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Caffeine (CAF) is a psychostimulant present in many beverages and with rapid bioabsorption. For this reason, matrices that effectuate the sustained release of a low amount of CAF would help reduce the intake frequency and side effects caused by high doses of this stimulant. Thus, in this study, CAF was loaded into magnetic gelatin/alginate (Gel/Alg/MNP) hydrogels at 18.5 mg/ghydrogel. The in vitro release of CAF was evaluated in the absence and presence of an external magnetic field (EMF) and Ca2+. In all cases, the presence of Ca2+ (0.002 M) retarded the release of CAF due to favorable interactions between them. Remarkably, the release of CAF from Gel/Alg/MNP in PBS/CaCl2 (0.002 M) at 37 °C under an EMF was more sustained due to synergic effects. In PBS/CaCl2 (0.002 M) and at 37 °C, the amounts of CAF released after 45 min from Gel/Alg and Gel/Alg/MNP/EMF were 8.3 ± 0.2 mg/ghydrogel and 6.1 ± 0.8 mg/ghydrogel, respectively. The concentration of CAF released from Gel/Alg and Gel/Alg/MNP hydrogels amounted to ~0.35 mM, thereby promoting an increase in cell viability for 48 h. Gel/Alg and Gel/Alg/MNP hydrogels can be applied as reservoirs to release CAF at suitable concentrations, thus forestalling possible side effects and improving the viability of SH-SY5Y cells. [ABSTRACT FROM AUTHOR]

In this work the formation of multilayers composed by carboxymethylcellulose (CMC), chitosane and bovine serum albumin (BSA) was studied by ellipsometry. First, the adsorption behavior of carboxymethylcellulose onto amino-terminated surfaces was investigated as a function of molecular weight and average degree of substitution of CMC. The influence of these parameters on the adsorbed amount of CMC onto amino-terminated substrates was absent. However, the interaction of CMC covered surfaces with chitosane and BSA was favored when the average degree of substitution of CMC was increased. The adsorption of BSA onto the polysaccharide systems was studied as a function of pH. At the isoelectric point of BSA a maximum in the adsorbed amount was found.

The adsorption of a new cellulose derivative,6-O-(2,3-bis(thiosulfato) propyl-oxy-2-hydroxy-propyl)-cellulose (TSHP), onto silver surfaces was investigated by means of ellipsometry, contact angle measurements and X-ray photoelectron spectroscopy (XPS). The results showed that the formation of a dense TSHP monolayer on silver surfaces is an irreversible and slow process. Based on XPS results a model was proposed to explain the chemisorption of TSHP on silver substrates. This model considers the homolytical cleavage of the thiosulfate groups attached to the cellulose chains with the formation of thio radicals, which bind covalently to the silver surface. The formation of silver thiolates lead to a stable TSHP monolayer on silver surfaces.

Persistent luminescent materials are present in several recent studies on new applications and novel properties. In this work, we demonstrate, for the first time, the production of translucent flexible persistent composites based on Sr2MgSi2O7:Eu2+,Dy3+ (SMSO) into cellulose ether matrix film. The composite was successfully prepared through a new optimized route of co-precipitation and microwave-assisted annealing followed by (3-aminopropyl)triethoxysilane (APTES) coating and dispersion in hydroxypropyl methylcellulose (HPMC). The SMSO@APTES/HPMC films show persistent luminescence emission at 475 nm (blue) and high transmittance in the visible range. To understand the fine distribution of the nanoparticles in the matrix, we have investigated their structure and dispersion by using Synchrotron Radiation X-ray fluorescence mapping and Scanning Transmission X-ray Microscopy. This innovative composite could bring new perspectives for the class of persistent luminescence materials, enhancing technologies in progress throwing light on new applications never perceived. [ABSTRACT FROM AUTHOR]

A metallo‐supramolecular polymer poly{4‐(((3,4‐dihydroxyphenyl)(6‐oxidodibenzo[c,e][1,2]oxaphosphinin‐6‐yl)methyl)amino)phenyl‐2,2‐dimethylbutanoate} (HP) is synthesized through a Kabachnik–Fields reaction. Then HP is coated on the surface of β‐FeOOH by coordination interaction to generate organic–inorganic hybrid β‐FeOOH@HP (Fe@P) nanorods, which are used for preparing flame retardant epoxy resin (EP) nanocomposites. The structure of HP is characterized by nuclear magnetic resonance and fourier transform infrared spectroscopy, the morphology and composition of β‐FeOOH and Fe@P nanorods are also studied by scanning electron micrograph and transmission electron microscope instruments. With the presence of 2 wt% of Fe@P, the limiting oxygen index value of EP nanocomposite increased to 32.8% with UL‐94 vertical burning V‐1 rating, and 31.4% of flexural strength enhancement, indicating the improvement of both flame retardant and mechanical properties with low loading amount. The reduction of total smoke production, average CO and CO2 yield for EP nanocomposites with 0.5 wt% of Fe@P reflected the good smoke suppression. The flame retardant mechanism of Fe@P is also discussed. [ABSTRACT FROM AUTHOR]

