Enhancement Of Adhesion Research Articles

Modification of Ganoderma lucidum spore shells into probiotic carriers: selective loading and colonic delivery of Lacticaseibacillus rhamnosus and effective therapy of inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic inflammation with a high incidence rate. Many probiotics, including Lacticaseibacillus rhamnosus (L. rhamnosus), have shown promise in IBD treatment. The therapeutic effects of most probiotics are greatly decided by the available live cells in the disease lesion, which is compromised as they pass through the gastric juice and intestinal tract, resulting in a loss of activity. To improve probiotic delivery efficiency in the intestinal tract, broken Ganoderma lucidum spore shells (bGLS) were explored as a carrier to enhance the intestinal tract delivery of L. rhamnosus SHA113, a probiotic that has been verified to have capability to treat IBD. It was found the bGLS treated with iturin A and hydrochloric acid (IH-bGLS) had much higher affinity to probiotic cells than the untreated ones. This is possibly due to the enhancement of hydrophobic and positive charge of bGLS. Furthermore, IH-bGLS demonstrated an 81% loading efficiency for L. rhamnosus SHA113 and 2.2% for Escherichia coli. More importantly, loading in IH-bGLS greatly enhanced the delivery of L. rhamnosus SHA113 cells to the colon and prolonged their retention time from 48 to over 120 h (P < 0.01). The mechanisms might be related to the enhancement of probiotic cell adhesion to the gastrointestinal mucosa, increase of mucus secretion and the upregulated expression of tight junction proteins, occludin and ZO-1, in the colon. The results of the animal experiment showed that the therapeutic effects of L. rhamnosus SHA113 on IBD were greatly enhanced when they were loaded with IH-bGLS. The novelty of this research is in the development of probiotic carriers from bGLS, which has significance in the improvement of intestinal delivery efficiency and the therapeutic effects of probiotics on IBD. This system may have attractive application in the enhancement of probiotic delivery efficiency in the intestinal tract, which is important to ensure and enhance the beneficial effects of probiotics.

Functionalization of Polyethylene Terephthalate (PETE) Membranes for the Enhancement of Cellular Adhesion in Organ-on-a-Chip Devices.

Experimental reproducibility in organ-on-chip (OOC) devices is a challenging issue, mainly caused by cell adhesion problems, as OOC devices are made of bioinert materials not suitable for natural cellularization of their surfaces. To improve cell adhesion, several surface functionalization techniques have been proposed, among which the simple use of an intermediate layer of adsorbed proteins has become the preferred one by OOC users. This way, the cells use surface receptors to adhere to the adsorbed proteins, which are in turn attached to the surface. However, as protein adsorption is based on weak electrostatic bonding between the coating proteins and the substrate, this method produces suboptimal results: as the weak electrostatic bonds break, cells detach, leading to poor, heterogeneous cellularization. To solve this problem, we present a surface functionalization method for polyethylene terephthalate (PETE) membranes, commonly used in multilayer organ-on-chip devices to support cellular layers. This protocol involves hydrolyzation of the membrane, followed by (3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) activation, resulting in covalent bonding between the membrane and coating proteins, much stronger than the weak electrostatic bonding provided by simple adsorption. As evaluation, we first measured the effect of the functionalization protocol in the morphological and mechanical integrity of the membranes. Next, we confirmed protein coating efficiency using the ζ potential and surface tension of the functionalized membranes coated with collagen type I, polylysine, gelatin, albumin, fetal bovine serum (FBS), and Matrigel. Finally, we showed that our method significantly improves the attachment of epithelial (A549) and endothelial (EA.hy926) cell lines under static conditions, especially in collagen-coated membranes, which were further tested under dynamic conditions, showing statistically significant improvement in cell attachment compared to uncoated or collagen-adsorbed only membranes.

Laser-induced adhesives with excellent adhesion enhancement and reduction capabilities for transfer printing of microchips.

