Fabrication of chitosan/graphene oxide composite aerogel microspheres with high bilirubin removal performance

Preparation of sodium alginate / quaternary ammonium-functionalized chitosan adsorbents: For the removal of high-molecular-weight invert sugar alkaline degradation products

The composite adsorbent consisting of sodium alginate (SA) and quaternary ammonium-functionalized chitosan (QACS) was prepared using the calcium slow-release method to remove high-molecular-weight invert sugar alkaline degradation products (HISADPs) from the beet juice. The SA/QACS composite adsorbent has a honeycomb porous structure. Comparing the single-component QACS dispersion and SA adsorbent, the incorporation of SA increased the storage/elastic modulus (G') and loss/viscous modulus (G'') of the SA/QACS composite hydrogels, while the incorporation of QACS enhanced the adsorption capacity of the SA/QACS composite adsorbents. Specifically, when 5 % QACS and 2 % SA were added, both G' and G" of the SA/QACS adsorbent were approximately 100 times greater than those corresponding to the QACS dispersion. Concurrently, its maximum adsorption capacity attained 164.5 mg/g, which was superior to that of the SA adsorbent. The adsorption isotherms and adsorption kinetics further demonstrated that the Langmuir model and the pseudo-second-order (PSO) model were congruent with the adsorption data of the SA/QACS composite adsorbent concerning HISADPs. Overall, these findings highlight the potential of the SA/QACS adsorbent as an effective adsorbent for the removal of HISADPs from beet juice.

Research progress on blood compatibility of hemoperfusion adsorbent materials

This comprehensive review examines the latest developments in improving the blood compatibility of hemoperfusion adsorbents. By leveraging advanced coating and modification techniques, including albumin-collodion, cellulose, hydrogel, and heparin coatings, notable enhancements in blood compatibility have been achieved across diverse adsorbent types, such as carbon-based, resin-based, and polysaccharide-based materials. Despite promising laboratory results, the intricate manufacturing processes and elevated costs present significant challenges for broad clinical application. Therefore, future endeavors should focus on cost-benefit analysis, large-scale production strategies, in-depth exploration of blood-material interactions, and innovative technologies to propel the development of safer and more effective blood purification therapies.

[Application of Modified Polyether Sulfone Microspheres in Hyperbilirubinemia]

Objective

To design and prepare a high efficiency bilirubin adsorbent with good mechanical properties and biocompatibility.

Methods

In this study, quaternary ammonium pyridine was designed and synthesized, and then modified polyether sulfone microspheres, or PES/p(4-VP-co-N-VP)@6 microspheres, were prepared by phase conversion and electrostatic spraying. The morphology of the polymer components and the microspheres were studied by means of nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy. The basic properties of the microspheres and their bilirubin adsorption efficiency were tested, and the adsorption mechanism was further explored. Blood cell counts and the clotting time of the microspheres were also measured.

Results

The diameter of the modified polyether sulfone microspheres prepared in the study was approximately 700-800 μm. Compared with the original PES microspheres, the surface and internal structure of PES/p(4-VP-co-N-VP)@6 microspheres did not change significantly, and they also had a loose porous structure, with some micropores scattered around in addition to irregular large pores. Compared with the control group, the bilirubin removal effect of the modified microspheres was (94.91±0.73)% after static adsorption in bilirubin PBS buffer solution for 180 min, with the difference being statistically significant (P<0.0001). According to the findings for the clotting time, the activated partial thromboplastin time (APTT) of the blank plasma group, the control PES group, and the modified PES microsphere group were (27.57±1.25) s, (28.47±0.45) s, and (30.4±0.872) s, respectively, and the difference between the experimental group and the other two groups was statistically significant (P<0.01, P<0.05). There was no significant change in red blood cell and white blood cell counts.

Conclusion

The microspheres prepared in the study have high efficiency in bilirubin adsorption, excellent mechanical properties and thermal stability, and good blood biocompatibility, and are expected to be used in the clinical treatment of patients with liver failure.

High-Efficiency Adsorption of Uranium from Wastewater Using Graphene Oxide/Graphene Oxide Nanoribbons/Chitosan Nanocomposite Aerogels

A chemical exfoliation and freeze-drying technique was used to create graphene oxide/graphene oxide nanoribbons/chitosan aerogels (GO/GONRs/CS). Aerogels were utilized to study uranium adsorption through batch experiments. Environmental influences on U(VI) adsorption were studied, including the starting concentration of U(VI), contact time, pH, and temperature. In order to characterize the composite, FTIR, SEM, XRD, and TEM analyses were used. A pseudo-second-order kinetic model may adequately represent the kinetics of U(VI) adsorption onto the surface of aerogels. The Freundlich model can explain the adsorption isotherm; the maximal adsorption capacity for U(VI) was determined to be 1208.85 mg/g; the adsorption process for U(VI) was endothermic, spontaneous, and pH-dependent; and the mechanism of adsorption is the chemisorption process. Chemisorption typically involves strong chemical interactions between the adsorbate (uranium ions) and the functional groups present on the surface of the adsorbent (the aerogel). Graphene oxide and graphene oxide nanoribbons contain oxygen-containing functional groups such as carboxyl (-COOH), hydroxyl (-OH), and epoxy (-O-) groups, which can act as active sites for chemical bonding. Chitosan, a polysaccharide derived from chitin, also possesses functional groups like amino (-NH2) and hydroxyl groups. Uranium ions, in their U(VI) form, can form chemical bonds with these functional groups through various mechanisms such as electrostatic interactions, complexation, and coordination bonds. The combination of graphene oxide-based materials and chitosan in the nanocomposite aerogel offers several advantages, including a large specific surface area, chemical stability, and the presence of functional groups for effective uranium adsorption.

