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Materials found in nature exhibit remarkable properties allowing natural living systems to survive. An outstanding example of this is the byssus of marine mussels. Mussels utilize byssal threads in the byssus to anchor themselves onto a variety of surfaces and endure the harsh intertidal environment. Byssal threads display a composite microstructure as well as intricate macro-scale architectures. This dissertation presents four studies that address questions regarding byssal thread geometry, physical parameters affecting adhesion, and the relationship between the thread microstructure and mechanical properties. Mussels utilize a mushroom-shaped geometry for their byssal threads: the threads consist of a distal thread (stalk) terminating in a plaque (mushroom-tip). Previous studies on adhesion associated with the mushroom-shaped geometry have focused on the effects of geometrical parameters such as tip thickness and the ratio of the stalk to tip radius. Mussels deposit byssal threads radially, which are loaded at various angles during wave motion. This introduces a more complex geometry than previously studied in regard to adhesion and detachment. Due to these differences, we focused on the effects of casting angle and loading angle on adhesive strength utilizing synthetic mimics. We find that the optimal configuration for adhesive strength is when the loading angle and casting angle are equivalent. Evidence suggests that suction may play a role in the adhesive strength of mushroom shaped structures. Using byssal threads as inspiration, we utilized synthetic mimics to study the effects of suction at the macroscopic scale. To determine the critical stress necessary for defect propagation and detachment a fracture mechanics-based model is introduced, and compared with experimental results. The findings indicate that there is a greater increase in adhesive strength due to suction at the macro-scale, which is length-scale dependent. Lastly, we assess the relationship between the thread microstructure and mechanicalproperties. Different protein domains in the collagenous core were targeted with chemicaltreatments and stress relaxation measurements were conducted to determine which energydissipative mechanisms are present during the relaxation process. This complements previous studies which largely focused on elastic properties, by concentrating on the viscoelastic properties of the threads. Results show that the silk-like domains are largely responsible for energy dissipation via protein unfolding and/or rearrangement during the relaxation process. Under cyclic loading, distal threads exhibit a stress-strain behavior reminiscent of shapememory and superelastic effects observed in some metal alloys. Previous studies have revealed that distal threads undergo phase transitions in their microstructure as they are loaded. A hyperelastic Neo-Hookean-based model is introduced that incorporates the mechanical properties from two distinct phases in the microstructure to address the contributions from the collagen core. In addition, a Mullins-based model is used to fit the composite cyclic data and provide insight into the mechanical response of the composite thread.

Epoxy resin powder coating has been successfully applied on the corrosion protection of magnesium lithium alloys. However, poor wear resistance and microcracks formed during the solidification have limited it extensive application. There are limited approaches to exploit such anti-corrosion and mechanical properties of magnesium lithium alloys. Herein, the epoxy resin powder coating with polydopamine modified molybdenum disulfide (MoS2@PDA-EP powder coating with 0, 0.1, 0.2, 0.5, 1.0 wt.% loading) was well prepared by melt extrusion to investigate its anticorrosion performance and wear resistance. The results revealed that the addition of MoS2@PDA enhanced the adhesion strength between coatings and alloys, wear resistance and corrosion protection of the powder coatings. Among them, the optimum was obtained by 0.2 wt.% MoS2@PDA-EP powder coating which could be attributed to well dispersion and efficient adhesion with coating matrix. To conclude, MoS2@PDA-EP powder coating is meaningfully beneficial for the anticorrosive and wear performance improvement of magnesium lithium alloys.

Abstrct Polycaprolactone/hydroxyapatite (PCL/HA) composite coating was fabricated by a combination of hydrothermal and dipping methods to delay the degradation of Mg alloy AZ31 as bioresorbable materials. The PCL/HA coating was composed of nano rod-shape HA crystals and PCL filled in the space of HA crystals. Compared with the single HA coating, the binding strength between the PCL/HA composite coating and Mg alloy was obviously improved and the PCL/HA coating still adhered to the surface of AZ31 substrate even after 38 days of immersion. The electrochemical corrosion rate of HA coated sample was reduced by ten times after being filled by PCL. The electrochemical impedance spectroscopy (EIS) and immersion test results showed that the PCL/HA composite coating could provide a more effective barrier for Mg substrate than the HA coating alone. The cytocompatibility and the antibacterial property of HA coating and PCL/HA coating were evaluated by culturing with bone marrow-derived mesenchymal stem cells (BMSCs) and methicillin-resistant staphylococcus aureus (MRSA) for 24 h under direct culture conditions, respectively. The PCL/HA composite coating showed better BMSC cell compatibility, more suitable for BMSC adhesion than HA coating alone and showed a potential application prospect as a biological materials. However, from the perspective of clinical applications, the antibacterial property of PCL/HA composite coating needs to be further improved.