Dual functional photosensitive epoxy resins were synthesized by solution polycondensation of 1,3-bis(4-hydroxyphenyl)propenone (BHPP) and 3-(4-hydroxy-3-methoxyphenyl)-1-(4-hydroxyphenyl)propenone (HMPHPP) with epichlorohydrin. The characterization of synthesized epoxy resins comprised Fourier transform infrared (FTIR) spectroscopy, 1H-NMR, and 13C-NMR spectroscopic techniques. The thermal properties of the epoxy resins were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) under a nitrogen atmosphere and found that the synthesized resins were stable up to 300 °C. The effect of curing agents diaminodiphenylsulfone (DDS) and diaminodiphenylmethane (DDM) on the thermal stability of epoxy resin was compared and found that DDS cured epoxy resin has higher thermal than DDM. The photocrosslinking properties of the epoxy resins were studied with UV-Visible spectroscopy, and we observed that the olefinic double bond undergoes 2π-2π cycloaddition and leads to cyclobutane ring. Also, the effect of solvents on the photocrosslinking of the epoxy resin was also studied. Solvents with higher polarity favored the 2π-2π cycloaddition. The dual functionality of the resins was confirmed by FTIR study. The storage stability of the synthesized epoxy resins remained over more than 60 days. The synthesized epoxy resins successfully applied as negative photoresists. [ABSTRACT FROM AUTHOR]

Composite cryogels were prepared from xanthan gum (XG) precursor gels at 20 g L-1 containing TiO2 load at 5, 10, and 20 wt% and citric acid, as crosslinker. The effect of the pH over precursor gel on the properties of the resulting cryogels was evaluated. The characterization of the XG/TiO2 cryogels comprised compression tests, swelling degree (SD) determination, Fourier transform infrared vibrational spectroscopy in the attenuated total reflectance mode (FTIR-ATR), scanning electron microscopy (SEM), and X-ray microtomography (CT) analyses. The largest compressive modulus (E) was observed for XG/TiO2 10% cryogels prepared at pH 4.0, which amounted to 100±7 kPa, whereas the E value determined for bare XG cryogels was 29±3 kPa. XG/TiO2 10% cryogels presented larger pores and thicker walls than bare XG cryogels, as evidenced by SEM and CT analyses. FTIR-ATR spectra evidenced the ester bonds stemming from the esterification among carboxylic acid groups and/or XG hydroxyl groups. XG/TiO2 10% cryogels presented SD of (61±2) gwater/gcryogel, long-term stability in water, and outstanding photocatalytic properties in the presence of Cr(VI) ions and methylene blue (MB). The photocatalytic processes for the reduction of Cr(VI) to Cr(III) and for the photobleaching of MB fitted the first-order kinetic model, yielding rate constants of 0.019 varying min-1 and 0.0096 min-1, respectively. For both processes, the XG/TiO2 10% cryogels could be recycled five times without losing shape or efficiency. [ABSTRACT FROM AUTHOR]

ABSTRACT Xanthan gum is an extracellular polymer produced mainly by the bacterium Xanthomonas campestris. Traditionally it plays an important role in industrial applications as thickener, emulsion stabilizer and it has been added to water-based drilling fluids due to its pseudoplastic behavior and thermal stability. The structural properties of xanthan in solution can be tuned by the temperature and ionic strength; under high ionic strength or low temperature, xanthan chains are arranged in helical conformation, whereas under low ionic strength or high temperature, xanthan chains are coiled. Xanthan high molecular weight favors the building up of physical and chemical networks, which have been used as carriers for drugs and proteins and as scaffolds for cells. In combination with other polymers xanthan has been applied as excipient in tablets or as supporting hydrogels for drug release applications, particularly due to its acid resistance. The large versatility of xanthan gum opens the possibility for the creation of new architectures and additional applications involving this fascinating polymer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42035. [ABSTRACT FROM AUTHOR]