A CO-releasing coating based on carboxymethyl chitosan-functionalized graphene oxide for improving the anticorrosion and biocompatibility of magnesium alloy stent materials

Due to its biofunctions similar to NO, the CO gas signaling molecule has gradually shown great potential in cardiovascular biomaterials for regulating the in vivo performances after the implantation and has received increasing attention. To construct a bioactive surface with CO-releasing properties on the surface of magnesium-based alloy to augment the anticorrosion and biocompatibility, graphene oxide (GO) was firstly modified using carboxymethyl chitosan (CS), and then CO-releasing molecules (CORM401) were introduced to synthesize a novel biocompatible nanomaterial (GOCS-CO) that can release CO in the physiological environments. The GOCS-CO was further immobilized on the magnesium alloy surface modified by polydopamine coating with Zn2+ (PDA/Zn) to create a bioactive surface capable of releasing CO in the physiological environment. The outcomes showed that the CO-releasing coating can not only significantly enhance the anticorrosion and abate the corrosion degradation rate of the magnesium alloy in a simulated physiological environment, but also endow it with good hydrophilicity and a certain ability to adsorb albumin selectively. Owing to the significant enhancement of anticorrosion and hydrophilicity, coupled with the bioactivity of GOCS, the modified sample not only showed excellent ability to prevent platelet adhesion and activation and reduce hemolysis rate but also can promote endothelial cell (EC) adhesion, proliferation as well as the expression of nitric oxide (NO) and vascular endothelial growth factor (VEGF). In the case of CO release, the hemocompatibility and EC growth behaviors were further significantly improved, suggesting that CO molecules released from the surface can significantly improve the hemocompatibility and EC growth. Consequently, the present study provides a novel surface modification method that can simultaneously augment the anticorrosion and biocompatibility of magnesium-based alloys, which will strongly promote the research and application of CO-releasing bioactive coatings for surface functionalization of cardiovascular biomaterials and devices.

Alleviation of endothelial dysfunction of Pheretima guillemi (Michaelsen)-derived protein DPf3 in ponatinib-induced thrombotic zebrafish and mechanisms explored through ox-LDL-induced HUVECs and TMT-based proteomics

ETHNOPHARMACOLOGICAL RELEVANCE

Thrombus generation is one of the leading causes of death in human, and vascular endothelial dysfunction is a major contributor to thrombosis. Pheretima guillemi (Michaelsen), a traditional medicinal animal known as "Dilong", has been utilized to cure thrombotic disorders for many years. DPf3, a group of functional proteins extracted from P. guillemi, has been characterized and identified to possess antithrombotic bioactivity via in vitro and ex vivo experiments.

AIM OF THE STUDY

This study is aimed to investigate the vascular-protection activity and related mechanism of antithrombotic protein DPf3 purified from Pheretima guillelmi systematically.

MATERIALS AND METHODS

The antithrombotic activity and vascular endothelium protection effect of DPf3 was explored in vivo using ponatinib-induced vascular endothelial injury zebrafish thrombus model. Then, (hi) ox-LDL-induced HUVECs was applied to investigate the protection mechanism of DPf3 against the injury of vascular endothelium. In addition, TMT-based proteomics analysis was used to study the biomarkers, biological processes and signal pathways involved in the antithrombotic and vascular protective effects of DPf3 holistically.

RESULTS

DPf3 exerted robust in vivo antithrombosis and vascular endothelial protection ability. DPf3 was identified to prevent HUVECs from damage by reducing ROS production, and to reduce monocyte adhesion by decreasing the protein content of adhesion factor VCAM 1. DPf3 was also observed to weaken the migration ability of injured cells and inhibit abnormal angiogenesis. The mechanism of DPf3's antithrombotic and vascular protective activity was mainly related to the regulation of lipid metabolism, energy metabolism, complement and coagulation system, ECM receptor interaction, MAPK signal pathway, etc. CONCLUSIONS: This study demonstrates that DPf3 has strong antithrombotic and endothelial protective effects. The endothelial protective ability and related mechanisms of DPf3 provide a scientific reference for the traditional use of earthworms in the treatment of thrombosis.

Adsorption of Levofloxacin onto Graphene Oxide/Chitosan Composite Aerogel Microspheres

The removal of pharmaceutical residues from water resources using bio-based materials is very important for human safety and health. Bio-based graphene oxide/chitosan (GO/CS) aerogel microspheres were fabricated with emulsification and cross-linking, followed by freeze drying, and were used for the adsorption of levofloxacin (LOF). The obtained GO/CS aerogel microspheres were characterized with scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and thermogravimetry (TG). The effects of GO content, pH value, and temperature on their adsorption capacity were investigated. With the incorporation of 40 wt% GO, the adsorption capacity increased from 9.9 to 45.6 mg/g, and the highest adsorption capacity, 51.5 mg/g, was obtained at pH = 8 and T = 25 °C. In addition, to obtain deeper insight into the adsorption process, the thermodynamics and kinetics of the process were also investigated with four different models of LOF adsorption. The thermodynamic modeling results revealed that LOF adsorption is exothermic, and the kinetic investigation demonstrated that LOF adsorption is generally consistent with a pseudo-first-order rate law.

