Bilirubin recognition via molecularly imprinted supermacroporous cryogels

Molecularly imprinted polymers for sensing/depleting human serum albumin (HSA): A critical review of recent advances and current challenges

Human serum albumin (HSA) is an essential biomacromolecule in the blood circulatory system because it carries numerous molecules, including fatty acids (FAs), bilirubin, metal ions, hormones, and different pharmaceuticals, and plays a significant role in regulating blood osmotic pressure. Fluctuations in HSA levels in human biofluids, particularly urine and serum, are associated with several disorders, such as elevated blood pressure, diabetes mellitus (DM), liver dysfunction, and a wide range of renal diseases. Thus, the ability to quickly and accurately measure HSA levels is important for the rapid identification of these disorders in human populations. Molecularly imprinted polymers (MIPs), well known as artificial antibodies (Abs), have been extensively used for the quantitative detection of small molecules and macromolecules, especially HSA, in recent decades. This review highlights major challenges and recent developments in the application of MIPs to detect HSA in artificial and real samples. The fabrication and application of various MIPs for the depletion of HSA are also discussed, as well as different MIP preparation approaches and strategies for overcoming obstacles that hinder the development of MIPs with high efficiency and recognition capability for HSA determination/depletion.

Cryogels and Monoliths: Promising Tools for Chromatographic Purification of Nucleic Acids

The increasing demand for highly pure biopharmaceuticals has put significant pressure on the biotechnological industry to innovate in production and purification processes. Nucleic acid purification, crucial for gene therapy and vaccine production, presents challenges due to the unique physical and chemical properties of these molecules. Meeting regulatory standards necessitates large quantities of biotherapeutic agents of high purity. While conventional chromatography offers versatility and efficiency, it suffers from drawbacks like low flow rates and binding capacity, as well as high mass transfer resistance. Recent advancements in continuous beds, including monoliths and cryogel-based systems, have emerged as promising solutions to overcome these limitations. This review explores and evaluates the latest progress in chromatography utilizing monolithic and cryogenic supports for nucleic acid purification.

How the Crosslinker Amount Influences the Final Properties of Hydroxyethyl Methacrylate Cryogels

The investigation of the mechanical, thermal, and adsorption properties of hydroxyethyl methacrylate (HEMA) cryogels as a function of a reactant ratio is herein reported to better address materials for specific applications. To this aim, cryogels have been synthesized using different monomer/crosslinker (N,N'-methylene-bisacrylamide-MBAA) ratios. The study of SEM images made it possible to identify the trend in the material's macroporosity. As would be expected, the average measured pore width decreased as the amount of MBAA increased while the number of pores grew. Swelling capacity ranges from 8.7 gW/ggel (grams of water per gram of gel) to 9.3 gW/ggel. These values are strictly connected with the pore's size and distribution, revealing that the water uptake for the most crosslinked sample is inferior to other samples. The equilibrium-adsorption capacity (Qe) towards the methylene violet (MV) was also assessed, revealing no remarkable differences after 24 h of a batch test. As expected, thermogravimetric analysis (TGA) also showed no significant changes in stability that ranged from a maximum weight loss temperature (T Max) of 420 °C to 425 °C, which increased as a function of crosslinker content. Conversely, compression strength measurements showed a notable difference of about 50% in modulus (Ec), moving from the higher to the lower HEMA/MBAA ratio. These new comparative results indicate how slight variations in the reactant's ratio can steadily improve the mechanical properties of the HEMA cryogel without affecting its adsorption efficiency. This can be helpful in the design of materials for water and energy purposes. Since swelling properties are needed in the case of biomedical applications, the HEMA/MBAA ratio should be tuned versus high values.

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.

Molecularly imprinted polymers for selective extraction/microextraction of cancer biomarkers: A review

Over recent years, great efforts have been extensively documented in top scientific journals on the development of methods for early diagnosis, treatment, and monitoring of cancers which are prevalent critical diseases with a high mortality rate among men and women. The determination of cancer biomarkers using different optimum methodologies is one of the finest options for achieving these goals with more precision, speed, and at a lower cost than traditional clinical procedures. In this regard, while focusing on specific biomarkers, molecularly imprinted technology has enabled novel diagnostic techniques for a variety of diseases. Due to the well-known advantages of molecularly imprinted polymers (MIPs), this review focuses on the current trends of MIPs-based extraction/microextraction methods, specifically targeting cancer biomarkers from various matrices. These optimized methods have demonstrated high selectivity, accuracy, sorbent reusability, extraction recovery, and low limits of detection and quantification for a variety of cancer biomarkers, which are a powerful tool to provide early diagnosis, prognosis, and treatment monitoring, with potential clinical application expected soon. This review highlights the key progress, specific modifications, and strategies used for MIP synthesis. The future perspectives for cancer biomarkers purification and determination by fabricating MIP-based techniques are also discussed.