The mussel byssus is a collection of extra-organismal, acellular, proteinaceous load bearing structures that are radial displayed and utilized by marine mussels to secure themselves to a multitude of substrates. A single byssal thread can be subdivided into the loading bearing thread and adhesive plaque, which provide tensile strength and adhesive strength respectively. Both regions of the byssus face their own unique challenges and have devised independent mechanisms to protect themselves against oxidative stresses. Here we present evidence the mussel utilizes isolated redox compartments to protect 3, 4-dihydroxyphenylalanine (Dopa) from oxidative damage in both the thread and plaque, permitting long lasting mechanical performance of the byssus. The byssus thread is an extremely tough core-shelled fiber that dissipates substantial amounts of energy during tensile loading. The mechanical performance of the shell is critically reliant on Dopa’s ability to form reversible iron-catecholate complexes at pH 8. However, the formation of these coordinate crosslinks is undercut by Dopa’s oxidation to Dopa-quinone, a spontaneous process at seawater conditions. Using a combination of electron and atomic force microscopy we identify a previously undescribed stratum situated between the core and shell. Spectroscopy results indicate this region is rich in thiol and thus will be called the thiol rich layer (TRL). We propose the TRL acts as an electron sink to protect the shell against oxidation. Additionally, indentation type atomic force microscopy reveals the TRL has intermediate mechanical properties which act as a mechanical buffer between the shell and core. The adhesive plaque is also reliant on Dopa. Dopa in the plaque is primarily responsible for strong adhesion but only if protected from oxidation at the adhesive-substratum interface. Dopa oxidation is thermodynamically favorable in seawater yet barely detectable in mature plaques. Experiments were designed to understand how plaques insulate Dopa-containing mfps against oxidation. Spectrometry and confocal fluorescence results indicate seawater sulfate triggers a mfp3 and mfp6 liquid-liquid phase separation (LLPS). Subsequently, cyclic voltammetry of LLPS material demonstrates DOPA’s redox potential is phase dependent. Furthermore, mass spectrometry and redox exchange assays indicate Dopa-containing mfp-3 and mfp-6 in phase-separated droplets remain stable despite rapid oxidation in the equilibrium solution. Taken together, the results suggest that a cohort of oxidation-prone proteins is endowed with phase-dependent redox stability. Moreover, in forming LLPS compartments, Dopa-proteins become reservoirs of chemical energy which can be called upon in the event of oxidative damage.

Interfacial phenomena and materials properties are not only influenced by the chemical makeup, and therefore the highly localized intermolecular forces, between surface and bulk molecules, but also can heavily depend on geometry, self-assembly, dynamic/transient interactions, and the development of specific micro- and nano-structure. This general principle can be applied to a variety of systems including inorganic materials, polymeric materials, complex fluids and colloidal systems, and biological and bio-inspired materials. This dissertation explores how micro-/nano-structure and dynamic phenomena influence the macroscopic properties and performance of two broad classes of materials: (i) mussel-mimetic polymer materials and adhesives and (ii) consumer skincare and hair care products. In Part 1 (Chapters 2 and 3) of this dissertation, two different materials systems inspired by Mytilus mussels have been synthesized. Chapter 2 presents nanoscale adhesion and cohesion force measurements of a mussel-mimetic adhesive peptoid between mica surfaces to further elucidate the mechanisms mussels employ to achieve robust wet adhesion. Comparing these results to those measured using peptide molecules of identical sequence, we determine that nano-scale aggregation and the formation of transient secondary structure, driven by backbone hydrogen bonding, exists only in the peptide molecules, causing differences in the nano-structure and hydration of solution-deposited films in each system, and therefore influencing the intermolecular interactions available between opposing surfaces. Chapter 3 focuses on translating strong but reversible iron-catechol coordination chemistry found in the mussel’s byssal threads to dry epoxy networks in order to achieve enhanced mechanical strength and toughness through reversible energy dissipation. We find that there exists a critical iron-catechol complex concentration above which the materials develop an ionomeric nano-structure, which provides an additional mode of stress translation, thereby further increasing the material’s mechanical properties.Part 2 (Chapters 4 and 5) shifts focus from mussel-mimetic materials to measuring the friction and adhesion of consumer skincare and hair care products. Chapter 4 explores the friction dynamics of model skin creams using a high-speed friction attachment to the surfaces forces apparatus. We demonstrate that analysis of the time-varying frequency components of friction signals can unambiguously differentiate between different modes of sliding, giving insights into how surface and fluid properties impact tribological properties. Finally, Chapter 5 details the development of a custom instrument designed to measure the exceedingly weak adhesion forces between human hair fibers both clean and coated with consumer hair care products. Calibrating the native elasticity of the hair fibers, we can use their own mechanical properties to measure forces as low as ~1 nN using a simple optical microscope. We find that the micro-/nano-structure on the hair surface causes broad, spatially-variant distributions in the adhesion force between fibers and necessitates large numbers of replicate experiments, which have been automated. A model which uses topographical measurements of the hairs’ surfaces has also been developed which can predict the magnitude, breadth, and shape of the complex, multimodal adhesion force distributions from the differential surface geometry.

