Influence of PVA Molecular Weight and Concentration on Electrospinnability of Birch Bark Extract-Loaded Nanofibrous Scaffolds Intended for Enhanced Wound Healing

Abstract

Triterpenes from the outer bark of birch (TE) are known for various pharmacological effects including enhanced wound healing. Apart from an already authorized oleogel, electrospun nanofiber mats containing these triterpenes in a polyvinyl alcohol (PVA) matrix appear to be an advantageous application form. The effects of PVA molecular weight and concentration on the fiber morphology have been investigated. Three different molecular weights of PVA ranging from 67 to 186 kDa were used. The concentration of PVA was varied from 5 to 20 wt%. Polymer solutions were blended with colloidal dispersions of birch bark extract at a weight ratio of 60:40 (wt.%). The estimated viscosity of polymer solutions was directly linked to their concentration and molecular weight. In addition, both pure and blended solutions showed viscoelastic properties with a dominant viscous response in the bulk. Fiber morphology was confirmed using scanning electron microscopy (SEM). Both polymer concentration and molecular weight were found to be significant factors affecting the diameter of the fibers. Fiber diameter increased with a higher molecular weight and polymer concentration as more uniform fibers were obtained using PVA of higher molecular weight (146–186 kDa). In vitro drug release and ex vivo permeation studies indicated a faster drug release of betulin from electrospun scaffolds with lower PVA molecular weight. Our research suggests that the fabricated TE-loaded PVA electrospun dressings represent potential delivery systems of TE for wound care applications.

In Situ Gelling Electrospun Ocular Films Sustain the Intraocular Pressure-Lowering Effect of Timolol Maleate: In Vitro, Ex Vivo, and Pharmacodynamic Assessment

“…Similar fiber diameters (174 nm ± 25 nm) were also obtained from electrospun mats containing the same type of PVA (∼67 kDa molecular weight and 87−89% hydrolysis) at the same concentration (12% w/ v). 26 Consistent with previous studies, increasing Poloxamer 407 concentration did not induce considerable alterations to both the fiber diameter and morphology, 30 despite the increase of the viscosity of the solutions. Drug-loaded formulations exhibited slightly lower average diameters ranging between 123 nm ± 28 nm and 145 nm ± 36 nm.…”

“…The average diameter of the nanofibers ranged between 153 nm ± 30 nm and 176 nm ± 48 nm with no significant variations observed among the different formulations. Similar fiber diameters (174 nm ± 25 nm) were also obtained from electrospun mats containing the same type of PVA (∼67 kDa molecular weight and 87–89% hydrolysis) at the same concentration (12% w/v) . Consistent with previous studies, increasing Poloxamer 407 concentration did not induce considerable alterations to both the fiber diameter and morphology, despite the increase of the viscosity of the solutions.…”

“…Electrical conductivity values of the electrospinning solutions are presented in Table S3. Although PVA is a nonelectrolyte, the recorded values might be attributed to salt residues during manufacturing (e.g., sodium acetate), whereas the presence of Poloxamer 407 did not significantly alter the conductivity values of the solutions, as shown in Table S3. This is consistent with previous findings where no changes to the conductivity values of polycaprolactone (PCL) solutions in glacial acetic acid were observed upon addition of increasing amounts of Poloxamer 407, which was attributed to the nonionic character of Poloxamer …”

Optimization, Characterization and Pharmacokinetic Study of Meso-Tetraphenylporphyrin Metal Complex-Loaded PLGA Nanoparticles

“…However, the interaction of PVA with PLGA and the O/W ratio was positively significant. The reduction of the aqueous phase volume relative to the organic one led to a decrease in PS [51]. The described conditions probably stabilized the droplets of particles better in the aqueous phase and prevented their aggregation in the presence of a high PVA concentration [52,53].…”

The Effect of Gamma-Ray Irradiation on the Physical, Mechanical, and Morphological Characteristics of PVA-Collagen-Chitosan as a Guided Tissue Regeneration (GTR) Membrane Material

“…In this study, chitosan and PVA were added with collagen which are expected to improve the physical characteristic of GTR membranes. 14,15 Gamma-rays irradiation was used to sterilize the membrane to produce sterile and ready to use membrane. The method commonly used for sterilization is gamma rays from cobalt-60 because it is practical (easy to use), predictable, has good enough penetrating ability, and the sample can be sterilized after final packaging.…”