Synthesis and characterization of 2-hydroxyethyl methacrylate-ethylene glycol dimethacrylate polymeric granules intended for selective removal of uric acid

Synthesis and Characterization of a New Cryogel Matrix for Covalent Immobilization of Catalase

The advantages of cryogels for enzyme immobilization applications include their mechanical and chemical robustness, ease of production, superior porosity, and low cost. Currently, many researchers are exploring porous material-based systems for enzyme immobilization that are more efficient and economically viable. Here, poly(2-Hydroxyethyl methacrylate-co-allyl glycidyl ether) (p(HEMA-co-AGE)) cryogel matrices were synthesized via the free radical cryopolymerization method to be employed as the support material. For the immobilization of the catalase enzyme onto the p(HEMA-co-AGE) cryogel matrix (catalase@p(HEMA-co-AGE), the best possible reaction conditions were determined by altering parameters such as pH, catalase initial concentration, and flow rate. The maximum catalase immobilization amount onto the p(HEMA-co-AGE) cryogel was found to be 48 mg/g cryogel. To determine the advantages of the cryogel matrix, e.g., the stability and reusability of the cryogel matrix, the adsorption–desorption cycles for the catalase enzyme were repeated five times using the same cryogel matrix. At the end of the reusability tests, it was found that the cryogel was very stable and maintained its adsorption capacity with the recovery ratio of 93.8 ± 1.2%. Therefore, the p(HEMA-co-AGE) cryogel matrix affords repeated useability, e.g., up to five times, without decreasing its catalase binding capacities significantly and has promising potential for many industrial applications. Cryogels offer clear distinctive advantages over common materials, e.g., micro/nano particles, hydrogels, films, and composites for these applications. At present, many researchers are working on the design of more effective and economically feasible, porous material-based systems for enzyme immobilization

Towards the Use of Adsorption Methods for the Removal of Purines from Beer

Beer corresponds to a fermented alcoholic beverage composed of several components, including purine compounds. These molecules, when ingested by humans, can be catabolized into uric acid, contributing to uric acid’s level increase in serum, which may lead to hyperuricemia and gout. To assure a proper management of this disease, physicians recommend restrictive dietary measures, particularly by avoiding the consumption of beer. Therefore, it is of relevance to develop efficient methods to remove purine compounds from alcoholic beverages such as beer. In this review, we provide an introduction on fermented alcoholic beverages, with emphasis on beer, as well as its purine compounds and their role in uric acid metabolism in the human body in relation to hyperuricemia and gout development. The several reported enzymatic, biological and adsorption methods envisaging purine compounds’ removal are then reviewed. Some enzymatic and biological methods present drawbacks, which can be overcome by adsorption methods. Within adsorption methods, adsorbent materials, such as activated carbon or charcoal, have been reported and applied to beer or wort samples, showing an excellent capacity for adsorbing and removing purine compounds. Although the main topic of this review is on the removal of purine compounds from beer, other studies involving other matrices rather than beer or wort that are rich in purines are included, since they provide relevant clues on designing efficient removal processes. By ensuring the selective removal of purine compounds from this beverage, beer can be taken by hyperuricemic and gouty patients, avoiding restrictive dietary measures, while decreasing the related healthcare economic burden.

Preparation of Ethylene Glycol Dimethacrylate (EGDMA)-Based Terpolymer as Potential Sorbents for Pharmaceuticals Adsorption

Ethylene glycol dimethacrylate (EGDMA) is used as a crosslinker in poly(acrylonitrile (AN)-co-vinylbenzyl chloride (VBC)) to investigate the effect of long-chain crosslinker to the porosity of the terpolymer system. Poly(AN-co-EGDMA-co-VBC) is synthesized by using precipitation polymerization method and further hypercrosslinked by Friedel-Crafts reaction. FT-IR spectra of poly(AN-co-EGDMA-co-VBC) show that the absorption bands at ~1290 cm-1 that are assigned to the C-Cl vibrations are almost disappeared in hypercrosslinked (HXL) poly(AN-co-EGDMA-co-VBC) polymers, confirming that the hypercrosslinking reaction is successful. SEM images show that the morphologies of the polymers are retained through the hypercrosslinking reactions. Brunauer-Emmett-Teller (BET) analysis shows that hypercrosslinked polymers had a specific surface area up to 59 m2·g-1. The preliminary performance of the terpolymer adsorbent to capture polar analyte is evaluated by adsorbing salicylic acid and mefenamic acid from aqueous solution in a batch system. The maximum adsorption capacity of salicylic acid and mefenamic acid were up to 416.7 mg·g-1 and 625 mg·g-1, respectively, and the adsorption kinetic data obeyed pseudo-second-order rate equation.

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.

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.