Transfer printing based on tunable and reversible adhesive that enables the heterogeneous integration of materials is essential for developing envisioned electronic systems. An adhesive with both adhesion enhancement and reduction capabilities in a rapid and selective manner is challenging. Here, we report a laser-induced adhesive, featuring a geometrically simple shape memory polymer layer on a glass backing, with excellent adhesion modulation capability for programmable pickup and noncontact printing of microchips. Selective and rapid laser heating substantially enhances the adhesive's adhesion strength from kilopascal to megapascal within 10 ms due to the shape fixing effect, allowing for precise and programmable pickup. Conversely, the enhanced adhesion can be quickly reduced and eliminated within 3 ms through the shape recovery effect, enabling noncontact printing. Demonstrations of transfer printing microlight-emitting diodes (LEDs) and mini-LEDs onto various low-adhesive flat, rough, and curved surfaces highlight the unusual capabilities of this adhesive for deterministic assembly.

Advances in surface coating and performance enhancement of ammonium perchlorate

Abstract Ammonium perchlorate (AP), which has the advantages of high oxygen content, good thermal and chemical stability, and no solid residue after thermal decomposition, is considered to be the most widely used oxidiser for solid propellant applications. However, the high mechanical sensitivity, moisture absorption, and thermal decomposition temperature of AP seriously affect the performance of the solid propellant. In this paper, we systematically review the research progress of the improvement of desensitization, anti-hygroscopicity, and thermal decomposition performance by surface coating of AP. At the same time, the surface coating methods are focusing on electrospray technology, reduced pressure distillation, ultrasonic synthesis, liquid phase deposition, supercritical fluid, intermittent spray coating, and electrostatic self-assembly coating method. Among above, intermittent spray coating and liquid phase deposition method are the preferred surface coating method due to their uniformity of coating, ease of adhesion and good performance enhancement. It is expected that the research on surface coating and performance enhancement of AP can greatly promote the innovation and development of AP in the field of high burning rate solid propellant.

The Future of Die-to-Die Copper Interconnects and Epoxy Dielectrics

Recent Die-to-Die (D2D) interconnects require high data rates operating at high frequencies (> 10 GHz) in multichip packages. Mechanical adhesion was utilized to improve the reliability of traditional packages by increasing interface roughness between epoxy dielectrics and electrochemically deposited copper interconnects. The classical packages, operating at low frequencies below 1 GHz, showed a negligible scattering of electromagnetic waves (S21 < 0.5 dB/m) on the rough surface [1, 2]; however, recent interconnects present considerable degradation in power losses (S21 > 1.0 dB/m) on the rough surface due to skin effect at high frequencies (> 10 GHz) [2]. While previous works have shown the impact of surface roughness on adhesion enhancement, a trade-off between adhesion and power losses has not been precisely considered.This study investigates the trade-off between reliability and performance. We explore the impact of surface roughness on adhesion and power efficiency of electrochemically deposited copper interconnects at high frequencies up to 18 GHz. Wet etching was performed to modify surface roughness for low-cost production. The root-mean-square roughness (RRMS) is regulated at ~10-100 nm to examine smooth copper-epoxy interfaces for future D2D interconnects. The surface morphology is analyzed by atomic force microscopy (AFM). Adhesion and insertion losses are investigated by peel test and vector network analyzer. A direction for future work is provided to improve chemical adhesion at a smooth copper-epoxy interface. Chemical adhesion is expected to improve the reliability of future multichip packages while maintaining power integrity. For example, surface oxidation and silane coupling agents are discussed to improve chemical adhesion at the smooth interface (< 100 nm RRMS).REFERENCES:[1] Lau, J.H., Recent Advances and Trends in Advanced Packaging. IEEE Transactions on Components, Packaging and Manufacturing Technology, 2022. 12(2): p. 228-252.[2] Gold, G. and K. Helmreich, A physical surface roughness model and its applications. IEEE Transactions on Microwave Theory and Techniques, 2017. 65(10): p. 3720-3732.

