Calcium carbonate (CaCO3) has attracted scientific attention due to its essential role in both inorganic and bioorganic chemistry. Vaterite is the least thermodynamically stable CaCO3 polymorph and has elicited great interest as an advanced biomaterial for tissue engineering, drug delivery, and a broad range of personal care products. Numerous methods of vaterite particle synthesis with different sizes and morphologies have highlighted the submicron porous particles of spherical or ellipsoidal shape as the most useful ones. In this regard, the current study is aimed at development of a reliable method for synthesis of such structures. Herein, submicron vaterite particles are synthesized by dropwise precipitation from saturated sodium carbonate and calcium chloride solutions in the presence of ethylene glycol while manipulating the concentration ratios of reagents. We demonstrate that our novel technique named “dropwise precipitation” leads to changing calcium concentrations in the reaction solution at each moment affecting the crystallization process. The proposed technique allows routine obtainment of vaterite particles of a required shape, either spherical or ellipsoidal, and a controlled size in the range from 0.4 to 2.7 μm and (0.4 × 0.7) to (0.7 × 1.1) μm, respectively. The key parameters influencing the size, shape, and percent of vaterite fraction for synthesized CaCO3 particles are discussed.

Superficial fungal infections are of serious concern worldwide due to their morbidity and increasing distribution across the globe in this era of growing antimicrobial resistance. Delivery of antifungals to target...

The interest in functional supramolecular systems for the design of innovative materials and technologies, able to fundamentally change the world, is growing at a high pace. The huge array of publications that appeared in recent years in the global literature calls for systematization of the structural trends inherent in the formation of these systems revealed at different molecular platforms and practically useful properties they exhibit. The attention is concentrated on the topics related to functional supramolecular systems that are actively explored in institutes and universities of Russia in the last 10–15 years, such as the chemistry of host–guest complexes, crystal engineering, self-assembly and self-organization in solutions and at interfaces, biomimetics and molecular machines and devices. The bibliography includes 1714 references.

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The acid-induced cloud-point extraction (CPE) technique based on sodium dodecylsulfate (SDS) micelles has been used for preconcentration of ten representatives of polycyclic aromatic hydrocarbons (PAHs) for the following fluorescence determination. The effect of the acidity of solution, SDS and electrolyte concentrations, centrifugation time and rate on the two-phase separation process and extraction percentages of PAHs have systematically been examined. Extraction percentages have been obtained for all PAHs after CPE ranged from 67 to 93%. Pyrene was used as a fluorescent probe to monitor the micropolarity of the surfactant-rich phase compared with SDS micelles and this allows one to conclude that water content in micellar phase after CPE is reduced. The spectral, metrological and analytical characteristics of PAH fluorimetric determination after acid-based CPE with sodium dodecylsulfate are presented. Advantages provided by using CPE in combination with fluorimetric determination of PAHs are discussed. The determination of benz[a]pyrene in tap water is presented as an example.

CE is well known not only as an efficient separation method, but also as a viable tool for studying chemical reactions, including kinetic assaying and analysis of chemical equilibria. In this communication, the latter feature of CE interfaced with ICP-MS was exploited to determine the stoichiometric composition of the protein corona of gold nanoparticles (AuNPs) at equilibrium conditions. For both individual albumin and human serum involved in binding, the number of protein molecules bound per AuNP (n) was calculated. Since the time scale of the corona formation was previously found to be dependent on the particle size, two calculation algorithms were adopted here. In the case of 5-nm AuNPs, rather slowly associating with the protein, the peak areas measured for the conjugated and free particles were taken in computation (the (34) S signal due to bound protein was also monitored simultaneously to confirm that equilibrium is reached). In binding labile systems (10-50 nm AuNPs), the particles are converted into the protein-bound form relatively fast due mostly to the favor of a much greater excess of the protein so that no peak of the free particles interacting with serum being recorded. Therefore, the n value was estimated by relating the sulfur peak area of each of these conjugates to that of 5-nm AuNPs to calculate the number of bound albumin molecules that was then divided by the number of AuNPs. The AuNPs were found to react with from 13 to 292 albumin molecules that is in good agreement with the literature data.

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