This research seeks to draw scientific insights from the interplay of processes, which combined lead to the failure of adhesion between paint and cellulose diacetate (CDA), which as a substrate represents the majority of the animation cel collection at Walt Disney Animation Research Library (ARL). In collaboration with a team of conservation researchers at Getty Conservation Institute (GCI), this research has utilized an approach with a rescuer’s mentality, but is thus limited to deaccessioned animation cels, blank interleaving sheets, blank coversheets, or paint mockups pre-approved as samples for experimental research. The scientific value of this manuscript, however, relies on this important material collection in order to ensure representative naturally-aged samples to help evaluate the weakest links of decay in each layer of this laminate, heterogeneous material, that no mockup could ever equal. The interdisciplinary nature of this research is focused between materials science, polymer organic and physical chemistry, mechanical and chemical engineering, and conservation science of plastics and photographic materials, making it possible to delve into fundamental aspects of the chemical mechanisms and physical engineering of these systems from the macro to the nano-scale. As a compilation of future research papers into chapters, this dissertation overall considers properties that influence the conservation challenge to preserve the paint adhesion to the substrate, so one can continue to interpret the artwork visually. The first chapter includes a multi-analytical case study investigating natural aging properties of cellulose diacetate sheets through the worst case scenarios of the ~80 year old Walt Disney animation cels alongside accelerated aging of blank CDA sheets. By tracking these chemical properties through various visualization methodologies, one can better understand the relevant chemical properties to consider for future storage solutions. The polymer decay is monitored through an improved ion chromatography detection method of percent free acetic acid in a water extract of an improved sample size of 100 mg, published here for the first time [Chapter 2 & 3]. The time-scale of the process of the paint delamination is dependent on the rate of water sorption (usually minutes-hours), where the timescale of the process of plastic failure is dependent on the availability of water to react with the polymer and then the buildup of the acetic acid, which is on the timescale of months at elevated temperatures, or mere decades in hotter climates. Therefore, one chapter also utilized different adhesion methodologies for the purpose of easier quantification of this important property of failure of the different layers of the system [Chapter 4]. Adhesion was measured through the application of interfacial fracture mechanics by laser spallation and through surface nano-mechanical properties through atomic force microscopy (AFM), paired with contact angle measurements and thermodynamic calculations to evaluate standards of polymers with different degree of substitution (DS). Major contributions of this work forward approaches to quantify the buildup of % free acetic acid, to quantify the interfacial adhesion of the animation cel and the adhesion of paint, and within the final chapter the development of two scientific assays developed for finding and monitoring storage solutions for animation cels. Advanced chemical engineering is paired with paintings conservation to create the sensor in 5.1, and 5.2 utilizes molecular correlations between standards and extracted samples through nondestructive attenuated total reflectance Fourier transform infrared (ATR-FTIR). Efforts presented in this dissertation to identify the driving forces of adhesion in animation cels demonstrate quantitative materials science based structure-property relations relevant to decision-makers of art storage guidelines, in order to engineer practical, prescriptive, and preventive solutions.

Bacterial cellulose (BC) is one of the most versatile natural biopolymers with unique physical, chemical, and biological features. However, the lack of intrinsic antibacterial property of native BC limits its broad biomedical applications where such property is highly required to prevent contamination or infection caused by attached bacteria. In this work, we developed a simple and facile method to fabricate a dual-functional BC membrane by physical incorporation of gold nanorods (GNRs) followed by deposition of a phase-transitioned bovine serum albumin (PTB) film. Due to the broad-spectrum antifouling property of the PTB film, the resulting membrane could prevent the adhesion and accumulation of bacteria. A few bacteria that broke through the protection of the PTB film could be eradicated under short-term irradiation of a near-infrared laser due to the excellent photothermal property of incorporated GNRs. The whole fabrication was conducted in a simple and environmentally friendly manner, avoiding complicated processes and toxic organic solvents. Moreover, because all the components were biocompatible, the resulting membrane showed negligible cytotoxicity in vitro and good histocompatibility in vivo. This work thus provided a reliable way to endow BC with antibacterial property, being beneficial for diverse biomedical applications.

Superhydrophobic surfaces with various water adhesion behaviours have received tremendous attention in both fundamental research and practical applications. In this work, a novel laser–chemical hybrid process was developed to fabricate superhydrophobic surface with both low and high water adhesion. Periodic cross-hatch micro-bulge arrays were fabricated on aluminum alloy surface by way of nanosecond laser irradiation. After surface chemical treatment, the laser–chemical treated surface showed either superhydrophobicity with low water adhesion using silane treatment only, or superhydrophobicity with high water adhesion using both silane treatment and sodium chloride (NaCl) treatment. The change of water adhesion on the laser–chemical treated superhydrophobic surface was attributed to the simultaneous decrease of surface energy and increase of attraction between the water droplet and sodium chloride salt. This approach could provide a novel but simple solution to tune the water adhesion of superhydrophobic metallic surfaces, thus benefiting related research and industrial areas.

