Antifouling zwitterionic hydrogel coating improves hemocompatibility of activated carbon hemoadsorbent

Polycarboxybetaine in advanced drug delivery systems: From structure-function relationship to therapeutic applications

Zwitterionic polycarboxybetaines (PCBs), combining quaternary ammonium cations and carboxylate anions in their repeating units, have emerged as promising materials for drug delivery applications. Their exceptional hydration, biocompatibility, and antifouling properties make them attractive alternatives to polyethylene glycol (PEG), particularly given growing concerns about immunogenicity of PEG. PCBs can be functionalized through various methods, including modification of side-chain moieties, adjustment of spacer length between charged groups, and incorporation of responsive elements. When applied to delivery drug, PCBs have been successfully developed into multiple formats including micelles, hydrogels, liposomes, and nanoparticles. Notably, in protein drug delivery, PCBs demonstrate significant advantages such as enhancing protein stability, extending circulation time, improving penetration through biological barriers, and reducing immunogenicity. Despite these promising features, several challenges remain, including complex synthesis requirements, limited mechanical properties, and pending FDA approval as pharmaceutical excipients. This review provides a comprehensive analysis of PCBs from the structure-function relationship, synthesis methods, and applications in drug delivery systems, while examining current limitations and future prospects.

Microfibrillated cellulose reinforced polyethyleneimine cryogels fabricated via cryo-induced chemical crosslinking for enhanced removal of albumin-bound bilirubin

Bilirubin exists as albumin-bound complexes in the bloodstream of patients with hyperbilirubinemia. Developing adsorbents with high removal efficiency for albumin-bound bilirubin and excellent hemocompatibility is essential for effective hemoperfusion therapy. Herein, microfibrillated cellulose-reinforced polyethyleneimine cryogels (PEI/MFC) with robust mechanical properties were fabricated through cryo-induced chemical crosslinking, using bis(vinylsulphonyl)methane (BVSM) as chemical cross-linker. The cryogel showed excellent fatigue resistance, retaining its shape after 100 underwater compression-decompression cycles at 80 % strain. The inherent properties of raw materials confer the PEI/MFC cryogel with exceptional blood compatibility in hemolysis, coagulation, and blood cell adhesion. Compared with conventional materials modified with PEI, our innovative PEI/MFC cryogel presents a higher density of amino groups, resulting in superior removal efficacy for bilirubin. The PEI/MFC cryogel achieved a remarkable removal efficiency of 99.6 % for free bilirubin and 64.3 % for albumin-bound bilirubin, at bilirubin concentrations of 200 mg/L and cryogel dosages of 2 mg/mL. The maximum adsorption capacity for albumin-bound bilirubin was determined to be 210.5 mg/g, representing a notable achievement. Furthermore, fixed-bed column adsorptions exhibit a 50 % breakthrough volume of 760.9 mL/g for free bilirubin and 334.6 mL/g for albumin-bound bilirubin. The successful simulation of hemoperfusion using the PEI/MFC cryogel indicates its potential for the treatment of hyperbilirubinemia.

Chitosan/κ-Carrageenan/Carbon Nitride Hydrogel Adsorbent for Removing Free Hemoglobin from Extracorporeal Circulation

Extracorporeal circulation often causes mechanical damage to erythrocytes, which release hemoglobin into the plasma, resulting in postsurgical hazard, so lowering the free hemoglobin (f-Hb) level in the blood is important. In this study, based on the good biocompatibility of chitosan/κ-carrageenan and the adsorption effect of carbon nitride, a chitosan/κ-carrageenan/carbon nitride (CS/κ-Car/C3N4) hydrogel was prepared through the charge electrostatic interaction between polysaccharides. The incorporation of C3N4 enhanced both the adsorptive capacity and the stability of the hydrogel. Specifically, the CS/κ-Car/C3N4-0.4% hydrogel exhibited an adsorption amount of 185.79 mg/g for human hemoglobin, approximately twice that of the CS/κ-Car hydrogel. The CS/κ-Car/C3N4 hydrogel also showed a significantly lower breakage and degradation rate. In addition, the CS/κ-Car/C3N4 hydrogel did not induce hemolysis, complement activation, or coagulate when in contact with blood and showed good blood compatibility. Furthermore, in vivo studies in rabbits revealed that the CS/κ-Car/C3N4 hydrogel significantly reduced elevated f-Hb levels to near-normal concentrations postcirculation, without inducing any severe adverse effects on the subjects. This investigation has elucidated that the CS/κ-Car/C3N4 hydrogel possesses superior adsorptive efficacy and biocompatibility, effectively clearing f-Hb in vivo. Consequently, the findings of this study offer novel insights into the design paradigm for adsorbents intended for blood circulation applications.

Nanocellulose/activated carbon composite aerogel beads with high adsorption capacity for toxins in blood

Activated carbon is extensively utilized in blood purification applications. However, its performance has been significantly limited by their poor blood compatibility. In this work, 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCN) and activated carbon (AC) were used to form composite beads by the drop curing method to improve hemocompatibility. The TOCN/AC composite beads had porous surface and exhibited extraordinary adsorption properties. The beads had a high adsorption capacity for creatinine with the optimal adsorption capacity of 83.33 mg g-1. And the equilibrium adsorption of bilirubin, uric acid and Cu2+ by TOCN/AC beads was as high as 159.80 mg g-1, 114.61 mg g-1 and 154.0 mg g-1, respectively, with a mass ratio of TOCN to AC of 1:4. It is also observed that the adsorption behavior of TOCN/AC beads on creatinine was consistent with the second-order kinetics and Langmuir isothermal model. The hemolysis rate of TOCN/AC was 1.21 %, indicating that TOCN/AC beads had good blood compatibility. The clearance of creatinine toxin in blood by TOCN/AC beads was as high as 87 % within 90 min. Overall, our produced composite beads had great potential for application in the field of blood purification.

