PubMed · 13502472
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L W PROGER. 1958. Perspex jars for pathological museums.. https://doi.org/10.1136/jcp.11.1.92
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Foldable hydrogel films with micropatterns measuring 480 microm by 45 microm by 54 microm by 2 cm (width of microchannel by width of microwall by height of wall by length of pattern) were made by UV embossing of a block copolymer of polycaprolactone (PCL) and poly(ethylene glycol) (PEG), specifically PCL-b-PEG-b-PCL-diacrylate (DA), with a polydimethylsiloxane mold. The mold was treated with Ar/CF(4) plasma to simultaneously promote microchannel filling and demolding, and the glass substrate was modified with 3-(trimethoxysilyl) propyl acrylate to promote hydrogel adhesion to avoid delamination of the gel during demolding. The micropatterned hydrogel film was detached from the glass substrate by freeze-drying. As the films were demolded, the microstructured pattern was well replicated in the hydrogel. The gel pattern dimensions shrank with freeze-drying and increased with water swelling, but under both conditions, the gel micropattern morphology was perfectly preserved. PCL-b-PEG-b-PCL-DA hydrogel was found to have good biocompatibility compared with PEGDA hydrogel. A micropattern with a smaller microchannel width of 50 microm was also made. Micropatterned foldable and biocompatible hydrogel films have potential applications in the construction of tissue-engineering scaffolds.
Surface-active microporous membranes were prepared from the poly(vinylidene fluoride)-graft-poly(2-(2-bromoisobutyryloxy)ethyl acrylate) copolymer (PVDF-g-PBIEA copolymer) by phase inversion in water. The PBIEA side chains could function as initiators for the atom transfer radical polymerization (ATRP) of 2-(N,N-dimethylamino)ethyl methacrylate on the membrane surfaces to give rise to the PVDF-g-PBIEA-ar-PDMAEMA membranes. N-alkylation with hexyl bromide and nitromethane gave rise to the quanternized PVDF-g-PBIEA-ar-QPDMAEMA membranes with polycation chains chemically tethered on the membrane surface, including the pore surfaces. The changes in the surface morphology and the surface chemical composition were confirmed by scanning electron microscopy and X-ray photoelectron spectroscopy. The scanning electron microscopy revealed that, in comparison to the pristine PVDF-g-PBIEA membranes, not only could the PVDF-g-PBIEA-ar-QPDMAEMA membranes remove the Gram-negative bacterium Escherichia coli but also inhibited the bacterial reproduction on the membranes to a significant extent.
We report here a study on the microstructure formation process of polymeric nanoparticles based on polyelectrolyte complexes. When polyanion poly(acrylic acid) (PAA) was dropped into polycation chitosan (CS) solution, CS-PAA nanoparticles with diverse microstructure would be formed under different experimental conditions. The microstructure of CS-PAA nanoparticles changed from solid spherical nanoparticles to core-shell separative ones and turned back to solid spherical ones with the variation of preparation conditions. The influence of molecular weight of CS and PAA, shell cross-linking, dropping temperature on the size, stability and morphology of CS-PAA nanoparticles were also studied. The nanoparticle size was affected by the molecular weight of CS and PAA, the ratio of amino group to carboxyl group (na/nc) and the incubation temperature as well. The shell-cross-linking provides a means to stabilize these nanoparticles. These nanoparticles can encapsulate plasmid DNA very well, which makes them have great potential in gene delivery.