Facile hydrothermal synthesis of branched polyethylenimine grafted electrospun polyacrylonitrile fiber membrane as a highly efficient and reusable bilirubin adsorbent in hemoperfusion

Recent progress in the development of encapsulated fertilizers for time-controlled release

This review describes the latest achievements in the development of encapsulated controlled-release fertilizers, which encompasses sustainability issues in agriculture. The research community's interest in this particular area of science has doubled over the last couple of years due to the yearly increasing complexity of the food and supply situation, as well as maintaining the development of modern society in the era of population outbreak. This review covers demand in timely systematization and comprehensive analysis of emerging research in so-called "smart fertilizers" that release mineral components in accordance with the needs for nutrients classified into controlled- and slow-release fertilizers (CRFs and SRFs). Along with the thoroughly selected fundamental studies published in this area, the review specially focuses on the materials-based classification, emphasizing the importance of the host matrix in the time-controlled release of dopant. This substantially differentiates our review and renders scientific novelty and relevancy to it. The review is divided into sections, dealing with the types of slow- and controlled-release fertilizers each, and supplemented with the critical view on their usage. All data regarding encapsulated fertilizers in this review are systematized for the convenience of the readership when becoming familiarized with the latest achievements in this area. Perspectives and potential pathways are also described to recommend and guide researchers working on the related academic fields.

An Evolutionary Review of Hemoperfusion Adsorbents: Materials, Preparation, Functionalization, and Outlook

Accumulation of pathogenic factors in the blood may cause irreversible damage and may even be life-threatening. Hemoperfusion is an effective technique for eliminating pathogenic factors, which is widely used in the treatment of various diseases including liver failure, renal failure, sepsis, and others. Hemoperfusion adsorbents are crucial in this process as they specifically bind and remove the target pathogenic factors. This review describes the development of hemoperfusion adsorbents, detailing the different properties exhibited by inorganic materials, organic polymers, and new materials. Advances in natural and synthetic polymers and novel materials manufacturing techniques have driven the expansion of hemoperfusion adsorbents in clinical applications. Stimuli-responsive (smart responsive) adsorbents with controllable molecular binding properties have many promising and environmentally friendly biomedical applications. Knowledge gaps, future research directions, and prospects for hemoperfusion adsorbents are discussed.

Theory-Driven Tailoring of the Microenvironment of Quaternary Ammonium Binding Sites on Electrospun Nanofibers for Efficient Bilirubin Removal in Hemoperfusion

Efficient adsorbents for excess bilirubin removal are extremely important for the treatment of hyperbilirubinemia. However, traditional adsorbents, such as activated carbons and ion-exchange resins, still suffer from dissatisfactory adsorption performance and poor blood compatibility. Herein, we adopted a rational design strategy guided by density functional theory (DFT) calculations to prepare blood-compatible quaternary ammonium group grafted electrospun polyacrylonitrile nanofiber adsorbents. The calculation analysis and adsorption experiments were used to investigate the structure-function relationship between group types and bilirubin adsorption, both indicating that quaternary ammonium groups with suitable configurations played a crucial role in bilirubin binding. The obtained nanofiber adsorbents showed the bilirubin removal efficiency above 90% even at a coexisting BSA concentration of 50 g L-1. The maximum adsorption capacities were 818.9 mg g-1 in free bilirubin solution and 163.7 mg g-1 in albumin bound bilirubin solution. The nanofiber adsorbents also showed considerable bilirubin removal in dynamic adsorption to reduce the bilirubin concentration to a normal level, which was better than commercial activated carbons. Our study demonstrates the high feasibility of a theory-driven design method for the development of grafted electrospun nanofibers, which have good potential as bilirubin adsorbents in hemoperfusion applications.

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.

Preparation of chitin/MXene/poly(L-arginine) composite aerogel spheres for specific adsorption of bilirubin