Novel hemoperfusion adsorbents based on collagen for efficient bilirubin removal - A thought from yellow skin of patients with hyperbilirubinemia

Hemoperfusion is a well-developed method for removing bilirubin from patients with hyperbilirubinemia. The performance of adsorbents is crucial during the process. However, most adsorbents used for bilirubin removal are not suitable for clinical applications, because they either have poor adsorption performance or limited biocompatibility. Patients with hyperbilirubinemia usually have distinctive yellow skin, indicating that collagen, a primary component of the skin, may be an effective material for absorbing bilirubin from the blood. Based on this idea, we designed and synthesized collagen (Col) and collagen-polyethyleneimine (Col-PEI) microspheres and employed them as hemoperfusion adsorbents for bilirubin removal. The microspheres have an efficient adsorption rate, higher bilirubin adsorption capacity, and competitive adsorption of bilirubin in the bilirubin/bovine serum albumin (BSA) solution. The maximum adsorption capacities of Col and Col-PEI microspheres for bilirubin are 150.2 mg/g and 258.4 mg/g, respectively, which are higher than those of most traditional polymer microspheres. Additionally, the microspheres exhibit excellent blood compatibility originating from collagen. Our study provides a new collagen-based strategy for the hemoperfusion treatment of hyperbilirubinemia.

Injectable hydrogel for sustained delivery of progranulin derivative Atsttrin in treating diabetic fracture healing

Hydrogels with long-term storage stability, controllable sustained-release properties, and biocompatibility have been garnering attention as carriers for drug/growth factor delivery in tissue engineering applications. Chitosan (CS)/Graphene Oxide (GO)/Hydroxyethyl cellulose (HEC)/β-glycerol phosphate (β-GP) hydrogel is capable of forming a 3D gel network at physiological temperature (37 °C), rendering it an excellent candidate for use as an injectable biomaterial. This work focused on an injectable thermo-responsive CS/GO/HEC/β-GP hydrogel, which was designed to deliver Atsttrin, an engineered derivative of a known chondrogenic and anti-inflammatory growth factor-like molecule progranulin. The combination of the CS/GO/HEC/β-GP hydrogel and Atsttrin provides a unique biochemical and biomechanical environment to enhance fracture healing. CS/GO/HEC/β-GP hydrogels with increased amounts of GO exhibited rapid sol-gel transition, higher viscosity, and sustained release of Atsttrin. In addition, these hydrogels exhibited a porous interconnected structure. The combination of Atsttrin and hydrogel successfully promoted chondrogenesis and osteogenesis of bone marrow mesenchymal stem cells (bmMSCs) in vitro. Furthermore, the work also presented in vivo evidence that injection of Atsttrin-loaded CS/GO/HEC/β-GP hydrogel stimulated diabetic fracture healing by simultaneously inhibiting inflammatory and stimulating cartilage regeneration and endochondral bone formation signaling pathways. Collectively, the developed injectable thermo-responsive CS/GO/HEC/βG-P hydrogel yielded to be minimally invasive, as well as capable of prolonged and sustained delivery of Atsttrin, for therapeutic application in impaired fracture healing, particularly diabetic fracture healing.

Bilirubin Removal by Polymeric Adsorbents for Hyperbilirubinemia Therapy

Hyperbilirubinemia, presenting as jaundice, is a life-threatening critical illness in newborn babies and acute severe hepatic failure patients. Over the past few decades, extracorporeal hemoadsorption by adsorbent therapy has been widely applied in the treatment of hyperbilirubinemia. The capability of hemoadsorption depends on the adsorbents. Most of the clinically used bilirubin adsorbents are made up of styrene/divinylbenzene copolymer and quaternary ammonium salt, which usually have poor biocompatibility and weak mechanical strength. To overcome the drawbacks of commercial polymer adsorbents, advanced synthetic and natural polymers with/without nanomaterials have been designed, and novel adsorbent fabrication technologies have also been developed. In this review, the adsorption mechanism of bilirubin adsorbents has been summarized, which is the basic criterion in adsorbent development. Furthermore, the preparation method, adsorption mechanism, relative merits and practicability of the emerging bilirubin adsorbents have been evaluated. Based on the existing studies, this work highlights the future direction of the efforts on how to design and develop bilirubin adsorbents with good overall clinical performance. Perhaps this study can change traditional perspectives and propose new strategies for bilirubin clearance from the aspects of pathogenic mechanisms, metabolic pathways, and material-based innovation.