Enhancing Interface Performance Through Self-Assembly Mechanisms of APTES on Surface-Modified Tuff Aggregates

To enhance the adhesion between tuff and asphalt, this study investigates the efficacy of alkalinization treatment technology using a molecular self-assembly layer derived from the silane-coupling agent γ-aminopropyltriethoxysilane (APTES). APTES hydrolysis solutions at varying concentrations were prepared to assess their impact on the adhesive strength of the aggregate–asphalt interface and water damage resistance. Using surface energy theory, the interface adhesion work of tuff was analyzed, while SEM and EDS were employed to examine changes in surface morphology and composition after treatment. The results demonstrate that an APTES:water:ethanol mass ratio of 5:45:50, along with a curing temperature of 200 °C, significantly improves the bonding strength between tuff and asphalt. The silanol groups on APTES react with hydroxyl groups on the tuff surface to form siloxane bonds (Si-O-Si), anchoring APTES to the tuff. This study elucidates the self-assembly mechanisms of APTES on tuff aggregates and demonstrates the consequent enhancement of interfacial adhesion, providing valuable insights for the application of tuff as tunnel spoil in road engineering.

Effects of fish meal replacement with composite proteins source on growth performance, antioxidant capacity and swim bladder quality of chu’s croaker (Nibea coibor)

Collagen, as a commercial functional protein, is widely applied in food, cosmetics, biomedicine and other industries, and swim bladder is regarded as an ideal source of raw materials due to its rich collagen content. Chu’s croaker (Nibea coibor), as an economical fish that can produce high-grade swim bladder, is popularly farmed, however, its high fishmeal demand limits the development of the feed industry. Therefore, it is worth thinking about how to reduce the use of fish meal without affecting the swim bladder quality. Given that, an 8-week feeding trial was conducted to investigate the effects of fish meal partially replaced (0.0%, 5.0%, 10.0%, 15.0%, 20.0%) with composite proteins (CPs, consisted of corn protein meal and hydrolyzed feather meal) on growth, antioxidant capacity and swim bladder quality (texture and collagen deposition) of chu’s croaker. Results showed that although growth performance decrease with the increase of CPs’ replacement level, it did not compromise the swim bladder quality. Specifically, 5% - 10% CPs did not affect the growth significantly, but can improve antioxidant capacity, protein content, collagen synthesis and texture quality of swim bladder. The enhancement of swim bladder texture, including hardness, chewiness, springiness, and adhesiveness may be caused by changes in the expression of related genes, such as colga1t1, col12a1, cyp27a1, etc. These results indicated that appropriate fish meal replaced by CPs could be applied during aquaculture practice after comprehensive consideration of feed cost, growth rate and quality of swim bladder. This study provides support for the development of cost-effective feed formulations that improve the sustainability and economic viability of chu’s croaker culture.

Preparation and Characterization of Tensile Properties of PMMA/SiC Nanowhiskers Nanocomposite Films: Effect of Filler Loading and Silane Treatment

The preparation of nanocomposites through melt mixing was challenging as the nanofillers tend to form agglomeration. The silicon carbide nanowhiskers (SiCNWs) filled poly (methyl methacrylate) (PMMA) thin film in this study was prepared by means of solution casting. Acetone with low toxicity was used as solvent to dissolve the PMMA pellets. A coupling agent, silane was used to enhance the properties of composite films. Besides, the untreated and treated SiCNWs were filled into PMMA matrix, respectively with the filler loading varied from 0.2 to 0.8 wt%. The universal testing machine was used to investigate the tensile properties of composites. It was found out that the tensile strength of the PMMA was reduced in the presence of SiCNWs. However, the tensile strength had increased with the rise of filler loading. At 0.8 wt% of SiCNWs, the composites’ tensile strength was comparable to virgin PMMA. Meanwhile, the SiCNWs had reduced the elongation at break but increased the elastic modulus of PMMA/SiCNWs nanocomposite films. In addition, silane surface treatment on SiCNWs had improved the tensile strength and ductility but lowered the elastic modulus of the nanocomposites. The improvement was due to the enhancement of interfacial adhesion between SiCNWs and PMMA.

