Search Results (13)

Regrettably, glioblastoma multiforme (GBM) remains the deadliest form of brain cancer, with a very unfavorable prognosis for life expectancy for the patient. We report, for the first time, the green colloidal synthesis of cobalt-doped magnetic iron oxide nanoparticles (Co-MNPs) as aqueous ferrofluids, using two anionic polysaccharide biopolymers, hyaluronic acid (HA) and carboxymethyl cellulose (CMC), as surfactants. These ferrofluids based on magnetite nanoparticles (HA@Co-MNP and CMC@Co-MNP) demonstrated superparamagnetic properties and magnetic-to-thermal conversion upon exposure to an alternating magnetic field (AMF), with the extent of conversion dependent on surfactant type. In addition, the ferrophase acted as a nanozyme, mimicking peroxidase-like activity in response to hydrogen peroxide, which is present at higher levels in tumor cells. The coupling of magnetic-heat capabilities with biocatalytic behavior enhances glioblastoma cell elimination and suppresses 3D neurospheroid growth. The results also showed that active targeting based on the HA biopolymer shell, due to its affinity for CD44 membrane receptors overexpressed in GBM, outperformed CMC-coated ferrofluid analogs. These magnetocatalytic-responsive nanoplatforms offer a broad avenue for the diagnosis and therapy of numerous cancers, potentially improving patients’ quality of life and prognoses. Full article

In the paper, a hybrid magnetic fluid is prepared by adding carbon nanotubes to pure ferrofluid to improve its thermal conductivity. Furthermore, an electromagnet is used as magnetic source equipment, and the magnetic field strength in the air gap of the electromagnet is analyzed in theory, simulations, and experiments. A thermal conductivity measurement apparatus for magnetic fluid is established according to the transient hot-wire method. The effects of weight fraction and the length of carbon nanotubes, the external magnetic field strength, and the magnetic field duration time on the thermal conductivity of hybrid magnetic fluid are experimentally investigated. The results show that the thermal conductivity of the hybrid magnetic fluid is significantly improved by adding long carbon nanotubes (10–30 μm), and the thermal conductivity could be enhanced by 23.39% when its weight fraction is 1%. The magnetic field strength (41, 81, 122, 162 mT) and magnetic field duration time have little influence on the thermal conductivity of the hybrid magnetic fluid. The thermal conductivity of the hybrid magnetic fluid has good stability. Full article

The main objective of this study is to explore the inventive conception of the magnetohydrodynamic flow of a hybrid nanofluid over-porous stretching/shrinking sheet with the effect of radiation and mass suction/injection. The hybrid nanofluid advances both the manufactured nanofluid of the current region and the base fluid. For the current investigation, hybrid nanofluids comprising two different kinds of nanoparticles, aluminium oxide and ferrofluid, contained in water as a base fluid, are considered. A collection of highly nonlinear partial differential equations is used to model the whole physical problem. These equations are then transformed into highly nonlinear ordinary differential equations using an appropriate similarity technique. The transformed differential equations are nonlinear, and thus it is difficult to analytically solve considering temperature increases. Then, the outcome is described in incomplete gamma function form. The considered physical parameters namely, magnetic field, Inverse Darcy number, velocity slip, suction/injection, temperature jump effects on velocity, temperature, skin friction and Nusselt number profiles are reviewed using plots. The results reveal that magnetic field, and Inverse Darcy number values increase as the momentum boundary layer decreases. Moreover, higher values of heat sources and thermal radiation enhance the thermal boundary layer. The present problem has various applications in manufacturing and technological devices such as cooling systems, condensers, microelectronics, digital cooling, car radiators, nuclear power stations, nano-drag shipments, automobile production, and tumour treatments. Full article