Hydrogel-Forming Microneedles and Applications in Interstitial Fluid Diagnostic Devices

Hydrogel-forming microneedles are constructed from or coated with polymeric, hydrophilic materials that swell upon insertion into the skin. Designed to dissolve or disintegrate postinsertion, these microneedles can deliver drugs, vaccines, or other therapeutics. Recent advancements have broadened their application scope to include the collection, transport, and extraction of dermal interstitial fluid (ISF) for medical diagnostics. This review presents a brief introduction to the characteristics of dermal ISF, methods for extraction and sampling, and critical assessment of the state-of-the-art in hydrogel-forming microneedles for ISF diagnostics. Key factors are evaluated including material composition, swelling behavior, biocompatibility, and mechanical strength necessary for effective microneedle performance and ISF collection. The review also discusses successful examples of dermal ISF assays and microneedle sensor integrations, highlighting notable achievements, identifying research opportunities, and addressing challenges with potential solutions. Despite the predominance of synthetic hydrogels in reported hydrogel-forming microneedle technologies due to their favorable swelling and gelation properties, there is a significant variety of biopolymers and composites reported in the literature. The field lacks consensus on the optimal material, composition, or fabrication methods, though emerging evidence suggests that processing and fabrication techniques are critical to the performance and utility of hydrogel-forming microneedles for ISF diagnostics.

Mesoporous activated carbon derived from Chinese herbal medicine residues for hemoperfusion removal of uremia toxins from progressive chronic kidney diseases patients

Hemoperfusion is one of the most important therapies for progressive chronic kidney disease (CKD) and is effective at removing toxins from the blood. Increasing the efficiency of adsorbents applied in hemoperfusion is crucial. In the present study, shell of areca nut, one of the most common waste Chinese herb medicine residue with a porous structure was carbonized and activated at different temperatures to obtain two kinds of porous materials. The biocompatibility of the as-prepared porous materials was estimated via a hemolytic test, and the removal efficiency of the materials toward toxins was tested via an adsorption experiment in solution and blood samples from CKD patients, simulated hemoperfusion and in vivo hemoperfusion. After 4 h of adsorption, free and protein-bound toxins in solution were efficiently removed by the prepared porous materials, and the removal efficiency was better than that of commonly used hemoperfutor adsorbents. Most of the tested toxins can be removed from CKD blood samples and simulated hemoperfusion samples. Blood uremic toxins from CKD mice were also efficiently and safely removed after in vivo hemoperfusion using the as-prepared adsorbent. This work highlights promising adsorbents for hemoperfusion that could increase the therapeutic efficacy in patients with progressive CKD.

Bioactive Carbon@CeO2 Composites as Efficient Antioxidants with Antiamyloid and Radioprotective Potentials

Blending carbon particles (CPs) and nanoscale bioactive cerium dioxide is a promising approach for designing composites for biomedical applications, combining the sorption and antioxidant potentials of each individual component. To address this issue, it is crucial to assess the correlation between the components' ratio, physicochemical parameters, and biofunctionality of the composites. Thus, the current research was aimed at fabricating C@CeO2 composites with different molar ratios and the examination of how the parameters of the composites affect their bioactivity. XRD, X-ray photoelectron spectroscopy, and electron microscopy data verified the formation of C@CeO2 composites. CeO2 nanoparticles (NPs) of 4-6 nm are highly dispersed on the surfaces of amorphous CPs. The presence of CeO2 NPs on the carbon surface decreased its adsorption potential in a dose-dependent manner. Besides, the coexistence of carbon and CeO2 in a single composite promotes some redox interactions between O-functionalities and Ce3+/Ce4+ species, resulting in changes in the chemical state of the surface of the composites. These observations suggest the strong connection between these parameters and the biofunctionality of the composites. The presence of CeO2 NPs on the surface of carbon led to a significant increase in the stability of the prepared composites in their aqueous suspensions. The enhancement of bioactivity of the newly prepared C@CeO2 compared to bare carbon and CeO2 was validated by testing their pseudomimetic (catalase/peroxidase-like and superoxide dismutase-like), antiamyloid, and radioprotective activities.

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.

Recent advances of multifunctional zwitterionic polymers for biomedical application

Zwitterionic polymers possess equal total positive and negative charges in the repeating units, making them electrically neutral overall. This unique property results in superhydrophilicity, which makes the zwitterionic polymers highly effective in resisting protein adsorption, thus endowing the drug carriers with long blood circulation time, inhibiting thrombus formation on biomedical devices in contact with blood, and ensuring the good sensitivity of sensors in biomedical application. Moreover, zwitterionic polymers have tumor-targeting ability and pH-responsiveness, rendering them ideal candidates for antitumor drug delivery. Additionally, the high ionic conductivity of zwitterionic polymers makes them an important raw material for ionic skin. Zwitterionic polymers exhibit remarkable resistance to bacterial adsorption and growth, proving their suitability in a wide range of biomedical applications such as ophthalmic applications, and wound dressings. In this paper, we provide an in-depth analysis of the different structures and characteristics of zwitterionic polymers and highlight their unique qualities and suitability for biomedical applications. Furthermore, we discuss the limitations and challenges that must be overcome to realize the full potential of zwitterionic polymers and present an optimistic perspective for zwitterionic polymers in the biomedical fields. STATEMENT OF SIGNIFICANCE: Zwitterionic polymers have a series of excellent properties such as super hydrophilicity, anti-protein adsorption, antibacterial ability and good ionic conductivity. However, biomedical applications of multifunctional zwitterionic polymers are still a major field to be explored. This review focuses on the design and application of zwitterionic polymers-based nanosystems for targeted and responsive delivery of antitumor drugs and cancer diagnostic agents. Moreover, the use of zwitterionic polymers in various biomedical applications such as biomedical devices in contact with blood, biosensors, ionic skin, ophthalmic applications and wound dressings is comprehensively described. We discuss current results and future challenges for a better understanding of multifunctional zwitterionic polymers for biomedical applications.