On the Sorbent Ability and Reusability of Graphene-Oxide-Chitosan Aerogels for the Removal of Dyes from Wastewater

One of the most persistent issues affecting people worldwide is water contamination due to the indiscriminate disposal of pollutants, causing severe environmental problems. Dyes are among the most harmful contaminants because of their high chemical stability and consequently difficult degradation. To remove contaminants from water, adsorption is the most widely used and effective method. In this work, we recall the results already published about the synthesis, the characterization and the use of porous graphene-oxide-chitosan aerogels as a sorbent material. Those systems, prepared by mixing GO sheets and CS chains, using APS as a cross-linking agent, and by further lyophilization, were further characterized using nano-computed tomography, supplying more understanding about their micro and nano-structure. Their sorbent ability has been investigated also by the study of their isotherm of adsorption of two different anionic dyes: Indigo Carmine and Cibacron Brilliant Yellow. Those analyses confirmed the potentialities of the aerogels and their affinity for those anionic dyes. Moreover, the possibility of regenerating and reusing the material was evaluated as a key aspect for applications of this kind. The treatment with NaOH, to promote the desorption of adsorbed dyes, and subsequent washing with HCl, to re-protonate the system, ensured the regeneration of the gels and their use in multiple cycles of adsorption with the selected water contaminants.

Development of Regular Hydrophobic Silica Aerogel Microspheres for Efficient Oil Adsorption

The objective of this research was to develop new hydrophobic silica aerogel microspheres (HSAMs) with water glass and hexmethyldisilazane for oil adsorption. The effects of the hexmethyldisilazane concentration and drying method on the structure and organic liquid adsorption capacity were investigated. The hexmethyldisilazane concentration of the modification solution did not influence the microstructure and pore structure in a noteworthy manner, which depended more on the drying method. Vacuum drying led to more volume shrinkage of the silica gel microsphere (SGM) than supercritical CO₂ drying, thus resulting in a larger apparent density, lower pore volume, narrower pore size distribution, and more compact network. Owing to the large pore volume and pore size, the HSAMs synthesized via supercritical CO₂ drying had a larger organic liquid adsorption capacity. The adsorption capacities of the HSAMs with pore volumes of 4.04-6.44 cm³/g for colza oil, vacuum pump oil, and hexane are up to 18.3, 18.9, and 11.8 g/g, respectively, higher than for their state-of-the-art counterparts. The new sorbent preparation method is facile, cost-effective, safe, and ecofriendly, and the resulting HSAMs are exceptional in capacity, stability, and regenerability.

Auto-Continuous Synthesis of Robust and Hydrophobic Silica Aerogel Microspheres from Low-Cost Aqueous Sodium Silicate for Fast Dynamic Organics Removal

An efficient auto-continuous globing process was developed with a self-built apparatus to synthesize pure silica aerogel microspheres (PSAMs) using sodium silicate as a precursor and water as a solvent. A hydrophobic silica aerogel microsphere (HSAM) was obtained by methyl grafting. A reinforced silica aerogel microsphere (RSAM) was prepared by polymer cross-linking on the framework of the silica gel. The pH value of the reaction system and the temperature of the coagulating bath were critical to form perfect SAMs with a diameter of 3.0 ± 0.2 mm. The grafted methyl groups are thermally stable up to 400 °C. Polymer cross-linking increased the strength significantly, owing to the polymer coating on the framework of silica aerogel. The pore volumes of HSAM (6.44 cm³/g) and RSAM (3.17 cm³/g) were much higher than their state-of-the-art counterparts. Their specific surface areas were also at a high level. The HSAM and RSAM showed high organic sorption capacities, i.e., 17.9 g/g of pump oil, 11.8 g/g of hexane, and 22.2 mg/g of 10 mg/L methyl orange. The novel preparation method was facile, cost-effective, safe, and eco-friendly, and the resulting SAM sorbents were exceptional in capacity, dynamics, regenerability, and stability.

Freezing-triggered gelation of quaternized chitosan reinforced with microfibrillated cellulose for highly efficient removal of bilirubin

The highly efficient removal of bilirubin from blood by hemoperfusion for liver failure therapy remains a challenge in the clinical field due to the low adsorption capacity and poor hemocompatibility of currently used carbon-based adsorbents. Polysaccharide-based cryogels seem to be promising candidates for hemoperfusion adsorbents owing to their inherited excellent hemocompatibility. However, the weak mechanical strength and relatively low adsorption capacity of polysaccharide-based cryogels limited their application in bilirubin adsorption. In this work, we presented a freezing-triggered strategy to fabricate QCS/MFC cryogels, which were formed by quaternized chitosan (QCS) crosslinked with divinylsulfonyl methane (BVSM) and reinforced with microfibrillated cellulose (MFC). Ice crystal exclusions triggered the chemical crosslinking to generate the cryogels with dense pore walls. The obtained QCS/MFC cryogels were characterized by FTIR, SEM, stress-strain test, and hemocompatibility assay, which exhibited interconnected macroporous structures, excellent shape-recovery and mechanical performance, and outstanding blood compatibility. Due to the quaternary ammonium functionalization of chitosan, the QCS/MFC showed a high adsorption capacity of 250 mg g^-1 and a short adsorption equilibrium time of 3 h. More importantly, the QCS/MFC still exhibited high adsorption efficiency (over 49.7%) in the presence of 40 g L^-1 albumin. Furthermore, the QCS/MFC could also maintain high dynamic adsorption efficiency in self-made hemoperfusion devices. This facile approach provides a new avenue to develop high-performance hemoperfusion adsorbents for bilirubin removal, showing great promise for the translational therapy of hyperbilirubinemia.

