RESUMO
Salvinia minima Baker is a small floating aquatic fern that is efficient for the removal and storage of heavy metals such as lead and cadmium. In this study, we report that lead removal by S. minima causes large accumulation of lead inside the cells in the form of nanoparticles (PbNPs). The accumulation pattern of lead was analyzed in both, submerged root-like modified fronds (here named "roots"), and in its aerial leaf-like fronds ("leaves"). Analysis by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) confirmed the biosynthesis of PbNPs by the plant. In both, roots and leaves, PbNPs were found to accumulate almost exclusively at the cell wall and closely associated to the cell membrane. Two types of PbNPs shapes were found in cells of both tissues, those associated to the cell wall were quasi-spherical with 17.2±4.2 nm of diameter, while those associated to the cell membrane/cytoplasm were elongated. Elongated particles were 53.7±29.6 nm in length and 11.1±2.4 nm wide. Infrared spectroscopy (IR) results indicate that cellulose, lignin and pectin are the major components that may be acting as the reducing agents for lead ions; these findings strongly suggest the potential use of this fern to further explore the bio-assisted synthesis of heavy metal nanostructures.
Assuntos
Organismos Aquáticos/metabolismo , Exposição Ambiental , Gleiquênias/metabolismo , Chumbo/toxicidade , Nanopartículas Metálicas/química , Organismos Aquáticos/citologia , Organismos Aquáticos/efeitos dos fármacos , Biodegradação Ambiental/efeitos dos fármacos , Gleiquênias/citologia , Gleiquênias/efeitos dos fármacos , Chumbo/isolamento & purificação , Nanopartículas Metálicas/ultraestrutura , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Soluções , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Nanobiotechnology, bionanotechnology, and nanobiology are terms that have emerged in reference to the combination of nanotechnology and biology. Through the convergence of these disciplines, the production of metallic nanoparticles (NPs) using biological material as reducing agents is rapidly progressing. In the near future, the application of clean, non-toxic, and eco-friendly nanostructured material will be possible in industry and/or biomedicine. Currently, there is a wide range of organisms that have been reported to be useful in producing NPs. However, the development of finer protocols and the applicability of biosynthesized nanostructures are presently under study. Silver and gold are among the most studied metals due to their potential use in medical treatment. In fact, silver NPs have been evaluated as antimicrobial agents, having been successfully used against several types of fungi and bacteria. However, the use of such material in our daily life must be carefully evaluated. This article summarizes some of the most significant results using organisms to produce metallic NPs as well as the microscopic analyses used to characterize the nanostructured material obtained, providing a valuable database for future research.
Assuntos
Biotecnologia/métodos , Nanopartículas Metálicas/ultraestrutura , Metais/metabolismo , OxirreduçãoRESUMO
The development of production processes that can reduce the environmental impact, offer waste reduction and increase energy efficiency is an important step in the field of application of nanotechnology. In this work the filamentous fungus Neurospora crassa was screened and found to be successful for the production of mono and bimetallic Au/Ag nanoparticles (NPs). Analysis by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) confirmed the biosynthesis of NPs by the fungus. The shape of NPs was found to be mainly spherical with average diameter of 11nm for silver and 32nm for gold, when the fungus was exposed to the aqueous solutions of 10(-3)M of AgNO(3) and HAuCl(4), respectively. EDS analysis also confirmed the formation of alloy-type Au/Ag bimetallic NPs when three different ratios of AgNO(3)/HAuCl(4) were used. TEM images of thin sections of N. crassa cells confirmed the intracellular formation of silver and gold NPs. The results obtained indicate that N. crassa can be a potential "nanofactory" for the synthesis of metallic NPs. The use of this organism will offer several advantages since it is considered as a non-pathogenic organism, has a fast growth rate, rapid capacity of metallic ions reduction, NPs stabilization and facile and economical biomass handling.