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Summary: Sand samples from Tampa (T) and Panama (P) City beaches in Florida were used as catalysts for dehydrogenation of NaBH4 in methanol. T and P sand samples were sieved to <250, 250 to 500, and >500 μm sizes, and the smallest fractions resulted in faster hydrogen generation rates (HGR), 565 ± 18 and 482 ± 24 mL H2 (min.g of catalyst)−1, respectively. After various base/acid treatments, HGR values of 705 ± 51 and 690 ± 47 mL H2 (min g of catalyst)−1 for HCl‐treated T and P sand samples were attained, respectively. Next, T and P sand samples were modified with polyethyleneimine (PEI) that doubled the HGR values, 1344 ± 103, and 1190 ± 87 mL H2 (min.g of catalyst)−1 and increased ~8‐fold, 4408 ± 187, and 3879 ± 169 mL H2 (min g of catalyst)−1, correspondingly after protonation (PEI+). The Ea values of T and P sand samples were calculated as 24.6 and 25.9 kJ/mol, and increased to 36.1, and 36.6 kJ/mol for T‐PEI+ and P‐PEI+ samples, respectively. [ABSTRACT FROM AUTHOR]

Polyethyleneimine (PEI) cryogels with interconnected superporous morphology were synthesized via the cryopolymerization technique. Then, conductive polymers, poly(Aniline) (PANi), poly(Pyrrole) (PPy), and poly(Thiophene) (PTh) were prepared within these PEI cryogels. Then, the conductive polymer embedding PEI composites' characterization was carried morphologically using scanning electron microscope (SEM) by means of Fourier Transform Infrared Radiation (FT-IR) spectrometer, and by means of electrical conductivity measurements using an electrometer. Among all the prepared cryogel conductive polymer composites, the highest value in terms of conductivity was determined for PEI/PANi cryogel composites with 4.80 x 10-3 S.cm-1. Afterward, to prepare polymeric ionic liquid (PIL) forms of PEI and PEI/PANi composites. To assess the effect of anions on the conductivities of the prepared composites, PEI-based cryogels were anion ex-changed after protonation with HCl by treatment of aqueous solutions of sodium dicyanamide (Na+[N(CN)2]-), ammonium hexafluorophosphate (NH4+[PF6]-), sodium tetrafluoroborate (Na+[BF4]-), and potassium thiocyanate (K+[SCN]-), separately. Furthermore, PEI-based cryogel composites and their PIL forms were tested as a sensor for CO2 gas. The higher conductivity changes were observed on bare PEI cryogel and PEI+[BF4]- PIL cryogels with 1000-fold decrease on conductivity upon 240 min CO2 exposure. The sensitivity and recovery percent of bare PEI and PEI+[BF4]- PIL cryogels were shown almost the same with a two-fold decrease in the presence of 0.009 mole of CO2 gas, and approximately 30% recovery after the fifth consecutive reuse. [ABSTRACT FROM AUTHOR]

Polymeric ionic liquid (PIL) microgel of poly([2‐(methacryloyloxy)ethyl]trimethylammonium chloride) (p(MTMA)) was synthesized by using an inverse suspension polymerization technique. The anion‐exchanged PIL microgels via chloride replacement from p(MTMA) were prepared as p(MTMA)‐potassium thiocyanate (p(MTMA)‐KSCN), p(MTMA)‐sodium tetrafluoroborate (p(MTMA)‐NaBF4), and p(MTMA)‐sodium dicyanamide (p(MTMA)‐NaN(CN)2) microgels by treatment with corresponding salts of potassium thiocyanate (KSCN), sodium tetrafluoroborate NaBF4, and sodium dicyanamide NaN(CN)2 in aqueous media. The prepared microgels were found to be efficient metal‐free catalysts, and their catalytic activity in H2 production from the methanolysis of NaBH4 was investigated. Moreover, various parameters affecting H2 production such as the effect of microgel size, the concentration of NaBH4, the effect of the anion in the microgel, the reusability of the microgel, and temperature were investigated. The Ea value calculated for the methanolysis reaction of NaBH4 catalyzed by p(MTMA) microgels was found as 24.1 ± 0.7 kJ mol−1 ranging from −15 to 45°C, and this Ea value is lower than some Ea values for the same reaction. Interestingly, 10‐time successive use of p(MTMA) microgel as catalyst in NaBH4 methanolysis reduced its catalytic activity to 49%, whereas the anion‐exchanged forms of p(MTMA) microgel, p(MTMA)‐KSCN, p(MTMA)‐NaBF4, and p(MTMA)‐NaN(CN)2 only reduced their catalytic activity to 89, 86, and 79%, respectively, after 10 consecutive uses. Therefore, these anion‐exchanged microgel catalysts are highly efficient in comparison with virgin p(MTMA) microgels for regenerable H2 generation from the methanolysis of NaBH4. [ABSTRACT FROM AUTHOR]