Currently, hemoperfusion is clinically the most rapid and effective treatment for removing toxins from the blood. The core of hemoperfusion is the sorbent inside the hemoperfusion device. Due to the complex composition of the blood, adsorbents tend to adsorb substances such as proteins in the blood (non-specific adsorption) while adsorbing toxins. Hyperbilirubinemia is caused by excessive levels of bilirubin in the human blood, causing irreversible damage to the patient's brain and nervous system, and even leading to death. High adsorption and high biocompatibility adsorbents with specific bilirubin adsorption are urgently needed to treat hyperbilirubinemia. Herein, poly(L-arginine) (PLA) which can specifically adsorb bilirubin, was introduced into chitin/MXene (Ch/MX) composite aerogel spheres. Ch/MX/PLA prepared by supercritical CO₂ technology had higher mechanical properties than Ch/MX and can withstand 50,000 times its own weight. The in vitro simulated hemoperfusion test showed that the adsorption capacity of Ch/MX/PLA was as high as 596.31 mg/g, which was 15.38 % higher than that of Ch/MX. Binary and ternary competitive adsorption tests showed that Ch/MX/PLA also had good adsorption capacity in the presence of a variety of interfering molecules. In addition, hemolysis rate testing and CCK-8 testing confirmed that Ch/MX/PLA had better biocompatibility and hemocompatibility. Ch/MX/PLA can meet the required properties of clinical hemoperfusion sorbents and has the ability to produce mass production. It has good application potential in the clinical treatment of hyperbilirubinemia.

Advances in Enhancing Hemocompatibility of Hemodialysis Hollow-Fiber Membranes

Hemodialysis, the most common modality of renal replacement therapy, is critically required to remove uremic toxins from the blood of patients with end-stage kidney disease. However, the chronic inflammation, oxidative stress as well as thrombosis induced by the long-term contact of hemoincompatible hollow-fiber membranes (HFMs) contribute to the increase in cardiovascular diseases and mortality in this patient population. This review first retrospectively analyzes the current clinical and laboratory research progress in improving the hemocompatibility of HFMs. Details on different HFMs currently in clinical use and their design are described. Subsequently, we elaborate on the adverse interactions between blood and HFMs, involving protein adsorption, platelet adhesion and activation, and the activation of immune and coagulation systems, and the focus is on how to improve the hemocompatibility of HFMs in these aspects. Finally, challenges and future perspectives for improving the hemocompatibility of HFMs are also discussed to promote the development and clinical application of new hemocompatible HFMs.

Graphical Abstract

MOFs-alginate/polyacrylic acid/poly (ethylene imine) heparin-mimicking beads as a novel hemoadsorbent for bilirubin removal in vitro and vivo models

Metal-organic frameworks (MOFs) have a potential application in blood purification, but their microcrystalline nature has hampered their industrial application. Here, novel MOFs-polymer beads based on UiO, sodium alginate, polyacrylic acid, and poly (ethylene imine) were prepared and applied as a whole blood hemoadsorbent for the first time. The amidation among polymers immobilized UiO66-NH₂ into the network of the optimal product (SAP-3), and the NH₂ of UiO66-NH₂ significantly increased the removal rate (70 % within 5 min) of SAP-3 on bilirubin. The adsorption of SAP-3 on bilirubin mainly obeyed the pseudo-second-order kinetic, Langmuir isotherm and Thomas models with a maximum adsorption capacity (q_m) of 63.97 mg·g^-1. Experimental and density functional theory simulation results show that bilirubin was mainly adsorbed by UiO66-NH₂via electrostatic force, hydrogen bonding, and π-π interactions. Notably, the adsorption in vivo show that the total bilirubin removal rate in the whole blood of the rabbit model was up to 42 % after 1 h of adsorption. Given its excellent stability, cytotoxicity, and hemocompatibility, SAP-3 has a great potential in hemoperfusion therapy. This study proposes an effective strategy for settling the powder property of MOFs and could provide experimental and theoretical references for application of MOFs in blood purification.

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.

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.

Recent Progress in Electrospun Polyacrylonitrile Nanofiber-Based Wound Dressing

Bleeding control plays a very important role in worldwide healthcare, which also promotes research and development of wound dressings. The wound healing process involves four stages of hemostasis, inflammation, proliferation and remodeling, which is a complex process, and wound dressings play a huge role in it. Electrospinning technology is simple to operate. Electrospun nanofibers have a high specific surface area, high porosity, high oxygen permeability, and excellent mechanical properties, which show great utilization value in the manufacture of wound dressings. As one of the most popular reactive and functional synthetic polymers, polyacrylonitrile (PAN) is frequently explored to create nanofibers for a wide variety of applications. In recent years, researchers have invested in the application of PAN nanofibers in wound dressings. Research on spun nanofibers is reviewed, and future development directions and prospects of electrospun PAN nanofibers for wound dressings are proposed.

