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The recipe for making Turkish coffee in some parts of former Yugoslavia calls for the dilution of the turbid liquid with lukewarm water just before the boiling point is reached. The enigmatic gastronomic purpose of this step notwithstanding, here it is being used as an inspiration for deriving a simple stabilization step for protocols for the synthesis of fine particle colloids. The dilution step inspired by coffee-making was performed in a protocol for the synthesis of hydroxyapatite nanoparticles by their precipitation from supersaturated alkaline aqueous solutions. The implementation of this step in the post-precipitation stage, concurrently with boiling, evidently improved the stability of the nanoparticle colloids. The stabilization effect was limited to the suspensions where the parent solution was equilibrated with the fresh precipitate and was not reproduced in colloids comprising HAp nanoparticles redispersed in deionized water. The dilution step produced a mild and counterintuitive increase in crystallinity, suggesting complex recrystallization mechanisms driven by mutually antagonistic dissolution caused by the dilution and reprecipitation caused by the heating to be responsible for the observed increase in stability. Incongruent dissolution favoring a less entropic surface order and reduced charge screening entailing the expansion of the Debye lengths were suggested as complementary mechanisms explaining the improvements in stability caused by adding this simple and economical, yet very efficacious touch to the synthesis. It is concluded that unconventional protocols in spheres other than the scientific and heritages routinely discarded as disreputable could be sources of insight relevant to a plethora of distant domains and disciplines. [ABSTRACT FROM AUTHOR]

The Russian-Ukrainian scientist, G. V. Samsonov left an enormous legacy in materials science, even though a large portion of his and his group's work remained hidden behind the Iron Curtain. One of his crowning theoretical contributions that received but a slight tidbit of resonance in the west was the configurational model of the solid state based on the statistical weight of atoms with stable configuration (SWASC). Only a handful of papers employing this model were published in the western journals since the model was developed, in 1965. Here, the configurational model was tested for its ability to explain the effects of divalent transition elements on solubility of hydroxyapatite when they acted as dopants in it. It is shown that the SWASC values for half-filled d orbitals of transition elements in the ± 5 pm range of ionic radii centered around iron do correlate monotonously with the solubility change induced by the dopant ions relative to the solubility of stoichiometric hydroxyapatite synthesized and analyzed under the same conditions when the solubility values are extrapolated to identical atomic ratios between the dopant ions and the constitutive calcium ions. The effect of SWASC, however, competes with that of the dopant concentration, producing a complex plexus of mutually antagonistic effects. With this work, it is hoped that the interest in the work of G. V. Samsonov and the generation of his Soviet and Yugoslavian scientific contemporaries gets revived and their legacy in the west popularized. [ABSTRACT FROM AUTHOR]

The synthetic analogue to biogenic apatite, hydroxyapatite (HA) has a number of physicochemical properties that make it an attractive candidate for diagnosis, treatment of disease and augmentation of biological tissues. Here we describe some of the recent studies on HA, which may provide bases for a number of new medical applications. The content of this review is divided to different medical application modes utilizing HA, including tissue engineering, medical implants, controlled drug delivery, gene therapies, cancer therapies and bioimaging. A number of advantages of HA over other biomaterials emerge from this discourse, including (i) biocompatibility, (ii) bioactivity, (iii) relatively simple synthesis protocols for the fabrication of nanoparticles with specific sizes and shapes, (iv) smart response to environmental stimuli, (v) facile functionalization and surface modification through noncovalent interactions, and (vi) the capacity for being simultaneously loaded with a wide range of therapeutic agents and switched to bioimaging modalities for uses in theranostics. A special section is dedicated to analysis of the safety of particulate HA as a component of parenterally administrable medications. It is concluded that despite the fact that many benefits come with the usage of HA, its deficiencies and potential side effects must be addressed before the translation to the clinical domain is pursued. Although HA has been known in the biomaterials world as the exemplar of safety, this safety proves to be the function of size, morphology, surface ligands and other structural and compositional parameters defining the particles. For this reason, each HA, especially when it comes in a novel structural form, must be treated anew from the safety research angle before being allowed to enter the clinical stage. [ABSTRACT FROM AUTHOR]