The polyethyleneimine (PEI) microgels prepared via microemulsion polymerization are protonated by hydrochloric acid treatment (p-PEI) and quaternized (q-PEI) via modification reaction with methyl iodide and with bromo alkanes of different alkyl chain lengths such as 1-bromoethane, 1-bromobutane, 1-bromohexane, and 1-bromooctane. The bare p-PEI and q-PEI microgels are used as catalysts directly without any metal nanoparticles for the methanolysis reaction of sodium borohydride (NaBH4). Various parameters such as the protonation/quaternization reaction on PEI microgels, the amount of catalyst, the amount of NaBH4, and temperature are investigated for their effects on the hydrogen (H2) production rate. The reaction of self-methanolysis of NaBH4 finishes in about 32.5 min, whereas the bare PEI microgel as catalyst finishes the methanolysis of NaBH4 in 22 min. Surprisingly, it is found that when the protonated PEI microgels are used as catalyst, the same methanolysis of NaBH4 is finished in 1.5 min. The highest H2 generation rate value is observed for protonated PEI microgels (10 mg) with 8013 mL of H2/(g of catalyst.min) for the methanolysis of NaBH4. Moreover, activation parameters are also calculated with activation energy value of 23.7 kJ/mol, enthalpy 20.9 kJ/mol, and entropy −158 J/K.mol. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Monodispersed poly(acrylonitrile) [p(AN)] particles were prepared by surfactant free emulsion polymerization and the hydrophobic nitrile groups were converted to hydrophilic amidoxime groups by treatment with hydroxylamine hydrochloride (NH2OH.HCl) in water. The p(AN) and amidoximated p(AN) [amid-p(AN)] particles were characterized by Fourier transformation infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The prepared particles were used as adsorbents in the removal from aqueous media of three different types of pollutants; organic dyes methylene blue (MB), and rhodamine 6 G (R6G), a heavy metal ion Cd (II), and a herbicide paraquat (PQ). The effects of various parameters such as amidoximation, pH of solution, amount of particles, and the initial concentration of solution were investigated. Upon amidoximation, a great increase in the adsorption capacity of the prepared particles was observed as the adsorbed amounts were increased to 87, 91, 74, and 91 mg/g from 5, 1.54, 1.06, and 1.22 mg/g for Cd (II), MB, R6G, and PQ, respectively. The amid-p(AN) particles were also able to remove considerable amounts of these pollutants from tap, river, and sea water. Langmuir, Freundlich, and Temkin adsorption isotherms were applied and it was found that the adsorption of Cd (II) and PQ followed the Langmuir adsorption model, whereas the adsorption of MB was found to obey the Freundlich adsorption isotherm. Pseudo first-order and pseudo second-order kinetics were also applied and the results showed that the adsorption processes of Cd (II), PQ, MB, and R6G follow pseudo second-order kinetics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43032. [ABSTRACT FROM AUTHOR]

[Display omitted] • Various metal ions contain ZIF particles were synthesized with HmIm. • ZIF-Co(II) and ZIF-Zn(II) particles showed higher surface area with 1423.4 ve 1467.1 m2/g, respectively. • The MBC of ZIF-Co(II) particles against P. aeruginosa , S. aureus , and C. albicans were determined as 0.25, 1.0, and 5.0 mg/mL. • Inhibition zones were measured as 22.7 ± 1.5, 24.3 ± 1.1, and 25.7 ± 0.6 mm against P. aeruginosa , S. aureus , and C. albicans in the presence of 10 mg of ZIF-Cu(II). • Prepared ZIF particles promise versatile usability in antibacterial applications. Herein, the synthesis of zeolitic imidazolate framework particles in