Supramolecular Organic Frameworks as Adsorbents for Efficient Removal of Excess Bilirubin in Hemoperfusion

Excess bilirubin accumulates in the bodies of patients suffering from acute liver failure (ALF) to cause much irreversible damage and bring about serious clinical symptoms such as kernicterus, hepatic coma, or even death. Hemoperfusion is a widely used method for removing bilirubin from the blood, but clinically used adsorbents have unsatisfactory adsorption capacity and kinetics. In this study, we prepared four supramolecular organic framework microcrystals SOF-1-4 via slow evaporation of their aqueous solutions under infrared light. SOF-1-4 possess good regularity and excellent stability. We demonstrate that all the four SOFs could serve as adsorbents for bilirubin with fast adsorption kinetics within 20 min and ultrahigh adsorption capacity of 609.1 mg g^-1, driven by electrostatic interaction and hydrophobicity. The superior adsorption performance of the SOFs outperformed most of the reported bilirubin adsorbents. Remarkably, SOF-3 could remove about 90% of bilirubin in the presence of 40 g L^-1 BSA with a minimal loss of albumin and was thus further processed to a bead-shaped composite with a diameter of 2 mm with poly(ether sulfone) (PES). This PES-loaded SOF could efficiently adsorb bilirubin to the normal level from human plasma with an adsorption equilibrium concentration of 7.8 mg L^-1 in 6 h through a dynamic hemoperfusion process. This work provides a new vitality for the development of novel bilirubin adsorbents for hemoperfusion therapy.

Microfluidic electrospray generation of porous magnetic Janus reduced graphene oxide/carbon composite microspheres for versatile adsorption

HYPOTHESIS

Graphene-based microparticles materials are broadly utilized in all sorts of fields owing to their outstanding properties. Despite great progress, the present graphene microparticles still face challenges in the aspects of size uniformity, motion flexibility, and tailorable surface chemistry, which limit their application in some specific fields, such as versatile adsorption. Hence, the development of novel graphene microparticles with the aforementioned characteristics is urgently required.

EXPERIMENTS

We presented a simple microfluidic electrospray strategy to generate magnetic Janus reduced graphene oxide/carbon (rGO/C) composite microspheres with a variety of unique features. Specifically, the microfluidic electrospray method endowed the obtaiend microspheres with sufficient size uniformity as well as magnetic responsive motion ability. Additionally, magnetic-mediated surface assembly of phase transition lysozyme (PTL) nanofilm on the microspheres rendered the deposited area hydrophilic while non-deposited area hydrophobic.

FINDINGS

Such magnetic Janus rGO/C composite microspheres with regionalized wettability characteristics not only showed prominent performance in adsorbing organic liquids with high adsorption capacity and remarkable reusability but also displayed satisfying biocompatibility for the efficient uptake of bilirubin. More encouragingly, the microspheres could serve as adsorbents in a simulative hemoperfusion setup, which further demonstrated the clinical application potential of the magnetic Janus rGO/C microspheres. Thus, we anticipate that the obtained magnetic Janus rGO/C composite microspheres could show multifunctional properties toward water treatment and blood molecule cleaning.

Development of tannin-bridged cerium oxide microcubes-chitosan cryogel as a multifunctional wound dressing

Efficient resolution of oxidative stress, inflammation, and bacterial infections is crucial for wound healing. To surmount these problems, tannic acid (TA)-bridged CeO₂ microcubes and chitosan (CS) (CS-TA@CeO₂) cryogel was fabricated through hydrogen bonding interactions as a multifunctional wound dressing. Successful introduction and uniform incorporation TA@CeO₂ microtubules enter the CS network. Thus-obtained CS-TA@CeO₂ cryogels displayed a suitable porous structure and swelling rate. Cryogels has excellent tissue adhesion, blood cell coagulation and hemostasis, anti-infection, and cell recruitment functions. In addition, the cryogel also showed good antibacterial activity against gram-positive bacteria and gram-negative bacteria. Based on the in vivo study of the multifunctional mixed cryogels, it promotes fibroblasts' adhesion and proliferation and significantly improves cell proliferation and tissue remodelling in wound beds. Furthermore, the chronic wound healing process in infected full-thickness skin defect models showed that cryogels significantly enhanced angiogenesis, collagen deposition and granulation tissue formation by providing a large amount of antioxidant activity. Therefore, this multifunctional mixed cryogels has potential clinical application value.

Two-dimensional material-based functional aerogels for treating hazards in the environment: synthesis, functional tailoring, applications, and sustainability analysis

Environmental pollution is a global problem that endangers human health and ecological balance. As a new type of functional material, two-dimensional material (2DM)-based aerogel is one of the most promising candidates for pollutant detection and environmental remediation. The porous, network-like, interconnected three-dimensional (3D) structure of 2DM-based aerogels can not only preserve the characteristics of the original 2DMs, but also bring many distinct physical and chemical properties to offer abundant active sites for adsorbing and combining pollutants, thereby facilitating highly efficient monitoring and treatment of hazardous pollutants. In this review, the synthesis methods of 2DM aerogels and their broad environmental applications, including various sensors, adsorbents, and photocatalysts for the detection and treatment of pollutants, are summarized and discussed. In addition, the sustainability of 2DM aerogels compared to other water purification materials, such as activated carbon, 2DMs, and other aerogels are analyzed by the Sustainability Footprint method. According to the characteristics of different 2DMs, special focuses and perspectives are given on the adsorption properties of graphene, MXene, and boron nitride aerogels, as well as the sensing and photocatalytic properties of transition metal dichalcogenide/oxide and carbon nitride aerogels. This comprehensive work introduces the synthesis, modification, and functional tailoring strategies of different 2DM aerogels, as well as their unique characteristics of adsorption, photocatalysis, and recovery, which will be useful for the readers in various fields of materials science, nanotechnology, environmental science, bioanalysis, and others.

