Ueber die anwendung von in vivo zersetzbaren polymeren in der thoraxchirurgie

Bioabsorbable materials for use in a clinical situation are required to have specific mechanical characteristics and predictable degradation. We have been studying the mechanical properties and the bioabsorbability of polyesters of aliphatic α-hydroxyacids, such as polylactide, polyglycolide (PGA) and their copolymers, to applying them for surgery, and classifying the effects of the factors governing their biodegradation behavior. Poly-L-lactide (P-L-LA) showed slow degradation and maintained initial mechanical properties for a period of more than 3 months after implantation. In contrast, PGA showed rapid degradation and after its absorption at the site of implantation, good replacement of the tissue was observed. On th basis of these results, various clinical applications for thoracic surgery were evaluated as follows: 1) For the fixation of fractured ribs, pins made from either P-L-LA or a composite of P-L-LA and hydroxyapatite were prepared. 2) For reconstruction of the chest wall, Tricot-Knit PGA mesh and P-L-LA mesh were fabricated. In vivo tests in dogs were then carried out. P-L-LA pins maintained the strength required for connecting the fractured ribs until complete reunion was achieved, while the meshes acted as scaffolding for reconstruction of the connective tissue. In both cases, these materials showed minimal tissue reaction and sufficient biocompatibility.     

Versatile PEG-derivatized phosphine oxide ligands for water-dispersible metal oxide nanocrystals

We report the simple synthesis of poly(ethylene glycol)(PEG)-derivatized phosphine oxide ligands for water-dispersible metal oxide nanocrystals.     

Synthesis and Characterization of a Thermoresponsive Polyoxometalate–Polymer Hybrid

We report the synthesis of the first organo‐POM with thermoresponsive properties. Our concept will provide chemists with a new tool to design POMs whose solubility is reversibly controllable through an external stimulus. POM–polymer TBA₇[POM]‐poly(N,N‐diethylacrylamide) (POM–PDEAAm), was prepared by grafting PDEAAm‐NH₂ (obtained by RAFT polymerization) onto the activated Dawson acyl‐POM, α₂‐[P₂W₁₇O₆₁SnCH₂CH₂C(?O)]^6?. Extensive MS analysis was used to monitor the chain‐functionalization steps and to confirm the formation of the hybrid. Aqueous solutions of the (NH₄)₇[POM–PDEAAm] exhibited a LCST of 38 °C. Thus, the solubility/aggregation of the hybrid was reversibly controlled by changing the temperature. Above 38 °C, the solution became cloudy, and cleared again upon cooling. Dynamic light scattering (DLS) revealed the formation of small aggregates in the range 100 nm. We assumed that the charged POM head units prevented the formation of the larger‐scattering aggregates that are usually observed for PDEAAm, and promoted the formation of micelle‐like structures. The conjugate exhibited a temperature transition, which was different from that of the polymer and depended on the counterions associated with the POM. This result demonstrates the potential for merging organic (in this case, polymer) and inorganic structures to afford materials that exhibit new properties.     

Visual determination of hydrogen peroxide and glucose by exploiting the peroxidase-like activity of magnetic nanoparticles functionalized with a poly(ethylene glycol) derivative

Microchimica Acta - A colorimetric assay is described for the determination of H2O2 and glucose based on the peroxidase-mimicking activity of Fe3O4 magnetic nanoparticles functionalized with a...     

The structural properties of Al doped ZnO films depending on the thickness and their effect on the electrical properties

In this study, the structural and electrical properties of AZO films with different film thickness deposited by r.f. magnetron sputtering were interpreted in relation with film growth process. The result shows that the grain size increases during film growth, which is accompanied by decrease of compressive stress, indicating the enhancement of crystallinity. The relationship between grain size and compressive stress follows the same tendency for the samples regardless of deposition temperature, which implies the strong dependencies between the grain size and the compressive stress. The XPS analysis shows that the defects such as chemisorbed oxygen and segregated Al₂O₃ cluster at grain boundary are reduced with increase of film thickness or deposition temperature, leading to increase of carrier concentration and mobility. The mobility increase is accompanied by grain size increase and compressive stress reduction, indicating the influences of grain boundary and crystallinity on the mobility.     

Toward active-matrix lab-on-a-chip: programmable electrofluidic control enabled by arrayed oxide thin film transistors

Agile micro- and nano-fluidic control is critical to numerous life science and chemical science synthesis as well as kinetic and thermodynamic studies. To this end, we have demonstrated the use of thin film transistor arrays as an active matrix addressing method to control an electrofluidic array. Because the active matrix method minimizes the number of control lines necessary (m + n lines for the m×n element array), the active matrix addressing method integrated with an electrofluidic platform can be a significant breakthrough for complex electrofluidic arrays (increased size or resolution) with enhanced function, agility and programmability. An amorphous indium gallium zinc oxide (a-IGZO) semiconductor active layer is used because of its high mobility of 1-15 cm(2) V(-1) s(-1), low-temperature processing and transparency for potential spectroscopy and imaging. Several electrofluidic functionalities are demonstrated using a simple 2 × 5 electrode array connected to a 2 × 5 IGZO thin film transistor array with the semiconductor channel width of 50 μm and mobility of 6.3 cm(2) V(-1) s(-1). Additionally, using the TFT device characteristics, active matrix addressing schemes are discussed as the geometry of the electrode array can be tailored to act as a storage capacitor element. Finally, requisite material and device parameters are discussed in context with a VGA scale active matrix addressed electrofluidic platform.     

Crystal structure of stereocomplex of poly(L-lactide) and poly(D-lactide)

An equimolar mixture of poly(L-lactide) and poly(D-lactide) was crystallized into a stereocomplex whose crystal system is triclinic (P1) with cell dimensions: a = 0.916 nm, b = 0.916 nra, c (chain axis) = 0.870 nm, α = 109.2°, β - 109.2°, and γ = 109.8°. In the unit cell, a poly(L-lactide) segment and a poly (D-lactide) segment are contained as a pair and packed laterally in parallel fashion. The L- and D-poly(lactides) in the complex take a 3₁ helical conformation, which is a little extended from a 10₃ helix in the homopolymer crystal with the α-form. Homopolymers are also able to take the 3₁ helical conformation and form the β-form crystal. The 3₁ helix in the homopolymer crystal is less stable than the 10₃ one, and hence the β-form is easily transformed to the α-form by annealing.