The Development of Solvent Cast Films or Electrospun Nanofiber Membranes Made from Blended Poly Vinyl Alcohol Materials with Different Degrees of Hydrolyzation for Optimal Hydrogel Dissolution and Sustained Release of Anti-Infective Silver Salts

Abstract

Introduction: We previously described the manufacture and characterization of hydrogel forming, thin film, anti-infective wound dressings made from Poly Vinyl Alcohol (PVA) and silver nanoparticles, crosslinked by heat. However, these films were designed to be inexpensive for simple manufacture locally in Africa. In this new study, we have further developed PVA dressings by manufacturing films or electrospun membranes, made from blends of PVA with different degrees of hydrolyzation, that contain silver salts and degrade in a controlled manner to release silver in a sustained manner over 12 days. Methods: Films were solvent cast as films or electrospun into nanofibre membranes using blends of 99 and 88% hydrolyzed PVA, containing 1% w/w silver sulphadiazine, carbonate, sulphate, or acetate salts. Dissolution was measured as weight loss in water and silver release was measured using inductively coupled plasma (ICP) analysis. Results: Cast films generally stayed intact at PVA 99: PVA 88% ratios greater than 40:60 whereas electrospun membranes needed ratios greater than 10:90. Films (40:60 blend ratio) and membranes (10:90) all released silver salts in a sustained fashion but incompletely and to different extents. Electrospun membranes gave more linear release patterns in the 2–12 day period and all salts released well. Conclusion: Blended PVA cast films offer improved control over hydrogel dissolution and silver release without the need for high temperature crosslinking. Blended PVA electrospun membranes further improve membrane dissolution control and silver release profiles. These blended PVA films and membranes offer improved inexpensive systems for the manufacture of long lasting anti-infective hydrogel wound dressings.

The Manufacture and Characterization of Silver Diammine Fluoride and Silver Salt Crosslinked Nanocrystalline Cellulose Films as Novel Antibacterial Materials

“…The concentration dependent nature of this crosslinking was confirmed using lower amounts of silver, which were associated with more swelling and subsequent break up (1 and 3.3 mg SDF, Figure 4). These properties clearly demonstrate a strong crosslinking effect of SDF on the CNC chains similar to those previously reported by our group for silver on PVA 88% with heat [28]. The robust swollen nature of the SDF-CNC films at day 1 and 5 are shown in Figure 5.…”

“…This type of swelling is consistent with previous reports [29] and may simply reflect the low solubility of the 99% version of the PVA. The PVA films turned brown to a certain degree as this indicates silver nanoparticle formation in situ, as previously described [28,29]. A more intense browning occurred with CNC-SDF films using the same SDF loading such that this nanoparticle formation effect was probably minor in PVA.…”

“…These browning effects were insignificant in comparison to those caused by SDF. Silver nitrate loaded dried PVA films were transparent and only slightly brown but heating resulted in increased browning, as well as crosslinking for PVA 88% [28]. Whereas pure CNC dried films swelled (2 days) but broke up over 7 days, indicating only mild molecular interactions.…”

“…PVA is a synthetic, biodegradable, biocompatible, water-soluble polymer utilized in medical applications such as wound dressings, artificial skin, coatings, transdermal patches, cardiovascular devices, and drug delivery systems [27]. As the degree of hydrolysis of the PVA increases, such does the resistance to dissolution [28]. PVA was used in this study in either the 99% or 88% hydrolyzed forms.…”

The Combined Use of Gentamicin and Silver Nitrate in Bone Cement for a Synergistic and Extended Antibiotic Action against Gram-Positive and Gram-Negative Bacteria

“…We have previously shown that the addition of sodium chloride or dextran up to 18% in bone cement has no significant effect on the mechanical strength but greatly enhanced antibiotic release [ 20 ]. In the present study we chose to use only dextran as an additive, as the presence of sodium ions with the use of NaCl would have compromised silver detection by ICP methods [ 44 ]. Furthermore, while both beads and films were used in a previous study [ 20 ] only films were used in the present studies as the geometry allows for a greater surface area to volume ratio, increasing drug release and the ability to better investigate the antibiotic effects of released drug at later time points.…”