Interface wettability is a vital role in directly impacting the electrical contact characteristics of oxides/Cu-based composites under arc erosion. Exploring its influence mechanism, especially at atomic/electronic scales, is significant but challenging for the rational design of oxides/Cu contacts. Here, we designed Zn2SnO4/Cu electrical contacts aiming to solve the poor wettability of SnO2/Cu composites. It was found that Zn2SnO4 could remarkably improve the arc resistance of Cu-based electrical contacts, which was benefited by the excellent interface wettability of Zn2SnO4/Cu. The characterization of eroded surface indicated that Zn2SnO4 particles distributed uniformly on the contact surface, leading to stable electrical contact characteristic. Nevertheless, SnO2 considerably deteriorated the arc resistance of SnO2/Cu composite by agglomerating on the surface. The effect mechanism of wettability on arc resistance was investigated through density function theory (DFT) study. It revealed that strong polar covalent bonds across the Zn2SnO4/Cu interface contributed to improving the interfacial adhesion strength/wettability and thus significantly enhanced the arc resistance. For binary SnO2/Cu interface, ionic bonds resulted in weak interface adhesion, giving rise to deterioration of electrical contact characteristic. This work discloses the bonding mechanism of oxide/Cu interfaces and paves an avenue for the rational design of ternary oxide/Cu-based electrical contact materials.

It is increasing evidence that the synergistic effects of magnetic scaffolds and magnetic fields can accelerate bone repairing and regeneration, and the bone tumor may be treated using magnetite nanoparticles (MNPs) with hyperthermia. In this study, in order to apply the magnetocaloric performance of MgFe2O4 to bone tissue engineering, porous MgFe2O4 magnetic scaffolds were successfully prepared by chemical coprecipitation method and 3D gel-printing (3DGP) technology. The printing slurry based on polyvinyl alcohol (PVA) system exhibited shear thinning properties, and its maximum solid loading was about 63wt%. When the slurry was squeezed out of the needle, the slurry viscosity was 0.58 Pa·s at the shear rate of 316.3 s-1. The scaffolds sintered above 1100 °C were superparamagnetic and their compressive strength was within 1.8–12.51MPa, which is suitable for human cancellous bone. The highest saturation magnetization of porous MgFe2O4 scaffolds printed by 3DGP was 10.63 emu/g when they were sintered at 1200 °C. The weight loss rate of the scaffolds was 2.15% after degradation in simulated body fluid (SBF) for 5 weeks, pH value of SBF was between 6.78 and 7.4. Preliminary biological experiment shows that MC3T3-E1 cells had good adhesion and proliferation on MgFe2O4 scaffolds surface, and MgFe2O4 scaffolds can promote alkaline phosphatase (ALP) activation, which explain that porous MgFe2O4 magnetic scaffolds may be used for bone repairing.

Contaminants on architectural ceramics have become a major problem in people's lives. Interestingly, superhydrophobic surfaces offer a new avenue for anti-fouling applications. In this work, a UV-laser process for constructing groove-like microstructures on architectural ceramics and subsequent fluoridation treatment were used to create superhydrophobic surfaces. After laser processing, nanoporous structures were generated inside the grooves, while the cracked layer was deposited on the non-irradiated area, building up a micro/nanoscale morphology on the ceramic surface. Moreover, the effects of groove pitch and laser scanning cycle on surface morphology and wettability were investigated. Results indicate that the fluoridated groove-like microstructured surface showed good superhydrophobicity based on the Cassie-Baxter model. Dynamic behavior of water droplets impacting on the as-prepared superhydrophobic surface was studied to verify its low adhesion. Additionally, the superhydrophobic surface exhibited remarkable repellency to various stain liquids and outstanding self-cleaning properties. These findings may contribute to developing anti-fouling applications for the architectural ceramics industry.

When applying an additional coating method to fabricate micro-nano hierarchical structure required for superhydrophobic function on glass surface, the hierarchical structure does generally not have good abrasion resistance, due to the weak adhesion between coating and glass surface. However, glass itself is a material with good abrasion resistance. A micro-nano hierarchical structure with honeycomb-shaped micro-armor protection on glass surface by a two-step hydrothermal corrosion method has been constructed: the first step of hydrothermal corrosion in water to construct micro-armor structure, and the second step of hydrothermal corrosion in sodium citrate aqueous solution to fabricate micro-nano hierarchical structure. The advantages of this new method are: the treatment process is simple, and there is no need to apply additional coatings. The micro-nano hierarchical structure constructed on glass surface by this method has a great abrasion resistance. After 1,000 cycles of abrasion under harsh conditions, the nano-structure on glass surface can still be remained intact. It provides a new method for fabricating abrasion-resistant micro-nano hierarchical structure on glass surface, as well as a new approach to the preparation of abrasion-resistant superhydrophobic glass.

SnO2 powders with four distinct morphologies of prismoids, hollow rhomboidal tubes, solid rhomboidal rods, and needles have been prepared through morphology-conserved transformation from SnC2O4 precursors. The SnC2O4 precursors were synthesized by a facile oxalate precipitation method. A controllable periodic bond chain (PBC) growth was found to be critical for the formation of these SnC2O4 samples. In the case of forward titration, SnC2O4 prismoids were generated because the formed Sn3O(OH)2SO4 was attached on { 1 ( _ ) 01} polar facets and inhibited the PBC growth along the c axis. By contrast, in the case of reverse titration, SnC2O4 samples preferably formed one-dimensional shapes. Dissolution and ripening were observed during the formation of hollow tubes in the case of low molar ratio of Sn2+ to C2O42−. Further, the formation of SnC2O4 needles was ascribed to the selective coordination of polyvinylpyrrolidone (PVP) on the side surface. The as-prepared SnO2 powders were used as reinforcement of Ag–SnO2 electrical contact materials, and a good adhesion was observed at the Ag (111)/SnO2 (200) interface. Further, the characterization results revealed that the sample reinforced by SnO2 tubes (with one-dimensional shape and hollow structure) had the lowest degradation rate under cathode arc erosion, which might be attributed to its good resistance to the dual action (heat and force) of cathode arc.

