Use of hypocrea lixii for the production of copper nanoparticles in laboratory scale.

Author(s)

Mariana Marangoni

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2016-05-12

Examining board members

Cláudio Augusto Oller do Nascimento; Benedito Correa; Jorge Alberto Soares Tenório

• Advisor: Cláudio Augusto Oller do Nascimento

Abstract

In this work, the synthesis of copper nanoparticles using fungus Hypocrea lixii was evaluated. Therefore, the culture of the fungus was optimized in terms of cell concentration and hyphae qualitative aspect. It was found that cultures inoculated through frozen spore suspensions and using nutrient rich medium containing malt extract reached cell concentrations of 10g/L consistently, in addition to an aggregates-free hyphae aspect. The biossorption of copper (II) ions using non-viable biomass of Hypocrea lixii was measured, and sorption isotherms were constructed. It was found that the maximum removal calculated using the Langmuir model was 17,4mg/g, which was considered consistent with the value previously reported for this fungus. For the nanoparticle synthesis, the viable and non-viable biomasses of the fungus were initially used. Transmission electron microscopy (TEM) analysis demonstrated the formation of nanoparticles of 15nm of mean diameter inside the cells and in the cell wall for the non-viable biomass. For the viable biomass the particles obtained had 30nm of mean diameter and were located exclusively outside the cells. The use of viable and non-viable biomass suspension extracts was also investigated. The extracts were obtained after contact with double deionized water for 24 hours. Transmission electron microscopy (TEM) analysis showed the formation of particles with mean diameter of 12nm, for the viable biomass extract, and 10nm for the non-viable biomass extract. A method of obtaining cell extracts through centrifugation was also evaluated for the synthesis of copper nanoparticles. Transmission electron microscopy (TEM) analysis confirmed the formation of nanoparticles with mean diameter of 13nm. Energy dispersive X-ray spectroscopy (EDS) was performed on the particles found in samples of the centrifuged cells extract and they were found to be composed of copper only, endorsing the ability of synthesis for this extract. Other characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and spectrophotometry (UV-Vis) were performed but the results were inconclusive. In order to define which compounds present in the cell extracts could be involved in the synthesis reaction, mass spectrometry (MALDI-TOF) and gas chromatography analyses were performed for the different extracts produced. Through the results of those analyses it was seen that the compounds that interact with the copper (II) ions are amino acids and sugars. Only for the centrifuged cells extract it was possible to confirm the presence of compounds with molecular weights between 4kDa and 20kDa, compatible with proteins. Having confirmed the ability of the fungus of synthesizing copper nanoparticles through different methods, a central rotational composite design of experiments was established as a way of assessing the influence of the pH and temperature on the diameter of the particles formed using the centrifuged cells extract. The diameter of the particles was measured using dynamic light scattering (DLS). Through the results, a second order model was calculated using the software Minitab® and it was found that neither the pH nor the temperature had significant contributions to the size of the particles. Moreover, the diameter found for the experiments were considerably larger than the observed through transmission electron microscopy. It was considered that this observation was a result of the presence of ligands that act as stabilizers for the particles and that contribute to a virtual increase of the diameter measured. These ligands are compounds present in the extract and that are not shown in electron microscopy due to the lack of contrast. Furthermore, the DLS analysis is an indirect measurement of the diameter and other analyses are needed to confirm the results obtained. Through the results found in this work, there was a confirmation of the ability of the fungus Hypocrea lixii to synthesize copper nanoparticles. Promising methodologies were proposed that might, after further studies, become an industrial process. (AU)

• FAPESP's process: 14/01870-1 - Application of dead biomass of Hypocrea lixii in the synthesis od copper nanoparticles: bench scale
• Grantee: Mariana Marangoni Carezzato
• Support Opportunities: Scholarships in Brazil - Master