This paper discusses a numerical study performed in analysing the performance regarding the magnetic effect on the mixed convection stagnation-point flow of hybrid ferrofluid, examining the influence of viscous dissipation, convective boundary condition as well as Joule heating across a nonlinearly moving surface. Additionally, the hybrid ferrofluid exhibits an asymmetric flow pattern due to the buoyancy force affecting the flow. Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ is employed as the base fluid collectively with the mixtures of nanoparticles containing magnetite $\left(\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4\right)$ and cobalt ferrite $\left(\mathrm{CoF}{\mathrm{e}}_2{\mathrm{O}}_4\right)$, forming a hybrid ferrofluid. The partial differential equation’s complexity is reduced by similarity transformation into a system of ordinary differential equations, which are then numerically solved by applying the MATLAB function bvp4c for a specific range of values regarding the governing parameters. Dual solutions were identified under both opposing and assisting flow conditions, and the stability analysis identified that the first solution was stable. Furthermore, it was also revealed that the addition of 1% $\mathrm{CoF}{\mathrm{e}}_2{\mathrm{O}}_4$ in hybrid ferrofluid led to a higher skin friction coefficient between 3.35% and 7.18% for both assisting and opposing flow regions. Additionally, the growth of magnetic fields results in a reduced heat transfer rate between 8.75% to 10.65%, whilst the presence of the suction parameter expands the range of solutions, which then delays the boundary layer separation. With the Eckert number included, the heat transfer rate continuously declined between 7.27% to 10.24%. However, it increased by about 280.64% until 280.98% as the Biot number increased. Full article

This paper investigates the mixed convection flow related to ${\mathrm{Fe}}_3{\mathrm{O}}_4$-${\mathrm{CoFe}}_2{\mathrm{O}}_4/\mathrm{water}$ hybrid ferrofluids on stagnation point over an exponentially stretching/shrinking surface with the influence of magnetohydrodynamic (MHD), velocity slip, and heat source/sink. The proposed system of differential equations is reduced using the similarity transformation procedure that is numerically solvable using MATLAB. Dual solutions are obtained for various governing parameters, in which the first solution is found to be in a stable state via the stability analysis. The CoFe₂O₄ nanoparticles volume fraction increases the heat transfer rate and the skin friction coefficient while delaying the separation of the boundary layer at the bifurcation point. Adding CoFe₂O₄ nanoparticles in hybrid ferrofluids gives a better heat transfer rate than that obtained with ferrofluids. The presence of a magnetic field enhances the fluid flow velocity. The increased strengths of the heat sink and stretching parameters give better results on the heat transfer, while the results are reversed for the heat source and shrinking parameters. The presence of velocity slip does influence the skin friction and the fluid flow. Full article

This paper examines the unsteady separated stagnation point (USSP) flow and thermal progress of Fe₃O₄–CoFe₂O₄/H₂O on a moving plate subject to the heat generation and MHD effects. The model of the flow includes the boundary layer and energy equations. These equations are then simplified with the aid of similarity variables. The numerical results are generated by the bvp4c function and then presented in graphs and tables. The magnetic and acceleration (strength of the stagnation point flow) parameters are the contributing factors in the augmentation of the skin friction and heat transfer coefficients. However, the enhancement of heat generation parameter up to 10% shows a reduction trend in the thermal rate distribution of Fe₃O₄–CoFe₂O₄/H₂O. This finding reveals the effectiveness of heat absorption as compared to the heat generation in the thermal flow process. From the stability analysis, the first solution is the physical solution. The streamline for the first solution acts as a normal stagnation point flow, whereas the second solution splits into two regions, proving the occurrence of reverse flow. Full article

The flow of fluids over the boundaries of a rotating disc has many practical uses, including boundary-layer control and separation. Therefore, the aim of this study is to discuss the impact of unsteady magnetohydrodynamics (MHD) hybrid ferrofluid flow over a stretching/shrinking rotating disk. The time-dependent mathematical model is transformed into a set of ordinary differential equations (ODE’s) by using similarity variables. The bvp4c method in the MATLAB platform is utilised in order to solve the present model. Since the occurrence of more than one solution is presentable, an analysis of solution stabilities is conducted. Both solutions were surprisingly found to be stable. Meanwhile, the skin friction coefficient, heat transfer rate—in cooperation with velocity—and temperature profile distributions are examined for the progressing parameters. The findings reveal that the unsteadiness parameter causes the boundary layer thickness of the velocity and temperature distribution profile to decrease. A higher value of magnetic and mass flux parameter lowers the skin friction coefficient. In contrast, the addition of the unsteadiness parameter yields a supportive effect on the heat transfer rate. An increment of the magnetic parameter up to 30% reduces the skin friction coefficient by 15.98% and enhances the heat transfer rate approximately up to 1.88%, significantly. In contrast, the heat transfer is rapidly enhanced by improving the mass flux parameter by almost 20%. Full article