PURPOSE To evaluate the micro-shear bond strength (μSBS) of different bonding protocols to commercially pure titanium (CP Ti) using two universal adhesives and Alloy Primer. MATERIALS AND METHODS A total of 120 cubes of CP Ti were airborne-particle abraded and then divided into 6 groups (n = 20 each) according to bonding protocol: (1) Scotchbond Universal (SU; 3M ESPE), (2) Alloy Primer (AP; Kuraray) + SU; (3) G-Premio Bond (GP; GC); or (4) AP + GP. The specimens from groups 1 to 4 were cemented with RelyX Unicem (3M ESPE), while those from groups 5 and 6 were cemented using Panavia F2.0 cement (PAN; Kuraray) without and with prior AP application, respectively. After 24 hours, half the specimens were subjected to μSBS measurement and the other half to thermocycling (5,000 cycles) before testing. Data were analyzed using Shapiro-Wilk, two-way analysis of variance, Games-Howell, and independent sample t test (α = .05). RESULTS The μSBS values obtained from the AP + SU group were significantly higher than from the GP (P = .003) and the AP + GP (P = .022) groups. After thermocycling, the μSBS of both groups treated with SU were significantly higher than those other groups (P < .001). The application of AP could not improve adhesion of resin cements to CP Ti. Thermocycling significantly reduced the μSBS values of the PAN group, whereas it noticeably enhanced the adhesion of SU and AP + SU. The predominant failure mode in all groups was adhesive. CONCLUSION The application of AP, followed by SU, produced the most effective bonding to CP Ti, which was able to endure limited thermal aging.

Native bone is piezoelectric in nature and generates abundant surface charges under mechanical compression, which regulate osteoblast proliferation, differentiation, adhesion, and so on. Poly (vinylidene fluoride) (PVDF) is becoming one of the most popular piezoelectric polymers because of its easy processability and good biocompatibility. Unfortunately, because only the β and γ crystal phases of PVDF have piezoelectricity, post-treatments, for example, polarizing at high temperature, are required to enhance the piezoelectricity of PVDF scaffolds after fabrication. In this study, we reported a phase-separation-hydration method to fabricate a calcium phosphate silicate (CPS)-doped PVDF scaffold. Our method fabricated a better piezoelectric scaffold than native bone without further processing (∼ 3 pC/N vs. 0.7 pC/N). In addition, the scaffold was mechanically compatible (∼ 7 MPa) with the cancellous bone with sufficient porosity (∼ 45%) to facilitate osteoblast infiltration and bone ingrowth. The in vitro biocompatibility analyses proved that the prepared CPS-PVDF scaffold was biocompatible with osteoblast cells and encouraged osteoblast redifferentiation. In conclusion, our results suggest that this CPS-PVDF scaffold is a promising candidate for bone tissue engineering applications.

Fracture conformance control in reservoir can effectively improve water channel to increase crude oil displacement efficiency of subsequent waterflooding. Inspired by the remarkable underwater wet adhesion of mussel byssus, hydrogel particles which can adhere stably on the fracture rock surface in reservoir conditions could achieve long-lasting reservoir control effect. In this work, the size-controllable biomimetic functional hydrogel particles were prepared by mechanical shearing after bulk hydrogel was constructed by catechol-functionalized polyacrylamide and phenolic resin crosslinking agent. The influence of solution salinity on the aggregation and adhesion of hydrogel particles was investigated via scanning electron microscope (SEM), colloidal probe atomic force microscope (AFM) and quartz crystal microbalance with dissipation (QCM-D). The results showed that hydrogel particles maintained well-dispersed state in low-salinity water, while exhibited significant adhesion and adsorption capacity to the silica surface in simulated reservoir salinity water. This is of great importance to the practical applications that the hydrogel particles would not show enhanced adhesion to rock surfaces until the reservoir salinity water was met, which was beneficial to the in-depth migration of hydrogel particles to achieve effective deep reservoir profile control. Furthermore, the visible micro-model was designed and applied to evaluate profile control effect of hydrogel particles, and the results showed that hydrogel particles could withstand water flushing and adhere stably to the fracture surface. The waterflooding sweep efficiency was increased remarkably from 20.3%±2.0% to 38.8%±2.0%. This work would help better understand the function mechanism of hydrogel particles in reservoir control and provide novel and efficient method for the practical application in enhanced oil recovery.

