Potential of superabsorbent hydrogels to improve agriculture under abiotic stresses

Hydrogels are a promising management option to increase the efficiency of water use in agriculture in arid and semi-arid regions. However, abiotic factors may affect hydrogel efficacy. The effect of abiotic stress on the swelling and residual acrylamide in hydrogels was evaluated. The treatments were three hydrogels (A, B and C), four temperatures (20, 30, 40 and 65 °C) and two salinities (0.003 and 3.0 dS m−1). The swelling degree and the residual acrylamide concentration of the hydrogels were measured. Data were analyzed with univariate and multivariate statistics. The swelling order of hydrogels under low salinity was A>C>B; at high salinity was B>A>C. All hydrogels presented swelling reduction at high salinity, with swelling reductions in A and C of 97% and 85%, respectively, while B presented a swelling reduction of 37% at 20 °C and greater than 89% at higher temperatures. Hydrogel B achieved good swelling under saline conditions, but only at 20 °C. Thus, the temperature tolerance of this hydrogel should be improved so it can be used to improve water use efficiency in regions with high temperatures and salinity levels. Residual acrylamide levels of hydrogels decreased by 95% over 30 days, being safe for agricultural application

Acetylated cashew gum-based nanoparticles for the incorporation of alkaloid epiisopiloturine

The natural alkaloid epiisopiloturine has recently become the focus of study for various medicinal properties, particularly for its anti-inflammatory and antischistosomal effect. The incorporation of active molecules in natural polymeric matrices has garnered increasing interest during recent decades. A new derivative of cashew gum successfully obtained by gum acetylation has shown great potential as a carrier in controlled drug release systems. In this work, epiisopiloturine was encapsulated in acetylated cashew gum nanoparticles in order to increase solubility and allow slow release, whereas the morphology results were supported by computer simulations. The particles were produced under a variety of conditions, and thoroughly characterized using light scattering and microscopic techniques. The particles were spherical and highly stable in solution, and showed drug incorporation at high levels, up to 55% efficiency. Using a dialysis-based in vitro assay, these particles were shown to release the drug via a Fickian diffusion mechanism, leading to gradual drug release over approximately 6 h. These nanoparticles show potential for the use as drug delivery system, while studies on their potential anti-inflammatory action, as well as toxicity and efficacy assays would need to be performed in the future to confirm their suitability as drug delivery candidates.This work was conducted in partnership with the Polymer Laboratory of the Federal University of Ceará for polymer modification. The authors thanks Foundation for Science and Technology (FCT) for the fellowships SFRH/BD/97995/2013 (AP) and SFRH/BD/95983/2013 (MPA), in the context of the POCH program. The work at UCIBIO/REQUIMTE was supported by FCT through project UID/MULTI/04378/2013 – POCI/01/0145/FEDER/007728 with financial support from FCT/MCTES through national funds and co-financed by FEDER, under the Partnership Agreement PT2020. The work at REQUIMTE/LAQV received financial support from the European Union (FEDER funds through COMPETE) and National Funds (FCT) through project UID/QUI/50006/2013. The computational time was provided by GRID-Unesp, SICC/IFSP and CENAPAD/SP. The authors also acknowledge CNPq and CAPES for a scholarship and financial aid.info:eu-repo/semantics/publishedVersio

Cellulose Source Tailors the Physical and Structural Properties of Double-Functionalized Aerogels

Cellulose aerogels are solid materials with high porosity, low density, and large surface area, and show excellent absorption of mechanical stress. These characteristics are appropriate for the development of new high-value products. However, over the years, it has been increasingly difficult to compare different studies about this material due to the different approaches used. In the present work, three different raw materials, bacterial cellulose from synthetic medium (BC), bacterial cellulose from cashew juice permeate (BCP), and eucalyptus nanocellulose (EC) were double-functionalized with TEMPO oxidation followed by silanization and freeze-dried, resulting in three different types of cellulose aerogels. These aerogels were evaluated for their performance in the absorption of organic oils/solvents and mechanical properties. The raw materials lead to aerogels with different characteristics. BC aerogel has the best mechanical properties and absorption capacity after 7 cycles; BCP aerogel presented the highest values for oil absorption and EC aerogel for organic solvent absorption