Poly(ethylene glycol) (PEG)-decorated polystyrene (PS) nanoparticles with mean hydrodynamic diameter (D) and zeta-potential (ζ) of (286 ± 15) nm and (-50 ± 5) mV, respectively, were modified by the adsorption of Congo red (CR). The PS/PEG/CR particles presented D and ζ values of (290 ± 19) nm and (-36 ± 5) mV, respectively. The adsorption of lipase onto PS/PEG or PS/PEG/CR particles at (24 ± 1) °C and pH 7 changed the mean D value to (380 ± 20) and (405 ± 11) nm, respectively, and ζ value to (-32 ± 4) mV and (-25 ± 2) mV, respectively. The kinetic parameters of the hydrolysis of p-nitrophenyl butyrate were determined for free lipase, lipase immobilized onto PS/PEG and PS/PEG/CR particles. Lipase on PS/PEG/CR presented the largest Michaelis-Menten constant (KM), but also the highest Vmax and kcat values. Moreover, it could be recycled seven times, losing a maximum 10% or 30% of the original enzymatic activity at 40 °C or 25 °C, respectively. Although lipases immobilized onto PS/PEG particles presented the smallest KM values, the reactions were comparatively the slowest and recycling was not possible. Hydrolysis reactions performed in the temperature range of 25 °C to 60 °C with free lipases and lipases immobilized onto PS/PEG/CR particles presented an optimal temperature at 40 °C. At 60 °C free lipases and lipases immobilized onto PS/PEG/CR presented ∼80% and ∼50% of the activity measured at 40 °C, indicating good thermal stability. Bioconjugation effects between CR and lipase were evidenced by circular dichroism spectroscopy and spectrophotometry. CR molecules mediate the open state conformation of the lipase lid and favor the substrate approaching. [ABSTRACT FROM AUTHOR]

Cryogels of hydroxypropyl methylcellulose (HPMC) and bacterial cellulose nanocrystals (CNC) were prepared with 0, 5, or 15 wt% contents of CNC. Two types of CNC were used, namely, CNC‐SO4 and CNC, with ζ‐potential values of − (46 ± 1) mV and − (5 ± 1) mV, respectively. Regardless the CNC type or content, all cryogels presented similar density, capillarity constant, contact angle, swelling rate values, and morphology. However, the addition of only 5% of CNC‐SO4 to HPMC cryogels increased the compressive modulus from (120 ± 15) kPa to (150 ± 19) kPa. The cryogels were tested as adsorbents for 17α‐ethinyl estradiol (EE) and methylene blue (MB). In the dilute range, the pollutants removal efficiency of reinforced cryogels was considerably larger than that of neat cryogels. In the more concentrated range, all adsorbents presented similar efficiency. The adsorption isotherms of EE and MB onto cryogels fitted with sigmoidal and Freundlich adsorption models, indicating higher affinity for aerogels with 5% CNC‐SO4. Cryogels could be recycled 10 and 5 times, respectively, for MB and EE adsorption/desorption under flow without losing efficiency, disclosing their potential for preconcentration of pollutants, and environmental remediation. [ABSTRACT FROM AUTHOR]