Addressing thrombosis and biofouling of indwelling medical devices within healthcare institutions is an ongoing problem. In this work, two types of ultra-low fouling surfaces (i.e., superhydrophobic and lubricant-infused slippery surfaces) were fabricated to enhance the biocompatibility of commercial medical grade silicone rubber (SR) tubes that are widely used in clinical care. The superhydrophobic (SH) coatings on the tubing substrates were successfully created by dip-coating in superhydrophobic paints consisting of polydimethylsiloxane (PDMS), perfluorosilane-coated hydrophobic zinc oxide (ZnO) and copper (Cu) nanoparticles (NPs) in tetrahydrofuran (THF). The SH surfaces were converted to lubricant-infused slippery (LIS) surfaces through the infusion of silicone oil. The anti-biofouling properties of the coatings were investigated by adsorption of platelets, whole blood coagulation, and biofilm formation in vitro. The results revealed that the LIS tubes possess superior resistance to clot formation and platelet adhesion than uncoated and SH tubes. In addition, bacterial adhesion was investigated over 7 days in a drip-flow bioreactor, where the SH-ZnO-Cu tube and its slippery counterpart significantly reduced bacterial adhesion and biofilm formation of Escherichia coli relative to control tubes (>5 log10 and >3 log10 reduction, respectively). The coatings also demonstrated good compatibility with fibroblast cells. Therefore, the proposed coatings may find potential applications in high-efficiency on-demand prevention of biofilm and thrombosis formation on medical devices to improve their biocompatibility and reduce the risk of complications from medical devices.

Thin films have emerged as an ideal surface treatment to the permanent implant materials to enhance properties such as biodegradation resistance, better mechanical strengths and biocompatibility. A perfect implant ought to have the ability of resistance to degradation, stimulate osseointegration, prevent bacterial adhesion, and decrease prosthetic infection. The clinical success of implants depends on the interaction of cells with material surfaces, which is an essential factor. Recent development in biomaterials has brought a variety of coatings on biomaterial to overcome these issues. The coatings impart biocompatibility, better mechanical property, and bioactivity to the biomaterial. In this review, the recent trends in surface modification by thin films of implants have been discussed in detail.

An Ag/TiO2 coating was deposited onto glazed ceramic tiles by a sol-gel and spraying method at high temperatures. The coating was characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The results showed that silver was present in rutile-TiO2, and the temperature did not change the phase composition of the samples. The Ag/TiO2 coating had a higher roughness than the TiO2 coating. The tape test (D 3359–08) showed that the coatings prepared at 950 °C and 1000 °C had good adhesion to the ceramic tile substrate. The antibacterial activity of the coating was tested by photocatalytic sterilization experiments. The results showed that the Ag/TiO2 coating had a higher antibacterial activity than the TiO2 coating, and the sterilization efficiency of Escherichia coli, Staphylococcus aureus, Shigella, and Salmonella exceeded 99.655% under 2 h of visible light irradiation. This research provides a method to create Ag/TiO2 coatings with good thermal resistance, adhesion, and antibacterial activity. This improves the low photocatalytic activity caused by the anatase-to-rutile transformation of TiO2 at high temperatures and the poor adhesion at low temperatures.

Flexible and transparent conductive films are highly desirable in some optoelectronic devices, such as smart windows, touch panels, as well as displays and electromagnetic protection field. Silver nanowire (Ag NW) has been considered as the best material to replace indium tin oxide (ITO) to fabricate flexible transparent electromagnetic interference (EMI) shielding films due to its superior comprehensive performance. However, the common substrates supporting Ag NWs require surface modification to enhance the adhesion with Ag NWs. In this work, a flexible and transparent Ag NWs EMI shielding film with sandwich structure through a facile rod-coating method, wherein Ag NWs network were embedded between biodegradable gelatin-based substrate and cover layer. The interfacial adhesion between Ag NWs and gelatin-based layers was enhanced by hydrogen-bonding interaction and swelling effect without any pretreatment. The shielding effectiveness (SE) of the G/Ag NW/G (G represents gelatin-based layer) film reaches 37.74 dB at X band with an optical transmittance of 72.0 %. What’s more, the flexible gelatin-based layer and encapsulated structure endow the resultant G/Ag NW/G film integrating excellent mechanical properties, reliable durability, antioxidation, as well as anti-freezing performance. This work paves a new way for fabricating flexible transparent EMI shielding films.

To meet the high demand for ceramic/superalloy composite structural components in various fields, an advanced high-temperature adhesion technique was firstly developed by preparing a novel inorganic/organic hybrid adhesive suitable for ZrO2 and TC4. Chemical bonding started to work at ∼600°C, and became the crucial bonding mechanism at elevated temperatures. The formation of ZrSiO4 and Ti5Si3 at the interfaces of two substrates not only increased the interfacial connection strength, but also formed two gradient layers with a size of ∼2 μm to effectively alleviate the difference of composition and performance between the adhesive and substrates. In the temperature range of 500–900°C, the matching degree of CTE among ZrO2, adhesive and TC4 is higher, and the maximum difference does not exceed 3×10-6 K-1. Meanwhile, the formation of a composite structure containing various ceramics (ZrO2, SiC and ZrB2) and intermetallics (Ni–Si, Al–Ni), and the improvement of structural compactness of adhesive from 500 to 900°C greatly improved the bonding strength to the maximum value of 31.4 MPa at 900°C. Also, the adhesive pretreated at 900°C showed good thermal cycling resistance, and the strength was still higher than 15 MPa after 50 cycles. For cured adhesive, when used directly in an extreme environment, it can provide bonding strength not less than 5 MPa in the whole temperature range, indicating that the adhesive possessed potential emergency repair convenience. This work significantly broadened the application of high-temperature-resistant adhesion technology in the connection of dissimilar ceramics and alloys.

