The synthesis and the characterization of a poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-blockpoly(2-methyloxazoline) (PMOXA-PDMS-PMOXA) triblock copolymer carrying polymerizable groups at both chain ends are described. This copolymer forms vesicular structures in dilute aqueous solution, the size of which can be controlled in the range from 50 nm up to about 500 nm. The methacrylate end groups of the triblock copolymer can be polymerized in the vesicular aggregates using an UV-induced free radical polymerization. Static and dynamic light scattering, scanning electron microscopy, and transmission electron microscopy on both the resulting nanocapsules and their nonpolymerized precursors clearly show that the cross-linking polymerization does not lead to morphological changes in the underlying vesicles. Moreover, due to their cross-linked structure, the nanocapsules are shape persistent, thus maintaining their integrity even after their isolation from the aqueous solution.

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In the past 10 years, many new components were synthesized and evaluated for an application in enamel-dentin adhesives and direct composite restoratives. New bisacrylamide cross-linkers with improved hydrolytic stability and new strongly acidic polymerizable phosphonic acids and dihydrogen phosphates, as well as novel photoinitator systems, in combination with the implementation of novel application devices, have significantly improved the performance of the current enamel-dentin adhesives. The currently used resins for direct composite restoratives are mainly based on methacrylate chemistry to this day. A continuous improvement of the properties of current composites was achieved with the use of new tailor-made methacrylate cross-linkers, new additives, and photoinitiators as well as tailor-made fillers. Nowadays, dental adhesives and methacrylate-based direct restorative materials have found wide-spread acceptance. Nevertheless, future developments in the field of dental adhesives and direct composite restoratives will focus on improving durability and biocompatibility as well as the development of materials with a broader application spectrum and of smart adhesives or composites. V C 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 2012

We describe the synthesis of micro-phase-segregated block-copolyesterurethanes from telechelic hydroxyterminated poly [ [(R)-3-hydroxybutyric acid]-co-[(R)-3-hydroxyvaleric acid]] (PHB-diol) as "hard segments" (i. e., crystallizable chain sections) and hydroxyterminated poly(ecapro1actone)-diethylene glycol-poly(8-caprolactone) (PCL-diol) or telechelic .hydroxyterminated pol y [(adipic acid)-alt-( 1,4-butanediol; diethylene glycol; ethylene glycol)] (Diorez") as "soft segments", with 2,2,4-triethylhexamethylene diisocyanate (TMDI) or methyl (S)-2,6-diisocyanatohexanoate (LDI). High molecular weights were obtained with or without catalyst, the properties of the polymers depending only slightly on the presence or absence of the catalyst. The materials thus obtained were investigated also with respect to their mechanical properties and it was found that Young's modulus directly depends on the fraction of crystallizable PHB-diol in the block copolymer while the type of non-crystallizable segment or diisocyanate had only a minor influence: Generally, the tensile strength increases and the elongation at break decreases with increasing content of PHB-diol. Around body temperature, these polymers exhibit only mild changes in their mechanical behavior. The chain length of the non-crystallizable segment indirectly influences the morphology and the mechanical properties of the polymers through changes in the phase-segregation behavior.

We describe the preparation of telechelic OH-terminated poly[(R)-3-hydroxybutyric acid] (PHB) and poly{ [(R)-3-hydroxybutyric acid]-co-[(R)-3-hydroxyvaleric acid] ] (PHB/HV), on a semi-preparative scale, by a transesterification procedure from the high-molecularweight polymers. The oligomers have well-defined reactive end groups and are well suited for the preparation of high-molecular-weight block copolymers by chain extension.

Polymeric vesicles can be used as diffusion barrier in hydrogels for the controlled release of water soluble drugs.

Background: We compared the accuracy and practicability of a new combined ear sensor device measuring pulse oximetry and transcutaneous carbon dioxide tension. Methods: Validation studies were done by comparing the results of the combined sensor with arterial blood gas measurements. In an observational part, monitoring data were obtained from 25 patients undergoing colonoscopy, sedated with midazolam and alfentanil and from 8 patients without sedation. Results: There was an excellent correlation between the oxygen saturation and carbon dioxide tension measurements comparing the combined sensor with arterial blood gas analysis (R 0.96 and 0.93, respectively). A mean rise in transcutaneous carbon dioxide tension of 7.6 mm Hg was detectable during sedation with midazolam/alfentanil and of 2.3 mm Hg without sedation. Conclusion: Combined POX/PcCO₂ monitoring at the ear lobe is a novel approach to improve patient safety during sedation and may be helpful in preventing an unintentional slide into a state of deep sedation with impairment of ventilation.

To evaluate the biocompatibility of a newly developed degradable class of polyesterurethanes and their possible use as biomaterials, we investigated the cell and tissue interactions with these polymers using a small number of chemical base entities. The polymers were prepared by chain extension with diisocyanates of PHB/HV-diol and either PCL-diol or Diorez, another aliphatic polyester-diol. Regardless of the chemical composition of the four tested polyesterurethanes used as substrates, no morphological difference was observed either in the macrophages (macrophage cell line J774) or in the fibroblasts (fibroblast cell line 3T3) cultured on the polymers. In contrast, however, cell adhesion and growth of macrophages and fibroblasts were affected by the polymer properties. Compared to macrophages cultured on tissue culture polystyrene (TCPS), cells cultured on the test polymers exhibited levels of cell adhesion that varied from 65-100% of TCPS, and the doubling time was 25-43% higher on the polymers than on TCPS. Likewise, fibroblasts adhered to the polymers at lower rates (50-85% of TCPS) and grew at higher doubling times (125-140% of TCPS). Furthermore, cells cultured on the test polymers preserved their phenotypes: fibroblasts produced high amounts (up to 280% of control cells) of collagens Type I and Type IV and fibronectin; and macrophages produced nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha) in the same concentrations as control cells and responded to lipopolysaccharide treatment by the elevation of the production of NO and TNF-alpha, indicating that the cell-to-polymer interactions allow fibroblasts and macrophages to maintain their phenotypes. In vivo investigations showed that all four test polymers exhibit favorable tissue compatibility. The formed capsule was 60-250 microns thick. In addition, the polymers are degradable. After one year's subcutaneous implantation in rats, the molecular weight of the test polymers were reduced to about 50%, depending on the composition. Taken collectively, the present data demonstrate that the newly developed polyesterurethanes are cell and tissue compatible and biodegradable.