Preparing high-performance microspheres based on the chitosan-assisted dispersion of reduced graphene oxide in aqueous solution for bilirubin removal

The removal of excess bilirubin from blood is of great clinical importance. Reduced graphene oxide (rGO) is often used to efficiently remove bilirubin. However, thin rGO pieces tend to aggregate in the aqueous phase because they are hydrophobic. In this context, we propose an effective strategy based on the chitosan-assisted (CS-assisted) dispersion of rGO to produce high-performance bilirubin-adsorbing microspheres. CS possesses a hydrophobic CH structure, which offers strong hydrophobic interactions with rGO that assist its dispersion, and the large number of hydrophilic sites of CS increases the hydrophilicity of rGO. CS serves as a dispersant in a surfactant-like manner to achieve a homogeneous and stable CS/rGO dispersion by simply and gently stirring CS and rGO in a LiOH/KOH/urea/H2O system. Subsequently, CS/rGO hybrid microspheres were prepared by emulsification. CS ensures blood compatibility as a base material, and the entrapped rGO contributes to mechanical strength and a high adsorption capacity. The CS/rGO microspheres exhibited a high bilirubin adsorption capacity (215.56 mg/g), which is significantly higher than those of the rGO and CS microspheres. The determined mass-transfer factors revealed that the rich pores of the CS/rGO microspheres promote mass transfer during bilirubin adsorption (equilibrium is almost achieved within 30 min). The CS/rGO microspheres are promising candidates for bilirubin removal owing to a combination of high strength, blood compatibility, and high adsorption capacity.

Reusable Zwitterionic Porous Organic Polymers for Bilirubin Removal in Serum

Herein, we report a straightforward strategy to construct reusable, hemocompatible, and highly efficient bilirubin adsorbents by installing zwitterionic modules into a porous organic polymer (POP) for hemoperfusion application. Three types of zwitterions with different amounts are used to evaluate their impacts on the characteristics of POPs, including carboxybetaine methacrylate (CB), sulfobetaine methacrylate (SB), and 2-methacryloyloxyethyl phosphorylcholine (MPC). Results show that zwitterions can improve hemocompatibility, hydrophilicity, and bilirubin uptake of the POP. Among all zwitterionic POPs, POP-CB-40% exhibits the best bilirubin uptake, ∼46.5 times enhancement compared with the non-zwitterionic POP in 100% serum. This enhancement can be attributed to the improved hydrophilicity and protein resistance ability in biological solutions. More importantly, the reusability test shows that POP-CB-40% maintains ∼99% of bilirubin uptake capacity at fifth recycling in 100% serum. Findings in this work provide a guideline for the design of biocompatible and efficient POP-based bilirubin adsorbents for hemoperfusion therapy.

Protein/Polysaccharide Composite toward Multi-in-One Toxin Removal in Blood with Self-Anticoagulation and Biocompatibility

Biocompatible adsorbents play an essential role in hemoperfusion. Nevertheless, there are no hemoperfusion adsorbents that can simultaneously remove small and medium toxins, including bilirubin, urea, phosphor, heavy metals, and antibiotics. This bottleneck significantly impedes the miniaturization and portability of hemoperfusion materials and devices. Herein, a biocompatible protein-polysaccharide complex is reported that exhibits "multi-in-one" removal efficacy for liver and kidney metabolism wastes, toxic metal ions, and antibiotics. Through electrostatic interactions and polysaccharide-mediated coacervation, adsorbents can be prepared by simply mixing lysozyme (LZ) and sodium alginate (SA) together in seconds. The LZ/SA absorbent presented high adsorption capacities for bilirubin, urea, and Hg2+ of up to 468, 331, and 497 mg g-1 , respectively, and the excellent anti-protein adsorption endowed LZ/SA with a record-high adsorption capacity for bilirubin in the interference of serum albumin to simulate the physiological environment. The LZ/SA adsorbent also has effective adsorption capacity for heavy metals (Pb2+ , Cu2+ , Cr3+ , and Cd2+ ) and multiple antibiotics (terramycin, tetracycline, enrofloxacin, norfloxacin, roxithromycin, erythromycin, sulfapyrimidine, and sulfamethoxazole). Various adsorption functional groups exposed on the adsorbent surface significantly contribute to the excellent adsorption capacity. This fully bio-derived protein/alginate-based hemoperfusion adsorbent has great application prospects in the treatment of blood-related diseases.

A modular hydrogel bioink containing microsphere-embedded chondrocytes for 3D-printed multiscale composite scaffolds for cartilage repair

Articular cartilage tissue engineering is being considered an alternative treatment strategy for promoting cartilage damage repair. Herein, we proposed a modular hydrogel-based bioink containing microsphere-embedded chondrocytes for 3D printing multiscale scaffolds integrating the micro and macro environment of the native articular cartilage. Gelatin methacryloyl (GelMA)/alginate microsphere was prepared by a microfluidic approach, and the chondrocytes embedded in the microspheres remained viable after being frozen and resuscitated. The modular hydrogel bioink could be printed via the gel-in-gel 3D bioprinting strategy for fabricating the multiscale hydrogel-based scaffolds. Meanwhile, the cells cultured in the scaffolds showed good proliferation and differentiation. Furthermore, we also found that the composite hydrogel was biocompatible in vivo. These results indicated that the modular hydrogel-based bioinks containing microsphere-embedded chondrocytes for 3D printing multiscale scaffolds could provide a 3D multiscale environment for enhancing cartilage repairing, which would be encouraging considering the numerous alternative applications in articular cartilage tissue engineering.

Heparin-Immobilized Polyethersulfone for Hemocompatibility Enhancement of Dialysis Membrane: In Situ Synchrotron Imaging, Experimental, and Ex Vivo Studies

