Modified Fe3O4 Nanoparticles for Foam Stabilization: Mechanisms and Applications for Enhanced Oil Recovery

Nanoparticles (NPs) have shown great potential in stabilizing foam for enhanced oil recovery (EOR). However, conventional NPs are difficult to recover and may contaminate produced oil, increasing operational costs. In contrast, superparamagnetic Fe3O4 NPs can be efficiently recovered using external magnetic fields, offering a sustainable solution for foam stabilization. In this study, Fe3O4 NPs were coated with SiO2 using tetraethyl orthosilicate (TEOS) and further modified with dodecyltrimethoxysilane to enhance their hydrophobicity. The modification effects were characterized, and the optimal foam-stabilizing Fe3O4@SiO2 NPs were found to have a contact angle of 77.01°. The foam system formed with α-olefin sulfonate (0.2 wt%) as the foaming agent and the optimal modified NPs exhibited a drainage half-life of 452 s. After foam-stabilization experiments, the NPs were recovered and reused, with the results indicating that three recovery cycles were optimal. Finally, visual microscopic displacement experiments demonstrated that the foam stabilized by modified NPs effectively mobilized clustered, membranous, and dead-end residual oil, increasing the recovery rate by 17.01% compared with unmodified NPs. This study identifies key areas for future investigation into the application of magnetic nanoparticles for enhanced oil recovery.

Detection of tetanus toxoid with iron magnetic nanobioprobe

Diagnosis of diseases with low facilities, speed, accuracy and sensitivity is an important matter in treatment. Bioprobes based on iron oxide nanoparticles are a good candidate for early detection of deadly and infectious diseases such as tetanus due to their high reactivity, biocompatibility, low production cost and sample separation under a magnetic field. In this study, silane groups were coated on surface of iron oxide nanoparticles using tetraethoxysilane (TEOS) hydrolysis. Also, NH2groups were generated on the surface of silanized nanoparticles using 3-aminopropyl triethoxy silane (APTES). Antibody was immobilized on the surface of silanized nanoparticles using TCT trichlorothriazine as activator. Silanization and stabilized antibody were investigated by using of FT-IR, EDX, VSM, SRB technique. UV/vis spectroscopy, fluorescence, agglutination test and ELISA were used for biosensor performance and specificity. The results of FT-IR spectroscopy showed that Si-O-Si and Si-O-Fe bonds and TCT chlorine and amine groups of tetanus anti-toxoid antibodies were formed on the surface of iron oxide nanoparticles. The presence of Si, N and C elements in EDX analysis confirms the silanization of iron oxide nanoparticles. VSM results showed that the amount of magnetic nanoparticles after conjugation is sufficient for biological applications. Antibody stabilization on nanoparticles increased the adsorption intensity in the uv/vis spectrometer. The fluorescence intensity of nano bioprobe increased in the presence of 10 ng ml-1. Nanobio probes were observed as agglomerates in the presence of tetanus toxoid antigen. The presence of tetanus antigen caused the formation of antigen-nanobioprobe antigen complex. Identification of this complex by HRP-bound antibody confirmed the specificity of nanobioprobe. Tetanus magnetic nanobioprobe with a diagnostic limit of 10 ng ml-1of tetanus antigen in a short time can be a good tool in LOC devices and microfluidic chips.

Decorated magnetic nanoparticles with polyvinyl alcohol brushes modified with metal chelate affinity groups for purification of proteins

Refining is a serious challenge in the production of recombinant proteins, and this study proposes a new and easy strategy for the synthesis of magnetic affinity nanoparticles. First, the nanoparticles attached to polyvinyl alcohol brushes were synthesized, and then the hydroxyl groups of this polymer were converted to chelate groups. The nanoparticles were examined by (SEM) scanning electron microscopy, (TEM) transmission electron microscopy, (DLS) dynamic light scattering, (FT-IR) Fourier transform infrared, (XRD) X-ray powder diffraction, (VSM) vibrating sample magnetometry, and (TGA) thermal gravimetric analysis. The results confirm that uniform and spherical magnetic polymer nanoparticles with high magnetization and superparamagnetic properties were successfully synthesized. The S100A9 protein, a His-tagged recombinant protein, was expressed and purified using the synthesized nanoparticles. According to the (SDS-PAGE) sulfate-polyacrylamide gel electrophoresis results, there is a high degree of resolution in protein separation. The synthesized nanoparticles have a high protein binding capacity of about 208 mg of protein per gram of nanoparticles.

