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Microspheres composed of poly (lactic-co-glycolic acid) (PLGA) were formed in liquid droplets using the electrospray technique. The structure of the microspheres was controlled by changing the electric voltage of the electrospray. PLGA microspheres with porous structures and micro-sized nanocomposite particles comprising PLGA nanosphere aggregates were formed at 5.0–7.0 kV and 2.5–3.5 kV, respectively. The structural change was related to the extent of evaporation of the solvent from the droplets during their flight. When the evaporation was completed in the relatively small droplets, the microspheres with porous structures were formed in the droplets. To study the mechanism, we observed the effects of the electric voltage of the electrospray, PLGA concentration, flight distance of the droplets, and molecular weight of PLGA on the structure of the PLGA particles. The novelty of this study is the analysis of the size and structure of the PLGA microparticles, which were controlled by the electrospray technique. Therefore, this research has important implications for the structural design and preparation of nanocomposite particles.

Microspheres composed of poly (lactic-co-glycolic acid) (PLGA) were formed in liquid droplets using the electrospray technique. The structure of the microspheres was controlled by changing the electric voltage of the electrospray. PLGA microspheres with porous structures and micro-sized nanocomposite particles comprising PLGA nanosphere aggregates were formed at 5.0-7.0 kV and 2.5-3.5 kV, respectively. The structural change was related to the extent of evaporation of the solvent from the droplets during their flight. When the evaporation was completed in the relatively small droplets, the microspheres with porous structures were formed in the droplets. To study the mechanism, we observed the effects of the electric voltage of the electrospray, PLGA concentration, flight distance of the droplets, and molecular weight of PLGA on the structure of the PLGA particles. The novelty of this study is the analysis of the size and structure of the PLGA microparticles, which were controlled by the electrospray technique. Therefore, this research has important implications for the structural design and preparation of nanocomposite particles. [ABSTRACT FROM AUTHOR]

To achieve rapid intraparticle diffusion when metal-organic frameworks are used as adsorbents and/or catalysts, it is preferable to reduce their crystal size and improve their monodispersity. The simplest method for reducing the crystal size in a synthetic aqueous solution is increasing the ligand concentration. However, this produces an environmental load, because a large amount of ligand remains in the waste solution. In this study, size-controlled synthesis of the zeolitic imidazolate framework 67 (ZIF-67) was achieved by using a fine liquid droplet as the reaction field. This droplet was generated by electrospraying in the liquid phase, which improved the crystal size, morphology, and monodispersity of ZIF-67. [ABSTRACT FROM AUTHOR]

A study on the interaction between metal ions and the metal ion-binding motif in hammerhead ribozymes is presented. The findings suggest that the metal ion at this motif is not catalytic center of hammerhead .

Coordination polymers can be attractive ion exchange materials because of their crystallinity and semiflexibility, which are rather opposing properties, and play integral and synergistic roles in introducing unique ion-exchange behavior. In this paper, Ln3+/Ce3+ exchange (Ln3+ = Nd3+, Gd3+, Dy3+, or Lu3+) in a coordination polymer, [Ce(dehp)3], based on di(2-ethylhexyl)phosphoric acid (Hdehp) is studied by distribution coefficient measurements, ion-exchange isotherms, Kielland plot analysis, and morphology observation. The ion-exchange selectivity is in the order Nd3+ < Gd3+ < Dy3+ < Lu3+ when a small amount of Ln3+ is loaded, but Lu3+ ≈ Nd3+ < Gd3+ ≈ Dy3+ for a high loading ratio. The Kielland plot suggests that a steric effect is involved in the reactions, which becomes stronger in the order of Nd3+/Ce3+ < Gd3+/Ce3+ < Dy3+/Ce3+ < Lu3+/Ce3+ for exchange systems. This trend is attributable to the differences in the ionic sizes between an incoming Ln3+ and original Ce3+. Scanning electron microscopy observations reveal the generation of a new phase via the Ln3+/Ce3+ exchange. Such a phenomena results from solid–solid transformation, rather than dissolution–recrystallization. The small steric strain in the Nd3+/Ce3+ system leads to the formation of a Nd3+-and-Ce3+ solid-solution, whereas the morphological change is possibly restrained by the strong strain caused by loaded Ln3+ with an ionic size significantly smaller than the original Ce3+. [ABSTRACT FROM AUTHOR]

Nucleation processes of alkali metal chlorides (MCl) in methanol were studied by specially designed electrospray ionization mass spectrometry at the cluster level. From solutions of LiCl, NaCl, KCl and RbCl, the M+(MCl)n clusters with n = 4, 13 and 22 were observed prominently as magic number clusters. These clusters correspond to a square-planar 3 × 3 × 1, cubic 3 × 3 × 3, and cuboid 3 × 3 × 5 structure, respectively. On the other hand, from the solution of CsCl, the Cs+(CsCl)n clusters were almost monotonically decreased with an increase in the cluster size n, without showing any magic number species. This has a good correlation with the difference in the crystalline structures. When nucleation occurs in the condensed phase, the difference in the crystalline structure will be realised at the cluster level. Moreover, it was demonstrated that the mass distributions of K+(KCl)n and Cl−(KCl)n′ clusters look very similar. When these inter-cluster interactions take place efficiently, the crystal growth will be accelerated rapidly. [ABSTRACT FROM AUTHOR]