Simulated-Sunlight-Driven Cell Lysis of Magnetophoretically Separated Microalgae Using ZnFe2O4 Octahedrons

Application of Nanomaterials in the Production of Biomolecules in Microalgae: A Review

Nanomaterials (NMs) are becoming more commonly used in microalgal biotechnology to empower the production of algal biomass and valuable metabolites, such as lipids, proteins, and exopolysaccharides. It provides an effective and promising supplement to the existing algal biotechnology. In this review, the potential for NMs to enhance microalgal growth by improving photosynthetic utilization efficiency and removing reactive oxygen species is first summarized. Then, their positive roles in accumulation, bioactivity modification, and extraction of valuable microalgal metabolites are presented. After the application of NMs in microalgae cultivation, the extracted metabolites, particularly exopolysaccharides, contain trace amounts of NM residues, and thus, the impact of these residues on the functional properties of the metabolites is also evaluated. Finally, the methods for removing NM residues from the extracted metabolites are summarized. This review provides insights into the application of nanotechnology for sustainable production of valuable metabolites in microalgae and will contribute useful information for ongoing and future practice.

New horizons in developing cell lysis methods: A Review

Cell lysis is an essential step in many studies related to biology and medicine. Based on the scale and medium that cell lysis is carried out, there are three main types of the cell lysis: 1) lysis of the cells in the surrounding environment, 2) lysis of the isolated or cultured cells and 3) Single cell lysis. Conventionally, several cell lysis methods have been developed, such as freeze-thawing, bead beating, incursion in liquid nitrogen, sonication and enzymatic and chemical based approaches. In recent years, various novel technologies have been employed to develop new methods of cell lysis. The aim of studies in this field is to introduce more precise and efficient tools or to reduce the costs of cell lysis procedures. Nanostructure based lysis methods, acoustic oscillation, electrical current, irradiation, bacteria-mediated cell lysis, magnetic ionic liquids, bacteriophage genes, monolith columns, hydraulic forces and steam explosion are some examples of new developed cell lysis methods. Beside the significant advances in this field, there are still many challenges and the tools must be further improved. This article is protected by copyright. All rights reserved.

Size-controllable synthesis of zinc ferrite/reduced graphene oxide aerogels: efficient electrochemical sensing of p-nitrophenol

In this study, a nonaqueous method for the synthesis of size-controlled highly crystalline zinc ferrite/reduced graphene oxide (ZFO/rGO) aerogel was provided by using benzyl alcohol as the medium. In our findings, benzyl alcohol was introduced not only as the solvent, but the structure-directing agent and strong reducing agent during the nucleation and growth of ZnFe₂O₄ nanoparticles (NPs). The characterization analysis indicated that ZnFe₂O₄ NPs were immobilized on the multilayer rGO with a controllable size of 12 nm. Moreover, the 3D ZFO/rGO aerogel shows excellent electrochemical property as a facile electrochemical sensor for the detection of p-nitrophenol (p-NP). The ZFO/rGO electrochemical sensing offers the advantages of wide linear range (1-500 μmol l^-1), excellent sensitivity (23.985 mA mM^-1 cm^-2), good stability and selectivity (<8.8%). In addition, the possible reaction mechanism of 3D ZFO/rGO aerogel was explained during the detection process under acidic condition. Significantly, our results not only provided insight into the possible reaction mechanism of 3D ZFO/rGO nanocomposite, but proposed the way for the synthesis of highly crystalline materials through a benzyl alcohol-mediated method.

Microalgae harvesting by magnetic flocculation for biodiesel production: current status and potential

With the increasing demand for energy, microalgae, as one of the promising feedstocks of biodiesel, has raised great awareness. Because of its small size, similar density to water and electrical stability, harvesting methods of microalgae that have low energy consumption and that are highly efficient, easy to large-scale and environmentally friendly have become a bottleneck restricting development of the whole process. Among the numerous possible harvesting methods, magnetic flocculation has the advantages of simple operation, fast separation and energy saving and thus is considered as a promising novel harvesting method. In this review, we have summarized the updated status and application potential of magnetic flocculation, including the principle of magnetic flocculation, magnetic flocculating materials, flocculating efficiency and its effect on downstream process. The major challenges such as magnetic materials recovery, large-scale magnetic flocculation device design, and magnetic flocculation costs are also discussed.

Efficient harvesting of Chlorella pyrenoidosa and Scenedesmus obliquus cultivated in urban sewage by magnetic flocculation using nano-Fe3O4 coated with polyethyleneimine

In this work, a novel flocculation process by using nano-Fe₃O₄ coated with polyethyleneimine (Fe₃O₄@PEI) as magnetic seeds was developed to harvest the microalgae cultivated in urban sewage. Experiment results indicated that the harvest efficiency of Chlorella pyrenoidosa (0.5 g/L) was 98.92 ± 0.41% under the optimal conditions of Fe₃O₄@PEI dose of 20 mL/L, flocculation time of 20 min, and stirring speed of 800 rpm (3 min), while that of Scenedesmus obliquus (0.4 g/L) was 98.45 ± 0.35% under a Fe₃O₄@PEI dose of 16 mL/L, flocculation time of 15 min, and stirring speed of 730 rpm (3 min). Moreover, the process did not reduce the lipid content of microalgae and quality of biodiesel. After microalgae harvest, Fe₃O₄@PEI could be recovered by ultrasonication, re-wrapped with polyethyleneimine and reused to reduce operational cost.

Recent developments and key barriers to advanced biofuels: A short review

Biofuels are regarded as one of the most viable options for reduction of CO₂ emissions in the transport sector. However, conventional plant-based biofuels (e.g., biodiesel, bioethanol)'s share of total transportation-fuel consumption in 2016 was very low, about 4%, due to several major limitations including shortage of raw materials, low CO₂ mitigation effect, blending wall, and poor cost competitiveness. Advanced biofuels such as drop-in, microalgal, and electro biofuels, especially from inedible biomass, are considered to be a promising solution to the problem of how to cope with the growing biofuel demand. In this paper, recent developments in oxy-free hydrocarbon conversion via catalytic deoxygenation reactions, the selection of and lipid-content enhancement of oleaginous microalgae, electrochemical biofuel conversion, and the diversification of valuable products from biomass and intermediates are reviewed. The challenges and prospects for future development of eco-friendly and economically advanced biofuel production processes also are outlined herein.