Microalgae-derived Co3O4 nanomaterials for catalytic CO oxidation.

Efficient carbon monoxide oxidation is important to reduce its impacts on both human health and the environment. Following a sustainable synthesis route toward new catalysts, nanosized Co3O4 was synthesized based on extracts of microalgae: Spirulina platensis, Chlorella vulgaris, and Haematococcus pluvialis. Using the metabolites in the extract and applying different calcination temperatures (450, 650, 800 °C) led to Co3O4 catalysts with distinctly different properties. The obtained Co3O4 nanomaterials exhibited octahedral, nanosheet, and spherical morphologies with structural defects and surface segregation of phosphorous and potassium, originating from the extracts. The presence of P and K in the oxide nanostructures significantly improved their catalytic CO oxidation activity. When normalized by the specific surface area, the microalgae-derived catalysts exceeded a commercial benchmark catalyst. In situ studies revealed differences in oxygen mobility and carbonate formation during the reaction. The obtained insights may facilitate the development of new synthesis strategies for manufacturing highly active Co3O4 nanocatalysts.

Cultivation of Chroococcidiopsis thermalis Using Available In Situ Resources to Sustain Life on Mars.

The cultivation of cyanobacteria by exploiting available in situ resources represents a possible way to supply food and oxygen to astronauts during long-term crewed missions on Mars. Here, we evaluated the possibility of cultivating the extremophile cyanobacterium Chroococcidiopsis thermalis CCALA 050 under operating conditions that should occur within a dome hosting a recently patented process to produce nutrients and oxygen on Mars. The medium adopted to cultivate this cyanobacterium, named Martian medium, was obtained using a mixture of regolith leachate and astronauts' urine simulants that would be available in situ resources whose exploitation could reduce the mission payload. The results demonstrated that C. thermalis can grow in such a medium. For producing high biomass, the best medium consisted of specific percentages (40%vol) of Martian medium and a standard medium (60%vol). Biomass produced in such a medium exhibits excellent antioxidant properties and contains significant amounts of pigments. Lipidomic analysis demonstrated that biomass contains strategic lipid classes able to help the astronauts facing the oxidative stress and inflammatory phenomena taking place on Mars. These characteristics suggest that this strain could serve as a valuable nutritional resource for astronauts.

Nanoparticles from Microalgae and Their Biomedical Applications.

Over the years, microalgae have been a source of useful compounds mainly used as food and dietary supplements. Recently, microalgae have been used as a source of metabolites that can participate in the synthesis of several nanoparticles through inexpensive and environmentally friendly routes alternative to chemical synthesis. Notably, the occurrence of global health threats focused attention on the microalgae application in the medicinal field. In this review, we report the influence of secondary metabolites from marine and freshwater microalgae and cyanobacteria on the synthesis of nanoparticles that were applied as therapeutics. In addition, the use of isolated compounds on the surface of nanoparticles to combat diseases has also been addressed. Although studies have proven the beneficial effect of high-value bioproducts on microalgae and their potential in medicine, there is still room for understanding their exact role in the human body and translating lab-based research into clinical trials.

Characterization of nanomaterials synthesized from Spirulina platensis extract and their potential antifungal activity.

Nowadays, fungal infections increase, and the demand of novel antifungal agents is constantly rising. In the present study, silver, titanium dioxide, cobalt (II) hydroxide and cobalt (II,III) oxide nanomaterials have been synthesized from Spirulina platensis extract. The synthesis mechanism has been studied using GCMS and FTIR thus confirming the involvement of secondary metabolites, mainly amines. The obtained products have been analysed using XRD, SEM, TGA and zeta potential techniques. The findings revealed average crystallite size of 15.22 nm with 9.72 nm for oval-shaped silver nanoparticles increasing to 26.01 nm and 24.86 nm after calcination and 4.81 nm for spherical-shaped titanium dioxide nanoparticles which decreased to 4.62 nm after calcination. Nanoflake shape has been observed for cobalt hydroxide nanomaterials and for cobalt (II, III) oxide with crystallite size of 3.52 nm and 13.28 nm, respectively. Silver nanoparticles showed the best thermal and water dispersion stability of all the prepared structures. Once subjected to three different Candida species (C. albicans, C. glabrata, and C. krusei) silver nanoparticles and cobalt (II) hydroxide nanomaterials showed strong antifungal activity at 50 µg/mL with minimum inhibitory concentration (MIC) values. After light exposition, MIC values for nanomaterials decreased (to 12.5 µg/mL) for C. krusei and increased (100 µg/mL) for C. albicans and C. glabrata.

Photodegradation of Biohazardous Dye Brilliant Blue R Using Organometallic Silver Nanoparticles Synthesized through a Green Chemistry Method.

Nowadays, nanostructures having tremendous chemical and physical properties are gaining attention in the biomedical industry. However, when they are prepared through classical methods (physical and chemical), they are often non-biocompatible and toxic. Considering the mentioned factors, in this research, organometallic silver nanostructures (OMAgNs) have been prepared by the green chemistry method using the acetone, methanol, and methanol-hexane-based extracts of the medicinally important plant Cichorium intybus. Secondary metabolites from C. intybus can be used as an alternative to synthetic reagents at an industrial scale to manufacture biosafe and economical nanostructures with enhanced physicochemical parameters. Prepared nanostructures were characterized using SEM, XRD, FTIR, TGA, UV, and zeta potential measurement. SEM analysis revealed different shapes of OMAgNs, prepared with various extracts. XRD analysis showed the crystallinity of the nanostructures. FTIR spectroscopy helped to identify groups of compounds present in the extracts and used for the OMAgNs synthesis. Out of the three tested OMAgNs, those prepared with methanol extract were selected due to the highest obtained yield and stability (highest negative zeta potential) and were tested as a cost-efficient and active agent to photodegrade organic pollutant, Brilliant Blue R, using energy from sunlight. A decrease in UV-VIS absorbance confirmed the rapid degradation of the dye.