Bioactive Coatings of Endovascular Stents Based on Polyelectrolyte Multilayers

Abstract

Layer-by-layer self-assembly of two polysaccharides, hyaluronan (HA) and chitosan (CH), was employed to engineer bioactive coatings for endovascular stents. A polyethyleneimine (PEI) primer layer was adsorbed on the metallic surface to initiate the sequential adsorption of the weak polyelectrolytes. The multilayer growth was monitored using a radiolabeled HA and shown to be linear as a function of the number of layers. The chemical structure, interfacial properties, and morphology of the self-assembled multilayer were investigated by time-of-flight secondary ions mass spectrometry (ToF-SIMS), contact angle measurements, and atomic force microscopy (AFM), respectively. Multilayer-coated NiTi disks presented enhanced antifouling properties, compared to unmodified NiTi disks, as demonstrated by a decrease of platelet adhesion in an in vitro assay (38% reduction; p = 0.036). An ex vivo assay on a porcine model indicated that the coating did not prevent fouling by neutrophils. To assess whether the multilayers may be exploited as in situ drug delivery systems, the nitric-oxide-donor sodium nitroprusside (SNP) was incorporated within the multilayer. SNP-doped multilayers were shown to further reduce platelet adhesion, compared to standard multilayers (40% reduction). When NiTi wires coated with a multilayer containing a fluorescently labeled HA were placed in intimate contact with the vascular wall, the polysaccharide translocated on the porcine aortic samples, as shown by confocal microscopy observation of a treated artery. The enhanced thromboresistance of the self-assembled multilayer together with the antiinflammatory and wound healing properties of hyaluronan and chitosan are expected to reduce the neointimal hyperplasia associated with stent implantation.

Controlled release from multilayer silk biomaterial coatings to modulate vascular cell responses

“…12-14 However, these polymers present challenges due to their poor mechanical properties and limited ability to sustain stent expansion and deployment, often requiring crosslinking and related treatments to enhance durability, which in turn alters biological responses. [12][13][14] Silks represent a new family of advanced biomaterials, which should help to overcome some of these key limitations in both coated-stent technology and the favorable clinical outcomes possible. A naturally-occurring biopolymer, silk fibroin has high strength, mechanical toughness, robust flexibility, while sustaining excellent biocompatibility, therein presenting considerable utility for a number of difficult-to-solve human therapeutic interventions.…”

Swelling Behavior of Hyaluronic Acid/Polyallylamine Hydrochloride Multilayer Films

“…17,18 In addition, recent studies have shown that there are many other promising applications for multilayered materials in such areas as drug delivery, sensors, wound healing, and membrane filtration. [19][20][21][22] Hyaluronic acid (HA) is a linear polysaccharide composed of repeating disaccharide units of D-glucuronic acid and N-acetyl-D-glucosamine. 23 In dilute solution the conformation of the HA chains can be converted from a random coil to a single helical structure with a change in pH or ionic strength.…”

Sustained delivery of siRNAs targeting viral infection by cell-degradable multilayered polyelectrolyte films

“…Self-assembled multilayer architectures can be built by using macromolecules or materials as different as polyelectrolytes, proteins, inorganic complexes, clay platelets, or colloidal particles, all adsorbed from aqueous solutions or suspensions. Although complex multilayered architectures were shown to deliver a variety of molecules including drugs (4)(5)(6)(7)(8) and DNA (9)(10)(11)(12), it is unknown whether this technique is feasible for the sustained delivery of siRNAs.…”