Inducing Dzyaloshinskii-Moriya interaction in symmetrical multilayers using post annealing.

The interfacial Dzyaloshinskii-Moriya Interaction (iDMI) is an antisymmetric exchange interaction that is induced by the broken inversion symmetry at the interface of, e.g., a ferromagnet/heavy metal. Thus, the presence of iDMI is not expected in symmetrical multilayer stacks of such structures. Here, we use thermal annealing to induce the iDMI in a [Py/Pt]×10 symmetrical multilayer stack. Brillouin light scattering spectroscopy is used to directly evidence the iDMI induction in the annealed sample. Structural characterizations highlight the modified crystallinity as well as a higher surface roughness of the sample after annealing. First principles electronic structure calculations demonstrate a monotonic increase of the iDMI with the interfacial disorder due to the interdiffusion of atoms, depicting the possible origin of the induced iDMI. The presented method can be used to tune the iDMI strength in symmetric multilayers, which are the integral part of racetrack memories, magnonic devices as well as spin-orbitronic elements.

Multifunctional Hybrid Magnetic Microgel Synthesis for Immune-Based Isolation and Post-Isolation Culture of Tumor Cells.

Circulating tumor cells are of utmost importance among various biomarkers in liquid biopsies as a prognosis indicator of metastasis as well as in chemotherapeutic monitoring. This study introduces an efficient tool composed of soft nano/hybrid immune microgels for magnetic isolation of targeted tumor cells. The development process involves the in situ synthesis of magnetic nanoparticles within the three-dimensional matrix of thermoresponsive microgels. Surface modification and anti-EpCAM conjugation are adjusted by changing the temperature, and a conjugation efficiency of around 70% is achieved by using a protein G linker. Anti-EpCAM-conjugated nano/hybrid magnetic microgels are used to isolate EpCAM-expressing breast adenocarcinoma MCF-7 cells from culture media and whole blood with an efficiency of 75 and 70%, respectively. Furthermore, we demonstrate the ability of the hybrid microgels to isolate cancer cells with a purity of 65% and culture the cells post-isolation for further drug studies. The multifunctional hybrid microcarriers reported in this work can be potentially used for continuous monitoring of cancers and in personalized medicine.

Efficient targeted cancer cell detection, isolation and enumeration using immuno-nano/hybrid magnetic microgels.

Magnetic nanomaterials have drawn ample attention in the field of biotechnology due to their excellent magnetic properties and biocompatibility. These materials have been widely used for exosome isolation, DNA separation, magnetic resonance imaging, and drug delivery. However, their application in cell isolation has been limited due to the lack of efficient antibody conjugation and instability in aqueous solutions. In this study, we produced hybrid maghemite nanorod/immuno-microgels with high capturing capacity for cell isolation and enumeration. Lepidocrocite (γ-FeOOH) and maghemite (γ-Fe2O3) nanorods with controlled morphology are synthesized using hydrolysis method. The effects of the different synthesis conditions on morphology, phase composition, and magnetic properties of lepidocrocite are studied to determine the best synthesis conditions. We coat the nanorods with chitosan and attach them to the poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-AA) microgel through chemical bonding to form a nano/hybrid microstructure. Our results suggest that the hybrid magnetic microgels have more antibody binding capacity and higher cancer cell capturing rate compared to pristine maghemite nanorods. In addition, new cell magnetometery method was applied for cancer cell quantification after capturing step in which different magnetized labelled cells were correlated to the saturation magnetization. In this method, higher concentrations of the primary cell suspension resulted in more binding of the magnetic immuno-microgels to the cells which was shown as saturation magnetization drop in the microgel-cell complex.

pH-responsive carbon nanotube-based hybrid nanogels as the smart anticancer drug carrier.

Tumour drug delivery using nanocarriers is attracting ample attentions due to their high drug-loading capacity. Regarding specific tumour microenvironment properties as acidic pH, smart nanocarriers with the ability of responding to the microenvironment, can have a profound effect on the level of drug release and subsequent tumour treatment. In this study, by combining the advantages of multiwall carbon nanotube and pH-sensitive nanogels, multifunctional magneto/pH-responsive nano-hybrid system is developed to deliver the doxorubicin as a general cancer chemotherapeutic drug. The chemical and physical properties of the nanocarrier, as well as drug-loading efficiency and drug releasing characteristics were analysed. It was showed functionalized CNT has low pH-responsiveness in acidic environment, whereas chitosan-coated magnetic nanocomposite can result in greater pH-responsiveness and subsequently higher drug release over a week compared to nanocomposite system without chitosan. This behaviour was proved in Live/Dead assay of the U-87 glioblastoma cell lines exposed to DOX release supernatant at different time intervals so that significant effect of DOX supernatant on cancer cell proliferation suppression was showed.

L-arginine modified magnetic nanoparticles: green synthesis and characterization.

In recent years, there has been considerable interest in Arg which is a unique, nontoxic, and biocompatible biomolecule since it can be utilized as an agent for the functionalization and subsequent stabilization of MNPs against oxidation and aggregation, during or after a synthesis procedure. Our studies demonstrate that Arg has great impacts on MNPs with the decreasing size of the particle. Also, saturation magnetization and electrostatic interactions of RMNPs have a direct impact on biological molecules such as proteins and nucleic acids. By controlling the concentration of Arg, it is possible to accurately control the above-mentioned characteristics, which are useful tools for applications such as connecting to antibodies, catalysis, drug loading, and modification of MNP stability. In the current study, three RMNPs with different Arg densities, i.e. 0.42, 1.62, and 2.29 µg per mg were successfully synthesized through a simple co-precipitation method (named p 0.5, p 1, and p 1.5, respectively) and verified by colorimetric determination. Also, the as-synthesized RMNP powders were characterized by XRD, SEM/EDAX, FTIR, VSM, and zeta potential analysis. The presence of a magnetic core was proved by XRD, FTIR, and EDAX. Colorimetric analysis showed the existence of Arg in the synthesized samples. According to the zeta potential and VSM results, increasing the cap of Arg on the MNP surface leads to an increase in the surface charge and decrease in the magnetization of the RMNPs, respectively.

Synthesis, Characterization, and Application of Partially Blocked Amine-Functionalized Magnetic Nanoparticles.

In this study, a novel technique was introduced for selective surface modification of amine-functionalized magnetic nanoparticles. The method was based on alignment of magnetic nanoparticles in an external magnetic field, which resulted in formation of chain-like assemblies in diluted suspensions. The aligned chains were then modified on the surface via reaction of isocyanate species with the particle functionalities. Finally, after removal from the reactor medium, particles with segmented distribution of surface functionalities were achieved. We named these partially blocked amine-functionalized magnetic nanoparticles as "Saturn" nanoparticles. Application of the particles in fabrication of magnetic assemblies was successfully demonstrated. Using methylene diphenyl diisocyanate (MDI) as the bridging agent, structures in different forms such as chains and filaments were produced by the Saturn particles and compared with cross-linked structures of the unmodified amine-functionalized particles. It is expected that this novel nanoparticle with its unique structure will have great potential in assembly fabrication with a variety of applications in biomedical fields.