Highly cross-linked narrow or monodisperse poly(divinylbenzene) (PDVB) microspheres were prepared by distillation-precipitation polymerization as a novel polymerization technique in acetonitrile with 2,2′-azobis(2-methylpropionitrile) (AIBN) as initiator. The polymeric microspheres were formed simultaneously through a precipitation polymerization manner during the distillation of acetonitrile off the reaction system. Narrow or monodisperse particles with spherical shape and smooth surface were prepared with diameters between 1.10 and 3.41 µm without any stabilizers. The particle size and size distribution depended on the reaction conditions. The maximum particle size of 2.14 µm with size distribution index of 1.058 was attained at cross-linking degree of 64%, and the size distribution became narrower with increasing cross-linking degree. The particle sizes increased with increasing monomer and initiator concentration. A series of polymer particles with diameter between 1.99 and 3.41 µm were obtained by multi-semibatch mode with successive introduction of a mixture of the designed amount of AIBN and divinylbenzene containing 80% divinylbenzene (DVB80) in acetonitrile into the distillationprecipitation polymerization, and the size distribution index was kept around 1.02. Furthermore, the conversion increased from 31% for the first aliquot to 76% for the sixth aliquot. All of the resulting microspheres were characterized with SEM.

Well‐rounded: Water‐dispersed colloidal spheres that are self‐assembled from nanocrystals with different size, shape, composition, and surface ligand were prepared through a versatile emulsion‐based self‐assembly (EBS) approach. Through this emulsification process, a dispersion of BaCrO4 nanocrystals in cyclohexane (see picture, left) can be transformed into a dispersion of colloidal spheres of BaCrO4 (see picture, right).

The use of nanoparticles as a potential building block for photosensitizers has recently become a focus of interest in the field of photocatalysis and photodynamic therapy. Porphyrins and their derivatives are effective photosensitizers due to extended π-conjugated electronic structure, high molar absorption from visible to near-infrared spectrum, and high singlet oxygen quantum yields as well as chemical versatility. In this paper, we report a synthesis of self-assembled porphyrin nanoparticle photosensitizers using zinc meso-tetra(4-pyridyl)porphyrin (ZnTPyP) through a confined noncovalent self-assembly process. Scanning electron microscopy reveals formation of monodisperse cubic nanoparticles. UV-vis characterizations reveal that optical absorption of the nanoparticles exhibits a red shift due to noncovalent self-assembly of porphyrins, which not only effectively increase intensity of light absorption but also extend light absorption broadly covering visible light for enhanced photodynamic therapy. Electron spin-resonance spectroscopy (ESR) studies show the resultant porphyrin nanoparticles release a high yield of singlet oxygen. Nitric oxide (NO) coordinates to central metal Zn ions to form stabilized ZnTPyP@NO nanoparticles. We show that under light irradiation ZnTPyP@NO nanoparticles release highly reactive peroxynitrite molecules that exhibit enhanced antibacterial photodynamic therapy (APDT) activity. The ease of the synthesis of self-assembled porphyrin nanoparticles and light-triggered release of highly reactive moieties represent a completely different photosensitizer system for APDT application.

Nanoparticle (NP) high pressure behavior has been extensively studied over the years. In this review, we summarize recent progress on the studies of pressure induced NP phase behavior, property, and applications. This review starts with a brief overview of high pressure characterization techniques, coupled with synchrotron X-ray scattering, Raman, fluorescence, and absorption. Then, we survey the pressure induced phase transition of NP atomic crystal structure including size dependent phase transition, amorphization, and threshold pressures using several typical NP material systems as examples. Next, we discuss the pressure induced phase transition of NP mesoscale structures including topics on pressure induced interparticle separation distance, NP coupling, and NP coalescence. Pressure induced new properties and applications in different NP systems are highlighted. Finally, outlooks with future directions are discussed.

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