Bacterial cellulose nanocrystals produced under different hydrolysis conditions: properties and morphological features

Bacterial cellulose (BC) is a polymer with interesting physical properties owing to the regular and uniform structure of its nanofibers, which are formed by amorphous (disordered) and crystalline (ordered) regions. Through hydrolysis with strong acids, it is possible to transform BC into a stable suspension of cellulose nanocrystals, adding new functionality to the material. The aim of this work was to evaluate the effects of inorganic acids on the production of BC nanocrystals (BCNCs). Acid hydrolysis was performed using different H2SO4 concentrations and reaction times, and combined hydrolysis with H2SO4 and HCl was also investigated. The obtained cellulose nanostructures were needle-like with lengths ranging between 622 and 1322 nm, and diameters ranging between 33.7 and 44.3 nm. The nanocrystals had a crystallinity index higher than native BC, and all BCNC suspensions exhibited zeta potential moduli greater than 30 mV, indicating good colloidal stability. The mixture of acids resulted in improved thermal stability without decreased crystallinity.The authors would like to thank Coordination for the Improvement of Higher Education Personnel (CAPES), National Counsel of Technological and Scientific Development (CNPq), and the Embrapa Tropical Agroindustry for funding this research and Strategic Technologies Center Northeast (CETENE) for supporting the transmission electron microscopy analysis

Efeito da modificação química na solubilidade e intumescimento de microesferas à base de goma do cajueiro carboximetilada e quitosana

Resumo Esferas de goma do cajueiro carboximetilada e quitosana foram produzidas via complexação polieletrolítica. As esferas foram modificadas quimicamente de modo a obter-se sistemas estáveis em meio ácido e que apresentassem uma resposta de intumescimento diferenciado frente à variação de pH. As esferas foram modificadas por reacetilação da quitosana e por reticulação com epicloridrina, glutaraldeído e genipina. As esferas reticuladas foram caracterizadas por meio de técnicas como: espectroscopia de absorção no infravermelho, análise termogravimétrica, microscopia eletrônica de varredura e quanto à solubilidade em pH 1,2 e ao intumescimento. As esferas de goma do cajueiro carboximetilada e quitosana reacetilada, e as esferas reticuladas com epicloridrina apresentaram baixa resistência à dissolução em pH 1,2. Entretanto, as esferas reticuladas com glutaraldeído e genipina apresentaram resistência à dissolução e baixo coeficiente de difusão. As esferas reticuladas com genipina apresentaram um grau de intumescimento maior do que as esferas reticuladas com glutaraldeído nas concentrações de 3% e 5% (massa/volume). As esferas reticuladas com genipina apresentaram intumescimento responsivo à variação de pH e estabilidade em pH 1,2, indicando que esses sistemas possuem potencial para uso em sistemas de liberação controlada de fármacos por via oral

Combined glucosamine and chondroitin sulfate provides functional and structural benefit in the anterior cruciate ligament transection model

Evidence that combined glucosamine sulfate and chondroitin sulfate (Gluchon) or isolated glucosamine (Glu) modifies joint damage in osteoarthritis (OA) is still lacking. We studied joint pain and cartilage damage using the anterior cruciate ligament transection (ACLT) model. Wistar rats were subjected to ACLT of the right knee ( OA) or sham operation. Groups received either Glu (500 mg/kg), Gluchon (500 mg/kg glucosamine +400 mg/kg chondroitin) or vehicle (non-treated-NT) per os starting 7 days prior to ACLT until sacrifice at 70 days. Joint pain was evaluated daily using the rat-knee joint articular incapacitation test. Structural joint damage was assessed using histology and biochemistry as the chondroitin sulfate ( CS) content of cartilage by densitometry (microgram per milligram dried cartilage), comparing to standard CS. The molar weight (Mw) of the CS samples, used as a qualitative biochemical parameter, was obtained by comparing their relative mobility on a polyacrylamide gel electrophoresis to standard CS. Gluchon, but not Glu, significantly reduced joint pain (P<0.05) compared to NT. There was an increase in CS content in the OA group (77.7 +/- 8.3 mu g/mg) compared to sham (53.5 +/- 11.2 mu g/mg) (P<0.05). The CS from OA samples had higher Mw (4:62 +/- 0:24 x 10(4) g/mol) compared to sham (4:18 +/- 0:19 x 10(4) g/mol) (P<0.05). Gluchon administration significantly reversed both the increases in CS content (54.4 +/- 12.1 mu g/mg) and Mw (4:18 +/- 0:2 x 104 g/mol) as compared to NT. Isolated Glu decreased CS content though not reaching statistical significance. Cartilage histology alterations were also significantly prevented by Gluchon administration. Gluchon provides clinical (analgesia) and structural benefits in the ACLT model. This is the first demonstration that biochemical alterations occurring in parallel to histological damage in OA are prevented by Gluchon administration.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq

Brazilian gutta-percha points: Part I: chemical composition and X-ray diffraction analysis

Eight nonstandardized gutta-percha points commercially available in Brazil (Konne, Tanari, Endopoint, Odous, Dentsply 0.04, Dentsply 0.06, Dentsply TP and Dentsply FM) were analysed chemically and by X-ray diffraction, and their chemical compositions were compared. The organic fraction (gutta-percha polymer and wax/resin) of the gutta-percha points was separated from the inorganic fraction (ZnO and BaSO4) by dissolving them in chloroform. The gutta-percha polymer was precipitated with acetone. The inorganic fraction was analysed by elemental microanalysis. Energy-dispersive X-ray microanalysis (EDX) and X-ray diffraction were employed to identify the chemical elements and compounds (barium sulfate and zinc oxide). The barium sulfate content was calculated based on the percentage of sulfur found in the elemental microanalysis. All analyses were repeated three times. The means and standard deviations of the percentage by weight of gutta-percha in the points were: Konne (17.6 ± 0.30), Tanari (15.2 ± 0.30), Endopoint (16.7 ± 0.23), Odous (18.8 ± 0.20), Dentsply 0.04 (15.7 ± 0.17), Dentsply 0.06 (16.6 ± 0.17), Dentsply TP (21.6 ± 0.15) and Dentsply FM (16.3 ± 0.23). The means and standard deviations of the zinc oxide content were: Konne (79.9 ± 0.10), Tanari (81.9 ± 0.07), Endopoint (81.3 ± 0.40), Odous (79.7 ± 0.26), Dentsply 0.04 (77.9 ± 0.03), Dentsply 0.06 (78.2 ± 0.07), Dentsply TP (69.8 ± 0.19) and Dentsply FM (72.6 ± 0.70). The method utilized was appropriate to quantify gutta-percha, wax/resin, zinc oxide and barium sulfate. Cone brands without barium sulfate were found. An unusual high wax/resin percentage was detected in Dentsply FM (p = 0.0003). Dentsply TP showed the highest gutta-percha percentage

Durability indicatives of hydrogel for agricultural and forestry use in saline conditions

This research tested the hypothesis that the interaction between time and salinity reduces the water absorption potential of a hydrogel – Poly (Acrylamide-co-Potassium Acrylate) and influence the degradation of residual acrylamide monomer. The experimental design was completely randomized split-plot with four replications. The treatments were time periods (30, 60, 90 and 120 days) and levels of salinity of the hydrating solution (distilled water = 0.003, 0.5; 1.5; 3.0 and 6.0 dS m−1). Swelling, hydrogel composition, and residual acrylamide monomer concentration were evaluated. The hydrogel showed lowest water absorption potential (8.1 g g−1) in a saline solution of 4.20 dS m−1 after 120 days. The C/N ratio of the hydrogel increased by up to 47% in a hydrating solution with an EC of 4.4 dS m−1 at 120 days. Additionally, there was an observed shift in the wavelength of methylene, amide, and acrylate bands, that indicates degradation. Residual acrylamide monomer concentration was <0.5 mg g−1 (safe for agricultural use). After 120 days up to 85% of the residual acrylamide monomer was degraded. About the water absorption potential, the results suggest that under semi-arid conditions hydrogel durability for forestry and crops applications may be impaired by the salinity of the hydrating solution