The goal of the current study is to enhance the hemocompatibility of polyethersulfone (PES) membranes using heparin immobilization. Heparin was immobilized covalently and via electrostatic interaction with the positively charged PES surface (pseudo-zwitterionic (pZW) complex) to investigate the influence of each method on the membrane hemocompatibility. In situ synchrotron radiation micro-computed tomography (SR-µCT) imaging, available at the Canadian Light Source (CLS), was used to critically assess the fibrinogen adsorption to the newly synthesized membranes qualitatively and quantitatively using an innovative synchrotron-based X-ray tomography technique. The surface roughness of the synthesized membranes was tested using atomic force microscopy (AFM) analysis. The membrane hemocompatibility was examined through the ex vivo clinical interaction of the membranes with patients' blood to investigate the released inflammatory biomarkers (C5a, IL-1α, IL-1β, IL-6, vWF, and C5b-9). The presence and quantitative analysis of a stable hydration layer were assessed with DSC analysis. Surface modification resulted in reduced surface roughness of the heparin-PES membrane. Both types of heparin immobilization on the PES membrane surface resulted in a decrease in the absolute membrane surface charge from -60 mV (unmodified PES) to -13 mV for the pZW complex and -9.16 mV for the covalently attached heparin, respectively. The loss of human serum fibrinogen (FB) was investigated using UV analysis. The PES membrane modified with the heparin pseudo-ZW complex showed increased FB retention (90.5%), while the unmodified PES membrane and the heparin covalently attached PES membrane exhibited approximately the same level of FB retention (81.3% and 79.8%, respectively). A DSC analysis revealed an improvement in the content of the hydration layer (32% of non-freezable water) for the heparin-coated membranes compared to the unmodified PES membrane (2.84%). An SR-µCT analysis showed that the method of heparin immobilization significantly affects FB adsorption distribution across the membrane thickness. A quantitative analysis using SR-µCT showed that when heparin is attached covalently, FB tends to be deposited inside the membrane pores at the top (layer index 0-40) membrane regions, although its content peak distribution shifted to the membrane surface, whereas the unmodified PES membrane holds 90% of FB in the middle (layer index 40-60) of the membrane. The ex vivo hemocompatibility study indicates an improvement in reducing the von Willebrand factor (vWF) for the heparin pseudo-ZW PES membrane compared to the covalently attached heparin and the untreated PES.

Green Synthesis of Silver Nanoparticles Loaded Hydrogel for Wound Healing; Systematic Review

Wound healing is a biological process that involves a series of consecutive process, and its impairment can lead to chronic wounds and various complications. Recently, there has been a growing interest in employing nanotechnology to enhance wound healing. Silver nanoparticles (AgNPs) have expanded significant attention due to their wide range of applications in the medical field. The advantages of AgNPs include their easy synthesis, change their shape, and high surface area. Silver nanoparticles are very efficient for topical drug administration and wound healing because of their high ratio of surface area to volume. The efficiency of AgNPs depends on the synthesis method and the intended application. Green synthesis methods offer an eco-friendly approach by utilizing natural sources such as plant extracts and fungus. The characterization of nanoparticles plays an important character, and it is accomplished through the use of several characterization methods such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). These techniques are employed to confirm the specific characters of the prepared Silver Nanoparticles. Additionally, the review addresses the challenges and future perspectives of utilizing green-synthesized AgNPs loaded in Polyacrylamide hydrogel for wound healing applications, including the optimization of nanoparticle size, and release kinetics. Overall, this review highlights the potential of green-synthesized AgNPs loaded in Polyacrylamide hydrogel as promising for advanced wound healing therapies. There are different approaches of usage of AgNPs for wound healing such as polyacrylamide -hydrogels, and the mechanism after their antibacterial action, have been exposed.

Investigation on Human Serum Protein Depositions Inside Polyvinylidene Fluoride-Based Dialysis Membrane Layers Using Synchrotron Radiation Micro-Computed Tomography (SR-μCT)

Hemodialysis (HD) membrane fouling with human serum proteins is a highly undesirable process that results in blood activations with further severe consequences for HD patients. Polyvinylidene fluoride (PVDF) membranes possess a great extent of protein adsorption due to hydrophobic interaction between the membrane surface and non-polar regions of proteins. In this study, a PVDF membrane was modified with a zwitterionic (ZW) polymeric structure based on a poly (maleic anhydride-alt-1-decene), 3-(dimethylamino)-1-propylamine derivative and 1,3-propanesultone. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and zeta potential analyses were used to determine the membrane's characteristics. Membrane fouling with human serum proteins (human serum albumin (HSA), fibrinogen (FB), and transferrin (TRF)) was investigated with synchrotron radiation micro-computed tomography (SR-μCT), which allowed us to trace the protein location layer by layer inside the membrane. Both membranes (PVDF and modified PVDF) were detected to possess the preferred FB adsorption due to the Vroman effect, resulting in an increase in FB content in the adsorbed protein compared to FB content in the protein mixture solution. Moreover, FB was shown to only replace HSA, and no significant role of TRF in the Vroman effect was detected; i.e., TRF content was nearly the same both in the adsorbed protein layer and in the protein mixture solution. Surface modification of the PVDF membrane resulted in increased FB adsorption from both the protein mixture and the FB single solution, which is supposed to be due to the presence of an uncompensated negative charge that is located at the COOH group in the ZW polymer.

Zwitterionic Biomaterials

The term "zwitterionic polymers" refers to polymers that bear a pair of oppositely charged groups in their repeating units. When these oppositely charged groups are equally distributed at the molecular level, the molecules exhibit an overall neutral charge with a strong hydration effect via ionic solvation. The strong hydration effect constitutes the foundation of a series of exceptional properties of zwitterionic materials, including resistance to protein adsorption, lubrication at interfaces, promotion of protein stabilities, antifreezing in solutions, etc. As a result, zwitterionic materials have drawn great attention in biomedical and engineering applications in recent years. In this review, we give a comprehensive and panoramic overview of zwitterionic materials, covering the fundamentals of hydration and nonfouling behaviors, different types of zwitterionic surfaces and polymers, and their biomedical applications.

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 advances of zwitterionic based topological polymers for biomedical applications

Zwitterionic polymers, comprising hydrophilic anionic and cationic groups with the same total number of positive and negative charges on the same monomer residue, have received increasing attention due to their...

A balanced charged hydrogel with anti-biofouling and antioxidant properties for treatment of irradiation-induced skin injury

Skin injury caused by large doses of ionizing radiation is the common and severe side effect of radiotherapy. However, its therapeutic efficacy is always hindered by early reactive oxygen species generation, repetitive inflammatory microenvironment and bacterial infection risk. Herein, we report an anti-biofouling hydrogel with anti-inflammation and anti-oxidative properties for the treatment of irradiation-induced skin injury. The anti-biofouling hydrogel can be achieved by balancing oppositely charged alginate, hyaluronic acid (HA) and polylysine (PLL) at the optimal ratio, which effectively resist protein and bacterial adhesion, and evades immune response. Moreover, curcumin and epigallocatechin gallate (EGCG) can be facially encapsulated and substantially released from the hydrogel. Results showed that the resulting AHP-Cur/EGCG hydrogel can significantly weaken the development of skin injury and accelerate its healing process by alleviating inflammation, scavenging ROS and promoting angiogenesis. Therefore, the findings presented in this work provide an effective strategy for clinical management and treatment of ionizing radiation-induced skin injury.