Biomedical applications of chitosan-graphene oxide nanocomposites

Chitosan (CS) and graphene oxide (GO) nanocomposites have received wide attention in biomedical fields due to the synergistic effect between CS which has excellent biological characteristics and GO which owns great physicochemical, mechanical, and optical properties. Nanocomposites based on CS and GO can be fabricated into a variety of forms, such as nanoparticles, hydrogels, scaffolds, films, and nanofibers. Thanks to the ease of functionalization, the performance of these nanocomposites in different forms can be further improved by introducing other functional polymers, nanoparticles, or growth factors. With this background, the current review summarizes the latest developments of CS-GO nanocomposites in different forms and compositions in biomedical applications including drug and biomacromolecules delivery, wound healing, bone tissue engineering, and biosensors. Future improving directions and challenges for clinical practice are proposed as well.

Bioadhesive hydrogel comprising bilirubin/β-cyclodextrin inclusion complexes promote diabetic wound healing

CONTEXT

Chronic non-healing diabetic wound therapy is an important clinical challenge. Manipulating the release of bioactive factors from an adhesive hydrogel is an effective approach to repair chronic wounds. As an endogenous antioxidant, bilirubin (BR) has been shown to promote wound healing. Nonetheless, its application is limited by its low water solubility and oxidative degradation.

OBJECTIVE

This study developed a bilirubin-based formulation for diabetic wound healing.

MATERIALS AND METHODS

Bilirubin was incorporated into β-CD-based inclusion complex (BR/β-CD) which was then loaded into a bioadhesive hydrogel matrix (BR/β-CD/SGP). Scratch wound assays were performed to examine the in vitro pro-healing activity of BR/β-CD/SGP (25 μg/mL of BR). Wounds of diabetic or non-diabetic rats were covered with BR or BR/β-CD/SGP hydrogels (1 mg/mL of BR) and changed every day for a period of 7 or 21 days. Histological assays were conducted to evaluate the in vivo effect of BR/β-CD/SGP.

RESULTS

Compared to untreated (18.7%) and BR (55.2%) groups, wound closure was more pronounced (65.0%) in BR/β-CD/SGP group. In diabetic rats, the wound length in BR/β-CD/SGP group was smaller throughout the experimental period than untreated groups. Moreover, BR/β-CD/SGP decreased TNF-α levels to 7.7% on day 3, and elevated collagen deposition and VEGF expression to 11.9- and 8.2-fold on day 14. The therapeutic effects of BR/β-CD/SGP were much better than those of the BR group. Similar observations were made in the non-diabetic model.

DISCUSSION AND CONCLUSION

BR/β-CD/SGP promotes wound healing and tissue remodelling in both diabetic and non-diabetic rats, indicating an ideal wound-dressing agent.

Enhanced mechanical properties and electrical conductivity of Chitosan/Polyvinyl Alcohol electrospun nanofibers by incorporation of graphene nanoplatelets

The subject of this paper is to develop a highly conductive Graphene nanoplatelets (GNPs)-Chitosan (CS)/Polyvinyl Alcohol (PVA) (GNPs-CP) nanofibers with excellent mechanical properties. An experimental study was designed to produce nanofibers based on CP nanofibers as matrix and GNPs as reinforcement materials. The microstructure and the surface morphology of the electrospun nanofibers along with their electrical and mechanical properties were examined to study the effect of GNPs content. The SEM results showed that the gradual increase in GNPs content led to a porous web like morphology with no bead. There is a decrease in the diameter of nanofibers by increasing the concentration of GNPs to 1 wt% GNPs from 370 ± 40 nm for CP blend to 144 ± 18 nm for 1 wt% GNPs. Transmission electron microscopy results depicted that GNPs were dispersed uniformly confirmed by the absence of characteristic peak of graphite at 2θ = 26.5°. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy results indicate the occurrence of a few interactions between GNPs and CP matrix. Nitrogen adsorption/desorption measurement demonstrated that increasing GNPs content increased the specific surface area of nanofibers from 238.377 to 386.708 m²/g for 0 and 1 wt% GNPs content. The test results also show that the presence of GNPs considerably enhances tensile strength, elastic modulus and electrical conductivity. Furthermore, the toughness of GNPs-CP nanofibers including 1 wt% GNPs significantly improved (12-fold) compared to the one for CP nanofibers. So, the proposed composite provides a decent functionality for nanofibers as scaffolds in tissue engineering applications.