Chitosan-melanin complex microsphere: A potential colonic delivery system for protein drugs

The characteristics and performance of chitosan-based colon delivery systems are significantly influenced by the method of preparation. Insect chitosan-melanin complex (CMC) may offer superior attributes over traditional shrimp and crab chitosan (CS) for colon-targeted administration. This study used dung beetle CMC as the carrier matrix and comprehensively examined the impact of various crosslinking techniques on the colonic drug delivery efficacy of microspheres, encompassing drug loading, swelling, drug release behavior, adhesion, enzymatic degradation, and absorption enhancement. The results indicate that F-TPPLC microspheres, crosslinked with a combination of formaldehyde and sodium tripolyphosphate, exhibit superior drug loading capabilities, optimal swelling behavior, and controlled in vitro drug release profiles in the colonic environment, along with excellent adhesion and enzymatic degradation properties within intestinal tract. Notably, these F-TPPLC microspheres increase paracellular permeability, possibly by disrupting the calcium-dependent adhesion junctions. In comparison to commercial CS, CMC demonstrates superior drug encapsulation efficiency, enhanced colonic drug release, adhesion, and absorption promotion, rendering it a favorable candidate as a carrier in colon-targeted drug delivery systems. Consequently, F-TPPLC microspheres derived from CMC are highly suitable for colon drug delivery applications and show promising potential for the oral delivery of peptide and protein-based therapeutics to the colon.

Adhesion performance and enhancement mechanism of FA/GGBFS based geopolymer modified bitumen and acidic aggregate

The primary challenge in utilizing acidic aggregates in bitumen mixtures lies in enhancing the adhesive bond between the bitumen and the acidic aggregates. In this manuscript, to investigate the adhesion of different geopolymer modified bitumen with acidic aggregates, fly ash geopolymer (FG), fly ash- ground granulated blast furnace geopolymer (SFG), and ground granulated blast furnace (SG) were prepared by fly ash (FA), ground granulated blast furnace (GGBFS) with alkali activator. The different geopolymers were characterized with SEM, XRD, FTIR. Different geopolymer modified bitumen was prepared by adding geopolymers into virginal bitumen. The conventional properties, viscosity, and rheological properties of modified bitumen were measured and analysed. The adhesion of bitumen to acidic aggregates was tested by Zeta potential test, the improved boiling water test and pull-off test. The results showed that the electronegativity of bitumen and acidic aggregates were weakened significantly by Na+ in skeletal structure of fly ash geopolymer. The high temperature stability of fly ash geopolymer modified bitumen was improved and the bond strength of bitumen with acidic aggregates increased remarkably with the addition of 9 % fly ash geopolymer.

Electrospun polyvinyl alcohol nanofiber scaffolds incorporated strontium-substituted hydroxyapatite from sand lobster shells: synthesis, characterization, and in vitro biological properties

The paper describes the synthesis of hydroxyapatite (HAp) and strontium-substituted hydroxyapatite (SrHAp) from sand lobster shells by a hydrothermal method. The HAp and SrHAp were incorporated into the polyvinyl alcohol (PVA) nanofiber scaffold through the eletrospinning method. The scaffolds were incorporated with 5wt% of hydroxyapatite (HAp), 5wt%, 10wt%, and 15% of SrHAp. The physicochemical, mechanical, and in vitro biological properties of the scaffold were evaluated. The incorporation of HAp or SrHAp was evidenced by the diffraction patterns and the phosphate functional groups related to HAp. The morphological results showed the decrement of fiber diameter in line with the increased SrHAp concentration. A tensile test was conducted to investigate the mechanical properties of the scaffolds, and the results showed that the scaffolds perform poorly at a higher SrHAp concentration because of exceeding agglomeration levels. The PVA/SrHAp15 performed the best antibacterial activity against E. coli and S. aureus with an inhibition zone of (15.2 ± 0.2) and (14.5 ± 0.8), respectively. The apatite formation was more abundant in PVA/SrHAp10 after immersion in a simulated body fluid (SBF). Cell viability results showed that the scaffold enabled the osteoblast cells to grow and proliferate. The biocompatibility of HAp and SrHAp resulted in the enhancement of cell adhesion. Based on all tests, the PVA/SrHAp 10 scaffold shows a strong candidate for further in vivo studies.