The numerical investigations of hybrid ferrofluid flow with magnetohydrodynamic (MHD) and heat source/sink effects are examined in this research. The sheet is assumed to stretch or shrink exponentially near the stagnation region. Two dissimilar magnetic nanoparticles, namely cobalt ferrite, CoFe₂O₄ and magnetite, Fe₃O₄, are considered with water as a based fluid. Utilizing the suitable similarity transformation, the governing equations are reduced to an ordinary differential equation (ODE). The converted ODEs are numerically solved with the aid of bvp4c solver from Matlab. The influences of varied parameters on velocity profile, skin friction coefficient, temperature profile and local Nusselt number are demonstrated graphically. The analysis evident the occurrence of non-unique solution for a shrinking sheet and it is confirmed from the analysis of stability that only the first solution is the stable solution. It is also found that for a stronger heat source, heat absorption is likely to happen at the sheet. Further, hybrid ferrofluid intensifies the heat transfer rate compared to ferrofluid. Moreover, the boundary layer separation is bound to happen faster with an increment of magnetic parameter, while it delays when CoFe₂O₄ nanoparticle volume fraction increases. Full article

In this report, the heating efficiencies of γ-Fe₂O₃ and hybrid γ-Fe₂O₃-TiO₂ nanoparticles NPs under an alternating magnetic field (AMF) have been investigated to evaluate their feasible use in magnetic hyperthermia. The NPs were synthesized by a modified sol-gel method and characterized by different techniques. X-ray diffraction (XRD), Mössbauer spectroscopy and electron microscopy analyses confirmed the maghemite (γ-Fe₂O₃) phase, crystallinity, good uniformity and 10 nm core sizes of the as-synthesized composites. SQUID hysteresis loops showed a non-negligible coercive field and remanence suggesting the ferromagnetic behavior of the particles. Heating efficiency measurements showed that both samples display high heating potentials and reached magnetic hyperthermia (42 °C) in relatively short times with shorter time (~3 min) observed for γ-Fe₂O₃ compared to γ-Fe₂O₃-TiO₂. The specific absorption rate (SAR) values calculated for γ-Fe₂O₃ (up to 90 W/g) are higher than that for γ-Fe₂O₃-TiO₂ (~40 W/g)_, confirming better heating efficiency for γ-Fe₂O₃ NPs. The intrinsic loss power (ILP) values of 1.57 nHm²/kg and 0.64 nHm²/kg obtained for both nanocomposites are in the range reported for commercial ferrofluids (0.2–3.1 nHm²/kg). Finally, the heating mechanism responsible for NP heat dissipation is explained concluding that both Neel and Brownian relaxations are contributing to heat production. Overall, the obtained high heating efficiencies suggest that the fabricated nanocomposites hold a great potential to be utilized in a wide spectrum of applications, particularly in magnetic photothermal hyperthermia treatments. Full article

A numerical treatment for the unsteady viscous-Ohmic dissipative flow of hybrid ferrofluid over a contracting cylinder is provided in this study. The hybrid ferrofluid was prepared by mixing a 50% water (H${}_2$O) + 50% ethylene glycol $\left(EG\right)$ base fluid with a hybrid combination of magnetite (Fe${}_3$O${}_4)$ and cobalt ferrite (CoFe${}_2$O${}_4)$ ferroparticles. Suitable parameters were considered for the conversion of partial differential equations (PDEs) into ordinary differential equations (ODEs). The numerical solutions were established by expanding the unknowns and employing the truncated series of shifted Legendre polynomials. We begin by collocating the transformed ODEs by setting the collocation points. These collocated equations yield a system of algebraic equations containing shifted Legendre coefficients, which can be obtained by solving this system of equations. The effect of the various influencing parameters on the velocity and temperature flow profiles were plotted graphically and discussed in detail. The effects of the parameters on the skin friction coefficient and heat transfer rates were further presented. From the discussion, we come to the understanding that Eckert number considerably decreases both the skin friction coefficient and the heat transfer rate. Full article

