Synthesis and Morphology of High-Molecular-Weight Polyisobutylene-Polystyrene Block Copolymers Containing Dynamic Covalent Bonds.

Incorporating dynamic covalent bonds into block copolymers provides useful molecular level information during mechanical testing, but it is currently unknown how the incorporation of these units affects the resultant polymer morphology. High-molecular-weight polyisobutylene-b-polystyrene block copolymers containing an anthracene/maleimide dynamic covalent bond are synthesized through a combination of postpolymerization modification, reversible addition-fragmentation chain-transfer polymerization, and Diels-Alder coupling. The bulk morphologies with and without dynamic covalent bond are characterized by atomic force microscopy  and small-angle X-ray scattering, which reveal a strong dependence on annealing time and casting solvent. Morphology is largely unaffected by the inclusion of the mechanophore. The high-molecular-weight polymers synthesized allow interrogation of a large range of polymer domain sizes.

Epoxides as reducing agents for low-catalyst-concentration atom transfer radical polymerization.

Activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) conditions utilizing a low concentration of catalyst are successfully applied for the preparation of well-defined poly(glycidyl methacrylate) without the addition of external reducing agents. The living character of polymerization is evidenced by successful chain extensions with methyl methacrylate and methyl acrylate, again, in the absence of additional reducing agents, yielding block copolymers. The epoxide groups in glycidyl methacrylate or the corresponding polymer can serve as an intrinsic reducing agent to continuously regenerate the Cu(I) -based ATRP activator from the Cu(II) halide complex present in the systems. The reactivity of various epoxides in the reduction of the Cu(II) Br2 complex of tris(2-pyridylmethyl)amine is compared.

Vortex disaggregation for flow cytometry allows direct histologic correlation: a novel approach for small biopsies and inaspirable bone marrows.

BACKGROUND: Many approaches to obtaining single cells from tissue for flow cytometric immunophenotyping are used; however, these methods result in tissue that is too disrupted for subsequent histologic examination. We introduce a new technique for cell dissociation of hematopoietic malignancies that preserves tissue for histology. This is especially important with small specimens for which this type of correlation is critical. METHODS: Fresh tissue from lymph node, gastrointestinal (GI) tract, skin, and other soft tissue biopsies, in addition to cores of inaspirable bone marrows, were briefly vortexed until the RPMI cell culture medium became cloudy. Larger specimens such as lymph nodes were sectioned before disaggregating, whereas smaller ones were vortexed in toto. Resultant flow cytometric analyses were compared with the histology and, in some cases, the immunohistochemistry (IHC) to determine whether the data were concordant. Cell suspensions of 104 specimens-composed of 48 lymph nodes, 19 bone marrow cores (BMCs), 11 GI biopsies, 11 skin/soft tissue biopsies, and 15 miscellaneous specimens-were prepared via vortex disaggregation. RESULTS: Flow cytometric analysis of 96 specimens (92.3%) showed adequacy of material and diagnostic correlation with the histology and IHC. Of the eight cases (7.7%) that were discordant, seven were attributable to significant specimen fibrosis or necrosis. With respect to tissue type, this method produced diagnostic cell suspensions for most lymph nodes (95.8%), GI biopsies (90.9%), and BMCs (89.5%); however, it was less useful for skin/soft tissue samples (81.8%). CONCLUSIONS: Disaggregation of tissue for flow cytometric analysis by vortexing appears to provide adequate and representative cellular material. This technique is ideal for inaspirable bone marrows and small biopsies where tissue preservation for histology is paramount.