water at room temperature using 2-methylimidazole (HmIm) as organic linker, and Co(II), Ni(II), Cu(II), Fe(II), Mg(II), Zn(II), Ce(III), La(III), Fe(III), and Ti(IV) ions is reported. The colors of the prepared ZIF particles varied depending on the metal ions used. The disappearance of N H ring-N out of plane bending peak at 1845 cm−1 and weakening of the N H bending peak at 1597 cm−1 in the FT-IR spectrum of HmIm after ZIF synthesis confirmed successful preparation. Higher surface area values were observed for ZIF-Co(II) and ZIF-Zn(II) with values of 1423.4 and 1467.1 m2/g, respectively. The prepared ZIF-Fe(II) particles showed magnetic property. The antibacterial activities of ZIF particles also varied depending on metal ions. The highest antibacterial activities were observed for ZIF-Co(II) and ZIF-Cu(II) particles against P. aeruginosa (gram -, ATCC 10145), S. aureus (gram +, ATCC 6538), and C. albicans (fungi, ATCC 10231). The MIC values of ZIF-Co(II) particles were determined as 0.125, 0.25, and 1.0 mg/mL against P. aeruginosa , S. aureus , and C. albicans , whereas MBC values were determined as 0.25, 1.0, and 5.0 mg/mL, respectively. The inhibition zones for P. aeruginosa , S. aureus , and C. albicans in the presence of 10 mg ZIF-Cu(II) particles were measured as 22.7 ± 1.5, 24.3 ± 1.1, and 25.7 ± 0.6 mm, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fluorescent metal organic frameworks based on PTCDA as organic linker. • Fluorescent Metal Organic frameworks with sensor abilities. • PTCDA-Co(II) and PTCDA-La(III) MOFs with optical device potentials. • Fluorescent quenching properties for Cu(II), Ni(II), As(III), and Hg(II) metal ions. Metal organic frameworks (MOFs) are unique porous materials with a high surface area employing variety of organic ligands and metal ion components. Moreover, the possibility of developing different additional features, such as magnetic, thermo-responsive, and fluorescent properties that come from the organic ligands and/or metal ions can methodically increase the industrial application of MOF structures. In this paper, perylene 3,4,9,10 tetracarboxylic dianhydride (PTCDA) based MOFs with fluorescent properties were synthesized using Co(II) and La(III) metal ions as nodules. The disappearance of carbonyl group peaks at 1756 cm−1 from PTCDA molecules confirmed the synthesis of PTCDA-based Co(II) and La(III) MOFs. The SEM image revealed that the prepared PTCDA-Co(II) MOFs are in ellipsoidal shapes, whereas the PTCDA-La(III) MOFs are in rod or fiber-like shapes. The BET surface area of prepared PTCDA-Co(II) and PTCDA-La(III) MOFs were determined as 125.9 m2/g and 29.9 m2/g, respectively. The prepared PTCDA-based Co(II) and La(III) MOF exhibit fluorescent properties, e.g., upon exposure to 465 nm excitation wavelength, they have fluorescence emission intensity of 10,500 and 13,000 (a.u) at 514 and 510 nm wavelength, respectively. The quenching activity of Cu(II), Ni(II), As(III), and Hg(II) metal ions on fluorescence properties of PTCDA-La(III) MOFs were examined. Moreover, it was observed that the prepared PTCDA-Co(II) and PTCDA-La(III) MOF show 82.9 ± 0.4 and 95.4 ± 4.1 % Fe(II) chelating activity at 1400 µg/mL concentration of PTCDA-Co(II) and PTCDA-La(III). Lastly, Quantum yield was calculated as 52 ± 1 % for PTCDA-La(III) MOF. [ABSTRACT FROM AUTHOR]

Polyethylene imine (PEI) particles were synthesized by a microemulsion polymerization technique, and were used as template for metal nanoparticle preparation. The PEI particles were loaded with Co(II), Ni(II) and Cu(II) ions from water and with CoCl2, NiCl2 and CuCl2 from ethanol and treated with NaBH4 to reduce the corresponding metal nanoparticles in situ. The PEI-M (Co, Ni, and Cu) composites were used in hydrogen generation from the hydrolysis of NaBH4 and NH3BH3 (AB). The PEI-Co composite catalyst system had better catalytic performances in the hydrolysis reactions of NaBH4 and AB than the other metal containing composites. The turnover frequency (TOF) value of PEI-Co in the hydrolysis of AB was found to be almost 12.5 fold more than NaBH4 hydrolysis. It is reported here that the PEI template offered better characteristics than the other templates providing many advantages; for example, the metal loading capacity of PEI increased by sequential loading and reduction cycles, and very high conversion (100%) and activity (100%) were obtained when PEI-Ni was used in fifteen consecutive runs for NaBH4 hydrolysis. The PEI-M composites have mild activation energy in comparison to the literature but better, more flexible characteristics, and very fast kinetics in AB hydrolysis. [ABSTRACT FROM AUTHOR]