The spotlight of this investigation is primarily the effectiveness of the magnetic field on the natural convective for a Fe₃O₄ ferrofluid flow over a vertical radiate plate using streamwise sinusoidal variation in surface temperature. The energy equation is reduplicated by interpolating the non-linear radiation effectiveness. The original equations describing the ferrofluid motion and energy are converted into non-dimensional equations and solved numerically using a new hybrid linearization-differential quadrature method (HLDQM). HLDQM is a high order semi-analytical numerical method that results in analytical solutions in $\eta$ -direction, and so the solutions are valid overall in the $\eta$ domain, not only at grid points. The dimensionless velocity and temperature curves are elaborated. Furthermore, the engineering curiosity of the drag coefficient and local Nusselt number are debated and sketched in view of various emerging parameters. The analyzed numerical results display that applying the magnetic field to the ferroliquid generates a dragging force that diminishes the ferrofluid velocity, whereas it is found to boost the temperature curves. Furthermore, the drag coefficient sufficiently minifies, while an evolution in the heat transfer rate occurs as nanoparticle volume fraction builds. Additionally, the augmentation in temperature ratio parameter signifies a considerable growth in the drag coefficient and Nusselt number. The current theoretical investigation may be beneficial in manufacturing processes, development of transport of energy, and heat resources. Full article

Superparamagnetic iron oxide nanoparticles (SPIONs) are frequently used for drug targeting, hyperthermia and other biomedical purposes. Recently, we have reported the synthesis of lauric acid-/albumin-coated iron oxide nanoparticles SEON^LA-BSA, which were synthesized using excess albumin. For optimization of magnetic treatment applications, SPION suspensions need to be purified of excess surfactant and concentrated. Conventional methods for the purification and concentration of such ferrofluids often involve high shear stress and low purification rates for macromolecules, like albumin. In this work, removal of albumin by low shear stress tangential ultrafiltration and its influence on SEON^LA-BSA particles was studied. Hydrodynamic size, surface properties and, consequently, colloidal stability of the nanoparticles remained unchanged by filtration or concentration up to four-fold (v/v). Thereby, the saturation magnetization of the suspension can be increased from 446.5 A/m up to 1667.9 A/m. In vitro analysis revealed that cellular uptake of SEON^LA-BSA changed only marginally. The specific absorption rate (SAR) was not greatly affected by concentration. In contrast, the maximum temperature T_max in magnetic hyperthermia is greatly enhanced from 44.4 °C up to 64.9 °C by the concentration of the particles up to 16.9 mg/mL total iron. Taken together, tangential ultrafiltration is feasible for purifying and concentrating complex hybrid coated SPION suspensions without negatively influencing specific particle characteristics. This enhances their potential for magnetic treatment. Full article

Chitosan is the deacetylated form of chitin and used in numerous applications. Because it is a good dispersant for metal and/or oxide nanoparticle synthesis, chitosan and its derivatives have been utilized as coating agents for magnetic nanoparticles synthesis, including superparamagnetic iron oxide nanoparticles (SPIONs). Herein, we demonstrate the water-soluble SPIONs encapsulated with a hybrid polymer composed of polyelectrolyte complexes (PECs) from chitosan, the positively charged polymer, and dextran sulfate, the negatively charged polymer. The as-prepared hybrid ferrofluid, in which iron chloride salts (Fe³⁺ and Fe²⁺) were directly coprecipitated inside the hybrid polymeric matrices, was physic-chemically characterized. Its features include the z-average diameter of 114.3 nm, polydispersity index of 0.174, zeta potential of −41.5 mV and iron concentration of 8.44 mg Fe/mL. Moreover, based on the polymer chain persistence lengths, the anionic surface of the nanoparticles as well as the high R2/R1 ratio of 13.5, we depict the morphology of SPIONs as a cluster because chitosan chains are chemisorbed onto the anionic magnetite surfaces by tangling of the dextran sulfate. Finally, the cellular uptake and biocompatibility assays indicate that the hybrid polymer encapsulating the SPIONs exhibited great potential as a magnetic resonance imaging T2 contrast agent for cell tracking. Full article