Abstract Previous studies have investigated the preparation of heterogeneous biocatalysts based on the immobilization of lipases on distinct types of supports. However, few works have investigated the influence of the textural properties of these supports on the immobilization parameters. Thus, the present article reports the preparation of copolymers based on divinylbenzene by aqueous suspension polymerizations, using different amounts of porogenic agents to prepare particles with distinct textural properties. The particles were used for immobilization of lipase from Candida antarctica fraction B and the performance of the biocatalysts was evaluated in hydrolysis reactions, using p-nitrophenyl laurate as substrate. The use of Sty/DVB particles resulted in higher immobilization yields (89.5% and 99.2%) and higher hydrolytic activities, when compared to the Sty/VBC/DVB particles. Particularly, the increase of the pore diameters of the particles resulted in higher immobilization yields. Also, the hydrolytic activities depended simultaneously on the average pore diameter, porosity, and specific area (the most influential variable) of the supports. Thus, it was observed that the distinct morphological features of the polymer support can exert significant and conflicting effects on the final biocatalyst performance, since the specific surface area is normally expected to decrease with the increase of the average pore size.

Abstract Copolymers based on glycidyl methacrylate (GMA) are considered attractive as sorbents because the epoxy groups can be easily converted into other groups. Studies involving the influence of the synthesis parameters on the morphological characteristics of these copolymers are scarce. This work investigates the synthesis of copolymers of poly(GMA-co-EGDMA) with different porosity degrees obtained by varying the synthesis parameters. GMA-EGDMA copolymers were synthesized by suspension polymerization employing varied conditions and characterized by measuring apparent density, surface area and pore volume distribution, optical and scanning electron microcopies, FT-IR, thermogravimetry and titration of epoxide rings. The copolymer with highest surface area and pore volume (260.4 m2/g and 0.5 cm3/g) was prepared employing cyclohexane as diluent, 80% EGDMA in monomeric composition and 100% of dilution degree. There was a relation between the epoxide content of the copolymers determined by titration and the residue content formed in the first decomposition stage.

Carriers with different functional groups (epoxy, aldehyde, ethyldiazonium, phenyldiazonium and amino) were tested for immobilization of T. versicolor laccase on GMA-co-EGDMA (glycidyl methacrylate-co-ethyleneglycol dimethacrylate) microspheres. Laccase immobilized on GMA-co-EGDMA containing the phenyldiazonium functional group showed the highest activity (96.3 U g-1). The immobilized laccase was used for removal of bisphenol-A (BPA) from aqueous solution. The temperature effect was significant on activity, but insignificant on BPA removal by the immobilized laccase. In the temperature range 10-60 °C, the removal of BPA by laccase in the immobilized form was about four times higher than that in the free form. Swelling does not affect the activity of immobilized laccase, but after 8 cycles of 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) oxidation, non-swollen immobilized laccase was able to retain 71% of the starting activity while the 24 h swollen kept 61%. At neutral pH, adsorption onto the immobilized laccase accounted for 92% of the BPA removed while enzymatic conversion accounted for 8%. However, when increasing the pH to 10, the fraction of BPA removed by adsorption decreased to 67% and by enzymatic conversion increased to 33%.

We report the development of copolymers based on 2-vinylpyridine with different porosity degrees. The copolymers were quaternized with methyl iodide and acrylonitrile to introduce quaternary ammonium groups on pyridine units. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized were impregnated with iodine. The antibacterial properties of all the polymers were evaluated ranging from of the Escherichia coli strain. The unmodified copolymers did not have antibacterial activity against E.Coli suspensions. The quaternization with methyl iodine and acrylonitrile increased the biocidal performance of these copolymers, but only the copolymer with the lowest porosity modified with methyl iodine showed significant bactericidal action for all E. Coli concentrations. The 2-vinylpiridine copolymers quaternized and impregnated with iodine had higher antibacterial activity than the impregnated ones. The charge transfer complexes derived from the copolymer with the lowest porosity and highest swelling capacity in water had the best bactericidal performance.

We report the development of two copolymers based on 2-vinylpyridine, styrene and divinylbenzene (2Vpy-Sty-DVB) with different porosity degrees. The copolymers were subsequently quaternized with methyl iodide. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized with methyl iodine were impregnated with iodine. The antibacterial properties of the polymers were evaluated in dilutions ranging from 10² to 10(7) cells/mL of the auxotrophic OHd5-K12 Escherichia coli strain. It was possible to obtain materials with complete antibacterial activity even in the highest cell concentrations tested.