Protonable polyethyleneimine (PEI) and citric acid (CA) based C-dots were prepared via a hydrothermal process, yielding particles with a hydrodynamic diameter of ~100 and ~80 nm, and zeta potential of − 2.3 ± 0.1 and + 23.4 ± 0.2 mV for PEI-CA C-dots and their protonated form, respectively. Treating Staphylococcus aureus with these C-dots resulted in a statistically significant reduction in bacterial growth, specifically growth in the planktonic phase as well as in the development of bacterial biofilm when compared to untreated (p < 0.05). When 24 h matured S. aureus biofilms were treated with C-dots, a significant disruption and dispersion of bacteria from the existing biofilms was noted as compared to untreated (p < 0.05). Other Gram-positive microorganisms (B. cereus, S. epidermidis, S. pyogenes) and Gram-negative (P. mirabilis, E. coli, and P. aeruginosa) were also susceptible to the antimicrobial activity of the PEI-CA C-dots with significant inhibition of bacterial growth noted for all organisms after C-dot treatment. Only for B. cereus, S. epidermidis, and P. aeruginosa was this reduction in total growth reflected in decreased planktonic growth. However, biofilm formation by all organisms was reduced significantly upon treatment with the C-dots, including those for which planktonic growth was not impacted. [Display omitted] • Fluorescent N-doped C-dots can be readily prepared via a facile solvothermal method. • Positively charged N-doped C-dots are effective as anti-biofilm agents. • C-dots successfully inhibit bacterial proliferation in the planktonic growth phase. • C-dots stop biofilm formation by several bacteria and disrupt established biofilms. [ABSTRACT FROM AUTHOR]

Hydrogels with reactive thiourea functional groups were prepared by radiation-induced crosslinking of N-(Hydroxymethyl) acrylamide (HMA) and N-allyl thiourea (ATU) at different ATU content and irradiation doses. P(HMA-co-ATU) hydrogels were then utilized as template for in situ metal nanoparticle (MNP) preparation by the reduction of Ni2+, Co2+, and Cu2+ ions within the hydrogel matrix using sodium borohydride (NaBH 4) as reducing agent. These MNP@p(HMA-co-ATU) hydrogel composites (MNP = Co, Ni, and Cu) were further used as catalysts in the reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol (AP). Various parameters such as the effect of ATU content, the total dose used in the hydrogel preparation, MNPs type, and temperature on the catalytic activity of hydrogel composites were investigated. The activation energy, enthalpy, and entropy of Ni@p(HMA-co-ATU) hydrogels for the reduction reaction of 4-NP to 4-AP were calculated as 42.5 kJ mol−1, 38.9 kJ mol−1, and −187.3 J mol−1 K−1, respectively. • Radiation induced synthesis of poly(HMA-co-ATU) hydrogel at different ATU content is reported. • Higher irradiation dose rendered higher ATU content in poly(HMA-co-ATU) hydrogels. • P(HMA-co-ATU) hydrogels were used as reactor for in situ Ni, Co or Cu metal nanoparticle preparation. • P(HMA-co-ATU)-Ni hydrogel composites have shown the best catalytic performance in 4-Nitrophenol reduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ionic liquid (IL) forms of polyethyleneimine (PEI) as metal free catalyst for H 2. • NaBH 4 methanolysis via PEI-X (X:Anion) catalyst for green H 2 production. • Highly reusable IL colloidal polymeric catalyst with low Ea in H 2 generation. • Green energy carrier, H 2 release from NaBH 4 via highly regenerable PEI-X catalyst. Ionic liquid (IL) forms of polyethyleneimine (PEI) microgels were prepared using anion exchange and direct acid treatment techniques employing tetrafluoroborate (TFB) and hexafluorophosphate (HFP) anions as well as their corresponding acids, tetrafluoroboric acid (TFBA) and hexafluorophosphoric acid (HFPA), respectively. Then, these polymeric ionic liquids (PIL) of PEI microgels were used as metal-free catalysts for hydrogen (H 2) production from sodium borohydride (NaBH 4) solution in methanol (methanolysis). The parameters affecting H 2 production rates such as the types of anions, the methods of PIL preparation, temperature, reusability, and regeneration of PEI-based microgels were investigated. In the dehydrogenation reaction of NaBH 4 in methanol catalyzed by PEI-based PIL microgels, the lowest Ea value in the temperature range of −10–40 °C was calculated as 16.0 ± 0.8 kJ/mol for PEI-HFP PIL microgel, prepared by anion exchange method. The reusability studies of PEI-TFB PIL microgels revealed that the catalytic activity was decreased to 89 ± 5% after 5 consecutive use with 100% conversions for every use. Additionally, independent of the anion exchange methods, PEI-based PIL microgels afford catalytic H 2 production from NaBH 4 methanolysis in a wide range of temperatures including subzero temperatures with facile regenerations by the treatments with TFBA and HFPA resulting in 100% recovery of catalytic activities at each regeneration. The metal-free PIL form of PEI microgel catalyst renders much better catalytic performances and advantages than metal nanoparticle-based catalysts for green H 2 production offering viable alternatives in industrial application. [ABSTRACT FROM AUTHOR]

[Display omitted] • − 3D super porous poly(β-Cyclodextrin) cryogels in 1–100 µm pore size are prepared. • - Poly(β-Cyclodextrin) cryogels with blood compatibility and partially hydrolytic degradable. • - Poly(β-Cyclodextrin) cryogels can release hydrophilic and hydrophobic drugs simultaneously. Here, one step, simple preparation of superporous p(β-cyclodextrin) (p(β-CD)) cryogels in the presence of various ratios of crosslinker, divinyl sulfone (DVS) e.g., 100, 150, 200% mole with respect to the mole ratio of 6 hydroxyl groups on β-CD unit under cryogenic conditions were reported for the first time. The swelling properties, and hydrolytic degradation of p(β-CD) cryogels was directly related to the used crosslinker ratio. It was observed that the p(β-CD) cryogels showed higher swelling% in DMSO and DMF than in DI water. The prepared p(β-CD)-1 cryogel that was 100% crosslinked exhibited 14 ± 3.7%, 34 ± 4.8%, and 45 ± 6.2% weight losses within 20 days in pH 5.4, 7.4, and 9.0 buffer solutions, respectively. An acceptable hemolysis index of < 5% and a blood coagulation index, >89% were observed for the p(β-CD) cryogels at 1 mg/mL concentrations. Additionally, the potential useability of p(β-CD) cryogels as in vitro drug delivery systems for both hydrophilic vancomycin, and hydrophobic tetracycline as model drugs were individually illustrated at pH 7.4 in PBS. The cumulative drug release from p(β-CD) cryogels, in sustained release profiles with 76.7 ± 9.0 mg/g of vancomycin (89.9 ± 10.5% of the loaded amount) and 146.5 ± 19.4 mg/g tetracycline g (83.1 ± 6.3% of the loaded amount) were attained in 6 and 54 h, respectively at pH 7.4 in PBS. Most importantly, p(β-CD) cryogels exhibited simultaneous loading and releasing the ability for both hydrophilic vancomycin, and hydrophobic tetracycline drugs by concurrently releasing 37.0 ± 2.7 mg/g (23.4 ± 1.8% of the loaded amount), and 36.3 ± 1.3 mg/g (23.6 ± 0.8% of the loaded amount), respectively at pH 7.4 (PBS) in 10 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOFs based on Polyethyleneimine (PEI) and Ce(NO 3) 3 as biomaterial were prepared. • PEI-Ce(III) MOFs possess <0.5% hemolysis, and >90% blood clotting index values. • P-PEI-Ce(NO 3) 3 MOFs with antibacterial, and antioxidant properties are attained. • PEI-based MOFs are promising and adaptable multipurpose material in biomedicine. Here, a