Biocompatible, antibacterial and anti-inflammatory zinc ion cross-linked quaternized cellulose‑sodium alginate composite sponges for accelerated wound healing

Bacterial infection has become one of the most challenges for wound healing, which causes serious inflammatory response and delays the healing process. Herein, a novel sponge with excellent biocompatible, antibacterial and anti-inflammatory properties based on quaternized cellulose (QC), sodium alginate (SA) and Zn²⁺ was reported. The existence of physical interactions, such as electrostatic interaction, chelation and hydrogen bonding endowed the sponges with enhanced mechanical property. The composite sponges exhibited outstanding biocompatibility and hemostatic efficiency due to the compatible nature of the component and physical cross-linking, as well as superior antibacterial property benefited from the synergistic effects of steady Zn²⁺ release and quaternary ammonium group. In vivo investigation validated that the enhanced antibacterial and anti-inflammatory effect of the sponges, which significantly promoted wound closure and the reconstruction of skin tissue through epithelial regeneration, collagen deposition and mitigating inflammatory cell infiltration. Overall, the novel sponge demonstrated great potentials in bacteria-associated wound management.

Antifouling Fibrous Membrane Enables High Efficiency and High-Flux Microfiltration for Water Treatment

Membrane biofouling has long been a major obstacle to highly efficient water treatment. The modification of the membrane surface with hydrophilic materials can effectively enhance biofouling resistance. However, the water flux of the membranes is often compromised for the improvement of antifouling properties. In this work, a composite membrane composed of a zwitterionic hydrogel and electrospinning fibers was prepared by a spin-coating and UV cross-linking process. At the optimum conditions, the composite membrane could effectively resist the biofouling contaminations, as well as purify polluted water containing bacteria or diatoms with a high flux (1349.2 ± 85.5 L m^-2 h^-1 for 10⁶ CFU mL^-1 of an Escherichia coli solution). Moreover, compared with the commercial poly(ether sulfone) (PES) membrane, the membrane displayed an outstanding long-term filtration performance with a lower water flux decline. Therefore, findings in this work provide an effective antifouling modification strategy for microfiltration membranes and hold great potential for developing antifouling membranes for water treatment.

A Uniform and Robust Bioinspired Zwitterion Coating for Use in Blood-Contacting Catheters with Improved Anti-Inflammatory and Antithrombotic Properties

Inflammation and thrombosis are two major complications of blood-contacting catheters that are used as extracorporeal circuits for hemodialysis and life-support systems. In clinical applications, complications can lead to increased mortality and morbidity rates. In this work, a biomimetic erythrocyte membrane zwitterion coating based on poly(2-methacryloyloxyethyl phosphorylcholine-co-dopamine methacrylate) (pMPCDA) copolymers is uniformly and robustly modified onto a polyvinyl chloride (PVC) catheter via mussel-inspired surface chemistry. The zwitterionic pMPCDA coating exhibits excellent antifouling activity and resists bacterial adhesion, fibrinogen adsorption, and platelet adhesion/activation. The material also demonstrates great hemocompatibility, cytocompatibility, and anticoagulation properties in vitro. Additionally, this biocompatible pMPCDA coating reduces in vivo foreign-body reactions by mitigating inflammatory response and collagen capsule formation, due to its outstanding ability to resist nonspecific protein adsorption. More importantly, when compared with a bare PVC catheter, the pMPCDA coating exhibits outstanding antithrombotic properties when tested in an ex vivo rabbit perfusion model. Thus, it is envisioned that this biomimetic erythrocyte membrane surface strategy will provide a promising way to mitigate inflammation and thrombosis caused by the use of blood-contacting catheters.

2D Black Phosphorus-Based Cytomembrane Mimics with Stimuli-Responsive Antibacterial Action Inspired by Endotoxin-Associated Toxic Behavior

Biomimetic membrane materials have been widely explored and developed for drug loading and tissue engineering applications due to their excellent biocompatibility and abundant reaction sites. However, novel cytomembrane mimics have been lacking for a long time. In this study, black phosphorus (BP) was used as the foundation for a new generation of promising cytomembrane mimics due to its multiple similarities to cytomembranes. Inspired by the dual function of endotoxins on membranes, we prepared a BP-based cytomembrane mimic with controllable antibacterial ability via electrostatic interaction between BP and [1-pentyl-1-quaternary ammonium-3-vinyl-imidazole]Br ([PQVI]Br). The release of PQVI could be manipulated in different conditions by adjusting the electrostatic force, thereby achieving controllable antibacterial ability. This report confirms the possibility of using BP as a new material to mimic cytomembranes and provides a new concept of controllable antibacterial action based on endotoxins.

Incorporation of Silver Nanoparticles in Hydrogel Matrices for Controlling Wound Infection

For centuries, silver has been recognized for its antibacterial properties. With the development of nanotechnology, silver nanoparticles (AgNPs) have garnered significant attention for their diverse uses in antimicrobial gel formulations, dressings for wound healing, orthopedic applications, medical catheters and instruments, implants, and contact lens coatings. A major focus has been determining AgNPs' physical, chemical, and biological characteristics and their potential to be incorporated in biocomposite materials, particularly hydrogel scaffolds, for burn and wound healing. Though AgNPs have been rigorously explored and extensively utilized in medical and nonmedical applications, important research is still needed to elucidate their antibacterial activity when incorporated in wound-healing scaffolds. In this review, we provide an up-to-date, 10-yr (2010-2019), comprehensive literature review on advancements in the understanding of AgNP characteristics, including the particles' preparation and mechanisms of activity, and we explore various hydrogel scaffolds for delivering AgNPs.

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.

