Water sorption isotherms on lyophilized jabuticaba (Myrciaria cauliflora) peel: potential byproduct for the production of dehydrated foods.

In this work, water sorption profiles on lyophilized jabuticaba peel were evaluated using the BET, GAB, Halsey, Henderson, Oswin and Smith isotherm models. All water sorption studies were conducted using the static gravimetric method and saturated CH3COOK, K2CO3, NaBr, SnCl2, KCl and BaCl2 solutions at 20, 30 and 35 °C. The best water sorption isotherm fits were determined with the GAB model at 20 °C, Oswin model at 30 °C and Halsey model at 35 °C. The curve profiles of the isotherm models employed were classified as type III. The results revealed that lyophilized jabuticaba peel can be safely stored at 20, 30 or 35 °C with the monitoring and control of relative humidity, equilibrium humidity and water activity. However, microbial action and undesirable enzymatic reactions may occur at 35 °C when the relative humidity is above 22%. The present results are useful for defining suitable storage and production conditions of a novel jabuticaba peel-based process for the production of dehydrated foods.

Magnetic-responsive polysaccharide hydrogels as smart biomaterials: Synthesis, properties, and biomedical applications.

This review reports recent advances in polysaccharide-based magnetic hydrogels as smart platforms for different biomedical applications. These hydrogels have proved to be excellent, viable, eco-friendly alternative materials for the biomedical field due to their biocompatibility, biodegradability, and possibility of controlling delivery processes via modulation of the remote magnetic field. We first present their main synthesis methods and compare their advantages and disadvantages. Next, the synergic properties of hydrogels prepared with polysaccharides and magnetic nanoparticles (MNPs) are discussed. Finally, we describe the main contributions of polysaccharide-based magnetic hydrogels in the targeted drug delivery, tissue regeneration, and hyperthermia therapy fields. Overall, this review aims to motivate the synthesis of novel composite biomaterials, based on the combination of magnetic nanoparticles and natural polysaccharides, to overcome challenges that still exist in the treatment of several diseases.

Principles and Procedures for Assessment of Acute Toxicity Incorporating In Silico Methods.

Acute toxicity in silico models are being used to support an increasing number of application areas including (1) product research and development, (2) product approval and registration as well as (3) the transport, storage and handling of chemicals. The adoption of such models is being hindered, in part, because of a lack of guidance describing how to perform and document an in silico analysis. To address this issue, a framework for an acute toxicity hazard assessment is proposed. This framework combines results from different sources including in silico methods and in vitro or in vivo experiments. In silico methods that can assist the prediction of in vivo outcomes (i.e., LD50) are analyzed concluding that predictions obtained using in silico approaches are now well-suited for reliably supporting assessment of LD50-based acute toxicity for the purpose of GHS classification. A general overview is provided of the endpoints from in vitro studies commonly evaluated for predicting acute toxicity (e.g., cytotoxicity/cytolethality as well as assays targeting specific mechanisms). The increased understanding of pathways and key triggering mechanisms underlying toxicity and the increased availability of in vitro data allow for a shift away from assessments solely based on endpoints such as LD50, to mechanism-based endpoints that can be accurately assessed in vitro or by using in silico prediction models. This paper also highlights the importance of an expert review of all available information using weight-of-evidence considerations and illustrates, using a series of diverse practical use cases, how in silico approaches support the assessment of acute toxicity.

Evaluation of soil contamination by heavy metals at public cemeteries in the municipality of Lages, southern Brazil / Avaliação da contaminação de solos por metais tóxicos em cemitérios públicos do município de Lages, Sul do Brasil

ABSTRACT The burial of bodies is a potentially polluting activity. Taking this into consideration, the aim of the present study was to verify the compliance of two cemeteries with environmental legislation and to quantify the concentrations of heavy metals in soils affected by burial activities. Physicochemical characterization of the soil was performed by analyzing control samples from areas near the cemeteries. Concentrations of cadmium, lead, chromium, nickel, zinc and copper were determined using high-resolution continuum source atomic absorption spectrometry. The two cemeteries had unsatisfactory properties for the retention of metal cations, with clay percentages ranging from 15.40 to 41.40% and sand percentages ranging from 28.75 to 66.85%. The control samples presented low cation exchange capacity (12.27 to 22.73 cmolc/dm³) and high aluminum (Al3+) saturation (66.74 to 90.16%). Although neither of the two cemeteries had concentrations above the limits established for the metals analyzed by Resolution No. 420/2009 of the National Environment Council, the contaminants may be leaching to groundwater due to inadequate soil characteristics.

