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Based on the search for new biodegradable materials that are low cost and easy to synthesize by environmentally friendly methods, we report the use of carrageenan membranes (mixture of κ and λ carrageenans) with different concentrations of titanium dioxide nanoparticles (TiO2 NPs) and Ni/CeO2 (10 wt % Ni) for the fabrication of a novel fuel cell electrode for the oxidation of ethanol. Each membrane was characterized to determine its physicochemical properties using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. Using impedance spectroscopy (IS), a maximum value of 2.08 × 10-4 S/cm in ionic conductivity was found for the carrageenan nanocomposite with a concentration of 5 wt % TiO2 NPs (CR5%). Due to its high conductivity values, the CR5% membrane was mixed with Ni/CeO2 to prepare the working electrode for cyclic voltammetry measurements. Using a solution of 1 M ethanol and 1 M KOH, the oxidation of ethanol over CR5% + Ni/CeO2 resulted in peak current density values at forward and reverse scan voltages of 9.52 and 12.22 mA/cm2, respectively. From our results, the CR5% + Ni/CeO2 membrane proves to be more efficient in the oxidation of ethanol compared with commercially available Nafion membranes containing Ni/CeO2.
RESUMO
Microalgae peptides have many medical and industrial applications due to their functional properties. However, the rapid degradation of peptides not naturally present in biological samples represents a challenge. A strategy to increase microalgae peptide stability in biological samples is to use carriers to protect the active peptide and regulate its release. This study explores the use of gold nanoparticles (AuNPs) as carriers of the Chlorella microalgae peptide (VECYGPNRPQF). The potential of these peptide biomolecules as stabilizing agents to improve the colloidal stability of AuNPs in physiological environments is also discussed. Spectroscopic (UV-VIS, DLS) and Microscopic (TEM) analyses confirmed that the employed modification method produced spherical AuNPs by an average 15 nm diameter. Successful peptide capping of AuNPs was confirmed with TEM images and FTIR spectroscopy. The stability of the microalgae peptide increased when immobilized into the AuNPs surface, as confirmed by the observed thermal shifts in DSC and high zeta-potential values in the colloidal solution. By optimizing the synthesis of AuNPs and tracking the conferred chemical properties as AuNPs were modified with the peptide via various alternative methods, the synthesis of an effective peptide-based coating system for AuNPs and drug carriers was achieved. The microalgae peptide AuNPs showed lower ecotoxicity and better viability than the regular AuNPs.
RESUMO
BACKGROUND: The roles of gorgonian sclerites as structural components and predator deterrents have been widely studied. Yet their role as barriers against microbes has only recently been investigated, and even less is known about the diversity and roles of the chemical compounds associated with sclerites. METHODS: Here, we examine the semi-volatile organic compound fraction (SVOCs) associated with sclerites from healthy and diseased Gorgonia ventalina sea fan corals to understand their possible role as a stress response or in defense of infection. We also measured the oxidative potential of compounds from diseased and healthy G. ventalina colonies. RESULTS: The results showed that sclerites harbor a great diversity of SVOCs. Overall, 70 compounds were identified, the majority of which are novel with unknown biological roles. The majority of SVOCs identified exhibit multiple immune-related roles including antimicrobial and radical scavenging functions. The free radical activity assays further confirmed the anti-oxidative potential of some these compounds. The anti-oxidative activity was, nonetheless, similar across sclerites regardless of the health condition of the colony, although sclerites from diseased sea fans display slightly higher anti-oxidative activity than the healthy ones. DISCUSSION: Sclerites harbor great SVOCs diversity, the majority of which are novel to sea fans or any other corals. Yet the scientific literature consulted showed that the roles of compounds found in sclerites vary from antioxidant to antimicrobial compounds. However, this study fell short in determine the origin of the SVOCs identified, undermining our capacity to determine the biological roles of the SVOCs on sclerites and sea fans.
RESUMO
Methodology using MAE/SPME/GC-MS is being pursued for the analysis of organic pollutants in sebum. The microwave-assisted extraction (MAE) of standards of semi volatile organic pollutants from sebum was optimized. All compounds were extracted from sebum with recoveries analyzed by GC/MS ranging from 94% to 100% under the optimum MAE conditions: 10mL acetone-hexane (2:1), 60 degrees C, and 10 min microwave heating. To improve the detection limits a SPME procedure was optimized. Linearity ranged from 0.70 ppb to 25 ppb. R.S.D. were in the range of 1-23% for the SPME step. Preliminary real samples were analyzed and a range of compounds was detected. The optimized MAE/SPME/GC-MS methodology promises to be useful for different applications.