Bacteria is one of the main culprits that cause human diseases and pose long-term challenges to people’s health. Rare earth elements have unique antibacterial advantages, but little research is available. In this paper, we reported an antibacterial composite film based on lanthanum-doped carbon quantum dot nanoparticles (La@N-P-CQDs) and polyvinyl alcohol (PVA) film for fluorescence of antibiotics and accelerating wound healing. PVA/La@N-P-CQDs composite film presented excellent hydrophilicity, biocompatibility, fluorescence intensity, and antibacterial effects. The antibacterial activity of La@N-P-CQDs was evaluated by employing antibacterial assay using Escherichia coli (E.coli)and Staphylococcus aureus (S.aureus) in vitro. La@N-P-CQDs showed enhanced antibacterial activity compared with N-P-CQDs. Moreover, the PVA/La@N-P-CQDs composite film with 0.5 mg/mL La@N-P-CQDs showed better antibacterial capability and wound healing performance than PVA and PVA/N-P-CQDs films in bacterial adhesion experiment. PVA/La@N-P-CQDs composite film could be used for wound dressing in vivo experiment and had no side effects on major organs in mice. The antibacterial composite film significantly promoted in vivo wound healing process because of its multifunctional properties. Therefore, it was an excellent candidate for wound dressing.

Bacterial adhesion and biofilm formation impose a heavy burden on the medical system. Bacterial adhesion on implant materials would induce inflammation and result in implant failure. The adhesion of bacteria on food-processing and handling equipment may lead to food-borne illness. To reduce and even prevent bacterial adhesion, some bacterial anti-adhesion surface designs have been developed. However, the effect of some surface properties (including surface patterning, roughness and wettability) on bacterial adhesion has not been systematically summarized. In this review, a comprehensive overview of bacterial anti-adhesion surface design is presented. Modifying the surface pattern and roughness could reduce the contact area between bacteria and surfaces to weaken the initial adhesion force. Fabricating superhydrophobic surface or modifying hydrophilic functional groups could hinder the bacterial adhesion. The analysis and discussion about influencing factors of bacterial anti-adhesion surfaces provide basic guidelines on antibacterial surface design for future researches.

In this paper we study numerically and experimentally non-reversible deformation of anisotropic, semi-flexible fibre networks. We formulate a Discrete Element Model (DEM) with bonded particles to simulate uniaxial compression of such networks and use this model to describe and quantify the effect of elasto-plastic fibre contacts and fibre-fibre adhesion on non-reversible deformation. Our results show that inter-fibre adhesion plays a role for compression in a low solid volume fraction range where adhesive forces can overcome fibre deformation forces and moments. Also, elasto-plastic contacts between fibres become important at higher solid volume fractions when the yield criterion is exceeded. The combined case of fibres having elasto-plastic contacts and adhesion shows a significant synergetic effect leading to a degree of non-reversible deformation of the network far beyond that of networks with only elasto-plastic fibre contacts or inter-fibre adhesion.

This research has addressed a complete study of the bioactivity of bioactive glass coatings obtained by atmospheric plasma spraying. The coatings have been characterized in terms of microstructure, adhesion, crystalline phases and bioactivity. Hydroxycarbonate apatite formation was also monitored following a standard protocol and the in vitro cell response was evaluated by human osteoblast-like cells (MG-63 cells) incubation. The obtained coatings shown a microstructure typical of glass coatings. A simulated body fluid test proved that coatings are capable of developing a surface layer of hydroxycarbonate apatite whereas the appearance of this phase takes place at a longer time than that observed for the powder feedstock. Cell-culture test showed multidirectional growth of MG-63 cells which promoted good contact between cells and the surface of the coating. This study has confirmed a positive effect of the coatings in terms of surface bioactivity and, more interestingly, it has proven an adequate cell-material interaction on the coating surface. Este trabajo ha abordado un estudio completo de la bioactividad de recubrimientos de vidrio bioactivo depositados mediante proyección térmica por plasma atmosférico. Se han caracterizado la microestructura, la adherencia, las fases cristalinas y la bioactividad de los recubrimientos obtenidos. También se ha estudiado la formación de hidroxiapatita carbonatada siguiendo un protocolo estándar y se ha evaluado la respuesta in vitro de los recubrimientos mediante su incubación con osteoblastos humanos (células MG-63). Los recubrimientos obtenidos han mostrado una microestructura típica de recubrimientos de vidrio. Tras la inmersión en fluido biológico simulado, se ha comprobado que el recubrimiento es capaz de desarrollar una capa superficial de hidroxiapatita carbonatada, aunque la velocidad de aparición de esta capa es menor que la observada para el polvo de vidrio de partida. El ensayo de cultivo celular ha mostrado un crecimiento multidireccional de las células MG-63, dando lugar a un buen contacto entre las células y la superficie del recubrimiento. Este estudio ha confirmado un efecto positivo de los recubrimientos en términos de bioactividad de la superficie y, lo que es más interesante, ha demostrado una adecuada interacción célula-material sobre la superficie del recubrimiento.