Biocompatible Composite Microspheres of Chitin/Ordered Mesoporous Carbon CMK3 for Bilirubin Adsorption and Cell Microcarrier Culture

Extra bilirubin in the blood can provoke serious illness in patients with severe liver disease. Hemoperfusion is an effective method to remove the extra bilirubin, but its application is limited by the low adsorption efficiency and poor biocompatibility of available adsorbent materials. In this study, chitin/ordered mesoporous carbon CMK3 (Ch/CMK3) microspheres were successfully prepared. Results of characterization experiments indicated that these composite microspheres possess a multilayered porous nanofibrous structure with an extremely large specific surface area (300.19 m² g^-1 ) and large pore size. Notably, the Ch/CMK3 microspheres demonstrated a high bilirubin adsorption capacity (228.19 mg g^-1 ) in phosphate buffer solution, and an outstanding bilirubin removal ratio (76.78%±4.40%) in the plasma of rabbits with hyperbilirubinemia without affecting the protein components. More importantly, the Ch/CMK3 microspheres showed no effect on other blood components, no cytotoxicity, and no systemic toxicity to mice. Cell coculture experiments revealed that the microspheres could provide a three-dimensional (3D) space to promote cell adhesion, proliferation, and nutrient exchange. These Ch/CMK3 microspheres featuring a strong ability for bilirubin adsorption and good biocompatibility could be a promising candidate in biomedical applications such as hemoperfusion, cell microcarrier, and 3D tissue engineering. This article is protected by copyright. All rights reserved.

Mussel-Inspired Fabrication of PDA@PAN Electrospun Nanofibrous Membrane for Oil-in-Water Emulsion Separation

Emulsified oily wastewater threatens human health seriously, and traditional technologies are unable to separate emulsion containing small sized oil droplets. Currently, oil-water emulsions are usually separated by special wettability membranes, and researchers are devoted to developing membranes with excellent antifouling performance and high permeability. Herein, a novel, simple and low-cost method has been proposed for the separation of emulsion containing surfactants. Polyacrylonitrile (PAN) nanofibers were prepared via electrospinning and then coated by polydopamine (PDA) by using self-polymerization reactions in aqueous solutions. The morphology, structure and oil-in-water emulsion separation properties of the as-prepared PDA@PAN nanofibrous membrane were tested. The results show that PDA@PAN nanofibrous membrane has superhydrophilicity and almost no adhesion to crude oil in water, which exhibits excellent oil-water separation ability. The permeability and separation efficiency of n-hexane/water emulsion are up to 1570 Lm-2 h-1 bar-1 and 96.1%, respectively. Furthermore, after 10 cycles of separation, the permeability and separation efficiency values do not decrease significantly, indicating its good recycling performance. This research develops a new method for preparing oil-water separation membrane, which can be used for efficient oil-in-water emulsion separation.

Molecularly-imprinted hydrogel beads via self-sacrificing micro-reactors as safe and selective bilirubin adsorbents

For patients who are suffering from liver dysfunction or metabolic obstruction, excessive bilirubin (BIL) in their bodies may cause jaundice with irreversible cerebral injury. Traditional exchange transfusion and photodynamic therapy pose a risk of serious adverse reactions or limited curative effects. Therefore, as a generally used treatment, hemoperfusion (HP) purifies patients' blood with solid adsorbents. However, the development of clinical BIL absorbents is greatly impeded by low selectivity and unsatisfactory blood compatibility. Herein, inspired by oviparity, we propose BIL-imprinted poly(acrylic acid-co-sodium p-styrenesulfonate)-reduced graphene oxide (PAA-SS-rGO@BIL) hydrogel beads as BIL adsorbents via self-sacrificing micro-reactors. In the micro-reactors, cross-linked polymerization is achieved and a solidified gel is formed. The received hydrogel beads show outstanding selective adsorption capabilities toward BIL due to the recognition sites, and π-π and hydrophobic interactions. Such hydrogel beads possess superior blood compatibility owing to their bioinspired heparin-mimicking gel structure. Simulated BIL selective adsorption experiments in vitro demonstrate that the BIL concentrations in the plasma of a patient with severe jaundice can be restored to a moderate level within 3 hours. Therefore, hydrogel beads offer new options for clinical BIL adsorption.

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.

Electrospun cationic nanofiber membranes for adsorption and determination of Cr(vi) in aqueous solution: adsorption characteristics and discoloration mechanisms