well-known antibacterial cationic branched polyethyleneimine (PEI) is used as organic linker in the preparation of metal organic frameworks (MOFs) with a lanthanide salt, Cerium (III) nitrate (Ce(NO 3) 3) for two types of MOFs. One of the MOF is PEI-Ce(III) prepared from the aqueous solutions of PEI and Ce (III) ions at room temperature. The second MOF is prepared from the HCl treated PEI (p-PEI) and Ce(NO 3) 3 in ethanol as p-PEI-Ce(NO 3) 3 MOFs. The MOFs are prepared at 1: 0.25, 1:0.5 and 1:1 mol ratios of PEI repeating unit to Ce(III) ions and named as p-PEI-Ce(NO 3) 3 –0.25, −0.5, and −1, respectively. The prepared PEI-Ce(III) MOFs are in powder form, whereas p-PEI-Ce(NO 3) 3 MOFs are sticky and viscous as gum and soluble in water. The surface areas of PEI-Ce(III) MOFs are found to decrease with the increase in the amount Ce(III) amount and maximum surface area is measured for PEI-Ce(III)-0.25 as 142.3 m2/g, while the surface area of p-PEI-Ce(NO 3) 3 MOFs cannot be measured. Additionally, all the PEI-Ce(III) MOFs are found blood compatible with < 0.5% hemolysis and >90% blood clotting index values up to 0.25 mg/mL concentration. Also, the antioxidant activity of PEI which is 1107 ± 26 Trolox Equivalent Antioxidant Capacity (TEAC mM/g) is retained as 166 ± 12, 186 ± 1.0, 194 ± 2.0 for p-PEI-Ce(NO 3) 3 –0.25, −0.5, and −1 MOFs, respectively whereas no antioxidant activity in for Ce(III) is measured at the same concentrations. More importantly, the antimicrobial activity of PEI that is measured by via both micro-dilution and disc diffusion antimicrobial tests is also maintained for p-PEI-Ce(NO 3) 3 MOFs against Escherichia coli , Pseudomonas aeruginosa , Bacillus subtilis , Staphylococcus aureus , and Candida albicans with the MIC values ranging 0.625–5.0 mg/mL and the MBC values of 1.25–10 mg/mL. [ABSTRACT FROM AUTHOR]

The biocompatible, viscoelastic properties of poly(vinyl alcohol) (PVA) in combination with the antimicrobial and antioxidant natural polyphenolic, tannic acid (TA), and the natural flavonoid and antioxidant curcumin (Cur), were used in the preparation of PVA:TA and PVA:TA:Cur cryogel composites using cryotropic gelation to combine the individually beneficial properties. The effect of TA content on the antioxidant and antimicrobial activities of PVA:TA cryogel composites and the antioxidant activities of PVA:TA:Cur cryogel composites was determined using Trolox equivalent antioxidant capacity (TEAC) and total phenol content (TPC) assays, and were compared. The PVA:TA:Cur cryogel composite showed the highest antioxidant activity, with a TEAC value of 2.10 ± 0.24 and a TPC value of 293 ± 12.00. The antibacterial capacity of the PVA:TA and PVA:TA:Cur 1:1:0.1 cryogel composites was examined against two different species of bacteria, E. coli and S. aureus. It was found that the minimum inhibition concentration (MIC) value of the PVA:TA:Cur 1:1:0.1 cryogel composites varied between 5 and 10 mg/mL based on the type of microorganism, and the minimum bactericidal concentration (MBC) value was 20 mg/mL irrespective of the type of microorganism. Furthermore, the hemocompatibility of the PVA:TA cryogel composites was evaluated by examining their hemolytic and coagulation behaviors. PVA:TA 1:1 cryogels with a value of 95.7% revealed the highest blood clotting index value amongst all of the synthesized cryogels, signifying the potential for blood contacting applications. The release of TA and Cur from the cryogel composites was quantified at different pH conditions, i.e., 1.0, 7.4, and 9.0, and additionally in ethanol (EtOH) and an ethanol–water (EtOH:Wat) mixture. The solution released from the PVA:TA cryogels in PBS was tested for inhibition capability against α-glucosidase (E.C. 3.2.1.20). Concentration-dependent enzyme inhibition was observed, and 70 µL of 83 µg/mL PVA:TA (1:1) cryogel in PBS inhibited α-glucosidase enzyme solution of 0.03 unit/mL in 70 µL by 81.75 ± 0.96%. [ABSTRACT FROM AUTHOR]

