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Silver nanoparticles have been increasingly used in industrial applications for a long time. Chemical methods of synthesizing silver nanoparticles can be toxic and expensive. Therefore, many studies have emerged to create ecologically correct synthetic routes that provide good dispersion and stability in the extractive medium. Plant species are investigated for the discovery of a new dispersive medium for silver nanoparticles (AgNPs) synthesized by the green route. AgNPs are disperse in plant extract, by plants available in Brazil. In this work, Melissa Officinalis leaves were used as a dispersive medium of nanoparticles. The characterization techniques used became possible to observe the superficial modifications with the presence of well-dispersed nanostructures, which are fundamental for the production of intelligent textiles with antimicrobial action. Thus, it was possible by means of each synthesis route to evaluate the dispersion and morphology of AgNPs in different dispersive media of Melissa Officinalis, concluding that it is very efficient for the stabilization of AgNPs. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) have a large number of technological applications, such as photonic devices, molecular diagnostics, antimicrobial coating and biomedical devices. These nanomaterials can be synthesized using common fungi, which represents a green approach with the additional advantage of biocompatibility. Here we applied Tip-Enhanced Raman Spectroscopy (TERS) to obtain optical characterization with resolution beyond the diffraction limit of AgNPs produced by Rhodotorula glutinis and Rhodotorula mucilaginosa fungi. Those fungi are conventional found in ordinary soil of north part of Brazil, which biosynthesize core-shell AgNPs with protein-capping layer. With TERS we were able to investigate with lateral resolution of few nanometers the size and structure of the protein capping layer, how it interacts with the Ag core, and how sensitive the system (core + protein) is to visible light illumination. Despite the complex data generated which depends on the orientation of the protein, which is highly, it was possible to detect the stretching of the S - S sulfur bridge in amino acids. This stretch band is induced by a trans C α - S conformation acid on Rm-AgNPs, thus showing the potential of characterization of TERS in nanobiosystems. [ABSTRACT FROM AUTHOR]