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Understanding the difference in physicochemical properties and biological response between colloidal and powder formulations of identical materials is important before the given materials are used in a medical milieu. In this study we compared a set of biological effects of colloidal and powder formulations of composite nanoparticles comprising superparamagnetic iron oxide cores and silicate/carbon shells. Magnetic dipole interaction between adjacent nanoparticles was more pronounced in their powders than in their colloidal formulations. Nanoparticles delivered as powders were thus more responsive to the magnetic field, but exhibited reduced uptake in bone and brain cancer cells, including K7M2 osteosarcoma line and U87 and E297 glioblastoma lines. Specifically, while the alternate magnetic field elicited a more rapid heat generation in cell culture media supplemented with the magnetic powders, the nanoparticles dispersed in the same media were uptaken by the cancer cells more copiously. The cellular uptake proved to be more crucial in defining the effect on cell survival, given that suspended formulations elicited a greater degree of cancer cell death in the magnetic field compared to the powder-containing formulations. Because of this effect, colloidal formulations were able to target cancer cells more effectively than the powders: they reduced the viability of all three tested cancer cell lines to a significantly greater degree that the viability of the normal, MDCK-MDR1 cell line. It is concluded that better uptake profile can make up for the lower heating rate in the AC field and lead to a more effective magnetic hyperthermia therapy. These results also demonstrate that the direct delivery of ferrofluids is more optimal than the administration of their constitutive particles as powders., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Scientific papers written as dialogues evoke Platonist philosophical discourses and are foreseen as elementary forms of expression in neoclassical scientific renaissance. Here we report on a study of the Brazil nut effect in a series of macroscopic and microscopic systems in the form of a play in three acts. The nut effect predicting the segregation of smaller grains at the bottom of the mixture and larger ones at the top was observed in a polydisperse mix of manually shaken playground pebbles, albeit following different kinetics than in an agitated pile of chess pieces. Common sense predicts that vertical, gravity-driven segregation in colloidal dispersions with heterogeneous particle size distributions is such that larger particles would settle toward the bottom and the lighter ones cream at the top. Here we refute this expectation and demonstrate that segregation of colloidal particles in the vertical direction conforms to the Brazil nut effect when the agitation is delivered in the forms of vortex mixing or audio vibration, but not when the colloids are manually shaken. The effect is demonstrated on aqueous dispersions of hydroxyapatite and iron oxide nanoparticles. Kinetic experiments showed that segregation increases with the agitation time in mixtures of pebbles and with the post-agitation aging time in fine particle colloids. The particle size gradient established due to agitation-induced segregation led to a corresponding gradient in optoelectronic properties—band gap, conductivity, lattice acoustics—in the vertical direction of the colloidal column for both types of nanoparticles. Such morphological gradients induced by the Brazil nut effect can be harnessed as affordable and facile templates for the synthesis of functionally gradient materials. Discussion of the mechanism and the application potential of the observed effect in colloidal and coarse systems is enriched with a literature review of this curious effect and entwined with the literary elements of the dramaturgical narrative involving a family of scientist in exile from mainstream scientific institutions: the mother, the father, an elementary school boy and a kindergarten girl. The narrative conforms in its structure to the shape of a Brazil nut and presents the first research study whose findings are enacted through a dream. The play questions the humaneness and creative prospects of modern science and celebrates children's science projects performed with meager resources and a plentiful of imagination, showing that they could be gateways to important scientific discoveries. [ABSTRACT FROM AUTHOR]

Abstract: Self-assembly is a ubiquitous physicochemical phenomenon. It is inherent to molecular recognition effects in the biological domain, and thus presents a basis for understanding the constitution and dynamic organization of living beings. However, it is argued in this paper that the very notion of self-assembly presents an incorrect and misleading one for the physical effects that it stands for. Self-assembly presents a misnomer as each self-assembly process not only depends on, but also includes a certain degree of ordering in the immediate surrounding of the ‘self-assembling’ entities. Claims are provided to support the idea that every self-assembly process is, in fact, a co-assembly event, as it implies mutual changes and structuring of both the ‘self-assembled’ system and its nearest surrounding. This point of view is related to the systemic observation that there could be no physical qualities independent on the context of their existence. In order to illustrate that the concept of co-assembly presents only an instance of a more profound and systemic philosophy of life, the examples of the interplay between internal and external factors of development are provided from the fields of quantum and classical physics, biology, evolutionary theory and psychology. [Copyright &y& Elsevier]

Abstract: Reverse micelles present self-assembled multi-molecular entities formed within specific compositional ranges of water-in-oil microemulsions. The structure of a reverse micelle is typically represented as nano-sized droplet of a polar liquid phase, capped by a monolayer of surfactant molecules, and uniformly distributed within a non-polar, oil phase. Although their role in serving as primitive membranes for encapsulation of primordial self-replicating chemical cycles that anticipated the very origins of life has been proposed, their first application for ‘parent(hesis)ing’ chemical reactions with an aim to produce ‘templated’ 2D arrays of nanoparticles dates back to only 25 years ago. Reverse micelles have since then been depicted as passive nano-reactors that via their shapes template the growing crystalline nuclei into narrowly dispersed or even perfectly uniform nano-sized particles. Despite this, numerous examples can be supported, wherefrom deviations from the simple unilateral correlations between size and shape distribution of reverse micelles and the particles formed within may be reasonably implied. A rather richer, dynamical role of reverse micelles, with potential significance in the research and design of complex, self-assembly synthesis pathways, as well as possible adoption of their application as an aspect of biomimetic approach, is suggested herein. [Copyright &y& Elsevier]

Abstract: Nanostructured NiZn ferrites were synthesized using two different techniques: first, a precipitation procedure in the reverse micelles of a CTAB/1-hexanol/H2O microemulsion, and second, precipitation in a bulk aqueous solution. XRD measurements, magnetic measurements, TEM imaging, analytical measurements and thermal analyses were used in an attempt to reveal the chemical pathway that leads to the formation of NiZn ferrite in the microemulsion and in the bulk aqueous solution. It was found that reverse micelles do not act as inert nano-sized reactors that influence only morphological properties of the synthesized powders, but have a decisive influence on the identity of the final product when compared to the non-microemulsion procedure, and therefore present the molecular structures which are actively engaged in the chemical pathway according to which the herein presented room temperature synthesis of NiZn ferrite nanoparticles takes place. The influence of the initial pH on the chemical pathway of reverse-micellar synthesis and the morphology of the synthesized particles was discussed after initially it was found that the pH of the precipitation ought to be higher than 8 in order to obtain the desired ferrite as a final product. [Copyright &y& Elsevier]