Correlations between adhesion and molecular interactions at buried interfaces of model polymer systems and in commercial multilayer barrier films.

Sum frequency generation vibrational spectroscopy (SFG) was applied to characterize the interfacial adhesion chemistry at several buried polymer interfaces in both model systems and blown multilayer films. Anhydride/acid modified polyolefins are used as tie layers to bond dissimilar polymers in multilayer barrier structures. In these films, the interfacial reactions between the barrier polymers, such as ethylene vinyl alcohol (EVOH) or nylon, and the grafted anhydrides/acids provide covalent linkages that enhance adhesion. However, the bonding strengths vary for different polymer-tie layer combinations. Here, using SFG, we aim to provide a systematic study on four common polymer-tie interfaces, including EVOH/polypropylene-tie, EVOH/polyethylene-tie, nylon/polypropylene-tie, and nylon/polyethylene-tie, to understand how the adhesion chemistry varies and its impact on the measured adhesion. Our SFG studies suggest that adhesion enhancement is driven by a combination of reaction kinetics and the interfacial enrichment of the anhydride/acid, resulting in stronger adhesion in the case of nylon. This observation matches well with the higher adhesion observed in the nylon/tie systems in both lap shear and peel test measurements. In addition, in the polypropylene-tie systems, grafted oligomers due to chain scission may migrate to the interface, affecting the adhesion. These by-products can react or interfere with the barrier-tie chemistry, resulting in reduced adhesion strength in the polypropylene-tie system.

Eutectogel adhesives with underwater-enhanced adhesion to hydrophilic surfaces and strong adhesion in harsh environments

It has been a challenge to achieve strong adhesion strength for gel adhesives in water. In this study, a novel eutectogel adhesive is synthesized via one-step photoinitiated polymerization of N-vinylpyrrolidone (NVP) in deep eutectic solvent (DES). The abundant hydrogen bonding interactions and the hydrophilic polyvinylpyrrolidone network structure endow the eutectogel with excellent adhesion to both hydrophilic and hydrophobic surfaces in air and underwater. Moreover, for hydrophilic substrates, the underwater adhesion strength of the eutectogel adhesives is 1.3 times larger than that in air, demonstrating an underwater-enhanced adhesion effect. In contrast, for hydrophobic substrates, the underwater adhesion strength is lower than in air. Furthermore, strong adhesion performance is maintained even in boiling water, strong acidic medium, strong basic medium, and organic solvents. The experimental and simulation results have unveiled the underwater adhesion enhancement mechanism of the eutectogel. It is believed that the designed eutectogel will show great promise in the development of the next-generation of gel adhesives with underwater adhesion capabilities and high environmental adaptability.

An integrated approach for developing a durable and superhydrophobic anti-corrosion coating inspired by biomimetic starfish surface structures

Applying superhydrophobic coatings with excellent anti-corrosion, anti-fouling, self-cleaning, antibacterial, and wear-resistant properties is a promising approach to protect metal surfaces. This study presents a novel and cost-effective approach, inspired by the biomimetic structure of starfish, to develop a durable and superhydrophobic coating. Unlike traditional methods, we introduce a meticulously engineered tetrapodal ZnO@SiO2-fluorosilane composite that forms a unique hierarchical micro-nano core-shell structure, reducing surface energy and exceptional performance. The formulation combines perfluorooctyl triethoxysilane (FOTS)-modified SiO2, silicone polyester, and tetrapodal ZnO (T-ZnO) in thermoplastic polyurethane (TPU), resulting in a first-of-its-kind T-ZnO@SiO2-FOTS (ZSF) coating with superhydrophobic properties, demonstrated by a water contact angle of 160°, a sliding angle of 3°, and the lowest surface free energy of 14.50 mN/m, contributing to excellent anti-corrosion properties (corrosion rate of 1.44 × 10−6 mm/year) and a corrosion inhibition efficiency of 99.87 %. In addition, the coating exhibits remarkable mechanical durability, adhesion enhancement, and stability against harsh environmental agents, including salt spray, HCl, and NaOH. Our biomimetic approach leverages the starfish-inspired surface design and highly crosslinked interface to enhance resilience, making this coating more robust under real-world conditions. These results provide a promising pathway for the development of multifunctional coating materials suitable for various solid surfaces.