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.

Molecularly imprinted composite cryogel for extracorporeal removal of uric acid

In this study, uric acid (UA)-imprinted poly (hydroxyethyl methacrylate-N-methacryloyl-amido-L-cysteine methyl ester)-Fe³⁺ [poly(HEMA-MAC)-Fe³⁺] nanoparticle-embedded poly(acrylamide-methyl methacrylate) cryogel [p(AAm-MMA)-MIP] was synthesized for selective UA adsorption. The nanoparticles were prepared via molecular imprinting. The prepared p(AAm-MMA)-MIP cryogel was characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and swelling test. The swelling degree of the p(AAm-MMA)-MIP cryogel was determined as to 7.56 g H₂O/g cryogel. The prepared cryogel was used for UA adsorption from aqueous solution.The effects of pH (4.0-8.0), initial UA concentration (5-40 mg/L), temperature (4 °C, 25 °C and 35 °C) and contact time on the UA adsorption capacity were detailedly investigated. UA adsorption data were applied to Langmuir and Freundlich isotherm models. The adsorption data were well fitted with pseudo-second order kinetic model. The thermodynamic parameters (ΔG ͦ, ΔH ͦ, ΔS^o) demonstrated that the adsorption process was endothermic and spotaneous at 4 °C, 25 °C and 35 °C. The cryogel was also used for UA adsorption from human serum. The effects of the composite cryogel treatment on blood cells and hemostatic parameters were evaluated by using hemogram analyses, coagulation studies, thromboelastography and platelet aggregation studies. The results showed that the cryogel treatment has an allowable effect on blood cell counts and hemostatic parameters demonstrating the applicability of prepared composite cryogel for UA removal from human serum.

Fabrication of regular macro-mesoporous reduced graphene aerogel beads with ultra-high mechanical property for efficient bilirubin adsorption

Three-dimensional graphene materials have been widely studied in many fields for their role as potential absorbent, especially for bilirubin adsorption. In this study, we developed a simple method to prepare reduced graphene aerogel beads as hemoperfusion materials for fast bilirubin adsorption. The graphene oxide (GO) aerogel beads were produced by self-assembly of GO nanosheet that cross-linked by Ca²⁺ previously in a coagulation bath, then it was reduced by ascorbic acid and lyophilized to yield the reduced graphene aerogel beads. The beads had a regular macroscopic spherical structure with a diameter of about 1.3-2 mm, where the macroporosity was about 10 μm and the mesoporosity was about 12 nm. The macro-mesoporous structure also gave the reduced graphene aerogel beads ultra-high mechanical strengths and high specific surface area, which were both important for hemoperfusion materials. Moreover, the fixed-bed column adsorption revealed that the reduced graphene aerogel beads manifested excellent bilirubin adsorption (649.512 mg/g) with a rapid adsorption equilibrium time (1.5 h) under the optimized conditions. Even in the bilirubin-enriched blood, the adsorption capacity of the beads could reach 367.14 mg/g. Furthermore, the aerogel beads had a low hemolysis ratio and improved anticoagulant property showing good blood compatibility. Hence, the spherical reduced graphene aerogel beads with millimeter-level size presented a good potential for clinical applications in hemoperfusion therapy.

Cholesterol removal from human plasma with biologically modified cryogels

In this study, low molecular weight heparin immobilized P(HEMA) cryogels were fabricated for the removal of LDL-C in hypercholesterolemic human plasma. After characterization studies for P(HEMA) cryogels, effects of the parameters including medium pH, CNBr concentration, heparin concentration and contact time on heparin immobilization were investigated. Blood compatibility and cell adhesion tests were also performed, and platelet and leucocyte loss for P(HEMA)-Hp cryogels were found to be 2.95% and 4.91%, respectively. Maximum adsorption capacity for LDL-C from hypercholesterolemic human plasma was found to be 26.7 mg/g for P(HEMA)-Hp cryogel while it was only 1.67 mg/g for bare P(HEMA) cryogel. The P(HEMA)-Hp cryogels exhibit high desorption ratios up to 96% after 10 adsorption-desorption cycles with no significant decrease in the adsorption capacity. The findings indicated that these reusable P(HEMA)-based cryogels proposed good alternative adsorbents for removal of LDL-C.

