An Omniphobic Spray Coating Created from Hierarchical Structures Prevents the Contamination of High-Touch Surfaces with Pathogens.

Engineered surfaces that repel pathogens are of great interest due to their role in mitigating the spread of infectious diseases. A robust, universal, and scalable omniphobic spray coating with excellent repellency against water, oil, and pathogens is presented. The coating is substrate-independent and relies on hierarchically structured polydimethylsiloxane (PDMS) microparticles, decorated with gold nanoparticles (AuNPs). Wettability studies reveal the relationship between surface texturing of micro- and/or nano-hierarchical structures and the omniphobicity of the coating. Studies of pathogen transfer with bacteria and viruses reveal that an uncoated contaminated glove transfers pathogens to >50 subsequent surfaces, while a coated glove picks up 104 (over 99.99%) less pathogens upon first contact and transfers zero pathogens after the second touch. The developed coating also provides excellent stability under harsh conditions. The remarkable anti-pathogen properties of this surface combined with its ease of implementation, substantiate its use for the prevention of surface-mediated transmission of pathogens.

Microstructural and in-vitro characteristics of functional calcium silicate topcoat on hydroxyapatite coating for bio-implant applications.

The delayed tissue-implant interactions in metallic implants coated with hydroxyapatite (HA) paved the way for the development of alternative bioactive coatings. In this study, bi-layered functional gradient (HA-CS) coating was formulated by the atmospheric plasma spray (APS) process on Ti6Al4V alloy. The HA layer was applied at the metal interface to ensure long-term stability, while the calcium silicate (CS) outer layer was applied to achieve fast tissue-implant interactions. Moreover, single-layered HA and CS coating were also formulated for comparative analysis. The phase compositions, coating microstructure, chemical properties, microhardness, porosity, surface roughness, and in-vitro bioactivity were investigated. The CS top layer showed high porosity and surface roughness with respect to the inner HA layer, which constitutes an optimum microstructure to promote bioactivity. The microhardness of the outer CS layer of HA-CS was 520.3 ± 80.8 HV, while the corresponding value for the inner HA layer was 291.7 ± 45.7 HV. HA-CS and CS coatings demonstrated higher in-vitro bioactivity compared to HA coating. On the contrary, HA coating (3.76 mpy) displayed better corrosion resistance than the HA-CS (4.17 mpy) and CS coatings (4.34 mpy). The in-vitro results indicated that the HA-CS coating could promote the healthy development of osteoblast-like MG-63.

Scalable Electrically Conductive Spray Coating Based on Block Copolymer Nanocomposites.

Currently available conductive inks present a challenge to achieving electrical performance without compromising mechanical properties, scalability, and processability. Here, we have developed blends of carbon black and the commercially available triblock copolymer (BCP), poly(styrene-ethylene-butylene-styrene)-g-maleic anhydride (SEBS-g-MAH) (FG1924G, Kraton), that can be readily applied as a conductive coating via a spray-coating process, for a wide range of insulating materials (fabric, wood, glass, and plastic). Simple but effective mechanical and chemical modifications of the ingredients can increase the electrical conductivity (∼100 S/m) by an order of magnitude more than previously reported for carbon black composites; moreover, the coatings display excellent mechanical flexibility (tensile strain ε ∼ 5.00 mm/mm). To correlate electrical conductivity and nanoscale structural changes with mechanical deformation, small-angle X-ray scattering (SAXS) during in situ tensile testing was performed. We show that the nanocomposite can be produced using low-cost ingredients (∼$ 10/kg), ensuring scalability for fabrication of large-scale devices without specialized material synthesis. Equally important, the phase behavior of block copolymers can enable recovery from physical damage via thermal annealing, which is critical for product longevity.

The effects of bone implants' coating mechanical properties on osseointegration: In vivo, in vitro, and histological investigations.

The main goal of this work was to investigate the effects of implants coatings' mechanical properties and morphology on the osseointegration. In order to produce different mechanical properties of coatings, two thermal spray techniques, high velocity oxy-fuel (HVOF) and air plasma spray (APS) were employed. Titanium pins were coated and implanted into the distal femurs and proximal tibias of fifteen New Zealand white rabbits, equally distributed in three study groups, and a total of 20 pins implanted in each group. Eight weeks after insertion, the rabbits were euthanized and the femur samples were taken out for biomechanical tests and tibia samples for histological evaluations of osseointegration. Scanning electron microscopy results showed enhanced density and a better morphology of HVOF coatings, compared to APS samples, and X-ray diffraction characterized an enhanced crystallinity of HVOF coatings. Nanoindentation tests revealed greater hardness and elastic modulus of HVOF coatings, whereas greater tensile residual stress and more pronounced creep was observed for APS coatings. Neither in biomechanical tests, nor in the histological analyses, a significant difference was observed between HVOF and APS coated samples (p > 0.05, and p > 0.05, respectively). The lack of significant difference between the HVOF and APS coated implants' osseointegration rejected our hypothesis to have a more enhanced osseointegration due to a better morphology, as well as stronger mechanical properties of HA coatings. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2679-2691, 2018.