Research Overview
This section provides a brief summary of my way as a researcher. I take this opportunity to describe my scientific experiences, partnership and desire for future projects.
Biosurfactant Production
The biosurfactants are molecules with surface activity produced by bacteria, fungus and yeasts. The microbial surfactants have many advantages over the synthetic counterparts because of their biodegradability and reduced toxicity, high stability in extreme conditions of pH, temperature and salinity, biocompatibility and availability of production using cheap and raw materials. These molecules are able to concentrate at interface of liquids decreasing the superficial tension and forming stable emulsions of oil in water. The emulsification processes can break oil substrates into small droplets allowing the microbial access to unsoluble carbon sources. These intrinsic physical chemical properties are necessary to application of biosurfactants in the bioremediation and biodegradation of xenobiotic compounds, in the microbial enhanced oil recovery (MEOR), pharmaceutical industry and biomedical field.
Un-conventional Carbon Sources to Produce Biosurfactants
Biosurfactants are of interest in comparison to chemical surfactants due to their high level of activity, ability to be produced from renewable feedstocks, and high degree of biodegradability. However, biosurfactants have not yet been employed extensively in industry because their production is not optimized. Among the reasons they have not yet been commercialized extensively is the high costs of feedstocks. The imiscible carbon sources traditionally used to produce biosurfactants are sometimes costly and highly toxic. In order to solve these problems, many studies have been carried out using low-cost feedstock or agricultural byproducts as substrates for biosurfactant production. Low-cost carbon sources that have been used for biosurfactant production by microorganisms include sludge palm oil, cassava wastewater, vegetable oil refinery waste, molasses and raw glycerol from brazilian biodiesel industries. However, there are still many agroindustrial residues in Brazil that can be used as renewable carbon source to biosurfactant production.
Nanomaterials: Antimicrobial Activity and Environmental Implications
The rapid growth in nanotechnology has spurred significant interest in the environmental applications of nanomaterials. Nanomaterials are excellent adsorbents, catalysts, and sensors due to their large specific surface area and high reactivity More recently, several natural and engineered nanomaterials have also been shown to have strong antimicrobial properties. My postdoc research is focused in the synthesis and chemical characterization of nanocomposites formed from graphene oxide and silver nanoparticles. The graphene oxide (GO) is a strongly oxygenated, highly hydrophilic layered material that can be readily exfoliated in water to yield stable dispersions consisting mostly of single-layer sheets. These nanosheets have been used as promising nanoscale building blocks for prepare new composites. The stable graphene oxide sheets are usually used as the starting material for preparing of graphene based materials. In special, the graphene oxide have been utilized as a support to stabilize silver, gold and paladium nanoparticles. The initial phase of this work developed in the Solid State Chemisty Laboratory at Unicamp shown that these graphene based silver composites presented excellent activity against Pseudomonas aeruginosa biofilm formation on stainless steel surfaces. Moreover, the GO-Ag nanocomposite showed inhibitory effect against several pathogens microorganisms generally associated to food and medical devices contamination.
Environmental Implications
Although humans have been exposed to airborne nanosized particles throughout their evolutionary stages, this exposure has increased dramatically over the last century due to anthropogenic sources. The entrance of these engineered nanomaterial can occurs through inhalation, ingestion and skin uptake. Information about safety and potential hazards is urgently needed. Environmental researchers are actively exploring nanomaterials as contaminants of emerging concern. Additional considerations for assessing safety of engineered nanomaterial should include careful observations about the doses/concentrations, shape, size and superficial area of the nanomaterials. The greater surface area per mass compared with larger-sized particles of the same chemistry renders to nanomaterials more active biologically. An interdisciplinary team approach (toxicology, materials science, medicine, molecular biology, and bioinformatics) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment. My interesting about this point consist in to explore the impact of the exposition of material nanostructured to microbial communities in soil and aquatic sediments.