Immobilization and Evaluation of Penicillin G Acylase on Hydroxy and Aldehyde Functionalized Magnetic α-Fe2O3/Fe3O4 Heterostructure Nanosheets

Effect and mechanism of paclitaxel loaded on magnetic Fe3O4@mSiO2-NH2-FA nanocomposites to MCF-7 cells

Magnetic Fe₃O₄ nanoparticles were prepared via a simple hydrothermal method and utilized to load paclitaxel. The average particle size of Fe₃O₄ nanoparticles was found to be 20.2 ± 3.0 nm, and the calculated saturation magnetization reached 129.38 emu/g, verifying superparamagnetism of nanomaterials. The specific surface area and pore volume were 84.756 m²/g and 0.265 cm³/g, respectively. Subsequently, Fe₃O₄@mSiO₂ nanoparticles were successfully fabricated using the Fe₃O₄ nanoparticles as precursors with an average size of 27.81 nm. The relevant saturation magnetization, zeta potential, and specific surface area of Fe₃O₄@mSiO₂-NH₂-FA were respectively 76.3 emu/g, -14.1 mV, and 324.410 m²/g. The pore volume and average adsorption pore size were 0.369 cm³/g and 4.548 nm, respectively. Compared to free paclitaxel, the solubility and stability of nanoparticles loaded with paclitaxel were improved. The drug loading efficiency and drug load of the nanoformulation were 44.26 and 11.38%, respectively. The Fe₃O₄@mSiO₂-NH₂-FA nanocomposites were easy to construct with excellent active targeting performance, pH sensitivity, and sustained-release effect. The nanoformulation also showed good biocompatibility, where the cell viability remained at 73.8% when the concentration reached 1200 μg/mL. The nanoformulation induced cell death through apoptosis, as confirmed by AO/EB staining and flow cytometry. Western blotting results suggested that the nanoformulation could induce iron death by inhibiting Glutathione Peroxidase 4 (GPX4) activity or decreasing Ferritin Heavy Chain 1 (FTH1) expression. Subsequently, the expression of HIF-1α was upregulated owing to the accumulation of reactive oxygen species (ROS), thus affecting the expression of apoptosis-related proteins regulated by p53, inducing cell apoptosis.

Fabrication of magneticα-Fe2O3/Fe3O4heterostructure nanorods via the urea hydrolysis-calcination process and their biocompatibility with LO2and HepG2cells

β-FeOOH nanorods were prepared via the urea hydrolysis process with the average length of 289.1 nm and average diameter of 61.2 nm, while magneticα-Fe2O3/Fe3O4heterostructure nanorods were prepared via the urea calcination process withβ-FeOOH nanorods as precursor, and the optimum conditions were the calcination temperature of 400 °C, the calcination time of 2 h, theβ-FeOOH/urea mass ratio of 1:6. The average length, diameter, and the saturation magnetization of the heterostructure nanorods prepared under the optimum conditions were 328.8 nm, 63.4 nm and 42 emu·g-1, respectively. The Prussian blue test demonstrated that the heterostructure nanorods could be taken up by HepG2 cells, and cytotoxicity tests proved that the heterostructure nanorods had no significant effect on the viabilities of LO2 and HepG2 cells within 72 h in the range of 100-1600μg·ml-1. Therefore, magneticα-Fe2O3/Fe3O4heterostructure nanorods had better biocompatibility with LO2 and HepG2 cells.

Immobilization and property of penicillin G acylase on amino functionalized magnetic Ni0.3Mg0.4Zn0.3Fe2O4 nanoparticles prepared via the rapid combustion process

Penicillin G acylase plays an important role in the biocatalytic process of semi-synthetic penicillin. In order to overcome the disadvantages of free enzymes and improve the catalytic performance of enzymes, it is a new method to immobilize enzymes on carrier materials. And magnetic materials have the characteristics of easy separation. In the present study, the Magnetic Ni0.3Mg0.4Zn0.3Fe2O4 nanoparticles were successfully prepared by a rapid-combustion method and calcined at 400°C for 2 h. The surface of the nanoparticles was modified with sodium silicate hydrate, and the PGA was covalently bound to the carrier particles through the cross-linking of glutaraldehyde. The results showed that the activity of immobilized PGA reached 7121.00 U/g. The optimum pH for immobilized PGA was 8 and the optimum temperature was 45°C, the immobilized PGA exhibited higher stability against changes in pH and temperature. The Michaelis–Menten constant (Km) values of the free and immobilized PGA were 0.00387 and 0.0101 mol/L and the maximum rate (Vmax) values were 0.387 and 0.129 μmol/min. Besides, the immobilized PGA revealed excellent cycling performance. The immobilization strategy presented PGA had the advantages of reuse, good stability, cost saving and had considerable practical significance for the commercial application of PGA.

Electrochemical sensor based on Fe3O4/α-Fe2O3@Au magnetic nanocomposites for sensitive determination of the TP53 gene

Considering the high cost and tedious process of gene sequencing, there is an urgent need to develop portable and efficient sensors for the TP53 gene. Here, we developed a novel electrochemical sensor that detected the TP53 gene using magnetic peptide nucleic acid (PNA)-modified Fe₃O₄/α-Fe₂O₃@Au nanocomposites. Cyclic voltammetry and electrochemical impedance spectroscopy confirmed the successful stepwise construction of the sensor, especially the high-affinity binding of PNA to DNA strands, which induced different electron transfer rates and resulted in current changes. Variations in the differential pulse voltammetry current observed during hybridization at different surface PNA probe densities, hybridization times, and hybridization temperatures were explored. The biosensing strategy obtained a limit of detection of 0.26 pM, a limit of quantification of 0.85 pM, and a wide linear range (1 pM-1 μM), confirming that the Fe₃O₄/α-Fe₂O₃@Au nanocomposites and the strategy based on magnetic separation and magnetically induced self-assembly improved the binding efficiency of nucleic acid molecules. The biosensor was a label-free and enzyme-free device with excellent reproducibility and stability that could identify single-base mismatched DNA without additional DNA amplification procedures, and the serum spiked experiments revealed the feasibility of the detection approach.