Reaction-passivation mechanism driven materials separation for recycling of spent lithium-ion batteries

Development of effective recycling strategies for cathode materials in spent lithium-ion batteries are highly desirable but remain significant challenges, among which facile separation of Al foil and active material layer of cathode makes up the first important step. Here, we propose a reaction-passivation driven mechanism for facile separation of Al foil and active material layer. Experimentally, >99.9% separation efficiency for Al foil and LiNi0.55Co0.15Mn0.3O2 layer is realized for a 102 Ah spent cell within 5 mins, and ultrathin, dense aluminum-phytic acid complex layer is in-situ formed on Al foil immediately after its contact with phytic acid, which suppresses continuous Al corrosion. Besides, the dissolution of transitional metal from LiNi0.55Co0.15Mn0.3O2 is negligible and good structural integrity of LiNi0.55Co0.15Mn0.3O2 is well-maintained during the processing. This work demonstrates a feasible approach for Al foil-active material layer separation of cathode and can promote the green and energy-saving battery recycling towards practical applications.

Heteropolysaccharides in sustainable corrosion inhibition: 4E (Energy, Economy, Ecology, and Effectivity) dimensions

Carbohydrate polymers (polysaccharides) and their derivatives are widely utilized in sustainable corrosion inhibition (SCI) because of their various fascinating properties including multiple adsorption sites, high solubility and high efficiency. Contrary to traditional synthetic polymer-based corrosion inhibitors, polysaccharides are related to the 4E dimension, which stands for Energy, Economy, Ecology, and Effectivity. Furthermore, they are relatively more environmentally benign, biodegradable, and non-bioaccumulative. The current review describes the SCI features of various heteropolysaccharides, including gum Arabic (GA), glycosaminoglycans (chondroitin-4-sulfate (CS), hyaluronic acid (HA), heparin, etc.), pectin, alginates, and agar for the first time. They demonstrate impressive anticorrosive activity for different metals and alloys in a variety of corrosive electrolytes. Through their adsorption at the metal/electrolyte interface, heteropolysaccharides function by producing a corrosion-protective film. In general, their adsorption follows the Langmuir isotherm model. In their molecular structures, heteropolysaccharides contain several polar functional groups like -OH, -NH₂, -COCH₃, -CH₂OH, cyclic and bridging O, -CH₂SO₃H, -SO₃OH, -COOH, -NHCOCH₃, -OHOR, etc. that serve as adsorption centers when they bind to metallic surfaces.

Bio-inspired hemocompatible surface modifications for biomedical applications

When blood first encounters the artificial surface of a medical device, a complex series of biochemical reactions is triggered, potentially resulting in clinical complications such as embolism/occlusion, inflammation, or device failure. Preventing thrombus formation on the surface of blood-contacting devices is crucial for maintaining device functionality and patient safety. As the number of patients reliant on blood-contacting devices continues to grow, minimizing the risk associated with these devices is vital towards lowering healthcare-associated morbidity and mortality. The current standard clinical practice primarily requires the systemic administration of anticoagulants such as heparin, which can result in serious complications such as post-operative bleeding and heparin-induced thrombocytopenia (HIT). Due to these complications, the administration of antithrombotic agents remains one of the leading causes of clinical drug-related deaths. To reduce the side effects spurred by systemic anticoagulation, researchers have been inspired by the hemocompatibility exhibited by natural phenomena, and thus have begun developing medical-grade surfaces which aim to exhibit total hemocompatibility via biomimicry. This review paper aims to address different bio-inspired surface modifications that increase hemocompatibility, discuss the limitations of each method, and explore the future direction for hemocompatible surface research.

Fabrication of PCL/keratin composite scaffolds for vascular tissue engineering with catalytic generation of nitric oxide potential

Tissue-engineered vascular grafts (TEVGs) have been proposed as a promising approach to fulfill the need for small-diameter blood vessel substitutes. However, common failure caused by thrombosis and neointimal proliferation after implantation has restricted their use in the clinic. Herein, a NO-generating scaffold for vascular tissue engineering was developed by coelectrospinning poly(ε-caprolactone) (PCL) with keratin. The morphology and surface chemical composition were characterized via SEM, ATR-FTIR spectroscopy and XPS. The biocomposite scaffold selectively enhanced the adhesion and growth of endothelial cells (ECs) while suppressing the proliferation of smooth muscle cells (SMCs) in the presence of GSH and GSNO due to the catalytic generation of NO. In addition, these mats displayed excellent blood compatibility by prolonging the blood-clotting time. In summary, these NO-generating PCL/keratin scaffolds have potential applications in vascular tissue engineering with rapid endothelialization and reduced SMC proliferation.