In this study, a novel cationic nanofiber membrane with various functional groups, good structural stability, and high adsorption capacity of Cr(vi) is presented. This nanofiber membrane is prepared by electrospinning a mixed aqueous solution of a cationic polycondensate (CP) and polyvinyl alcohol (PVA). With the aid of PVA, CP can be smoothly electrospun without using any organic solvents, and the cross-linking between CP and PVA improves the stability of membrane in acidic solution. Chemical and morphology characterization reveals that the CP/PVA membrane is composed of interwoven nanofibers that contain numerous cationic groups. Due to its high cationicity and hydrophilicity, the CP/PVA membrane shows great affinity for HCr₂O₇⁻ and Cr₂O₇²⁻. Adsorption experiments indicate that the CP/PVA membrane can remove Cr(vi) from simulated wastewater rapidly and efficiently in both batch and continuous mode. Besides, the presence of most coexisting ions will not interfere with the adsorption. Due to the redox reaction between the CP/PVA membrane and adsorbed Cr(vi), the CP/PVA membrane exhibits distinct color change after Cr(vi) adsorption and the discoloration is highly dependent on the adsorption amount. Therefore, in addition to serving as a highly efficient adsorbent, the CP/PVA membrane is also expected to be a convenient and low-cost method for semi-quantitative determination of Cr(vi) in wastewater.

Cationic nanofiber membranes are prepared by electrospinning mixed aqueous solution of a cationic polycondensate (CP) and PVA. Apart from being a highly efficient Cr(vi) adsorbent, it can also serve as a convenient method for Cr(vi) determination.

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.

Metal-Organic Framework Traps with Record-High Bilirubin Removal Capacity for Hemoperfusion Therapy

Adsorption-based hemoperfusion has been widely used to remove toxins from the blood of patients suffering acute liver failure (ALF). However, its detoxification effect has been severely hampered by the unsatisfactory adsorption performance of clinically used porous adsorbents, such as activated carbon (AC) and adsorption resin. Herein, two cage-based metal-organic frameworks (MOFs), PCN-333 (constructed from 4,4,4-s-triazine-2,4,6-triyl-tribenzoic acid (H₃TATB) ligands and Al₃ metal clusters) and MOF-808 (constructed from 1,3,5-benzenetricarboxylic acid (H₃BTC) ligands and Zr₆ metal clusters), are introduced for highly efficient hemoperfusion. They possess negligible hemolytic activity and can act as "bilirubin traps" to achieve outstanding adsorption performance toward bilirubin, a typical toxin related to ALF. Notably, PCN-333 shows a record-high adsorption capacity (∼1003.8 mg g^-1) among various bilirubin adsorbents previously reported. More importantly, they can efficiently adsorb bilirubin in bovine serum albumin (BSA) solution or even in 100% fetal bovine serum (FBS) due to their high selectivity. Strikingly, the adsorption rate and capacity of PCN-333 in biological solutions are approximately four times faster and 69 times higher than those of clinical AC, respectively. Findings in this work pave a new avenue to overcome the challenge of low adsorption efficiency and capacity in hemoperfusion therapy.

Electrospun Weak Anion-exchange Fibrous Membranes for Protein Purification

Membrane based ion-exchange (IEX) and hydrophobic interaction chromatography (HIC) for protein purification is often used to remove impurities and aggregates operated under the flow-through mode. IEX and HIC are also limited by capacity and recovery when operated under bind-and-elute mode for the fractionation of proteins. Electrospun nanofibrous membrane is characterized by its high surface area to volume ratio and high permeability. Here tertiary amine ligands are grafted onto the electrospun polysulfone (PSf) and polyacrylonitrile (PAN) membrane substrates using UV-initiated polymerization. Static and dynamic binding capacities for model protein bovine serum albumin (BSA) were determined under appropriate bind and elute buffer conditions. Static and dynamic binding capacities in the order of ~100 mg/mL were obtained for the functionalized electrospun PAN membranes whereas these values reached ~200 mg/mL for the functionalized electrospun PSf membranes. Protein recovery of over 96% was obtained for PAN-based membranes. However, it is only 56% for PSf-based membranes. Our work indicates that surface modification of electrospun membranes by grafting polymeric ligands can enhance protein adsorption due to increased surface area-to-volume ratio.

Construction of a phosphate-rich polyacrylonitrile fiber surface microenvironment for efficient purification of crystal violet wastewater

Wastewater purification using fibrous adsorbents has received much attention due to their high efficiency, low cost, and recyclability. In this work, phosphate modified polyacrylonitrile fiber (B-PANEAPF) was prepared and used to remove cationic dyes. The B-PANEAPF showed the best adsorption capacity for crystal violet (CV) when compared with rhodamine B, methyl green, Victoria blue B, methylene blue, and neutral red. The adsorption tests revealed that the fiber possessed high adsorption efficiency and achieved semi-saturated adsorption within 15 min. The maximum adsorption capacity of 354.46 mg g-1 as calculated by the Langmuir adsorption model was higher than many other adsorbents. Furthermore, the B-PANEAPF was used to remove 210 mL of CV in a continuous-flow process with a high removal efficiency over 90%. Besides, the phosphate functionalized fiber could easily decrease the concentration of CV to below 0.5 mg L-1 which is below the maximum effluent discharge standard of 15 mg L-1 prescribed in China. It could also be fully recovered and easily separated from the solution to achieve re-use 10 cycles. Moreover, the adsorption mechanism indicated that the adsorption process of the fiber for CV was mainly attributed to electrostatic interaction and hydrogen bonding. In conclusion, the results suggested that the B-PANEAPF characterized by its simplicity, efficiency, eco-friendliness, and reusability, could be a promising candidate for CV removal.