Three-dimensional porous gas-foamed electrospun nanofiber scaffold for cartilage regeneration

To achieve optimal functional recovery of articular cartilage, scaffolds with nanofibrous structure and biological function have been widely pursued. In this study, two-dimensional electrospun poly(l-lactide-co-ε-caprolactone)/silk fibroin (PLCL/SF) scaffolds (2DS) were fabricated by dynamic liquid support (DLS) electrospinning system, and then cross-linked with hyaluronic acid (HA) to further mimic the microarchitecture of native cartilage. Subsequently, three-dimensional PLCL/SF scaffolds (3DS) and HA-crosslinked three-dimensional scaffolds (3DHAS) were successfully fabricated by in situ gas foaming and freeze-drying. 3DHAS exhibited better mechanical properties than that of the 3DS. Moreover, all scaffolds exhibited excellent biocompatibility in vitro. 3DHAS showed better proliferation and phenotypic maintenance of chondrocytes as compared to the other scaffolds. Histological analysis of cell-scaffold constructs explanted 8 weeks after implantation demonstrated that both 3DS and 3DHAS scaffolds formed cartilage-like tissues, and the cartilage lacuna formed in 3DHAS scaffolds was more mature. Moreover, the reparative capacity of scaffolds was discerned after implantation in the full-thickness articular cartilage model in rabbits for up to 12 weeks. The macroscopic and histological results exhibited typical cartilage-like character and well-integrated boundary between 3DHAS scaffolds and the host tissues. Collectively, biomimetic 3DHAS scaffolds may be promising candidates for cartilage tissue regeneration applications.

Targeted perfusion adsorption for hyperphosphatemia using mixed matrix microspheres (MMMs) encapsulated NH2-MIL-101(Fe)

Hyperphosphatemia, a common complication of chronic renal failure patients, is described as an excess amount of serum phosphate >4.5 mg dL-1. Current therapy for hyperphosphatemia is limited by low removal efficiency, secondary hyperparathyroidism, uremic bone disease, and the promotion of vascular and visceral calcifications. Metal organic frameworks (MOFs) have aroused great interest in the field of blood purification because of their strong specific adsorption. Herein, we prepared mixed matrix microspheres (MMMs) encapsulated NH2-MIL-101(Fe) with specific adsorption to blood phosphate. Simultaneously, a heparinoid copolymer poly (acrylic acid-sodium 4-vinylbenzenssulfonate) (P(AA-SSNa)) was incorporated to improve the hemocompatibility. The proposed MMMs exhibited excellent phosphate adsorption capacity both in aqueous and human plasma environments. They also showed comprehensive hemocompatibility e.g. low tendency of protein adsorption, low hemolysis rate and extended blood coagulation time. In general, we envision that the MMMs are potentially suitable as highly efficient hemoperfusion adsorbents for hyperphosphatemia treatment.

Zn(ii)-Dipicolylamine analogues with amphiphilic side chains endow low molecular weight PEI with high transfection performance

To investigate the effect of amphiphilic balance of Zn(ii)-dipicolylamine analogues on the transfection process, we fabricated a series of Zn(ii)-dipicolylamine functional modules (DDAC-Rs) with different hydrophilic-phobic side chains to modify low molecular weight PEI (Zn-DP-Rs) by the Michael addition reaction. Zn-DP-Rs with hydrophilic terminal hydroxy group side chains demonstrate superior overall performance compared to those of hydrophobic alkyl side chains. In terms of the influence of the chain lengths in DDAC-Rs, from Zn-DP-A/OH-3 to Zn-DP-A/OH-5, the corresponding transfection efficiency shows an upward trend as the lengths increase. However, decreasing efficacy is observed with further increase in the length of side chains. In addition, the Zn-DP-Rs with amphiphilic side chains show prominent performance in every respect, highlighting the significance of balance in the amphipathy of side chains in DDAC-Rs. This work is of great significance for the development of polycationic gene carrier materials with excellent performance.

Combination of Multiple Hemodialysis Modes: Better Treatment Options for Patients Under Maintenance Hemodialysis

Purpose

Chronic renal failure has become a major public health concern and treatment strategies are urgently needed. We aimed to investigate whether combination of hemodialysis modes was superior to regular hemodialysis for patients under maintenance hemodialysis.

Patients and Methods

A total of 144 patients with end-stage renal failure (ESRF) were enrolled in this single-center retrospective study. Patients received regular hemodialysis (HD) were included in HD group (n=52), patients received regular HD plus hemodiafiltration (HDF) in HD/HDF group (n=47), patients received the combination of regular HD, HDF and hemoperfusion (HP) in HD/HDF/HP group (n=45). After 1-month and 24-months treatment, therapeutic effects were assessed in terms of nutritional status, control of complications, dialysis adequacy, mean arterial pressure (MAP), infection rate and living quality.

Results

When patients received 1-month treatment, there were no statistically significant differences among three groups. After 24-months treatment, patients in HD/HDF and HD/HDF/HP group presented with better dialysis adequacy, lower MAP and infection rate, higher serum albumin, hemoglobin and calcium levels, lower serum phosphorus and intact parathyroid hormone levels, lower incidence of malnutrition and the Hamilton Depression Scale score, higher the Barthel Index score than HD group (P<0.05). The levels of calcium, phosphorus and intact parathyroid hormone in HD/HDF/HP group were lower than those in HD/HDF group (P<0.05).

Conclusion

Our finding highly indicated that combination of hemodialysis modes was superior to regular HD for patients with ESRF in nutritional status, control of complications, dialysis adequacy, and living quality.

Fabrication of a novel nitrogen-containing porous carbon adsorbent for protein-bound uremic toxins removal

Protein-bound uremic toxins (PBUTs), the presence of which in the blood is an important risk factor for the progression of chronic kidney disease (CKD), have not been cleared efficiently via traditional hemodialysis methods until now. In this study, biosafe and efficient nitrogen-containing porous carbon adsorbent (NPCA) beads for the clearance of PBUTs were prepared from porous acrylonitrile/divinylbenzene cross-linked copolymer beads followed by pyrolysis. The resulting NPCA beads were characterized via SEM, XPS and nitrogen adsorption/desorption tests. The results demonstrated that the NPCA beads possessed a mesoporous/microporous hierarchical structure with rich nitrogen functional groups on their surfaces and realized efficient PBUTs adsorption in human plasma. More importantly, the efficacy of PBUTs removal was substantially higher than those of commercial adsorbents that are commonly used in clinical uremia treatments. The NPCA beads also exhibited satisfactory removal efficacy towards middle-molecular-weight uremic toxins. The PBUTs removal mechanism of the NPCA beads is ascribed to effective competition between nitrogen-containing NPCA and proteins for PBUT binding. According to hemocompatibility assays, the NPCA beads possessed satisfactory in vitro hemocompatibility. This nitrogen-containing porous carbon adsorbent is an attractive and promising material for blood purification applications in the treatment of clinical uremia.

