Barnabás Szabó

Polymer structure and antimicrobial activity of polyvinylpyrrolidone-based iodine nanofibers prepared with high-speed rotary spinning technique.

Poly(vinylpyrrolidone)/poly(vinylpyrrolidone-vinylacetate)/iodine nanofibers of different polymer ratios were successfully prepared by a high-speed rotary spinning technique. The obtained fiber mats were subjected to detailed morphological analysis using an optical and scanning electron microscope (SEM), while the supramolecular structure of the samples was analyzed by positron annihilation lifetime spectroscopy (PALS). The maximum dissolved iodine of the fiber samples was determined, and microbiological assay was carried out to test their effect on the bacterial growth. SEM images showed that the polymer fibers were linear, homogenous, and contained no beads. The PALS results, both the o-positronium (o-Ps) lifetime values and distributions, revealed the changes of the free volume holes of fibers as a function of their composition and the presence of iodine. The micro- and macrostructural characterisation of polymer fiber mats enabled the selection of the required composition from the point of their applicability as a wound dressing.

Effect of storage on microstructural changes of Carbopol polymers tracked by the combination of positron annihilation lifetime spectroscopy and FT-IR spectroscopy

Different types of Carbopols are frequently applied excipients of various dosage forms. Depending on the supramolecular structure, their water sorption behaviour could significantly differ. The purpose of the present study was to track the supramolecular changes of two types of Carbopol polymers (Carbopol 71G and Ultrez 10NF) alone and in their physical mixture with a water-soluble drug, vitamin B(12), as a function of storage time. The combination of FT-IR spectroscopy, positron annihilation lifetime spectroscopy (PALS) and Doppler-broadening spectroscopy was applied to follow the effect of water uptake on the structural changes. Our results indicate that water-induced interactions between polymeric chains can be sensitively detected. This enables the prediction of stability of dosage forms in the course of storage.

Tracking of the viability of Stenotrophomonas maltophilia bacteria population in polyvinylalcohol nanofiber webs by positron annihilation lifetime spectroscopy

Polyvinylalcohol (PVA) fiber web containing embedded bacteria was prepared by electrospinning technique. From the point of the complex functionality of such potential delivery systems, it will be of impact how bacteria can survive in such artificial biotopes. The present study suggests a possible fast method for the tracking of the viability of the embedded bacteria based on the changes of the supramolecular structure of the polymeric delivery system caused by the metabolic product of the bacteria. Positron annihilation lifetime spectroscopy (PALS) was applied to track the free volume changes of the system in the course of storage. The PALS method sensitively detected the free volume changes, thus the viability of the bacteria in the polymeric fiber web.

Development and Manufacturing of Coronary Stents in Hungary

Revascularisation by endovascular implant (stent) is of great importance in the treatment of coronary artery diseases. Hungary has a stent production since 1995, which is the only one in the new EU member countries. The paper presents the antecedents, achievements and main future objectives of the project, that have been started within the frameworks of the National Research and Development Program. The aim of the project is the development of a new stent family based on the results of the material science researches have started for 10 years and the clinical and production experiences of the experts of the consortium, which could result an equivalent Hungarian product to the market leader products in case of several product lines.

Real-time feedback control of twin-screw wet granulation based on image analysis

Graphical abstract Figure. No caption available. ABSTRACT The present paper reports the first dynamic image analysis‐based feedback control of continuous twin‐screw wet granulation process. Granulation of the blend of lactose and starch was selected as a model process. The size and size distribution of the obtained particles were successfully monitored by a process camera coupled with an image analysis software developed by the authors. The validation of the developed system showed that the particle size analysis tool can determine the size of the granules with an error of less than 5 &mgr;m. The next step was to implement real‐time feedback control of the process by controlling the liquid feeding rate of the pump through a PC, based on the real‐time determined particle size results. After the establishment of the feedback control, the system could correct different real‐life disturbances, creating a Process Analytically Controlled Technology (PACT), which guarantees the real‐time monitoring and controlling of the quality of the granules. In the event of changes or bad tendencies in the particle size, the system can automatically compensate the effect of disturbances, ensuring proper product quality. This kind of quality assurance approach is especially important in the case of continuous pharmaceutical technologies.

Stent Retention Measurement

This article introduces two original measurement methods (i.e. adhesive layer and pulloff edge) for the determination of the stent retention force, together with the results from these measurements. The measurement with the adhesive layer models and quantifies the stentobstruction occurring in the constrictions; meanwhile the pull-off edge method is based on modelling and quantifying the collisions and constrictions in the main catheter. For the evaluation of the measurements our research introduced the specific ‘stent pull-off’ force, which shows the force required for the ‘pull-off’ of the stent from the balloon, which is referred to as the stent unit length. This is the maximum force value shown on the retention diagram (insert diagram reference here). It is ascertainable, that the presence of the polyurethane coating and the increase of the pulling-speed are increasing the ‘stent pull-off’ force. During the test interval of the pull-off speed, the ‘stent pull-off’ force for the Chronoflex®-coated stents increased from 0.45 N/mm to 0.76 N/mm.