Direct purification and immobilization of his-tagged enzymes using unmodified nickel ferrite NiFe2O4 magnetic nanoparticles.

Purification of valuable engineered proteins and enzymes can be laborious, costly, and generating large amount of chemical waste. Whilst enzyme immobilization can enhance recycling and reuse of enzymes, conventional methods for immobilizing engineered enzymes from purified samples are also inefficient with multiple-step protocols, regarding both the carrier preparation and enzyme binding. Nickel ferrite magnetic nanoparticles (NiFe2O4 MNPs) offer distinct advantages in both purification and immobilization of enzymes. In this work, we demonstrate the preparation of NiFe2O4 MNPs via a one-step solvothermal synthesis and their use in direct enzyme binding from cell lysates. These NiFe2O4 MNPs have showed an average diameter of 8.9 ± 1.7 nm from TEM analysis and a magnetization at saturation (Ms) value of 53.0 emu g-1 from SQUID measurement. The nickel binding sites of the MNP surface allow direct binding of three his-tagged enzymes, D-phenylglycine aminotransferase (D-PhgAT), Halomonas elongata ω-transaminase (HeωT), and glucose dehydrogenase from Bacillus subtilis (BsGDH). It was found that the enzymatic activities of all immobilized samples directly prepared from cell lysates were comparable to those prepared from the conventional immobilization method using purified enzymes. Remarkably, D-PhgAT supported on NiFe2O4 MNPs also showed similar activity to the purified free enzyme. By comparing on both carrier preparation and enzyme immobilization protocols, use of NiFe2O4 MNPs for direct enzyme immobilization from cell lysate can significantly reduce the number of steps, time, and use of chemicals. Therefore, NiFe2O4 MNPs can offer considerable advantages for use in both enzyme immobilization and protein purification in pharmaceutical and other chemical industries.

Gold-iron oxide (Au/Fe3O4) magnetic nanoparticles as the nanoplatform for binding of bioactive molecules through self-assembly.

Nanomedicine plays a crucial role in the development of next-generation therapies. The use of nanoparticles as drug delivery platforms has become a major area of research in nanotechnology. To be effective, these nanoparticles must interact with desired drug molecules and release them at targeted sites. The design of these "nanoplatforms" typically includes a functional core, an organic coating with functional groups for drug binding, and the drugs or bioactive molecules themselves. However, by exploiting the coordination chemistry between organic molecules and transition metal centers, the self-assembly of drugs onto the nanoplatform surfaces can bypass the need for an organic coating, simplifying the materials synthesis process. In this perspective, we use gold-iron oxide nanoplatforms as examples and outline the prospects and challenges of using self-assembly to prepare drug-nanoparticle constructs. Through a case study on the binding of insulin on Au-dotted Fe3O4 nanoparticles, we demonstrate how a self-assembly system can be developed. This method can also be adapted to other combinations of transition metals, with the potential for scaling up. Furthermore, the self-assembly method can also be considered as a greener alternative to traditional methods, reducing the use of chemicals and solvents. In light of the current climate of environmental awareness, this shift towards sustainability in the pharmaceutical industry would be welcomed.

Antibacterial Activities of Ga(III) against E. coli Are Substantially Impacted by Fe(III) Uptake Systems and Multidrug Resistance in Combination with Oxygen Levels.

The continued emergence and spread of antimicrobial resistance (AMR), particularly multidrug resistant (MDR) bacteria, are increasing threats driving the search for additional and alternative antimicrobial agents. The World Health Organization (WHO) has categorized bacterial risk levels and includes Escherichia coli among the highest priority, making this both a convenient model bacterium and a clinically highly relevant species on which to base investigations of antimicrobials. Among many compounds examined for use as antimicrobials, Ga(III) complexes have shown promise. Nonetheless, the spectrum of activities, susceptibility of bacterial species, mechanisms of antimicrobial action, and bacterial characteristics influencing antibacterial actions are far from being completely understood; these are important considerations for any implementation of an effective antibacterial agent. In this investigation, we show that an alteration in growth conditions to physiologically relevant lowered oxygen (anaerobic) conditions substantially increases the minimum inhibitory concentrations (MICs) of Ga(III) required to inhibit growth for 46 wild-type E. coli strains. Several studies have implicated a Trojan horse hypothesis wherein bacterial Fe uptake systems have been linked to the promotion of Ga(III) uptake and result in enhanced antibacterial activity. Our studies show that, conversely, the carriage of accessory Fe uptake systems (Fe_acc) significantly increased the concentrations of Ga(III) required for antibacterial action. Similarly, it is shown that MDR strains are more resistant to Ga(III). The increased tolerance of Fe_acc/MDR strains was apparent under anaerobic conditions. This phenomenon of heightened tolerance has not previously been shown although the mechanisms remain to be defined. Nonetheless, this further highlights the significant contributions of bacterial metabolism, fitness, and AMR characteristics and their implications in evaluating novel antimicrobials.

Localization of Coated Iron Oxide (Fe3O4) Nanoparticles on Tomato Seeds and Their Effects on Growth.

Food demand due to the growing global population has been stretching the agriculture sector to the limit. This demands the cultivation of plants in shrinking land areas which makes the search for highly effective systems for plant nutrition and pest control important. In this context, the application of nanoparticles (NPs) in agriculture can have a transformative effect on food production techniques as it can enable the delivery of bioactive agents (including growth factors, pesticides, and fungicides) directly to plants. Herein, we report the application of unfunctionalized as well as amine-functionalized and polycaprolactone-coated Fe3O4 NPs to seed treatment in tomato (Solanum lycopersicum). The study reveals that the treatment has no side effects on plant germination and development. Furthermore, the translocation of NPs in seeds and seedlings posttreatment depends on the surface functionalization of the NPs. X-ray fluorescence spectroscopy analysis of seedlings suggested that around 66% of unfunctionalized Fe3O4 NPs were translocated in the cotyledons, while only 50% of functionalized NPs (both amine and polycaprolactone) were translocated. Our results demonstrate that all particles were taken up by the seeds, thus suggesting that the functionalized NPs can act as a versatile platform for delivering of active compounds, such as fungicides and growth factor agents.