Practical implementations of rechargeable lithium (Li) metal batteries have long been plagued by multiple problems of Li anode, such as Li dendrite growth, large volume change, low Coulombic efficiency. Here, we report a protein-enabled film that can provide effective protection for Li metal. The protective film with an integrated design of high flexibility, strong adhesion and high Li-ion transference number (0.80) is fabricated by incorporating denatured zein (corn protein) with polyethylene oxide (PEO) acting as an agent for sustaining the denatured protein chains against refolding via the intermolecular interactions between them. Thus, a conformable zein-enabled protective film (zein@PEO) with simultaneous enhancement in flexibility, modulus and adhesion strength is generated to offer both functions of self-adapting and anion-anchoring abilities. The results show that the zein@PEO film is able to accommodate the volume change, reduce the side reactions, and homogenize the ion deposition. Benefiting from these significant properties/functions, the Li/Cu cell with the zein@PEO film delivers prolonged cycle life for over 500 hours with stable performance. Paired with LiMn2O4 cathode, the capacity, cycle stability and rate performance of the cell are remarkably improved as well, demonstrating the effectiveness in stabilizing Li metal batteries.

In this study, the effect of Nb alloying on AlCrVN coatings was systematically investigated, with emphasis on their microstructure, mechanical and tribological properties and oxidation resistance. With the alloying of Nb, the phase composition of these coatings changed from c-AlCrVN soild solution, c-VN and a small amount of h-AlCrN to c-AlCrNbN soild solution and a small amount of h-NbCr2. The alloying of Nb transfered the preferred orientation from (111) to (200), and the intensity increased with an increase in Nb. The microstructure of the coatings transformed from short and coarse columnar to coarse columnar, and then to compact slender columnar. Although the vary in V and Nb content had little influence on the hardness, it had a comparatively influence on the elastic modulus. The synergistic effect of Nb and V was as follows: (1) the highest ratios of H/E (∼0.100) and H3/E2 (∼0.318) were obtained for Al0.6Cr0.28V0.08Nb0.04N, and the highest adhesion (∼79.5 ± 3.5 N) for Al0.59Cr0.28V0.04Nb0.09N; (2) the lowest coefficient of friction of ∼0.392 (Al0.6Cr0.28V0.08Nb0.04N) and the lowest wear rate of 1.42 × 10−7 mm3/(N·m) (Al0.59Cr0.28V0.04Nb0.09N); (3) the onset temperature of oxide from 800 °C (Al0.6Cr0.28V0.12N) to 1000 °C (Al0.59Cr0.28V0.04Nb0.09N).

Bacteria-associated infection and poor osseointegration are two main reasons for orthopedic implant failure. Ti-Cu alloy exhibited excellent antibacterial property, but still presented unsatisfied osteogenic activities. Therefore, Ti-Cu alloy was surface modified by an alkali-heat treatment in this paper to improve the osteogenic ability without reduction in antibacterial ability. A TiO2/CuO/Cu2O composite coating with nanostructure was deposited on Ti-Cu alloy. The coating showed increased roughness and great hydrophilicity. Antibacterial tests indicated that the modified Ti-Cu alloy exhibited stronger antibacterial ability against Staphylococcus aureus (S. aureus) than Ti-Cu alloy. Meanwhile, cell experiments demonstrated that the composite coating promoted initial adhesion and spreading of MC3T3-E1 cells, enhanced alkaline phosphatase (ALP) activities as well as extracellular matrix (ECM) mineralization, and significantly upregulated osteogenesis-related gene expressions. It was suggested that the nano-structured TiO2/CuO/Cu2O coating on Ti-Cu alloy might provide a potential strategy for orthopedic implant failure.

Statement of problem Whether the addition of different antifungal nanoparticles to denture base materials may affect physical or esthetic properties of the resulting nanocomposite is unclear. Purpose The purpose of this in vitro study was to determine how a new method of adding antifungal nanofiller affects the properties of the processed nanocomposite denture base material. Material and methods Heat-polymerized acrylic resin specimens were prepared according to each test specification. Zirconium dioxide nanoparticles (ZrO2NPs) and silver nanoparticles (AgNPs) were added in 0.5, 1.0, and 1.5% of acrylic resin powder. The specimens were divided into 2 groups according to the acrylic resin packing method: 1 layer packed conventionally in one step and 2 layers packed in 2 steps, first with unmodified acrylic resin and then by a thin layer of modified acrylic resin before the final closure. The control group was made of unaltered acrylic resin in 1 step. Flexural strength (FS), translucency, and surface roughness (Ra) were measured. A microbial assay was performed by using the direct culture and slide count methods. Three-way ANOVA and Tukey post hoc tests were used to identify statistical differences among groups (α=.05). Results The addition of ZrO2NPs and AgNPs in the 1- or 2-layer specimens reduced Candida albicans adhesion (P .05), while other AgNP groups exhibited increased surface roughness (P Conclusions The addition of ZrO2NPs in the double-layer technique decreased Candida adhesion and improved FS without affecting surface roughness, while AgNPs decreased Candida adhesion and FS and increased surface roughness. Both nanofillers decreased the translucency except 0.5% ZrO2NPs, which did not change translucency when applied in 2 layers.