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Drug-coated balloons (DCB), which have emerged as a therapeutic alternative to drug-eluting stents in percutaneous cardiovascular intervention, are well described with regard to clinical efficacy and safety within a number of clinical studies. In vitro studies elucidating the correlation between coating additive and DCB performance are however rare but considered important for the understanding of DCB requirements and the improvement of established DCB. In this regard, we examined three different DCB-systems, which were developed in former studies based on the ionic liquid cetylpyridinium salicylate, the body-own hydrogel hyaluronic acid and the pharmaceutically well-established hydrogel polyvinylpyrrolidone, considering coating morphology, coating thickness, drug-loss, drug-transfer to the vessel wall, residual drug-concentration on the balloon surface and entire drug-load during simulated use in an in vitro vessel model. Moreover, we investigated particle release of the different DCB during simulated use and determined the influence of the three coatings on the mechanical behavior of the balloon catheter. We could show that coating characteristics can be indeed correlated with the performance of DCB. For instance, paclitaxel incorporation in the matrix can reduce the drug wash-off and benefit a high drug transfer. Additionally, a thin coating with a smooth surface and high but delayed solubility can reduce drug wash-off and decrease particle burden. As a result, we suggest that it is very important to characterize DCB in terms of mentioned properties in vitro in addition to their clinical efficacy in order to better understand their function and provide more data for the clinicians to improve the tool of DCB in coronary angioplasty.

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The development of drug-eluting coatings based on hyaluronic acid (HA) is especially promising for implant-associated local drug delivery (LDD) systems, whose implantation provokes high insertion forces, as, for instance, cochlear implants or drug-coated balloons (DCB). The lubricious character of HA can then reduce the coefficient of friction and serve as drug reservoir simultaneously. In this context, we investigated several plasma- and wet-chemical methods for the deposition of HA-based coatings with LDD function on polyamide 12 as a model implant surface, conventionally used for DCB. In contrast to aminosilane, epoxy silane surface layers allowed the covalent attachment of a smooth and uniform HA base layer, which provided good adherence of further HA layers deposited by manual dip coating at a subsequent processing stage. The applied HA-crosslinking procedure during dip coating influences the transfer and release of paclitaxel, which could be reproducibly incorporated via infiltration. While crosslinking with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride provided HA coatings on DCB, which allowed for an efficient paclitaxel transfer upon expansion in a vessel model, crosslinking with glutardialdehyde resulted in a slower drug release being more appropriate for implants with longer residence time in the body. The developed HA coating is hence well suited for spontaneous and sustained LDD.

Polyvinylpyrrolidone (PVP) is a conventionally applied hydrophilic lubricious coating on catheter-based cardiovascular devices, used in order to ease movement through the vasculature. Its use as drug reservoir and transfer agent on drug-coated balloons (DCB) is therefore extremely promising with regard to the simplification of its approval as a medical device. Here, we developed a PVP-based coating for DCB, containing paclitaxel (PTX) as a model drug, and studied the impact of crosslinking via UV radiation on drug stability, wash off, and transfer during simulated use in an in vitro vessel model. We showed that crosslinking was essential for coating stability and needed to be performed prior to PTX incorporation due to decreased drug bioavailability as a result of photodecomposition and/or involvement in vinylic polymerization with PVP under UV radiation. Moreover, the crosslinking time needed to be carefully controlled. While short radiation times did not provide enough coating stability, associated with high wash off rates during DCB insertion, long radiation times lowered drug transfer efficiency upon balloon expansion. A ten minutes radiation of PVP, however, combined a minimized drug wash off rate of 34% with an OPEN ACCESSCoatings 2013, 3 254 efficient drug transfer of 49%, underlining the high potential of photochemically crosslinked PVP as a coating matrix for DCB.

The improvement of well‐established local drug delivery (LDD) systems, often providing drug release independently of their need, is a challenge of current implant technology. Systems that sense signals caused by a certain disease, judge the magnitude of the signal and act to release the right amount of drug in response are hence searched for. Specific responsive hydrogels with antibody–antigen cross‐links, whose non‐covalent interaction is broken in the presence of the corresponding antigen and reclosed in its absence, are a promising candidate. However, the challenging implementation of such antigen‐responsive hydrogels as implant coating and their applicability for implant‐associated LDD systems have not been explored so far. In this context and in order to define adequate gel properties for the envisaged application, we prepared a matrix at examples of polyacrylamide hydrogels of different gel architectures, gel contents and cross‐linking degrees and investigated their impact on the permeation of the differently sized model proteins bovine serum albumin (BSA), protein A and myoglobin in a specifically designed chamber simulating an implant‐associated LDD system and the mechanical stability of the polymeric network. Water uptake, as estimated by Karl Fischer titration, which was mainly influenced by gel content, seems to primarily govern drug permeability and mechanical stability. Within the investigated matrix, a medium gel content of 15.0 w% acrylamide and N,N′‐methylenebisacrylamide evidenced low drug permeability, enough tensile strength and flexibility for integration of antibody–antigen cross‐links, which we could successfully evidence via fluorescence microscopy. A stimulus‐triggered release of BSA through such a hydrogel could be moreover demonstrated. Copyright © 2014 John Wiley & Sons, Ltd.

To synthesize nickel(0) nanoparticles by wet chemical reduction using hydrazine with an average size distribution below 100 nm, two different reactor concepts were developed. With a cone channel nozzle, the reactant solutions were sprayed into a batch for further processing and reduction at elevated temperatures. Another concept uses a microcoaxial injection mixer connected to a heated tube to establish a fully continuously operating reactor. To shorten the time for reduction of the nickel, salt temperatures up to 180°C are applied. To avoid uncontrolled residence time, the whole system was pressurized up to 80 bar. Approximately 80 L reactant solution, i.e., 1 kg nickel(0) nanoparticles, could be processed within 30 h.

Translation of the Bible or any other text unavoidably involves a determination about its meaning. There have been different views of meaning from ancient times up to the present, and a particularly Enlightenment and Modernist view is that the meaning of a text amounts to whatever the original author of the text intended it to be. This article analyzes the authorial-intent view of meaning in comparison with other models of literary and legal interpretation. Texts are anchors to interpretation but are subject to individualized interpretations. It is texts that are translated, not intentions. The challenge to the translator is to negotiate the meaning of a text and try to choose the most salient and appropriate interpretation as a basis for bringing the text to a new audience through translation.