Mg-Phenolic Network Strategy for Enhancing Corrosion Resistance and Osteocompatibility of Degradable Magnesium Alloys

Magnesium-based alloys are the most widely used materials for degradable metallic implants and have considerable potential for bone applications owing to their excellent stimulating effect on osteogenesis. However, their high corrosion rate limits their structural stability and causes oxygen deficiency and an excessive increase in the pH around the defect area during bone healing. Magnesium oxides, which are the main corrosion products of Mg, are nontoxic materials with useful effects on new bone formation and pH neutralization. Metal-phenolic networks were introduced recently as a cost-effective and efficient surface modifier and were fabricated by deposition of nanosized metal oxides on different types of substrates using the chemical reaction between phenolic groups and metallic ions. In this study, magnesium oxide films were formed successfully on a Mg-based substrate using Mg-phenolic networks. The effects of various coating parameters on the surface morphology, corrosion resistance, degradation behavior, wettability, and osteocompatibility of degradable metallic materials after surface modification with Mg-phenolic networks were thoroughly investigated for the first time. The results showed that the initial concentration of Mg ions was the main parameter affecting the corrosion resistance, which was almost as much as 3 times that of uncoated samples. Additionally, cytotoxicity and viability assessment and observation of the morphological changes in bonelike cells showed that the in vitro osteocompatibility was significantly enhanced by coatings with Mg concentrations of 2.4-3.6 mg mL-1. Finally, in vivo animal studies using the rat calvarial defect model confirmed that the proposed coating method mitigated the formation of gas cavities around the implantation area by reducing the corrosion rate of the Mg-based implant. The nanosized metal oxides produced by the Mg-phenolic network significantly improved the biodegradability and osteocompatibility of Mg alloys, suggesting a potential approach to advancing the clinical application of Mg alloys.

Multistep Instead of One-Step: A Versatile and Multifunctional Coating Platform for Biocompatible Corrosion Protection

Magnesium alloys have potential application in cardiovascular stents and orthopedic implants. However, the rapid corrosion rate of magnesium limits their clinical application. In order to improve the corrosion resistance and biocompatibility of the substrate, a protective coating is constructed by alternate immersing of MgZnMn alloy in epigallocatechin gallate (EGCG) and polyethyleneimine (PEI) solution. The conventional method is immersing magnesium alloy into a conversion solution by simple one-step immersion. In the present work, the EGCG/PEI coating is prepared by a novel alternate immersion method. The number of alternate immersions resulted in a different density of phenolic hydroxyl groups and amino groups on the surface. The corrosion resistance and bonding strength of the coating also varied with alternating immersion times. As the corrosion resistance and density of the functional groups varies, endothelial cells (ECs), smooth muscle cells (SMCs), osteoblasts, and macrophages showed a different growth state on EGCG/PEI coatings. In summary, this EGCG/PEI coating addressed the rapid corrosion rate of the magnesium alloy and can adjust its function by controlling the number of alternate immersions. The EGCG/PEI coating exhibited multifunctions: improved corrosion resistance, good compatibility with ECs and osteoblasts, and inhibition of SMC growth and inflammation, and the effective groups on the coating make it possible for further modification by grafting biomolecules. This is an effective method for preparing a multifunctional platform on biomedical magnesium alloys.

An Albumin Biopassive Polyallylamine Film with Improved Blood Compatibility for Metal Devices

Nowadays, a variety of materials are employed to make numerous medical devices, including metals, polymers, ceramics, and others. Blood-contact devices are one of the major classes of these medical devices, and they have been widely applied in clinical settings. Blood-contact devices usually need to have good mechanical properties to maintain clinical performance. Metal materials are one desirable candidate to fabricate blood-contact devices due to their excellent mechanical properties and machinability, although the blood compatibility of existing blood-contact devices is better than other medical devices, such as artificial joints and artificial crystals. However, blood coagulation still occurs when these devices are used in clinical settings. Therefore, it is necessary to develop a new generation of blood-contact devices with fewer complications, and the key factor is to develop novel biomaterials with good blood compatibility. In this work, one albumin biopassive polyallylamine film was successfully established onto the 316L stainless steel (SS) surface. The polyallylamine film was prepared by plasma polymerization in the vacuum chamber, and then polyallylamine film was annealed at 150 °C for 1 h. The chemical compositions of the plasma polymerized polyallylamine film (PPAa) and the annealed polyallylamine film (HT-PPAa) were characterized by Fourier transform infrared spectrum (FTIR). Then, the wettability, surface topography, and thickness of the PPAa and HT-PPAa were also evaluated. HT-PPAa showed increased stability when compared with PPAa film. The major amino groups remained on the surface of HT-PPAa after annealing, indicating that this could be a good platform for numerous molecules' immobilization. Subsequently, the bovine serum albumin (BSA) was immobilized onto the HT-PPAa surface. The successful introduction of the BSA was confirmed by the FTIR and XPS detections. The blood compatibility of these modified films was evaluated by platelets adhesion and activation assays. The number of the platelets that adhered on BSA-modified HT-PPAa film was significantly decreased, and the activation degree of the adhered platelets was also decreased. These data revealed that the blood compatibility of the polyallylamine film was improved after BSA immobilized. This work provides a facile and effective approach to develop novel surface treatment for new-generation blood-contact devices with improved hemocompatibility.