RESUMO O sepultamento de corpos é uma atividade potencialmente poluidora. Este trabalho teve como objetivo verificar a adequação das áreas de dois cemitérios públicos à legislação ambiental e à atividade cemiterial e quantificar a concentração de metais pesados nos solos que estão sob influência desses empreendimentos. Realizou-se a caracterização físico-química do solo, com a análise de amostras testemunha de solo de cada cemitério. Também foram determinadas as concentrações dos metais pesados: cádmio, chumbo, cromo, níquel, zinco e cobre, por meio de espectrometria de absorção atômica de alta resolução com fonte contínua. As áreas dos cemitérios apresentam condições insatisfatórias para a retenção de íons catiônicos metálicos, com percentuais de argila variando entre 15,40 e 41,40% e de areia entre 28,75 e 66,85%. Os solos testemunha apresentaram reduzida capacidade de troca de cátions entre 12,27 e 22,73 cmolc/dm³) e elevada saturação por alumínio entre 66,74 e 90,16%. Apesar de nenhum dos cemitérios apresentar concentrações dos metais analisados acima dos limites de prevenção estabelecidos pela Resolução nº 420/2009 do Conselho Nacional do Meio Ambiente, em função das características dos solos, os contaminantes podem estar sendo lixiviados para os recursos hídricos subjacentes.

Methylene Blue Release from Chitosan/Pectin and Chitosan/DNA Blend Hydrogels.

Chitosan/DNA blend hydrogel (CDB) and chitosan/pectin blend hydrogel (CPB) were synthesized using an emulsion (oil-in-water) technique for the release of methylene blue (model molecule). Both hydrogels were characterized by swelling assays, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), before and after the methylene blue (MB) loading. Higher swelling degrees were determined for both hydrogels in simulated gastric fluid. FT-IR spectra inferred absorption peak changes and shifts after MB loading. The TGA results confirmed changes in the polymer network degradation. The SEM images indicated low porosities on the hydrogel surfaces, with deformed structure of the CPB. Smoother and more uniform surfaces were noticed on the CDB chain after MB loading. Higher MB adsorption capacities were determined at lower initial hydrogel masses and higher initial dye concentrations. The MB adsorption mechanisms on the hydrogel networks were described by the monolayer and multilayer formation. The MB release from hydrogels was studied in simulated gastric and intestinal fluids, at 25 °C and 37 °C, with each process taking place at roughly 6 h. Higher release rates were determined in simulated gastric fluid at 25 °C. The release kinetics of MB in chitosan/DNA and chitosan/pectin matrices follows a pseudo-second-order kinetic mechanism.

Phytotoxicity Increase Induced by Zinc Accumulation in Cichorium intybus.

The accumulation of zinc (Zn) in Cichorium intybus and effects of phytotoxicity during 90 days of growth on (natural) non-contaminated and Zn-contaminated soils were studied. The phytotoxicity effects were monitored by evaluating the leaf area, leaf biomass, leaf length and root length of the vegetable. The Zn concentrations ranged from 5.35 ± 1.05 to 37.5 ± 3.89 mg kg-1 in leaves of plants grown on natural soil, and from 334.0 ± 25.6 to 2232 ± 16.7 mg kg-1 when grown on Zn-contaminated soils. Zn accumulation caused a decrease in growth on contaminated soils and an increase in phytotoxicity. These effects were associated to high metal concentration, mobility and bioavailability in the soil as well as changes in the translocation mechanism from the roots to the leaves. Then, it must be avoided the organic fertilization of soils with either animal manure or other agricultural inputs containing high zinc concentrations.

Skin sensitization in silico protocol.

The assessment of skin sensitization has evolved over the past few years to include in vitro assessments of key events along the adverse outcome pathway and opportunistically capitalize on the strengths of in silico methods to support a weight of evidence assessment without conducting a test in animals. While in silico methods vary greatly in their purpose and format; there is a need to standardize the underlying principles on which such models are developed and to make transparent the implications for the uncertainty in the overall assessment. In this contribution, the relationship between skin sensitization relevant effects, mechanisms, and endpoints are built into a hazard assessment framework. Based on the relevance of the mechanisms and effects as well as the strengths and limitations of the experimental systems used to identify them, rules and principles are defined for deriving skin sensitization in silico assessments. Further, the assignments of reliability and confidence scores that reflect the overall strength of the assessment are discussed. This skin sensitization protocol supports the implementation and acceptance of in silico approaches for the prediction of skin sensitization.

