Lubricity, wear prevention, and anti-biofouling properties of macromolecular coatings for endotracheal tubes.

Macromolecular coatings can improve the surface properties of many medical devices by enhancing their wetting behavior, tribological performance, and anti-biofouling properties - and covalent coatings produced from mucin glycoproteins have been shown to be very powerful in all those aspects. However, obtaining highly functional mucin glycoproteins is, at the moment, still a time-consuming process, which renders mucins rather expensive compared to other biomacromolecules. Here, we study a set of commercially available macromolecules that have the potential of substituting mucins in coatings for endotracheal tubes (ETTs). We present an overview of the different properties these macromolecular coatings establish on the ETT surface and whether they withstand storage or sterilization processes. Our study pinpoints several strategies of how to enhance the lubricity of ETTs by applying macromolecular coatings but also demonstrates the limited anti-biofouling abilities of well-established macromolecules such as hyaluronic acid, polyethylene glycol, and dextran. Based on the obtained results, we discuss to what extent those coatings can be considered equivalent alternatives to mucin coatings for applications on medical devices - their applicability does not have to be limited to ETTs, but could be broadened to catheters and endoscopes as well.

Dopamine-Mediated Biopolymer Multilayer Coatings for Modulating Cell Behavior, Lubrication, and Drug Release.

Biopolymer coatings on implants mediate the interactions between the synthetic material and its biological environment. Owing to its ease of preparation and the possibility to incorporate other bioactive molecules, layer-by-layer deposition is a method commonly used in the construction of biopolymer multilayers. However, this method typically requires at least two types of oppositely charged biopolymers, thus limiting the range of macromolecular options by excluding uncharged biopolymers. Here, we present a layer-by-layer approach that employs mussel-inspired polydopamine as the adhesive intermediate layer to build biopolymer multilayer coatings without requiring any additional chemical modifications. We select three biopolymers with different charge states─anionic alginate, neutral dextran, and cationic polylysine─and successfully assemble them into mono-, double-, or triple-layers. Our results demonstrate that both the layer number and the polymer type modulate the coating properties. Overall, increasing the number of layers in the coatings leads to reduced cell attachment, lower friction, and higher drug loading capacity but does not alter the surface potential. Moreover, varying the biopolymer type affects the surface potential, macrophage differentiation, lubrication performance, and drug release behavior. This proof-of-concept study offers a straightforward and universal coating method, which may broaden the use of multilayer coatings in biomedical applications.

Tailored mechanosensitive nanogels release drugs upon exposure to different levels of stenosis.

Owing to the unhealthy lifestyle and genetic susceptibility of today's population, atherosclerosis is one of the global leading causes of life-threatening cardiovascular diseases. Although a rapid intervention is required for severe blood vessel constrictions, a systemic administration of anticoagulant drugs is not the preferred method of choice as the associated risk of bleeding complications is high. In this study, we present mechanosensitive nanogels that exhibit tunable degrees of disintegration upon exposure to different levels of stenosis. Those nanogels can be further functionalized to encapsulate charged drug molecules such as heparin, and they efficiently release their cargo when passing stenotic constrictions; however, passive drug leakage in the absence of mechanical shear stress is very low. Furthermore, heparin molecules liberated from those mechanosensitive nanogels show a similar blood clot lysis efficiency as the free drug molecules, which demonstrates that drug encapsulation into those nanogels does not interfere with the functionality of the cargo. Thus, the hemocompatible and mechanoresponsive nanogels developed here represent a smart and efficient drug delivery platform that can offer safer solutions for vascular therapy.