Abstract
A polypeptide nanofilm made by layer-by-layer (LbL) self-assembly was built on a surface that mimics nonwoven, a material commonly used in wound dressings. Poly-L-lysine (PLL) and poly-L-glutamic acid (PLGA) are the building blocks of the nanofilm, which is intended as an enzymatically degradable lid for release of bactericides to chronic wounds. Chronic wounds often carry infection originating from bacteria such as Staphylococcus aureus and a release system triggered by the degree of infection is of interest. The dry nanofilm was studied with ellipsometry. The thickness of the nanofilm was 60% less in its dry state than in its wet state. The measurements showed that a primer was not necessary to build a stable nanofilm, which is practically important in our case because a nondegradable primer is highly unwanted in a wound care dressing. Added V8 (glutamyl endopeptidase) enzymes only showed adsorption on the nanofilm at room temperature, indicating that the PLL/PLGA “lid” may remain intact until the dressing has been filled with wound exudate at the elevated temperature typical of that of the wound.
Highlights
Self-assembly techniques have become increasingly popular as a tool to create controlled release systems for drug delivery
The entire composition on which the ellipsometry measurements were conducted can be written (Au-SAM)-(PLL/poly-Lglutamic acid (PLGA))3, where the deposited polypeptide film thickness was solved by using a four-layer model using polypeptide bulk and polypeptide effective medium approximation (EMA) layers on top
The (PLL/PLGA)3 nanofilm was measured with ellipsometry to study the thickness in its dry state
Summary
Self-assembly techniques have become increasingly popular as a tool to create controlled release systems for drug delivery. One such technique is layer-by-layer (LbL) self-assembly, which was pioneered by Decher [1, 2] Based on this method targeted release of bactericides into an infected chronic wound can be developed. Many chronic wounds carry a bacterial infection [3, 4] generating high amounts of bacterial proteases [5] in the wound, which often disturbs the natural healing cascade. Such an infection is normally treated with oral antibiotics or with gels, creams, or wound dressings containing antimicrobial substances [6]. The underlying substrate was a model surface tailored by the use of self-assembling alkane thiols to give the same wetting characteristics as an existing nonwoven material
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