Pinus residue/pectin-based composite hydrogels for the immobilization of ß-D-galactosidase.

The aim of this work was to synthesize pinus residue/pectin-based composite hydrogels for the immobilization of ß-D-galactosidase. These hydrogels were synthesized via chemical crosslinking, and characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, thermal analysis, mechanical assays, X-ray diffraction, and swelling kinetics. The water absorption mechanism in the hydrogel networks occurs by non-Fickian transport. The ß-D-galactosidase immobilization capacities of the hydrogels containing 0, 5 and 10% of pinus residue were respectively 242.08 ± 0.36, 181.27 ± 0.50 and 182.71 ± 0.36 mg enzyme per g dried hydrogel, at pH 4.0 and after 600 min. These values were 182.99 ± 0.41, 219.99 ± 0.47 and 218.56 ± 0.39 mg g-1, respectively, at pH 5.6. Pectin-based hydrogels demonstrated to be excellent solid supports for the immobilization of enzymes. ß-D-Galactosidase immobilized in pectin-based hydrogels could be applied in the hydrolysis of lactose contained in either dairy foods or lactose-intolerant individuals.

Arabic gum-based composite hydrogels reinforced with eucalyptus and pinus residues for controlled phosphorus release.

Arabic gum-based composite hydrogels reinforced with eucalyptus and pinus residues were synthesized via free-radical reaction aiming to controlled phosphorus release. All hydrogels were characterized by swelling kinetics (SK), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and mechanical assays (MA). The water and solute transports through the hydrophilic three-dimensional networks of the hydrogels occur preferably by diffusion processes and macromolecular relaxation. Hemicellulose, lignin and cellulose fibers contained in eucalyptus and pinus residues affected the crosslinking density, crystalline structure, and water/solute diffusion due to reduction of free hydroxyl and amine groups in the hydrogel networks. Hence, the eucalyptus and pinus residues improved the mechanical and thermal resistances of the composite hydrogels. Finally, the Arabic gum-based hydrogel and Arabic gum-based composite hydrogels reinforced with eucalyptus and pinus residues demonstrated to be excellent alternatives for the controlled phosphorus release in agricultural nutrient-poor soils.

Full-factorial central composite rotational design for the immobilization of lactase in natural polysaccharide-based hydrogels and hydrolysis of lactose.

A full-factorial central composite rotational design (FFCCRD) was applied for studying the immobilization of lactase in Arabic gum-based and chitosan-based hydrogels, and hydrolysis of lactose. The optimal immobilization capacities of both hydrogels aiming to obtain high immobilized enzyme activity and low released fraction were determined at 25.0 °C, 39.88 mg mL-1 initial enzyme concentration and pH 6.5. The immobilized enzyme activity and released fraction from the Arabic gum-based hydrogel were 0.322 U mg-1 and 0.193, respectively, during the hydrolysis of lactose contained in UHT milk. These values were 0.289 U mg-1 and 0.136, respectively, using a chitosan-based hydrogel. The immobilized enzyme activity and released fraction from these hydrogels during the hydrolysis of standard lactose were 0.246 U mg-1 and 0.407, and 0.211 U mg-1 and 0.245, respectively. The best conditions for the immobilization of lactase and hydrolysis of lactose were achieved by applying FFCCRD, which were compared with experimental results.

Adsorption and removal of chromium (VI) contained in aqueous solutions using a chitosan-based hydrogel.

The aim of this work was to study the adsorption and removal of chromium (VI) ions contained in aqueous solutions using a chitosan-based hydrogel synthesized via chemical crosslinking of radical chitosan, polyacrylic acid, and N,N'-methylenebisacrylamide. Fourier-transform infrared spectroscopy confirmed the hydrogel synthesis and presence of reactive functional groups for the adsorption of chromium (VI) ions. The chromium (VI) adsorption mechanism was evaluated using non-linear Langmuir, Freundlich, Redlich-Peterson, and Sips isotherms, with the best fit found by the non-linear Redlich-Peterson isotherm. The maximum chromium (VI) adsorption capacities of the chitosan-based hydrogel were 73.14 and 93.03 mg metal per g dried hydrogel, according to the non-linear Langmuir and Sips isotherm models, respectively. The best kinetic fit was found with the pseudo-nth order kinetic model. The chromium (VI) removal percentage at pH 4.5 and 100 mg L-1 initial metal concentration was 94.72%. The results obtained in this contribution can be useful for future works involving scale-up of a water and wastewater treatment method from a pilot plant to full-scale plant.

