Nanostructured Materials for the Development of Superhydrophobic Coatings

This chapter describes the results of developing superhydrophobic coatings using porous ZnO nanostructures impregnated metal stearates and their applications. The porous ZnO nanostructures with a surface area of 9.7 m2/g and pores in the range from 200 to 400 nm have been prepared via precipitation cum calcination route. The superhydrophobic coatings comprising ZnO/metal stearate film have been deposited using a spray coating method. The developed superhydrophobic films possess a water contact angle of 161° that can be explained using the Cassie-Baxter model. The prepared films exhibited excellent floating properties and high load-bearing characteristics over a prolonged time. Additionally, the self-cleaning properties of the developed superhydrophobic films towards dust removal and self-cleaning urinary coatings are also demonstrated. This chapter collectively presented the novel applications of superhydrophobic coating in the development of biomedical coatings and applications in water surveillance and underwater robotics.

Nanoparticles based on the zwitterionic pillar[5]arene and Ag+: synthesis, self-assembly and cytotoxicity in the human lung cancer cell line A549

For the first time, stable pillar[5]arene/Ag+ nanoparticles, consisting of water-soluble pillar[5]arene containing γ-sulfobetaine fragments and Ag+ ions without Ag–Ag bonds, were synthesized and characterized. The pillar[5]arene/Ag+ (ratio 1:10) nanoparticles obtained were cubic with a rib length of 100 nm and are less cytotoxic than Ag+ ions. The survival of the A549 model cells in the presence of pillar[5]arene/Ag+ (1:10) nanoparticles at a concentration of 30 and 40 μM was 76% and 55%, while in the absence of pillar[5]arene, the cell survival for free Ag+ ions at the same concentration was 30% and 10%, respectively. The results can be used to create new antibacterial materials and 2D biomedical coatings.

MODULATION OF THE MICRO/NANOTOPOGRAPHY OF PLASMA-SPRAYED BIOMEDICAL COATINGS FOR ENHANCED OSTEOGENIC ACTIVITY

Surface micro/nanotopography of orthopedic implants plays a significant role in determining their biological performance. In this study, plasma jet was for the first time utilized to modulate the micro/nanostructure of the plasma-sprayed 50% Nb2O5-TiO2 coating on the biomedical Ti alloy based on its high temperature and super-high cooling rate characteristics. Results show that the plasma jet can modulate the shape, dimension and distribution of the surface grains in a process-parameter-dependent manner, thus being able to tailor the micro/nanotopography of the surface coating. In vitro cell culture experiments proved that the plasma jet-induced topographical changes have great effects on the osteogenic activity of the MC3T3-E1 cells cultured on the coating surface.

Hydrophilic Self-Replenishing Coatings with Long-Term Water Stability for Anti-Fouling Applications

Hydrophilic coatings have recently emerged as a new approach to avoid the adhesion of (bio)organisms on surfaces immersed in water. In these coatings the hydrophilic character is crucial for the anti-fouling (AF) performance. However, this property can be rapidly lost due to the inevitable damages which occur at the surface, reducing the long-term effectiveness of the AF functionality. We report hydrophilic polycarbonate-mPEG polyurethane coatings with tunable hydrophilic properties as well as an excellent and long-term stability in water. The coatings exhibit low protein adhesion values and are able to self-replenish their hydrophilicity after damage, due to the existence of a reservoir of hydrophilic dangling chains incorporated in the bulk. The combination of low Tg and sufficient mobility of the mPEG dangling chains (enabled by chains with higher molecular weight) proved to be crucial to ensure autonomous surface hydrophilicity recovery when the coatings were immersed in water. This coatings and design approach offer new possibilities towards high performance AF coatings with an extended service life-time which can be used in several major applications areas, such as marine and biomedical coatings, with major economic and environmental benefits.

RETRACTED: Hydrodynamic Simulation of an Orbital Shaking Test for the Degradation Assessment of Blood-Contact Biomedical Coatings

Biomedical coatings are used to promote the wear resistance and the biocompatibility of a mechanical heart valve (MHV). An orbital shaking test was proposed to assess the durability of the coatings by the amount of eroded material due to the surrounding fluid. However, the shaker’s rotating conditions and the corresponding physiological condition was still lack of understanding. This study implemented numerical simulations by establishing a fluid dynamic model to evaluate the intensity of the shear stress under various rotating speed and diameter of the shaker. The results are valuable to conduct in vitro tests for estimating the performance of biomedical coatings under real hemodynamic conditions and can be applied to other fluid-contact implants.