A zwitterionic hydrogel coated titanium surface with high-efficiency endothelial cell selectivity for rapid re-endothelialization

Coronary stent implantation is an effective procedure for percutaneous coronary intervention treatment. However, its long-term safety and efficacy are still hindered by the in-stent restenosis and late thrombus formation. Herein, an anti-biofouling and endothelial cell selective zwitterionic hydrogel coating was developed to simultaneously enhance the nonspecific resistance and rapid re-endothelialization of the titanium surface. An endothelial cell selective peptide, REDV, could be simply conjugated on the zwitterionic carboxybetaine (CB) hydrogel to prepare the REDV/CB coating. It was found that the REDV/CB hydrogel layer maintained antifouling properties, which could inhibit the protein adsorption, bacterial adhesion, platelet activation and aggregation, and smooth muscle cell proliferation. More importantly, the co-culture study confirmed that the conjugated REVD peptide could specifically capture endothelial cells and promote their migration and proliferation, and simultaneously decrease the adhesion and proliferation of smooth muscle cells. Therefore, the antifouling and endothelial cell selective coating proposed in this work provides a promising strategy to develop an intravascular stent for promoted re-endothelialization and inhibited neointimal hyperplasia in clinical applications.

Functional hydrogel coatings

Hydrogels—natural or synthetic polymer networks that swell in water—can be made mechanically, chemically and electrically compatible with living tissues. There has been intense research and development of hydrogels for medical applications since the invention of hydrogel contact lenses in 1960. More recently, functional hydrogel coatings with controlled thickness and tough adhesion have been achieved on various substrates. Hydrogel-coated substrates combine the advantages of hydrogels, such as lubricity, biocompatibility and anti-biofouling properties, with the advantages of substrates, such as stiffness, toughness and strength. In this review, we focus on three aspects of functional hydrogel coatings: (i) applications and functions enabled by hydrogel coatings, (ii) methods of coating various substrates with different functional hydrogels with tough adhesion, and (iii) tests to evaluate the adhesion between functional hydrogel coatings and substrates. Conclusions and outlook are given at the end of this review.

MOF-Based Antibiofouling Hemoadsorbent for Highly Efficient Removal of Protein-Bound Bilirubin

A metal-organic framework (MOF)-based antibiofouling hemoadsorbent (PCB-MIL101) was developed through a facile encapsulation of MIL-101(Cr) in zwitterionic poly carboxybetaine (PCB) hydrogel. PCB-MIL101 possessed strong mechanical strength and superior hemocompatibility, ensuring its safety in hemoperfusion applications. In addition, it showed efficient and effective adsorption toward bilirubin (BR), and its maximum adsorption capacity was ∼583 mg g^-1. Moreover, due to the protection of antibiofouling PCB hydrogel, PCB-MIL101 showed ability to resist protein adsorption, thus working effectively to remove BR molecules from their binding albumin in biological solutions. The finding in this study provides a novel insight into developing MOF-based hemoadsorbents for the improvement of hemoperfusion therapies.

Ex vivo evaluation of the blood compatibility of mixed matrix haemodialysis membranes

The patients with end stage kidney disease need haemodialysis therapies, using an artificial kidney. Nevertheless, the current therapies cannot remove a broad range of uremic toxins compared to the natural kidney. Adsorption therapies, using sorbent-based columns, can improve the clearance of uremic toxins, but the sorbent particles often require polymeric coatings to improve their haemocompatibility leading to mass transfer limitations and to lowering of their performance. Earlier, we have developed a dual layer Mixed Matrix fiber Membrane (MMM) based on polyethersulfone/polyvinylpyrrolidone (PES/PVP) polymer blends. There, the sorbent activated carbon particles are embedded in the outer membrane layer for achieving higher removal whereas the inner blood contacting selective membrane layer should achieve optimal blood compatibility. In this work, we evaluate in detail the haemocompatibility of the MMM following the norm ISO 10993-4. We study two generations of MMM having different dimensions and transport characteristics; one with low flux and no albumin leakage and another with high flux but some albumin leakage. The results are compared to those of home-made PES/PVP single layer hollow fiber and to various control fibers already applied in the clinic. Our results show that the low flux MMM successfully avoids contact of blood with the activated carbon and has good haemocompatibility, comparable to membranes currently used in the clinic. STATEMENT OF SIGNIFICANCE: Haemodialysis is a life-sustaining extracorporeal treatment for renal disease, however a broad range of uremic toxins cannot still be removed. In our previous works we showed that a double layer Mixed Matrix Membrane (MMM) composed of polyethersulfone/polyvinylpyrrolidone and activated carbon can achieve higher removal of uremic toxics compared to commercial haemodialysers. In this work we evaluate the haemocompatibility profile of the MMM in order to facilitate its clinical implementation. The lumen particle-free layer of the MMM successfully avoids the contact of blood with the poorly blood-compatible activated carbon. Moreover, thanks to the high amount of polyvinylpyrrolidone and to the smoothness of the lumen layer, the MMM has very good haemocompatibility, comparable to membranes currently used in the clinic.

Dual dynamically crosslinked thermosensitive hydrogel with self-fixing as a postoperative anti-adhesion barrier

