Highly porous drug-eluting structures

Abstract

For many biomedical applications, there is need for porous implant materials. The current article focuses on a method for preparation of drug-eluting porous structures for various biomedical applications, based on freeze drying of inverted emulsions. This fabrication process enables the incorporation of any drug, to obtain an “active implant” that releases drugs to the surrounding tissue in a controlled desired manner. Examples for porous implants based on this technique are antibiotic-eluting mesh/matrix structures used for wound healing applications, antiproliferative drug-eluting composite fibers for stent applications and local cancer treatment, and protein-eluting films for tissue regeneration applications. In the current review we focus on these systems. We show that the release profiles of both types of drugs, water-soluble and water-insoluble, are affected by the emulsion's formulation parameters. The former's release profile is affected mainly through the emulsion stability and the resulting porous microstructure, whereas the latter's release mechanism occurs via water uptake and degradation of the host polymer. Hence, appropriate selection of the formulation parameters enables to obtain desired controllable release profile of any bioactive agent, water-soluble or water-insoluble, and also fit its physical properties to the application.

Smart Dressings Based on Nanostructured Fibers Containing Natural Origin Antimicrobial, Anti-Inflammatory, and Regenerative Compounds

“…Moreover, self-assembly is another technique to produce nanofibers which results in the formation of a nanofibrous mesh through the organization of preexisting components [116]. Fiber mesh and fiber bonding are other methodologies that imply the deposition of a polymer over another polymer followed by an evaporation stage, and the joining of nanofibers at their cross-linking points in order to produce nanofibrous meshes [92,117]. …”

“…The fabrication of these dressings should be strictly controlled to obtain the appropriate features to perform a successful and rapid healing. In fact, porosity is a key factor in the promotion of new tissue formation because cell migration, proliferation, and differentiation are all affected by geometrical constraints from the surrounding microenvironment, and it should be adapted for each application [ 92 , 93 , 94 , 95 ]. However, the required porosity depends on the proximity of capillary vessels to irrigate the wounded tissue.…”

“…The structural characteristics of the final product can be modified changing the thermodynamics and kinetics of the specific reaction. In addition, this technique allows the loading of sensitive drugs without loss in their bioactivity [ 92 ]. Moreover, self-assembly is another technique to produce nanofibers which results in the formation of a nanofibrous mesh through the organization of preexisting components [ 116 ].…”

“…There are also studies regarding the production of drug-eluting porous structures for wound dressing through the methodology of freeze drying of inverted emulsions [ 92 , 99 ]. In this regard, Elsner et al [ 92 ] stated that drug loading can be performed with this technique at any stage of the fabrication without any drug loss or modification due to temperature or chemical interactions. In this case, drug release was modulated through the degree of porosity which in turn may be modified by controlling the organic:aqueous ratio or drug content.…”

Preparation of a Hydrogel Nanofiber Wound Dressing

“…The graphs illustrate that the fiber layers after crosslinking significantly evinced both higher strengths and elongation, thus indicating that the fibrous layers will be easier to handle in the case of application. If we compare the values with other fiber wound dressing [ 41 , 42 ], the tested layers achieve lower strength, but at the same time achieve higher ductility. An increase in strength could be achieved by increasing the area weight of the sample.…”