A PDMS/Silicon Adhesion Control Method at Millimeter‐Scale Based on Microvibration

Switchable surface adhesion at a small scale is crucial for robot end‐effector design, allowing the manipulation of small objects such as semiconductors, optical lenses, and precision mechanical parts. In this work, a detailed characterization of a millimeter‐scale (1–5 mm) adhesion modulation method is performed, demonstrating its effectiveness for switching adhesion on small, lightweight objects with smooth surfaces. This modulation phenomenon arises from the viscoelastic behavior when PDMS interacts with a rigid surface and is controlled via microvibration. A maximum apparent adhesion enhancement of 2400% and a reduction of 50% are achieved with a 1 mm‐diameter PDMS hemisphere vibrating at a 30 μm amplitude and a 700 Hz frequency. The effects of different parameters, including size, actuation amplitude/frequency, surface roughness, and material properties, on adhesion performance are carefully measured and analyzed. A monotonic increase in maximum adhesion is observed with increased device size and surface smoothness, while nonlinear relationships of other factors are generalized with a numerical model. A long working lifespan and high endurance are also observed during the characterization. This work serves as a practical reference for the further design of small‐scale soft grippers, highlighting its continuous, large modulation range, simple structure, and flexible control.

Experimental study on the influencing factors of particles jetting behavior in train sanding adhesion enhancement

Sanding is the most widely used adhesion enhancing measure for trains. However, the motion of adhesion enhancement particles is vulnerable to interference from complex operating environment resulting in reduced efficiency. This work focused on the effect of sanding device parameters (sand delivery hose, air pressure and sand-blasting gun) on particles jetting behavior and particles utilization rate based on the train sanding process simulation detecting equipment. Results show that the particles utilization rate gradually improves with jetting velocity increasing and diffusion angle decreasing. Jetting velocity increases with the increase in the air pressure, nozzle diameter of sand-blasting gun and installation angle of sand delivery hose. While jetting diffusion angle decreases with the increase in the delivery hose diameter and outlet diameter of sand-blasting gun. Sanding flow rate is susceptible to the air pressure. The regression models of influencing factors on particles jetting behavior are performed for prediction and optimization.

DEM modelling of surface indentations caused by granular materials: application to wheel–rail sanding

The presented surface indentation model is one step towards building a DEM model for wheel–rail sanding. In railways, so-called low-adhesion conditions can cause problems in traction and braking, and sanding is used to overcome this problem. Sand grains are blasted towards wheel–rail contact, fracture repeatedly as they enter the nip and are drawn into the contact and then increase adhesion. Research on this topic has mostly been experimental, but focussed on adhesion enhancement measurement. Thus, physical mechanisms increasing the adhesion are not well understood. Previous works involved experiments and DEM modelling of single sand grain crushing tests under realistic wheel–rail contact pressures of 900 MPa, focusing on sand fragment spread and formation of clusters of solidified fragments. In the experiments, indents in the compressing steel plates were also observed, which are also observed on wheel and rail surfaces in railway operation. These are now modelled by adapting an existing surface indentation model from literature to the case of surface indentations caused by granular materials. Two test cases are studied, and experimental spherical indentation tests for model parametrisation are presented. In a proof of concept, the mentioned single sand grain crushing tests under 900 MPa pressure are simulated including the surface indentation model. This work contributes to DEM modelling of wheel–rail sanding, which is believed to be a good approach to deepen the understanding of adhesion increasing mechanisms under sanded conditions.