Correction to: Adsorption and removal of chromium (VI) contained in aqueous solutions using a chitosan-based hydrogel.

The original publication of this paper contains an error. The correct 4th heading in Table 1 should be "Non-linear sips isotherm". The original article has been corrected.

Morphological diversity of springtails (Hexapoda: Collembola) as soil quality bioindicators in land use systems / Diversidade morfológica de colêmbolos (Hexapoda: Collembola) como bioindicadora de qualidade do solo em sistemas de uso

Abstract: The aim of this work was to evaluate the soil quality of native forest, eucalyptus plantations, pasture, integrated crop-livestock, and no-tillage systems, correlating the morphological diversity of springtails with physical and chemical soil properties. Springtail samples were captured from soils of the southern plateau of the State of Santa Catarina in Brazil, during winter and summer, by using Pitfall traps, using a 3 × 3 point grid. The morphotyping of springtails consisted of the observation of five traits and for each one a partial value of the eco-morphological index was assigned to obtain the modified Soil Quality Index. A correlation of the morphotype abundance and diversity with physical (soil moisture, bulk density, biopores, microporosity, and macroporosity) and chemical (pH in water, calcium/magnesium ratio and total organic carbon content) soil properties was studied, describing all results by variance and multivariate analyses. The springtail abundance and diversity were influenced by the different land use systems. Higher soil quality index was determined in native forest followed by eucalyptus plantations, pasture, no-tillage system and integrated crop-livestock, in the winter. Moreover, higher soil quality index was found in native forest followed by integrated crop-livestock, eucalyptus plantations, no-tillage system and pasture, in the summer. Therefore, the quality index of a soil can be evaluated by the springtail morphological traits in correlation with the physical and chemical properties such as calcium/magnesium ratio, total organic carbon contents, biopores, macroporosity, microporosity, soil moisture, bulky density and pH.

Resumo: O objetivo deste trabalho foi avaliar a qualidade do solo de florestas nativas, reflorestamento de eucalipto, pastagem, sistemas de integração lavoura-pecuária e plantio direto, correlacionando a diversidade morfológica de colêmbolos com propriedades físicas e químicas do solo. Amostras de colêmbolos foram coletadas de solos do planalto sul do Estado de Santa Catarina no Brasil, durante o inverno e o verão, usando armadilhas de queda, em grade amostral de 3 × 3. A morfotipagem dos colêmbolos consistiu na observação de cinco características e para cada uma foi atribuído um valor parcial do índice eco-morfológico para a obtenção do Índice de Qualidade do Solo modificado. As avaliações foram da abundância e diversidade de morfotipos e de atributos físicos (umidade do solo, densidade do solo, bioporos, microporosidade e macroporosidade) e químicos do solo (pH em água, relação cálcio/magnésio e carbono orgânico total), descrevendo os resultados por análises de variância e multivariada. A abundância e a diversidade de colêmbolos foram influenciadas pelos diferentes sistemas de uso do solo. Maior índice de qualidade do solo foi determinado em floresta nativa seguida de reflorestamento de eucalipto, pastagem, plantio direto e integração lavoura-pecuária, no inverno. Além disso, encontrou-se maior índice de qualidade do solo em floresta nativa seguida de integração lavoura-pecuária, reflorestamento de eucalipto, plantio direto e pastagem, no verão. Portanto, o índice de qualidade do solo pode ser avaliado pelas características morfológicas de colêmbolos em correlação com as propriedades físicas e químicas, como razão cálcio/magnésio, teores de carbono orgânico total, bioporos, macroporosidade, microporosidade, umidade do solo, densidade do solo e pH.

Ecotoxicological effects of fipronil, neem cake and neem extract in edaphic organisms from tropical soil.