• α-Glu enzyme can be entrapped within neutral, anionic and cationic cryogel reactors. • Higher stability for α-Glu@cryogels than free enzyme at wide range of Ts and pHs. • α-Glu@p(AMPS) cryogels bestow higher activity% at pH 8 versus pH 6.8 for free α-Glu. • α-Glu@p(APTMACl) afford higher activity% at pH 5 versus pH 6.8 for free α-Glu. • Superporous α-Glu@cryogels confer improved enzymatic activity and storage at 25 °C. Although enzymes are unique catalysts with highest selectivity for desired products, their cost, poor stability, and delicate reaction condition are the main drawbacks. To circumvent these obstacles and render viable enzymatic reactions with increased durability and stability, enzymes are generally immobilized in very different substrates. Therefore, herein, α-Glucosidase from Saccharomyces cerevisiae (α-Glu) as a model enzyme was entrapped within neutral, anionic and cationic synthetic cryogels such as poly(Acrylamide) (α-Glu@p(AAm)), poly(2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) (α-Glu@p(AMPS)), and poly(3‐acrylamidopropyltrimethyl ammonium chloride) (α-Glu@p(APTMACl)) during the synthesis process. The prepared α-Glu@p(AAm), α-Glu@p(AMPS), and α-Glu@p(APTMACl) cryogels were used as reactor and found to main their enzymatic activity of 80.9 ± 3.5, 61.5 ± 2.2, and 50.9 ± 3.1% with respect to free enzyme at its' optimum conditions, pH 6.8 and 37 °C, respectively. Interestingly, at harsher pH conditions, it was fond that α-Glu@p(AMPS) cryogels showed 100% activity at pH 8.0, and α-Glu@p(APTMACl) cryogels showed 100% activity at pH 5.0, whereas free α-Glu almost lost its catalytic activity completely at the same pHs. The operational and storage stability studies revealed that the entrapment of α-Glu within cryogels led to much better operational and storage stability than free α-Glu enzyme e.g., more than 50% activity after 10th usage and 10-day storage time at room temperature while almost no activity is attained for free enzyme. The kinetic parameters such as K m and V max of α-Glu@cryogel were also calculated by using Lineweaver-Burk plotting method and compared each other and free α-Glu enzyme. [ABSTRACT FROM AUTHOR]

• PEI based hydrogels aimed at water purification from toxic metal oxyanions. • PEI bulkgel, cryogel and microgel are effective in removing arsenate and dichromate. • PEI materials possess rapid and effective alternative in eliminating toxic metal ions. • Superior reusability of PEI hydrogels ensures higher water purification capabilities. Among the various metal ions, chromate (Cr(VI)) and arsenate (As(V)) are the two most hazardous toxic ion species and are found in nature in the form of dichromate and arsenate anions. In this investigation, polyethyleneimine (PEI)-based hydrogels were prepared with microgel, cryogel, and bulkgel morphologies employing glycerol diglycidyl ether as a crosslinker. The prepared PEI-based hydrogels were used to remove dichromate and arsenate anions from aqueous media. PEI microgel, cryogel, and bulkgels weighing 50 mg of each adsorbed 84.7 ± 0.8, 76.5 ± 5.2, and 108.9 ± 2.4 mg.g−1 of dichromate anions and 15.9 ± 0.7, 45.4 ± 1.9, and 79.2 ± 11.6 mg.g−1 of arsenate anions in 30, 120, and 240 min, respectively. The dichromate and arsenate anions adsorption of PEI-based hydrogels were found to fit to the pseudo-second-order kinetic, and nonlinear Langmuir isotherm models, respectively with higher R2 values. The highest distribution coefficient (K d) value of PEI-based hydrogels for dichromate adsorption was obtained on the cryogel forms of PEI as 1.89 ± 0.05. Likewise, the highest K d value for the arsenate adsorption was calculated on PEI-based bulkgels as 0.46 ± 0.01. The thermodynamic parameters of PEI based hydrogels in the adsorption of dichromate and arsenate anions e.g., ΔG (all negative (except for the arsenate adsorption by PEI microgels), and ΔH that is around 2−10 kJ.mol−1, and ΔS what is around 0.01−0.02 kJ.mol−1. K−1 were calculated. The reusability studies showed that PEI-based hydrogels can be used for at least 5 consecutive adsorption-desorption cycles with almost 70 % anion removal efficiency after the fifth cycle. [ABSTRACT FROM AUTHOR]