ABSTRACT
The vertical diffusion cell is an in vitro laboratory device for the study of drug release and permeation of semi-solid topical formulations and topical patches. Both static and dynamic versions of the diffusion cell are used in practice, the operation of which can be automated. The device is available at a reasonable cost for smaller, mainly transdermal patches, the amount of sampling fluid is replenished at the same time as the sample, in the same amount as the amount sampled without automation of the system, and simultaneous replenishment of acceptor fluid by hydrostatic pressure helps keeping the acceptor chamber bubble-free.
ABSTRACT
The production of polymer microfibres and nanofibres using rotary jet spinning as platforms for drug delivery and tissue engineering applications has been explored. The aligned orientation of fibres and consequent improvement in the mechanical properties of the scaffold are essential in several pharmaceutical and biomedical applications, where elastic materials with high tensile resistance are required. This study aimed to develop high-speed rotary jet devices to fabricate polyvinylpyrrolidone-based homopolymer and copolymer rotary-spun fibres and establish a correlation between the operational parameters of the devices and the morphology and microstructure of the fabricated fibres. Preconstruction modelling was carried out using computer-aided design through parametric 3D body modelling of the rotary device components by assigning appropriate dimensions and tolerances, as well as material parameters. Finite-element modelling was used to analyse the mechanical stress of the designed spinnerets. The obtained fibre mats were subjected to a detailed morphological analysis using optical and scanning electron microscopy, while the microstructural changes in the fibre samples, based on the free volume changes, were analysed by positron annihilation lifetime spectroscopy. The results indicate that the compact design and the controllability of the operational parameters enabled the formation of continuous aligned-oriented homogeneous fibres of variable diameters depending on the type of forming fibre polymer for further processing to formulate pharmaceutical drug delivery systems.
Subject(s)
Drug Delivery Systems , Pharmaceutical Preparations , Laboratories , Polymers , Tissue EngineeringABSTRACT
A study is presented on cold plasma treatment of the surfaces of two engineering polymers, polyamide 6 (PA6) and polyoxymethylene (POM-C), by diffuse coplanar surface barrier discharges under atmospheric air conditions. We found that plasma treatment improved the adhesion of both polymers for either polymer/polymer or polymer/steel joints. However, the improved adhesion was selective for the investigated adhesive agents that were dissimilar for the two studied polymers. In addition, improvement was significantly higher for PA6 as compared to POM-C. The observed variation of the adhesion was discussed in terms of the changes in surface chemistry, wettability and topography of the polymer surface.
ABSTRACT
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.
