Non-hydrolytic synthesis of caprylate capped cobalt ferrite nanoparticles and their application against Erwinia carotovora and Stenotrophomonas maltophilia

Current trends in management of bacterial pathogens infecting plants

Plants are continuously challenged by different pathogenic microbes that reduce the quality and quantity of produce and therefore pose a serious threat to food security. Among them bacterial pathogens are known to cause disease outbreaks with devastating economic losses in temperate, tropical and subtropical regions throughout the world. Bacteria are structurally simple prokaryotic microorganisms and are diverse from a metabolic standpoint. Bacterial infection process mainly involves successful attachment or penetration by using extracellular enzymes, type secretion systems, toxins, growth regulators and by exploiting different molecules that modulate plant defence resulting in successful colonization. Theses bacterial pathogens are extremely difficult to control as they develop resistance to antibiotics. Therefore, attempts are made to search for innovative methods of disease management by the targeting bacterial virulence and manipulating the genes in host plants by exploiting genome editing methods. Here, we review the recent developments in bacterial disease management including the bioactive antimicrobial compounds, bacteriophage therapy, quorum-quenching mediated control, nanoparticles and CRISPR/Cas based genome editing techniques for bacterial disease management. Future research should focus on implementation of smart delivery systems and consumer acceptance of these innovative methods for sustainable disease management.

In-situ construction of Zr-based metal-organic framework core-shell heterostructure for photocatalytic degradation of organic pollutants

Photocatalysis is an eco-friendly promising approach to the degradation of textile dyes. The majority of reported studies involved remediation of dyes with an initial concentration ≤50 mg/L, which was away from the existing values in textile wastewater. Herein, a simple solvothermal route was utilized to synthesize CoFe2O4@UiO-66 core-shell heterojunction photocatalyst for the first time. The photocatalytic performance of the as-synthesized catalysts was assessed through the photodegradation of methylene blue (MB) and methyl orange (MO) dyes at an initial concentration (100 mg/L). Under simulated solar irradiation, improved photocatalytic performance was accomplished by as-obtained CoFe2O4@UiO-66 heterojunction compared to bare UiO-66 and CoFe2O4. The overall removal efficiency of dyes (100 mg/L) over CoFe2O4@UiO-66 (50 mg/L) reached >60% within 180 min. The optical and photoelectrochemical measurements showed an enhanced visible light absorption capacity as well as effective interfacial charge separation and transfer over CoFe2O4@UiO-66, emphasizing the successful construction of heterojunction. The degradation mechanism was further explored, which revealed the contribution of holes (h+), superoxide (•O2 -), and hydroxyl (•OH) radicals in the degradation process, however, h+ were the predominant reactive species. This work might open up new insights for designing MOF-based core-shell heterostructured photocatalysts for the remediation of industrial organic pollutants.

Annealing temperature effect on cobalt ferrite nanoparticles for photocatalytic degradation

In this work, cobalt ferrite nanomaterials was prepared employing simple co-precipitation technique and annealed at 300, 400 and 600 °C. XRD study revealed the formation of cubic structure of CoFe₂O₄ nanoparticles and confirmed by high intense peak at 2θ value of 35.3°. The creation of ferrite phase was further confirmed by the studies such as FTIR, Raman and PL spectra. FTIR spectra confirmed the occurrence of Fe-O and Co-O metal oxygen vibrations and the lattice defects and oxygen vacancies of the CoFe₂O₄ nanoparticles were explored by PL spectra. No other signals were detected in Raman spectra, which explored pure spinal ferrites. The energy band gap values are obtained by using Tauc plot and the obtained band gap values for all the cobalt ferrite nanoparticles were 2.84, 2.75 and 2.89 eV respectively. The morphology of synthesized cobalt ferrite nanomaterials were observed from the SEM and TEM images. The product annealed at 400 °C showed the better morphology with least amount of agglomeration in comparison to other SEM images. In addition, SAED pattern of magnetic nanoparticles confirmed the existence of polycrystalline nature of the CoFe₂O₄ nanoparticles. The obtained surface area of CF2 sample was 5.082 m² g^-1 and pore volume and diameter of CF2 sample was found to be 0.013 cc/g and 3.937 nm respectively. Then, the product annealed at 400 °C exhibited most excellent activity and degraded 74% of cationic dye in 80 min, and it also exhibited excellent stability even maintain in three cycles.