Mode spectra of magnetic and dielectric plasmon spheres obtained from Mie scattering and free oscillation theories

This paper presents Mie scattering theory as compared to rigorous electromagnetic theory of free oscillations in magnetic and electric plasmon spheres. It is shown that the maxima of Mie scattering and absorption spectra well correspond to resonance frequencies of plasmon modes occurring in dielectric and magnetic spheres, similarly as it takes place for ordinary dielectric resonator modes. Mie theory is well applicable to determine resonance frequencies and scattering parameters of spherical plasmons. However, this theory cannot be applied to determine intrinsic properties of modes induced in the object by the incident plane wave, like quality factors. On the contrary, rigorous electromagnetic theory of free oscillations allows one to determine the complex resonance frequency of each mode that can occur in a given object, and the corresponding quality factor accounting for various kind of losses, including medium and radiation losses. The advantage of the free oscillations theory, as shown in this paper, is in the determination of the quality factors of modes occurring in magnetic plasmon spheres made of a strongly dispersive magnetic medium. Graphical Abstract

Depletion-Induced Chiral Chain Formation of Magnetic Spheres

Experimental evidence is presented for the spontaneous formation of chiral configurations in bulk dispersions of magnetized colloids that interact by a combination of anisotropic dipolar interactions and isotropic depletion attractions. The colloids are superparamagnetic silica spheres, magnetized and aligned by a carefully tuned uniform external magnetic field; isotropic attractions are induced by using poly(ethylene oxide) polymers as depleting agents. At specific polymer concentrations, sphere chains wind around each other to form helical structures–of the type that previously have only been observed in simulations on small sets of unconfined dipolar spheres with additional isotropic interactions.

Isolation of Circulating Tumor Cells of Ovarian Cancer by Transferrin Immunolipid Magnetic Spheres and Its Preliminary Clinical Application

Circulating tumor cells (CTCs) play an important role in cancer prognosis, treatment monitoring and metastasis diagnosis. However, due to the extremely low concentration of CTC in the peripheral blood, its isolation and enrichment are critical steps for early diagnosis. Herein, we used the transferrin modified lipid magnetic spheres for the isolation of ovarian cancer CTCs, and studied the relationship between the CTCs count and the clinical case parameters, prognosis of ovarian cancer. The result showed that no CTC was found in the peripheral blood of 30 patients with benign cysts, and 34 out of 46 patients with ovarian cancer were positive for CTC, with a positive rate of 73.9%. Analysis of the parameters of the clinical cases showed that the positive rate of CTC was related to the clinical stages, and that it was not significantly related to the age, histopathological types and pathological grades of patients. Of the 34 CTC-positive patients, 18 had progression-free survival, with a survival rate of 52.9%, and of the 11 CTC-negative patients, 9 had progression-free survival, with a survival rate of 81.8%. The results showed that the transferrin lipid magnetic spheres prepared in this study, could effectively isolate the CTCs in the peripheral blood of patients with ovarian cancer, that the level of CTC in ovarian cancer patients was related to its clinical stage, and that the progression-free survival of the patients with a high level of CTCs was relatively short. Therefore, this study shows that the transferrin lipid magnetic sphere can achieve effective isolation of ovarian cancer CTC, which can be used as an auxiliary diagnostic method in comprehensive diagnosis of ovarian cancer.

Enhanced Phosphate Removal from Water by Honeycomb-Like Microporous Lanthanum-Chitosan Magnetic Spheres

The removal of phosphate in water is crucial and effective for control of eutrophication, and adsorption is one of the most effective treatment processes. In this study, microporous lanthanum-chitosan magnetic spheres were successfully synthetized and used for the removal of phosphate in water. The characterization results show that the dispersion of lanthanum oxide is improved because of the porous properties of the magnetic spheres. Moreover, the contact area and active sites between lanthanum oxide and phosphate were increased due to the presence of many honeycomb channels inside the magnetic spheres. In addition, the maximum adsorption capacity of the Langmuir model was 27.78 mg P·g−1; and the adsorption kinetics were in good agreement with the pseudo-second-order kinetic equation and intra-particle diffusion model. From the results of thermodynamic analysis, the phosphate adsorption process of lanthanum-chitosan magnetic spheres was spontaneous and exothermic in nature. In conditional tests, the optimal ratio of lanthanum/chitosan was 1.0 mmol/g. The adsorption capacity of as-prepared materials increased with the augmentation of the dosage of the adsorbent and the decline of pH value. The co-existing anions, Cl− and NO3− had little effect on adsorption capacity to phosphate, while CO32− exhibited an obviously negative influence on the adsorption capacity of this adsorbent. In general, owing to their unique hierarchical porous structures, high-adsorption capacity and low cost, lanthanum-chitosan magnetic spheres are potentially applicable in eutrophic water treatment.