Hyperbranched thiourea-grafted electrospun polyacrylonitrile fibers for efficient and selective gold recovery

Research on the recovery of precious metals (including gold, Au), attracts attention of scientists worldwide. This paper reports synthesis of a novel fiber adsorbent consisting of hyperbranched thiourea-grafted electrospun polyacrylonitrile (HS-PAN) for Au(III) ion recovery. High-density functional groups of the hyperbranched structure allowed HS-PAN fibers to exhibit much higher affinity and selectivity towards Au(III) than towards Pt(IV), Cr(VI), Pb(II), Ni(II), Co(II), Fe(III), Mg(II), Cu(II) and Na(I). Au(III) adsorption proceeded according to the pseudo-second-order kinetic model and could be fitted very well using Langmuir isotherm. The maximum adsorption capacity of these fibers relative to Au(III) was 3257.3 mg/g, which is higher than the values reported in the literature for other Au(III) adsorbents. Our novel HS-PAN fibers can extract Au from real electronic waste with 99% recovery yield in just 1 h. Thus, this study demonstrates a very efficient and low-cost way to recover gold.

Hemocompatible hemoadsorbent for effective removal of protein-bound toxin in serum

Resin hemoperfusion is a life-saving treatment for drug intoxication or hepatic failure of patients. However, current resin adsorbents exhibit a limited hemocompatibility or low adsorption efficiency, representing a major roadblock to successful clinical applications. In this work, we developed a hemocompatible and effective hemoadsorbent based on polystyrene resin (H103) microparticles encapsulated in anti-biofouling zwitterionic poly(carboxybetaine) (PCB) hydrogels. Apart from a strong mechanical stability, this PCB-based adsorbent (PCB-H103) exhibited excellent hemocompatibility (hemolysis ratio was ∼0.64%), which was attributed to the anti-biofouling property of PCB hydrogel. In addition, it can efficiently adsorb both small and middle molecular weight molecules in phosphate-buffered saline, and the efficiencies were significantly higher than poly(ethylene glycol) methacrylate-based and poly(2-hydroxyethyl methacrylate)-based adsorbent counterparts, indicating the favorable permeability of PCB hydrogel coating. More importantly, PCB-H103 could effectively remove protein-bound toxins including phenol red and bilirubin in bovine serum albumin solution or even in 100% fetal bovine serum (FBS). In 100% FBS, the adsorption capacity of PCB-H103 towards bilirubin was 8.3 times higher than that of pristine clinical-scale resin beads. Findings in this work may provide a new strategy for the development of modern resin hemoperfusion technology.

Fabrication of Organic Hec Nanocomposites Modified with Lysine as a Potential Adsorbent for Bilirubin Removal

As one of the typical phyllosilicate clays, hectorite (Hec) has some excellent characteristics and has been greatly applied in adsorption field for the removal of dye, endotoxin, etc. In this study, organic Hec nanocomposites modified with L-Lysine (Lys/Hec NCs) were prepared via solution intercalation method for BR removal. The effects of ionic strength, pH values, initial concentration of BR, and BSA concentration on the adsorption capacity for BR of Lys/Hec NCs were investigated. Results indicated that the adsorption capacity for BR of nanocomposites could reach 40 mg/g when the initial bilirubin concentration was 200 mg/L. However, the adsorption amount of Lys/Hec NCs decreased with increasing the concentration of BSA, but Lys/Hec NCs could still maintain a higher adsorption rate. The adsorption kinetics and adsorption isotherms indicated that the adsorption process of Lys/Hec NCs agreed well with the pseudo-second-order model and the Langmuir isotherm, respectively. Moreover, Lys/Hec NCs also exhibited excellent cytocompatibility. These obtained results demonstrate that Lys/Hec NCs prepared in this study had great potential to be used in hemoperfusion.

Multi-functional wool fabrics by graft-copolymerisation with polystyrene sulphonate: their enhanced fire retardancy, mechanical properties, and stain-resistance

pSS-Grafted wool fabrics showed enhanced fire retardancy, tensile strength and stain-resistance against an acid dye-based stain.