Chemical Design of Hydrogels with Immobilized Laccase for the Reduction of Persistent Trace Compounds in Wastewater

Abstract

Hydrogels with immobilized enzymes are increasingly applied in biocatalytic industrial processes. Here, polymer hydrogels containing 2-hydroxyethyl methacrylate (HEMA), itaconic acid (ITA), (2-((2-(ethoxycarbonyl)­prop-2-en-1-yl)­oxy)­ethyl) phosphonic acid (ECPPA), and N,N′-diethyl-1,3-bis­(acrylamido)­propane (BAAP) as the cross-linker are synthesized by UV-initiated radical polymerization. Laccase from Trametes versicolor (LAC) is modified by reaction with itaconic anhydride (ITAn) yielding the LAC-immobilized monomer ITA-LAC with enhanced enzyme activity. ITA-LAC paves the way to an in situ method for enzyme immobilization. Hydrogels with HEMA, ECPPA, and BAAP with stepwise varied chemical composition and functionalization are prepared. The influence of the composition on the morphology, the swelling behavior, the mechanical stability, and the enzymatic activity is studied. The polymerization is monitored by the conversion of double bonds with in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The polymerization of HEMA is complete after 10 min of UV exposure, whereas hydrogels of HEMA/ITA/ECPPA (85/5/10) with 5 mol % cross-linker require 30 min. These hydrogels are compared with those containing ITA-LAC instead of ITA. The covalent binding of LAC is proven by ATR-FTIR spectroscopy and results in an enhanced enzyme activity. The incorporation of ECPPA induces pH-dependent swelling with an equilibrium degree of swelling of up to 6 at pH 8. Only a weak influence of temperature on the degree of swelling is found. The morphology strongly depends on the hydrogel composition. LAC-ITA hydrogels are characterized by an open morphology providing access to catalytic centers. The enzyme-immobilized hydrogels are used as granules as well as coatings on porous Al2O3 ceramic substrates as biocatalysts to convert models for organic trace compounds [bisphenol A (BPA), diclofenac, p-chlorophenol (pCP), 17α-ethinylestradiol (EED), triclosan, paracetamol, and 4-tert-octylphenol]. The highest conversion after 24 h in water is achieved for triclosan (>90%), while pCP, BPA, and EED reach a conversion between 60% and 70%. The conversions are even higher in citrate buffer.

Photodynamic Inactivation of Pseudomonas aeruginosa by PHEMA Films Loaded with Rose Bengal: Potentiation Effect of Potassium Iodide

“…Due to its excellent biocompatibility, PHEMA has been used for the manufacture of contact lenses [37], ureteral stents [38] and platforms for neural growth [39]. But the applications of PHEMA materials go beyond the medical field and PHEMA can be used in the development of oxygen sensing materials [40], ion-selective membranes [41], batteries [42], and polymers for environmental remediation [43]. Due to the transparency of such materials, the encapsulation of optically active systems is especially attractive.…”

Environmentally Friendly Polyvinyl Alcohol−Alginate/Bentonite Semi-Interpenetrating Polymer Network Nanocomposite Hydrogel Beads as an Efficient Adsorbent for the Removal of Methylene Blue from Aqueous Solution

“…Then, the supernatant was centrifuged and the concentration was measured by UV/Vis spectrophotometer. Effect of different Bent content (10, 20, and 30 wt%), different pH (2−10), contact time (20−320 min), initial MB concentration (50−350 ppm), PVA−Alg/Bent dosage (0.1−2 g), and temperature (20,30,40, and 50 • C) have been explored to evaluate the performance of adsorbent beads. The equilibrium adsorption capacity, qe, (mg/g) of MB onto adsorbent beads as well as the removal percentage (%) were calculated from Equation (2) [47] and Equation (3) [48,49] respectively:…”

“…Among all of these techniques, the adsorption method is easily employed, fast and highly efficient [18][19][20]. Numerous different adsorbents have been synthesized such as activated carbons [21,22], porous ceramics [23,24], metal oxides [25], and polymeric hydrogels [26][27][28][29][30] for the remediation of contaminated water. Indeed, from both an environmental and industrial point of view, an ideal adsorbent should have large surface area, porous structure, available active functional sites, high mechanical stability and strength, as well as low cost and be eco-friendly [31,32].…”

Expanding the Biocatalytic Scope of Enzyme-Loaded Polymeric Hydrogels

“…Enzyme-loaded nanocomposites and hydrogels are widely used in biocatalytic industrial processes. Horn et al [ 14 ] developed a new polymer-based hydrogels that contained itaconic acid (ITA), 2-hydroxyethyl methacrylate (HEMA), N , N ’-diethyl-1,3-bis(acrylamido)propane (BAAP) and 2-2-(ethoxycarbonyl)prop-2-en-1-yl-oxy-ethyl phosphonic acid (ECPPA) as the cross-linking agents. The as-synthesized hydrogel was applied to immobilize laccase from Trametes versicolor for enhancing its catalytic properties.…”