Veterinary medicines are widely applied for the treatment and prevention of animal diseases. Consequently, animal manure contains significant amounts of environmental pollutants that are potential sources of environmental pollution when inappropriately applied in soils. This work aimed to evaluate ecotoxicological effects of doses of commercial fipronil, neem cake and neem extract in the survival and reproduction of earthworms (Eisenia andrei), enchytraeidae (Enchytraeus crypticus) and springtails (Folsomia candida) in Oxisol and tropical artificial soil (TAS). Applications of fipronil, neem cake and extract in soil were carried out according to standardized ISO methodologies by using a random experimental design with five replicates. Toxic effects of fipronil for springtails in Oxisol and TAS were observed with LC50 of 0.26 mg kg-1 (0.18-0.35 mg kg-1) and 0.29 mg kg-1 (0.22-0.37 mg kg-1), respectively. It was not observed significant toxic effects of fipronil for earthworms and enchytraeidae in both soils. However, significant amounts of juvenile earthworm and adult enchytraeidae decreased in fipronil doses higher than 10 mg kg-1. Neem cake and extract were not toxic for earthworms and enchytraeidae but, significant amounts of juvenile springtails decreased in neem cake doses from 500 to 1000 mg kg-1. It can be concluded that the use of veterinary medicines containing synthetic compounds for preventing diseases in animals needs to be controlled to avoid environmental pollution after applying manure in soil. Veterinary medicines containing natural compounds as neem cake and extract are eco-friendly and could be efficiently applied in soil in a sustainable way.

Polysaccharide-based hydrogels for the immobilization and controlled release of bovine serum albumin.

Arabic gum-based and chitosan-based hydrogels were synthesized through chemical crosslinking for the immobilization and controlled release of bovine serum albumin (BSA) and characterized by Fourier-transform infrared spectrometry, scanning electron microscopy and swelling assays. The degrees of swelling of the Arabic gum-based hydrogel were 13.22 and 22.95 g water per g dried hydrogel at pH 4.5 and 7.0, respectively, whereas the degrees of swelling of the chitosan-based hydrogel were 15.32 and 36.10 g water per g dried hydrogel, respectively. The water absorption mechanism in both hydrogels was non-Fickian, which involves diffusion through pores and macromolecular relaxation of the hydrophilic three-dimensional polymer network. BSA immobilization capacities of the Arabic gum-based and chitosan-based hydrogels after 240 min at pH 4.5 were 71.0 and 175.6 mg protein per g dried hydrogel, respectively. BSA immobilization capacities after 240 min at pH 7.0 were 62.5 and 154.2 mg protein per g dried hydrogel, respectively. The controlled release of BSA from the Arabic gum-based hydrogel was slightly more efficient than that of the chitosan-based hydrogel due to its more porous structure and weaker physiochemical interactions between the polymer network and protein molecule. Both hydrogels could be employed as carriers of proteins and as capsules for food supplements.

Hydrolysis of lactose using ß-d-galactosidase immobilized in a modified Arabic gum-based hydrogel for the production of lactose-free/low-lactose milk.

ß-d-galactosidase was immobilized in a modified Arabic gum-based hydrogel for the hydrolysis of standard lactose and lactose contained in UHT milk with the aim of producing lactose-free/low-lactose milk. The hydrogel was synthesized by cross-linking the modified Arabic gum with acrylamide, using potassium persulfate as initiator. Fourier-transform infrared spectroscopy and scanning electron microscopy confirmed the formation of the hydrogel and its three-dimensional porous network. Swelling degrees in distilled water, drinking water, phosphate buffer solution at pH7.0 and acetate buffer solution at pH4.0 were 12.56 and 17.72, 10.65 and 12.58, 8.58 and 10.71, and 6.49 and 8.16g water per g dried hydrogel at room temperature and 37.0±1.0°C, respectively. The immobilization capacities of ß-d-galactosidase in acetate and phosphate buffer solutions at room temperature were 242.52±0.13 and 118.42±0.23mg enzyme per g dried hydrogel, respectively, after 1440min of contact. Higher enzymatic activities were found after immobilization in phosphate buffer solution due to the isoelectric point of ß-d-galactosidase. Hydrolysis of standard lactose and lactose contained in UHT milk was more efficient using immobilized ß-d-galactosidase than free ß-d-galactosidase. Immobilized ß-d-galactosidase was applied for three cycles of hydrolysis of lactose without significantly losing enzymatic activity.

Adsorption and controlled release of potassium, phosphate and ammonia from modified Arabic gum-based hydrogel.

