIA MARIANA; RASUK CECILIA; ALVAREZ ANALIA

Environmental Biotechnology

Springer, Nature

Año: 2020;

.The resistance of common or resurgent pathogens to standard antibiotic therapies is a significant health problem, so the need for new antimicrobial sources is imperative. It is widely known that the most promising source of new drugs remains natural products, mainly those of microbial origin. Such is the case of microbial nanoparticles (NPs) which have unusual physical, chemical, and biological properties like as powerful antibacterial activities. While NPs synthesized by chemical methods involve hazardous and expensive processes, nano-biosynthesis is a green technology by which NPs are obtained through biological processes such as the reduction of a metal salt by the action of biomolecules.The aim of this chapter is to provide an overview of the continuing central role of natural products like the NPs in the discovery and development of new pharmaceuticals. It is known that Actinobacteria are excellent producers of specialized biomolecules, such as NPs. Moreover, it was demonstrated that they have in their genomes many more biosynthetic pathways, which constitute an untapped promising source of new antibacterial molecules and other therapeutic agents. Here, we focus on those heavy metal-resistant strains, due to biogenic NPs are synthesized by simple processes of metal reductions which can naturally occur as part of cellular detoxification mechanisms. In this context, a brief description of the ways of the NPs bioproduction is given. Although extracellular production of metal NPs has more commercial applications in several areas, intracellular production is of the particular dimension and with less polydispersity. This is remarkable due to the control over particle size, and polydispersity is needed to be established for biotechnological purposes. Also, a brief overview of some of the most important methods for nanoparticle characterization is provided. The most applied techniques in NPs characterization are ultraviolet-visible (UV-vis) spectrophotometer, transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic light scattering (DLS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Zeta potential measurement, particle size analysis (PSA), and energy dispersive X-ray spectroscopy (EDX).By last, this chapter describes the mechanisms that explain the antimicrobial properties of NPs, and it is believed that the more relevant traits of NPs are related with their surface-reactive groups exposed, leading to the formation of reactive oxygen species (ROS). This is indirectly related to their size, as the size of the particle decreases and its surface area increases and determines the potential number of reactive groups on the particles