Hierarchical core-shell nanoplatforms constructed from Fe3O4@C and metal-organic frameworks with excellent bilirubin removal performance

Hemoperfusion has become the third-generation treatment strategy for patients suffering from hyperbilirubinemia, but adsorbents used for bilirubin removal mostly face intractable problems, such as unsatisfactory adsorption performance and poor hemocompatibility. Metal-organic frameworks (MOFs) are promising adsorbents for hemoperfusion due to their high specific surface areas and easily modified organic ligands. However, their microporous properties and separation have hampered their application. Here, a novel hierarchical core-shell nanoplatform (named Double-PEG) with tailored binding sites and pore sizes based on Fe3O4@C and Uio66-NH2 was constructed. Notably, Double-PEG showed excellent bilirubin uptake of up to 1738.30 mg g-1 and maintained excellent bilirubin removal efficiency in simulated biological solutions. A study on the adsorption mechanism showed that the adsorption of Double-PEG towards bilirubin tended to be chemical adsorption and in accordance with the Langmuir model. Besides, the good separability, recyclability, cytotoxicity and hemocompatibility of Double-PEG show great potential in hemoperfusion therapy. The finding of this study may provide a novel insight into the application of MOF materials in the field of hemoperfusion.

Graphene-Based Materials Immobilized within Chitosan: Applications as Adsorbents for the Removal of Aquatic Pollutants

Graphene and its derivatives, especially graphene oxide (GO), are attracting considerable interest in the fabrication of new adsorbents that have the potential to remove various pollutants that have escaped into the aquatic environment. Herein, the development of GO/chitosan (GO/CS) composites as adsorbent materials is described and reviewed. This combination is interesting as the addition of graphene to chitosan enhances its mechanical properties, while the chitosan hydrogel serves as an immobilization matrix for graphene. Following a brief description of both graphene and chitosan as independent adsorbent materials, the emerging GO/CS composites are introduced. The additional materials that have been added to the GO/CS composites, including magnetic iron oxides, chelating agents, cyclodextrins, additional adsorbents and polymeric blends, are then described and discussed. The performance of these materials in the removal of heavy metal ions, dyes and other organic molecules are discussed followed by the introduction of strategies employed in the regeneration of the GO/CS adsorbents. It is clear that, while some challenges exist, including cost, regeneration and selectivity in the adsorption process, the GO/CS composites are emerging as promising adsorbent materials.

Highly Efficient Adsorption of Bilirubin by Ti3 C2 Tx MXene

We discovered that the 2D Ti₃ C₂ T_x MXene sheet displays an ultra-high removal capability for bilirubin (BR). In particular, MXene shows 47.6 times higher removal efficiency over traditional activated carbon absorbents. The effect of MXene on the removal rate of BR in BR solution containing different concentrations of bovine serum albumin (BSA) was studied. The adsorption capacity of BSA for BR at high concentration of 5 g L^-1 was about 85% of the best adsorption capacity. The MXene before and after adsorption was characterized by SEM, FT-IR and XPS. Furthermore, MXene beads were prepared, and the hemoperfusion simulation experiment was carried out. The results show that the adsorption capacity of MXene for bilirubin can reach 1192.9 mg g^-1 . This study suggests that MXene may be promising in the treatment of hyperbilirubinemia.

Elimination of Uremic Toxins by Functionalized Graphene-Based Composite Beads for Direct Hemoperfusion

Conventional absorbents for hemoperfusions suffer from low efficiency and slow absorption with numerous side effects. In this research, we developed cellulose acetate (CA) functionalized graphene oxide (GO) beads (∼1.5-2 mm) that can be used for direct hemoperfusion, aiming at the treatment of kidney dysfunction. The CA-functionalized GO bead facilitates adsorption of toxins with high biocompatibility and high-efficiency of hemoperfusion while maintaining high retention for red blood cell, white blood cells, and platelets. Our in vitro results show that the toxin concentration for creatinine reduced from 0.21 to 0.12 μM (p < 0.005), uric acid from 0.31 to 0.15 mM (p < 0.005), and bilirubin from 0.36 to 0.09 mM (p < 0.005), restoring to normal levels within 2 h. Our in vivo study on rats (Sprague-Dawley, n = 30) showed that the concentration for creatinine reduced from 83.23 to 54.87 μmol L^-1 (p < 0.0001) and uric acid from 93.4 to 54.14 μmol L^-1 (p < 0.0001), restoring to normal levels within 30 min. Results from molecular dynamics (MD) simulations using free-energy calculations reveal that the presence of CA on GO increases the surface area for adsorption and enhances penetration of toxins in the binding cavities because of the increased electrostatic and van der Waals force (vdW) interactions. These results provide critical insight to fabricate graphene-based beads for hemoperfusion and to have the potential for the treatment of blood-related disease.

Preparation of aerogel beads and microspheres based on chitosan and cellulose for drug delivery: A review

Spherical aerogels are not easily broken during use and are easier to transport and store which can be used as templates for drug delivery. This review summarizes the possible approaches for the preparation of aerogel beads and microspheres based on chitosan and cellulose, an overview to the methods of manufacturing droplets is presented, afterwards, the transition mechanisms from sol to a spherical gel are reviewed in detail followed by different drying processes to obtain spherical aerogels with porous structures. Additionally, a specific focus is given to aerogel beads and microspheres to be regarded as drug delivery carriers. Furthermore, a core/shell architecture of aerogel beads and microspheres for controlled drug release is described and subjected to inspire readers to create novel drug release system. Finally, the conclusions and outlooks of aerogel beads and microspheres for drug delivery are summarized.

