Enhancement of adhesion bonding between titanium metal and electrodeposited calcium phosphate

Ni-Mo nanostructure alloys as effective electrocatalysts for green hydrogen production in an acidic medium

Achieving a net-zero emissions economy requires significant decarbonization of the transportation sector, which depends on the development of highly efficient electrocatalysts. Electrolytic water splitting is a promising approach to this end, with Ni-Mo alloys emerging as strong candidates for hydrogen production catalysts. This study investigates the electrodeposition of Ni and Ni-Mo nanostructured alloys with high molybdenum content onto low-carbon steel cathodes using a novel alkaline green lactate bath. Catalyst morphology, microstructure, and composition were characterized using SEM, XRD, XPS, and EDX. Results showed molybdenum content increased with current density, ranging from 40.14 wt% at 1.12 mA cm-2 to 61.68 wt% at 5.56 mA cm-2, with average particle sizes of 39.4 nm for Ni, 20.7 nm for Ni-2Mo (56% Mo), and 30.8 nm for Ni-4Mo (65% Mo). The alloys comprised tetragonal MoNi4, metallic Ni, metallic Mo, and MoO3 phases. Ni-4Mo exhibited superior HER performance in 0.5 mol L-1 H2SO4, with the lowest Tafel slope (-113 mV dec-1), highest exchange current density (1.250 mA cm-2), and good stability after 250 cycles. It also outperformed Ni-2Mo at -50 mA cm-2, demonstrating its promise as a durable and efficient HER catalyst in acidic media.

Reinforcement and Fatigue of a Bioinspired Mineral-Organic Bioresorbable Bone Adhesive

Bioresorbable bone adhesives may provide remarkable clinical solutions in areas ranging from fixation and osseointegration of permanent implants to the direct healing and fusion of bones without permanent fixation hardware. Mechanical properties of bone adhesives are critical for their successful application in vivo. Reinforcement of a tetracalcium phosphate-phosphoserine bone adhesive is investigated using three degradable reinforcement strategies: poly(lactic-co-glycolic) (PLGA) fibers, PLGA sutures, and chitosan lactate. All three approaches lead to higher compressive strengths of the material and better fatigue performance. Reinforcement with PLGA fibers and chitosan lactate results in a 100% probability of survival of samples at 20 MPa maximum compressive stress level, which is almost ten times higher compared to compressive loads observed in the intervertebral discs of the spine in vivo. High adhesive shear strength of 5.1 MPa is achieved for fiber-reinforced bone adhesive by tuning the surface architecture of titanium samples. Finally, biological and biomechanical performance of the fiber-reinforced adhesive is evaluated in a rabbit distal femur osteotomy model, showing the potential of the bone adhesive for clinical use.

Bioinspired Mineral-Organic Bioresorbable Bone Adhesive

Bioresorbable bone adhesives have potential to revolutionize the clinical treatment of the human skeletal system, ranging from the fixation and osteointegration of permanent implants to the direct healing and fusion of bones without permanent fixation hardware. Despite an unmet need, there are currently no bone adhesives in clinical use that provide a strong enough bond to wet bone while possessing good osteointegration and bioresorbability. Inspired by the sandcastle worm that creates a protective tubular shell around its body using a proteinaceous adhesive, a novel bone adhesive is introduced, based on tetracalcium phosphate and phosphoserine, that cures in minutes in an aqueous environment and provides high bone-to-bone adhesive strength. The new material is measured to be 10 times more adhesive than bioresorbable calcium phosphate cement and 7.5 times more adhesive than non-resorbable poly(methyl methacrylate) bone cement, both of which are standard of care in the clinic today. The bone adhesive also demonstrates chemical adhesion to titanium approximately twice that of its adhesion to bone, unlocking the potential for adherence to metallic implants during surrounding bony incorporation. Finally, the bone adhesive is shown to demonstrate osteointegration and bioresorbability over a 52-week period in a critically sized distal femur defect in rabbits.