Tissue adhesion is a severe postoperative complication. Various strategies have been developed to minimize postoperative adhesion, but the clinical efficacy is still far from satisfactory. Herein, we present a dual dynamically crosslinked hydrogel to serve as a physical postoperative anti-adhesion barrier. The hydrogel was generated by dynamic chemical oxime bonding from alkoxyamine-terminated Pluronic F127 (AOP127) and oxidized hyaluronic acid (OHA), as well as hydrophobic association of AOP127. Rheological analysis demonstrated that the hydrogel exhibits temperature sensitivity. At 37 °C, it shows much higher modulus and higher stability than the Pluronic F127 hydrogel. Hemolytic assays suggested that the hydrogel undergoes low hemolysis. In addition, it exhibited anti-adhesion to blood cells in blood cell adhesion tests. It also showed an anti-attachment effect to fibroblasts and biocompatibility in vitro cell studies. Macroscopic evaluation and lap-shear tests revealed that the hydrogel has a moderate adhesive capacity to tissue, which is important for self-fixation. A rat model of sidewall defect-bowel abrasion was established to evaluate the anti-adhesion effect in vivo. The gross observation and pathological analysis revealed a significant reduction in postoperative peritoneal adhesion in the AOP127/OHA hydrogel-treated group than those treated with normal saline or Pluronic F127 hydrogel. Hence, the dual dynamically crosslinked hydrogel with self-fixable capacity may be suitable as a physical barrier for postoperative adhesion prevention. STATEMENT OF SIGNIFICANCE: Despite the development of numerous postoperative anti-adhesion barriers, their anti-adhesion efficacy is still limited in clinical trials due to poor tissue adhesion and rapid clearance from injured areas. Herein, we have developed a dual dynamic crosslinked hydrogel, generated by dynamic oxime bonds and hydrophobic interactions. The hydrogel is temperature-sensitive and demonstrates moderate tissue adhesion capacity, which allows for self-fixation when applied to defects. The introduction of dynamic covalent bonds improves the stability of the hydrogel. Moreover, the hydrogel not only displays appropriate hemocompatibility, cytocompatibility and anti-adhesion of blood cells and fibroblasts, but it also effectively contributes to preventing postoperative peritoneal adhesions in vivo. Hence, this dual dynamic crosslinked hydrogel may have potential applications as a physical barrier in clinical practice.

Amides and Heparin-Like Polymer Co-Functionalized Graphene Oxide Based Core @ Polyethersulfone Based Shell Beads for Bilirubin Adsorption

Excessive bilirubin in the body of patient with liver dysfunction or metabolic obstruction may cause jaundice with irreversible brain damage, and new type of adsorbent for bilirubin is under frequent investigation. Herein, graphene oxide based core @ polyethersulfone-based shell beads are fabricated by phase inversion method, amides and heparin-like polymer are introduced to functionalize the core-shell beads. The beads are successfully prepared with obvious core-shell structure, adequate thermostability and porous shell. Clotting times and protein adsorption are investigated to inspect the hemocompatibility property of the beads. The adsorption of bilirubin is systematically investigated by evaluating the effects of contacting time, initial concentration and temperature on the adsorption, which exhibits improved bilirubin adsorption amount for the beads with amides contained cores or/and shells. It is worth believing that the amides and heparin-like polymer co-functionalized core-shell beads may be utilized in the field of hemoperfusion for bilirubin adsorption.

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.

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.

Encapsulation of AgNPs within Zwitterionic Hydrogels for Highly Efficient and Antifouling Catalysis in Biological Environments

Silver nanoparticles (AgNPs) have been widely used as catalysts in a variety of chemical reactions owing to their unique surface and electronic properties, but their practical applications have been hindered by severe aggregation. The immobilization of AgNPs is crucial to preventing their aggregation or precipitation as well as to improving their reusability. Herein, we developed a facile route for the reductant-free in situ synthesis of AgNPs in zwitterionic hydrogels. Via this method, the embedded AgNPs had a uniform distribution, high activity, and antibiofouling capability. The catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using polycarboxybetaine-AgNPs (PCB-AgNPs) could achieve >95% conversion efficiency within 5 min. Meanwhile, the normalized rate constant k_nor (10.617 s^-1mmol^-1) was higher than that of most of the reported immobilized nanocatalysts. More importantly, in a biofouling environment, PCB-AgNPs could still exhibit >97% initial catalytic activity while AgNPs in the PSB or PHEMA hydrogel lost ∼60% activity. This strategy holds great potential for the immobilization of nanoparticle catalysts, especially for applications in biological environments.

A facile modification to improve the biocompatibility and adsorbability of activated carbon with zwitterionic hydrogel

In this work, poly(carboxybetaine methacrylate) hydrogel (pCBMA) was employed to modify the activated carbon (AC) for improving the biocompatibility and adsorption capacity of AC in biological environments. First, size-controlled hydrogel beads and hydrogel coated AC (pCBMA-AC) were fabricated with a homemade device, and the preparation conditions were optimized. Then the physical and biological properties of pCBMA-AC with different diameters were investigated. 2 mm pCBMA-AC dispalyed excellent stability with leakage rate only 0.16% after 72 h shaking incubation, as well as remarkable biocompatibility with merely 0.13% hemolysis rate and 3.41% cell death, while 14.72% and 70.11% for the bare AC, respectively, indicating the acceptable lower hemolysis and cytotoxicity according to ISO 10993. Furthermore, the adsorption capacities of pCBMA-AC were evaluated in biological environments with methylene blue as model molecules. The pCBMA-AC displayed 93.50% and 97.32% adsorption rates in BSA solution and FBS, respectively, but only 70.33% and 40.26% for the uncoated AC. These results indicated that pCBMA endows AC remarkable biocompatibility and adsorption capacity, which could extend the applications of AC in biological environments.

Nanostructure-Enabled and Macromolecule-Grafted Surfaces for Biomedical Applications

Advances in nanotechnology and nanomaterials have enabled the development of functional biomaterials with surface properties that reduce the rate of the device rejection in injectable and implantable biomaterials. In addition, the surface of biomaterials can be functionalized with macromolecules for stimuli-responsive purposes to improve the efficacy and effectiveness in drug release applications. Furthermore, macromolecule-grafted surfaces exhibit a hierarchical nanostructure that mimics nanotextured surfaces for the promotion of cellular responses in tissue engineering. Owing to these unique properties, this review focuses on the grafting of macromolecules on the surfaces of various biomaterials (e.g., films, fibers, hydrogels, and etc.) to create nanostructure-enabled and macromolecule-grafted surfaces for biomedical applications, such as thrombosis prevention and wound healing. The macromolecule-modified surfaces can be treated as a functional device that either passively inhibits adverse effects from injectable and implantable devices or actively delivers biological agents that are locally based on proper stimulation. In this review, several methods are discussed to enable the surface of biomaterials to be used for further grafting of macromolecules. In addition, we review surface-modified films (coatings) and fibers with respect to several biomedical applications. Our review provides a scientific update on the current achievements and future trends of nanostructure-enabled and macromolecule-grafted surfaces in biomedical applications.