Porous Aromatic Framework with Tailored Binding Sites and Pore Sizes as a High-Performance Hemoperfusion Adsorbent for Bilirubin Removal

Highly efficient removal of bilirubin from blood by hemoperfusion for liver failure therapy remains a challenge in the clinical field due to the low adsorption capacity and slow adsorption kinetics of currently used bilirubin adsorbents (e.g., activated carbon and ion-exchange resin). Recently, porous aromatic frameworks (PAFs) with high surface areas, tunable structures, and remarkable stability provide numerous possibilities to obtain satisfying adsorbents. Here, a cationic PAF with more mesopores, named iPAF-6, is successfully constructed via a de novo synthetic strategy for bilirubin removal. The prepared iPAF-6 exhibits a record-high adsorption capacity of 1249 mg g-1 and can adsorb bilirubin from 150 mg L-1 to normal concentration in just 5 min. Moreover, iPAF-6 shows a removal efficiency of 96% toward bilirubin in the presence of 50 g L-1 bovine serum albumin. It is demonstrated that positively charged aromatic frameworks and large pore size make a significant contribution to its excellent adsorption ability. More notably, iPAF-6/polyethersulfone composite fibers or beads are fabricated for practical hemoperfusion adsorption, which also show better removal performance than commercial adsorbents. This work can offer a new possibility for designing PAF-based bilirubin adsorbents with an appealing application prospect.

Green fabrication of Cu/rGO decorated SWCNT buckypaper as a flexible electrode for glucose detection

As a paper-like membrane composed of single-walled carbon nanotube (SWCNT), buckypaper possesses high conductivity, ideal flexibility, large surface area, great thermal/chemical stability and biocompatibility, which has manifested its potential as an alternative support material. However, due to the lack of defects, high quality SWCNT synthesized by arc-discharge method is difficult to be modified with metal nanoparticles for electro-catalysis. In this paper, a novel green strategy has been developed to fabricate SWCNT buckypaper decorated with Cu/reduced graphene oxide (Cu/rGO-BP) for the first time, in which graphene oxide functions as the intermediate between SWCNT and Cu nanoparticles. The fabricated Cu/rGO-BP was applied as a flexible electrode for electrochemical glucose detection. The electrode exhibited excellent electro-catalytic activity for glucose oxidation. The sensor based on Cu/rGO-BP performed a high upper limit of linear range (25 mM), which is close to commercial glucose sensors. The proposed strategy for Cu/rGO-BP fabrication can be extended to modify buckypaper with other metal or metal oxide nanoparticles, and thus opens an innovative route to potential practical applications of flexible buckypaper in wearable bioelectronics.

Porous Fiber Processing and Manufacturing for Energy Storage Applications

The objective of this article is to provide an overview on the current development of micro- and nanoporous fiber processing and manufacturing technologies. Various methods for making micro- and nanoporous fibers including co-electrospinning, melt spinning, dry jet-wet quenching spinning, vapor deposition, template assisted deposition, electrochemical oxidization, and hydrothermal oxidization are presented. Comparison is made in terms of advantages and disadvantages of different routes for porous fiber processing. Characterization of the pore size, porosity, and specific area is introduced as well. Applications of porous fibers in various fields are discussed. The emphasis is put on their uses for energy storage components and devices including rechargeable batteries and supercapacitors.

Layer-by-layer deposition of bioactive layers on magnesium alloy stent materials to improve corrosion resistance and biocompatibility

Magnesium alloy is considered as one of the ideal cardiovascular stent materials owing to its good mechanical properties and biodegradability. However, the in vivo rapid degradation rate and the insufficient biocompatibility restrict its clinical applications. In this study, the magnesium alloy (AZ31B) was modified by combining the surface chemical treatment and in-situ self-assembly of 16-phosphonyl-hexadecanoic acid, followed by the immobilization of chitosan-functionalized graphene oxide (GOCS). Heparin (Hep) and GOCS were alternatively immobilized on the GOCS-modified surface through layer by layer (LBL) to construct the GOCS/Hep bioactive multilayer coating, and the corrosion resistance and biocompatibility were extensively explored. The results showed that the GOCS/Hep bioactive multilayer coating can endow magnesium alloys with an excellent in vitro corrosion resistance. The GOCS/Hep multilayer coating can significantly reduce the hemolysis rate and the platelet adhesion and activation, resulting in an excellent blood compatibility. In addition, the multilayer coating can not only enhance the adhesion and proliferation of the endothelial cells, but also promote the vascular endothelial growth factor (VEGF) and nitric oxide (NO) expression of the attached endothelial cells on the surfaces. Therefore, the method of the present study can be used to simultaneously control the corrosion resistance and improve the biocompatibility of the magnesium alloys, which is expected to promote the application of magnesium alloys in biomaterials or medical devices, especially cardiovascular stent.

•

The multilayer coating of GOCS and heparin was constructed on magnesium surface.

•

The coating can obviously improve the corrosion resistance of magnesium alloys.

•

The coating can enhance the hemocompatibility and endothelial cell growth behaviors.