Biomedical Applications of Polymeric Cryogels

The application of interconnected supermacroporous cryogels as support matrices for the purification, separation and immobilization of whole cells and different biological macromolecules has been well reported in literature. Cryogels have advantages over traditional gel carriers in the field of biochromatography and related biomedical applications. These matrices nearly mimic the three-dimensional structure of native tissue extracellular matrix. In addition, mechanical, osmotic and chemical stability of cryogels make them attractive polymeric materials for the construction of scaffolds in tissue engineering applications and in vitro cell culture, separation materials for many different processes such as immobilization of biomolecules, capturing of target molecules, and controlled drug delivery. The low mass transfer resistance of cryogel matrices makes them useful in chromatographic applications with the immobilization of different affinity ligands to these materials. Cryogels have been introduced as gel matrices prepared using partially frozen monomer or polymer solutions at temperature below zero. These materials can be produced with different shapes and are of interest in the therapeutic area. This review highlights the recent advances in cryogelation technologies by emphasizing their biomedical applications to supply an overview of their rising stars day to day.

Selective bilirubin sensor fabrication based on doped IAO nanorods for environmental remediation

In this approach, low-dimensional facile IAO nanorods were prepared by using the hydrothermal technique, which is efficiently applied to develop a non-enzymatic sensor coated with GCE probe by electrochemical reduction method.

Synthesis and characterization of albumin imprinted polymeric hydrogel membranes for proteomic studies

In this presented study, a novel molecularly imprinted polymeric hydrogel membranes (PHMs) were developed to use for the albumin depletion studies. For this, albumin imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-(L)-phenylalanine methyl ester) polymeric hydrogel membranes [p(HEMA-MAP) PHMs] were synthesized by the photopolymerization technique, and then characterized by SEM, EDX, FT-IR and swelling studies. Synthesized PHMs had spherical structure and the MAP monomer incorporation onto the PHMs was determined by EDX analysis by using nitrogen stoichiometry. Also, the swelling ratio of the albumin imprinted p(HEMA-MAP) PHMs was determined as 215%. The optimum albumin adsorption condition (adsorption capacity, medium pH, adsorption rate, temperature, ionic strength) were studied and the maximum albumin adsorption capacity was found to be as 34.28 mg/g PHMs. Selectivity experiments were also carried out with the presence of the competitive proteins such as lysozyme and amylase, and the results demonstrated that the albumin imprinted p(HEMA-MAP) PHMs showed high affinity towards the BSA molecules than the competitive proteins of lysozyme and amylase. Adsorbed albumin was desorbed from the PHMs by 1.0 M of NaCl, and the reusability of the imprinted PHMs was also demonstrated for five successive adsorption-desorption cycles without any significant loss in the albumin adsorption capacity. As an application, sodium-dodecyl sulfate polyacrylamide gel electrophoresis was used to indicate the albumin depletion efficiency of albumin imprinted p(HEMA-MAP) PHMs. This presented study showed that, these imprinted membranes are promising for proteomic studies and applications, and can be used for the investigations for human diagnostics.

Development of new methods for determination of bilirubin

The ever-increasing demand for a sensitive, rapid and reliable method for determination of serum bilirubin level has been inciting the interest of the researchers to develop new methods for both laboratory set up and point of care applications. These efforts embrace measurement of different forms of bilirubin, such as, unconjugated (free and albumin bound) bilirubin, conjugated (direct) bilirubin, and total (both conjugated and unconjugated) bilirubin in the serum that may provide critical information useful for diagnosis of many diseases and metabolic disorders. Herein, an effort has been made to provide a broad overview on the subject starting from the conventional spectroscopy based analytical methods widely practiced in the laboratory setup along with the sophisticated instrument based sensitive methods suitable for determination of different forms of bilirubin to various portable low cost systems applicable in point of care (POC) settings. In all these discussions emphasis is given on the novel methods and techniques bearing potential to measure the bilirubin level in biological samples reliably with less technical complexity and cost. We expect that this review will serve as a ready reference for the researchers and clinical professionals working on the subject and allied fields.

A surface molecularly imprinted electrospun polyethersulfone (PES) fiber mat for selective removal of bilirubin

Electrospinning and surface molecular imprinting were used together to prepare a surface molecularly imprinted electrospun polyethersulfone (PES) fiber mat for selective removal of bilirubin.

Preparation of imprinted cryogel cartridge for chiral separation of l-phenylalanine

l-Phe-imprinted cryogel cartridge was prepared for the chiral separation of l-Phe. N-Methacryloyl l-phenylalanine (MAPA) was used as a functional monomer for complexing with l-Phe. The selectivity of the membranes was investigated by using d-Phe, l-Trp, and d-Trp as competitor molecules. The PHEMAPA-l-Trp membranes were 6.4, 4.3, and 5.5 times more selective for l-Phe than d-Phe, l-Trp, and d-Trp, respectively. The PHEMAPA-l-Phe cryogel cartridge was incorporated into the fast protein liquid chromatography (FPLC) equipment and was able to separate D,l-Phe racemic mixture efficiently. The PHEMAPA-l-Phe membranes were shown to be reusable many times without significant loss of the adsorption capacity.

