Nanoparticles for New Pharmaceuticals: Metabolites from Actinobacteria

MARÍA CECILIA RASUK; ANALÍA ALVAREZ; CINTIA MARIANA ROMERO; DAIANA GUERRERO; DÁVILA COSTA, JOSÉ SEBASTIÁN; JULIÁN PEREYRA

Environmental Nanotechnology

Springer Nature

Año: 2020; p. 195 - 213

The resistance of common or resurgent pathogens to standard antibiotictherapies is a significant health problem, so the need for new antimicrobial sources isimperative. It is widely known that the most promising source of new drugs remainsnatural products, mainly those of microbial origin. Such is the case of microbialnanoparticles (NPs) which have unusual physical, chemical, and biological properties like as powerful antibacterial activities. While NPs synthesized by chemicalmethods involve hazardous and expensive processes, nano-biosynthesis is a greentechnology by which NPs are obtained through biological processes such as thereduction of a metal salt by the action of biomolecules.The aim of this chapter is to provide an overview of the continuing central role ofnatural 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 theirgenomes many more biosynthetic pathways, which constitute an untapped promising source of new antibacterial molecules and other therapeutic agents. Here, wefocus on those heavy metal-resistant strains, due to biogenic NPs are synthesized bysimple processes of metal reductions which can naturally occur as part of cellulardetoxification mechanisms. In this context, a brief description of the ways of the NPsbioproduction is given. Although extracellular production of metal NPs has morecommercial applications in several areas, intracellular production is of the particulardimension and with less polydispersity. This is remarkable due to the control overparticle size, and polydispersity is needed to be established for biotechnologicalpurposes. Also, a brief overview of some of the most important methods fornanoparticle characterization is provided. The most applied techniques in NPscharacterization are ultraviolet-visible (UV-vis) spectrophotometer, transmissionelectron microscopy (TEM), scanning electron microscopy (SEM), atomic forcemicroscopy (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 antimicrobialproperties of NPs, and it is believed that the more relevant traits of NPs are relatedwith their surface-reactive groups exposed, leading to the formation of reactiveoxygen species (ROS). This is indirectly related to their size, as the size of theparticle decreases and its surface area increases and determines the potential numberof reactive groups on the particle surface