A comprehensive wheel–rail contact model incorporating sand fragments and its application in vehicle braking simulation

Increasing the wheel–rail adhesion coefficient by spreading sand grains to the wheel–rail interface is a common approach to improve the traction and braking efficiency of trains. To simulate this process accurately, two highlights are presented in this paper. Firstly, this paper proposes a wheel–rail contact model considering sand fragments, a third body, based on the non-Hertzian theory, which includes a random sand-grain generator and a sand crushing model. The proposed wheel–rail model is used to analyze the wheel–rail adhesion state after sand grains enter the wheel–rail contact interface. How sand particles change the distribution of normal force and tangential force to affect the wheel–rail adhesion is clarified and, in addition, the influence of the parameters of sand fragments on the wheel–rail adhesion coefficient is given. Secondly, a vehicle system dynamics model considering sanding and wheel slip protection (WSP) control is developed to analyze the effect of sanding on braking distance and wheel slip during braking processes. The wheel–rail contact model and the vehicle system dynamics model presented in this paper can support the study of more effective sanding and adhesion enhancement devices.

Diamond coatings on copper surfaces through interface engineering

To address the challenges posed by the significant thermal stress and limited affinity of diamond coatings on copper (Cu) substrates, we developed a method combining femtosecond (fs) laser texturing with the application of a nickel (Ni) interlayer. This technique was utilized for adhesion enhancement of diamond coatings on Cu. By varying the deposition duration and microgrid depth through multiple fs laser scanning passes, it is possible to attain well-adhered diamond coatings on Cu substrates. These coatings demonstrate an outstanding quality factor of 93.4% and an average grain size of 5.5 μm. The enhanced adhesion results from the synergistic reinforcement of the mechanical interlock and anchoring mechanisms facilitated by the textured surface, further bolstered by the presence of the Ni interlayer. Moreover, the shape of the texture significantly influences the deposition outcome. Single-crystal diamonds with an average grain size of 10 μm were achieved on sharp microgrids at a substrate temperature of 550 °C. This work is expected to offer a general approach for deposition of diamond coatings on metallic materials with enhanced adhesion.

An in situ forming cartilage matrix mimetic hydrogel scavenges ROS and ameliorates osteoarthritis after superficial cartilage injury

Superficial cartilage defects represent the most prevalent type of cartilage injury encountered in clinical settings, posing significant treatment challenges. Here, we fabricated a cartilage extracellular matrix mimic hydrogel (GHC, consisting of Gelatin, Hyaluronic acid, and Chondroitin sulfate) to avoid the exacerbation of cartilage deterioration, which is often driven by the accumulation of reactive oxygen species (ROS) and a pro-inflammatory microenvironment. The GHC hydrogel exhibited multifunctional properties, including in situ formation, tissue adhesiveness, anti-ROS capabilities, and the promotion of chondrogenesis. The enhancement of tissue adhesion was achieved by chemically modifying hyaluronic acid and chondroitin sulfate with o-nitrobenzene, enabling a covalent connection to the cartilage surface upon light irradiation. In vitro characterization revealed that GHC hydrogel facilitated chondrocyte adhesion, migration, and differentiation into cartilage. Additionally, GHC hydrogels demonstrated the ability to scavenge ROS in vitro and inhibit the production of inflammatory factors by chondrocytes. In the animal model of superficial cartilage injury, the hydrogel effectively promoted cartilage ECM regeneration and facilitated the interface integration between the host tissue and the material. These findings suggest that the multifunctional GHC hydrogels hold considerable promise as a strategy for cartilage defect repair. Statement of significanceSuperficial cartilage defects represent the most prevalent type of cartilage injury encountered in the clinic. Previous cartilage tissue engineering materials are only suitable for full-thickness cartilage defects or osteochondral defects. Here, we developed a multifunctional GHC hydrogel composed of gelatin, hyaluronic acid, and chondroitin sulfate, which are natural cartilage extracellular matrix components. The drug-free and cell-free hydrogel not only avoids immune rejection and drug toxicity, but also shows good mechanical properties and biocompatibility. More importantly, the GHC hydrogel could adhere tightly to the superficial cartilage defects and promote cartilage regeneration while protecting against oxidation. This natural ingredients and multifunctional hydrogel is a potential material for repairing superficial cartilage defects.