Functional polyethersulfone particles for the removal of bilirubin

In this study, polyethersulfone/poly (glycidyl methacrylate) particles are prepared via in situ cross-linked polymerization coupled with a phase inversion technique. The surfaces of these particles are then further modified by grafting amino groups using tetraethylenepentamine, dethylenetriamine, ethylenediamine, or 1,6-hexanediamine for the removal of bilirubin. The particles are characterized by Flourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Batch adsorption experiments are performed to verify the adsorption capability, and the effect of bilirubin initial concentration, bovine serum albumin concentration, and solution ionic strength on the adsorption is also investigated. In addition, both adsorption kinetic and isotherm models are applied to analyze the adsorption process of bilirubin, and a particle column is used to further study the bilirubin removal ability.To prove that the method was a universal portal to prepare functional particles, polysulfone, polystyrene, and poly(vinylidene fluoride) based functional particles were also prepared and used for the removal of bilirubin. This study and the results indicated that the particles had a great potential to be used in hemoperfusion treatment for hyperbilirubinemia.

Affinity binding of antibodies to supermacroporous cryogel adsorbents with immobilized protein A for removal of anthrax toxin protective antigen

Polymeric cryogels are efficient carriers for the immobilization of biomolecules because of their unique macroporous structure, permeability, mechanical stability and different surface chemical functionalities. The aim of the study was to demonstrate the potential use of macroporous monolithic cryogels for biotoxin removal using anthrax toxin protective antigen (PA), the central cell-binding component of the anthrax exotoxins, and covalent immobilization of monoclonal antibodies. The affinity ligand (protein A) was chemically coupled to the reactive hydroxyl and epoxy-derivatized monolithic cryogels and the binding efficiencies of protein A, monoclonal antibodies to the cryogel column were determined. Our results show differences in the binding capacity of protein A as well as monoclonal antibodies to the cryogel adsorbents caused by ligand concentrations, physical properties and morphology of surface matrices. The cytotoxicity potential of the cryogels was determined by an in vitro viability assay using V79 lung fibroblast as a model cell and the results reveal that the cryogels are non-cytotoxic. Finally, the adsorptive capacities of PA from phosphate buffered saline (PBS) were evaluated towards a non-glycosylated, plant-derived human monoclonal antibody (PANG) and a glycosylated human monoclonal antibody (Valortim(®)), both of which were covalently attached via protein A immobilization. Optimal binding capacities of 108 and 117 mg/g of antibody to the adsorbent were observed for PANG attached poly(acrylamide-allyl glycidyl ether) [poly(AAm-AGE)] and Valortim(®) attached poly(AAm-AGE) cryogels, respectively, This indicated that glycosylation status of Valortim(®) antibody could significantly increase (8%) its binding capacity relative to the PANG antibody on poly(AAm-AGE)-protien-A column (p < 0.05). The amounts of PA which remained in the solution after passing PA spiked PBS through PANG or Valortim bound poly(AAm-AGE) cryogel were significantly (p < 0.05) decreased relative to the amount of PA remained in the solution after passing through unmodified as well as protein A modified poly(AAm-AGE) cryogel columns, indicates efficient PA removal from spiked PBS over 60 min of circulation. The high adsorption capacity towards anthrax toxin PA of the cryogel adsorbents indicated potential application of these materials for treatment of Bacillus anthracis infection.

Interpenetrating polymer network composite cryogels with tailored porous morphology and sorption properties

Cryogels, by their particular morphology and mechanical properties, proved to be invaluable materials in biomedicine and biotechnology as carriers for molecules and cells, chromatographic materials for cell separations and cell culture. Methods used in the characterization of porosity and sorption properties of cryogels are very needful tools, which assist the investigator in the decision on the performances of the gel. Herein, we describe the preparation of ionic interpenetrating polymer network composite cryogels and the characterization methods of their porous morphology, and then the methods used for testing their sorption properties for ionic dyes used as models for drugs.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Advances in interpenetrating polymer network hydrogels and their applications

Interpenetrating polymer network (IPN) hydrogels brought distinct benefits compared to single network hydrogels like more widely controllable physical properties, and (frequently) more efficient drug loading/release. However, IPN strategy is not sufficient to design hydrogels with enhanced mechanical properties required for regenerative medicine like replacement of natural cartilage or artificial cornea. Some of the novel techniques promoted last decade for the preparation of IPN hydrogels which fulfill these requirements are discussed in the review. Among them, “double network” strategy had a strong contribution in the development of a large variety of hydrogels with spectacular mechanical properties at water content up to 90 %. Using cryogelation in tandem with IPN strategy led to composite cryogels with high mechanical properties and high performances in separation processes of ionic species. Highly stretchable and extremely tough hydrogels have been obtained by combining a covalently cross-linked synthetic network with an ionically cross-linked alginate network. IPN hydrogels with tailored mesh size have been also reported.