In this work, a modified Arabic gum-based hydrogel copolymerized with acrylamide was synthesized and characterized for application in adsorption and controlled release of potassium, phosphate and ammonia. From FT-IR results, it would be reasonable to assume that the hydrogel was effectively synthesized. The degree of swelling at pure water with pH 6.0 was 21.0g water per g dried hydrogel whereas the degrees of swelling at buffer solutions with pH 4.5 and 7.0 were 7.2 and 9.2g water per g dried hydrogel, respectively. The water diffusion mechanism was governed by Fickian transport with tendency to occur macromolecular relaxation. The adsorption capacities of potassium, phosphate and ammonia were higher by increasing the initial concentrations due to availability of active sites in the hydrogel network, nutrient size and ionic charge. Potassium, phosphate and ammonia concentrations released from the modified Arabic gum-based hydrogel increased by increasing the release time from 0 to 1440min. Release profiles indicated that this hydrogel could be applied for the enrichment and hydration of deserted soil, avoiding losses of nutrients by leaching and percolation, with an advantage of being constituted by an eco-friendly polysaccharide.

Treatment of wastewater from the dairy industry using electroflocculation and solid whey recovery.

The aim of this study was to investigate the efficiency of electroflocculation for the treatment of wastewater from the dairy industry and the recovery of solid whey. An electrochemical apparatus containing two aluminum or iron electrodes, a power source, an electroflocculation cell and magnetic stirring was employed. The following experimental conditions were monitored: electroflocculation time, initial pH of wastewater and applied potential intensity. Chemical oxygen demand, turbidity and final pH were the response variables. The chemical oxygen demand and turbidity decreased by employing aluminum or iron electrodes, applied potential intensity of 5 V, distance between two electrodes of 2 cm, 60 min electroflocculation time and initial wastewater pH of 5.0. The removal rates of organic matter based on the measure of chemical oxygen demand and turbidity when employing aluminum electrodes were 97.0 ± 0.02% and 99.6 ± 3.00 × 10(-4)%, respectively, with a final pH of 6.72. The removal rates of organic matter when employing iron electrodes were 97.4 ± 0.01% and 99.1 ± 1.00 × 10(-4)%, respectively, with a final pH of 7.38. In conclusion, electroflocculation is an excellent alternative for the dairy wastewater treatment in comparison to conventional treatment methods. The water used in food production and equipment washing is recovered with this method, resulting in a liquid that can be properly disposed. It is also possible to recover solid whey after electroflotation, which can then be used in the production of food supplements for humans and animals. Therefore, the dairy wastewater treatment process employing electroflocculation leads to sustainable food production.

Immobilization and controlled release of ß-galactosidase from chitosan-grafted hydrogels.

Chitosan-grafted hydrogels were employed for immobilization and controlled released of ß-galactosidase. These hydrogels containing immobilized enzymes were employed to simulate the production of lactose-free food and controlled release of ß-galactosidase into lactose-intolerant individuals. The degree of swelling, efficiency of immobilization (i.e., fractional uptake of enzyme), and controlled release were studied as a function of pH and temperature. The degrees of swelling decreased in acidic media: 49.4 g absorbed water per g hydrogel at pH 7.0, and 8.4 g absorbed water per g hydrogel at pH 3.5. The immobilization efficiency was 19%, indicating that chitosan-grafted hydrogels are promising matrices for enzyme adsorption and immobilization. Cyclic experiments reveal that chitosan-grafted hydrogels containing immobilized enzymes can be reused several times without introducing additional enzyme prior to each cycle. There is no significant decrease in the activity of the immobilized enzyme during reutilization studies. All results were conducted in triplicate by considering t-tests at a 95% significance level. Analysis of ß-galactosidase activity and controlled release reveals that chitosan-grafted hydrogels containing immobilized enzymes are useful for the production of lactose-free food and controlled enzyme release with high performance.

Natural polymer-based magnetic hydrogels: Potential vectors for remote-controlled drug release.

The preparation and characterization of natural polymer-based hydrogels that contain 50-nm diameter magnetite (i.e., FeO:Fe(2)O(3)) nanoparticles are described herein. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the efficiency of the polysaccharide-modifying process. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and compressive moduli demostrate that the presence of magnetite improves thermal and mechanical resistance. Transient diffusion of water in magnetic hydrogels was analyzed via boundary layer mass transfer across an expaning interface, and the degree of swelling of these polysaccharide hydrogels decreases in the presence of magnetite, with no variation in the binary diffusion mechanism. The absence of hysteresis loops and coercivity observed via magnetometry suggests that magnetic hydrogels are useful for remote-controlled drug release, as demonstrated by magnetic-field-induced release of curcumin. Experiments reveal that magnetic hydrogels with greater magnetic susceptibility have the potential to release larger concentrations of drugs from the hydrogel network.