Immobilization of Cholesterol Oxidase from Streptomyces Sp. on Magnetite Silicon Dioxide by Crosslinking Method for Cholesterol Oxidation

Enzymatic biosensor has been paid much attention to the research fields due to its advantage in medical application. As one of the application, we determined the optimum value of cholesterol oxidase against cholesterol. In this work, we studied the behavior of cholesterol oxidation by enzymatic reaction to get the optimum condition for cholesterol oxidation. The enzyme that used were in two form, free cholesterol oxidase, and immobilized cholesterol oxidase. Cholesterol oxidase was produced from Streptomyces sp. by using solid state fermentation method and identified had high enzyme activity to be 5.12 U/mL. Cholesterol oxidase was simultaneously crosslinked immobilized onto magnetite coated by silicon dioxide (M-SiO₂). The support was characterized by Fourier transform infrared (FTIR) to determine the functional group of modified particle and scanning electron microscope (SEM) to observe the morphological or our prepared particle. Cholesterol oxidase sensitivity to substrate was analyzed by using HPLC with different interval time measurements. The oxidation of cholesterol by free enzyme and immobilized enzyme was also investigated. The best sensitivity of cholesterol oxidase was estimated to oxidize Cso (concentration of substrate) 1.46 mM of substrate with Ce (concentration of enzyme) 20 mg/mL for 180 min. Final oxidation value of cholesterol by immobilized enzyme was greater than 60%. The results of this study revealed that immobilized enzyme for cholesterol oxidation was stable, reproducible, and sensitive.

Antibacterial zinc oxide hybrid with gelatin coating

ZnO has been widely investigated as important biomaterials and antibacterial materials. However, the aggregation of nanoparticles and its potential toxicity may hinder its final application. Herein, biocompatible gelatin chains were grafted on the surface of ZnO via mussel inspired method to prevent the aggregation of the ZnO nanoparticles. The in vitro test showed that the gelatin can greatly improve the biocompatibility of ZnO, while the antibacterial properties of ZnO against both E. coli and S. aureus were maintained.

Phosphanamine-functionalized magnetic nanoparticles (PAFMNP): an efficient magnetic recyclable ligand for the Pd-catalyzed Heck reaction of chloroarenes

The reaction of MNPs with a phosphanamine-functionalized trimethoxysilyl compound resulted in the production of a novel and efficient magnetic reusable ligand for application in the Heck reaction of aryl chlorides.

Fabrication of Pd Nanoparticles Embedded C@Fe3O4 Core-Shell Hybrid Nanospheres: An Efficient Catalyst for Cyanation in Aryl Halides

Isolated chemical reactors were fabricated by integrating catalytically active sites (Pd) with magnetic functionality (Fe3O4) along with carbon while preserving the constituents functional properties to realize the structure-property relationship of Pd by comparing the catalytic activity of spherical Pd NPs with cubical Pd NPs for cyanation in aryl halides using K4[Fe(CN)6] as a green cyanating agent to yield corresponding nitriles. The superior catalytic reactivity of the cubical Pd NPs is attributed to the larger number of {100} surface facets. The TEM images of reused catalyst shows the change in structure from cubical to spherical nanoparticles, attributed to the efficient leaching susceptibility of Pd {100} surface facets. The cubical Pd NPs on carbon@Fe3O4 is attractive in view of its high catalytic efficiency, easy synthesis, magnetic separability, environmental friendliness, high stability, gram scale applicability, and reusability.

The effects of interfacial potential on antimicrobial propensity of ZnO nanoparticle

The work investigates the role of interfacial potential in defining antimicrobial propensity of ZnO nanoparticle (ZnONP) against different Gram positive and Gram negative bacteria. ZnONPs with positive and negative surface potential are tested against different bacteria with varying surface potentials, ranging −14.7 to −23.6 mV. Chemically synthesized ZnONPs with positive surface potential show very high antimicrobial propensity with minimum inhibitory concentration of 50 and 100 μg/mL for Gram negative and positive bacterium, respectively. On other hand, ZnONPs of the same size but with negative surface potential show insignificant antimicrobial propensity against the studied bacteria. Unlike the positively charged nanoparticles, neither Zn²⁺ ion nor negatively charged ZnONP shows any significant inhibition in growth or morphology of the bacterium. Potential neutralization and colony forming unit studies together proved adverse effect of the resultant nano-bacterial interfacial potential on bacterial viability. Thus, ZnONP with positive surface potential upon interaction with negative surface potential of bacterial membrane enhances production of the reactive oxygen species and exerts mechanical stress on the membrane, resulting in the membrane depolarization. Our results show that the antimicrobial propensity of metal oxide nanoparticle mainly depends upon the interfacial potential, the potential resulting upon interaction of nanoparticle surface with bacterial membrane.