The mechanical properties of scaffolds can significantly influence cell behavior. We propose a methodology for producing chitosan and vanillin-crosslinked chitosan films with tunable mechanical properties to be applied as scaffolds for C2C12 myoblasts. In this approach, aqueous polydimethylsiloxane (PDMS) elastomeric dispersions were prepared using polysorbate 20 as emulsifier. These dispersions were then cured and incorporated into chitosan or vanillin-crosslinked chitosan polymeric dispersions at two different volume fractions (1 % and 10 %), followed by casting into films. Atomic force microscopy in force spectroscopy mode was used to characterize the mechanical properties of the swollen systems in PBS buffer. The mechanical properties of the chitosan and vanillin-crosslinked chitosan scaffolds were modulated by the incorporation of the elastomer. The elastic modulus (E) of chitosan-based scaffolds varied from 60 to 200 kPa, while for vanillin-based scaffolds, it ranged from 200 to 600 kPa with the addition of PDMS elastomers. A general trend observed was that the softest scaffolds exhibited the highest swelling degree and the lowest gel content. After 24 h, good cell viability was observed for chitosan and chitosan-PDMS scaffolds, whereas vanillin-based scaffolds showed borderline cytotoxicity (∼70 %). C2C12 cells demonstrated good adhesion on scaffolds with E values ranging from 114 to 568 kPa., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, kapok fiber (KF) a hollow and hydrophobic fiber, was modified with cetyltrimethylammonium bromide (CTAB) or cetylpyridinium chloride (CPC), rendering adsorbed amount of ∼0.75 × 10 -3  mol/g. Small-angle X-ray scattering (SAXS) measurements of dry KF/CTAB and KF/CPC evidenced a periodic distance of ∼2.6 nm and 2.8 nm, respectively, suggesting the presence of hemimicelles on the surface. KF/CTAB and KF/CPC were used as adsorbents in batch and column adsorption experiments to remove Cr(VI) ions, Bisphenol A (BPA), and their binary mixtures from synthetic solution and fresh water. The adsorbed amounts of Cr(VI) ions on KF/CTAB and KF/CPC, as determined from batch experiments, were 48.62 mg/g and 34.17 mg/g, respectively. X-ray photoelectron spectroscopy (XPS) analysis showed that Cr(VI) adsorption on KF/CTAB involved bromide displacement, while chloride remained on KF/CPC. Moreover, Cr(VI) ions were reduced to Cr(III) ions due to a possible oxidation of γ-sitosterol, one component of the KF wax. Density Functional Theory (DFT) calculations indicated that the interaction energy of CTAB- Cr(VI) pair (-167.8 kcal/mol) is more favorable than that of the CPC-Cr(VI) pair (-147.8 kcal/mol). The adsorbed amounts of BPA on KF/CTAB and KF/CPC were 41.66 mg/g and 22.62 mg/g, respectively. XPS analysis indicated the appearance of an OH peak at 533 eV after the adsorption of BPA, aligning with DFT calculations that predicted interactions between the counter-ions (Br or Cl) and BPA hydroxy groups. In column adsorption experiments, Cr(VI) ions were more effectively adsorbed onto KF/CTAB in the presence of BPA, demonstrating the potential of KF/CTAB for the simultaneous remediation of mixed contaminants in water treatment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study aimed to evaluate effective treatment strategies for laboratory waste with an initial pH of 1.0, containing Cr 6+ , Mn 2+ , Co 2+ , Fe 3+ , Ni 2+ , Cu 2+ , Zn 2+ , Sr 2+ , Hg 2+ , and Pb 2+ ions, focusing on flocculation, precipitation, and adsorption techniques. The study utilized microparticles derived from Moringa oleifera seed husks (MS), cryogels of carboxymethyl cellulose (CMC), and hybrid cryogels combining CMC and MS (CMC-MS25 and CMC-MS50) as adsorbents. The optimal strategy involved raising the pH to 7 using NH 4 OH, leading to the partial precipitation of metal ions. The remaining supernatant was then passed through columns packed with the aforementioned adsorbents. Utilizing CMC-MS25 and CMC-MS50 adsorbents resulted in the simultaneous removal of over 90% of the targeted metal ions. The adsorption of Cu 2+ ions onto the adsorbents was facilitated by electrostatic interactions between Cu 2+ ions and carboxylate groups, as well as Cu-OH chelation, as confirmed by X-ray photoelectron spectroscopy. Under optimized conditions, the fixed-bed column adsorption capacity was determined as 88.2 mg g -1 . The CMC-MS25 adsorbents proved reusable at least 5 times, with the recovered Cu 2+ ions potentially suitable for other processes. The scalability and feasibility of producing these novel adsorbents suggest a promising, cost-effective solution for treating complex matrices and recovering high-value metals, as copper., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Hypothesis: The type and concentration of surfactants affect the rheological behavior of hydroxypropyl methylcellulose (HPMC) chains in hydrogels, influencing the microstructure and mechanical properties of HPMC cryogels., Experiments: Hydrogels and cryogels containing HPMC, AOT (bis (2-ethylhexyl) sodium sulfosuccinate or dioctyl sulfosuccinate salt sodium, two C8 chains and sulfosuccinate head group), SDS (sodium dodecyl sulfate, one C12 chain and sulfate head group), and sodium sulfate (salt, no hydrophobic chain) at different concentrations were investigated using small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), rheological measurements, and compressive tests., Findings: SDS micelles bound to the HPMC chains building "bead necklaces", increasing considerably the storage modulus G' values of the hydrogels and the compressive modulus E values of the corresponding cryogels. The dangling SDS micelles promoted multiple junction points among the HPMC chains. AOT micelles and HPMC chains did not form "bead necklaces". Although AOT increased the G' values of the hydrogels, the resulting cryogels were softer than pure HPMC cryogels. The AOT micelles are probably embedded between HPMC chains. The AOT short double chains rendered softness and low friction to the cryogel cell walls. Therefore, this work demonstrated that the structure of the surfactant tail can tune the rheological behavior of HPMC hydrogels and hence the microstructure of the resulting cryogels., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In this work, chitosan chains were crosslinked with different contents of vanillin (Van), characterized and loaded with curcumin (CUR), a hydrophobic drug. Sodium dodecyl sulfate (SDS), Tween 20® (T20) and β-cyclodextrin (βCD) were used as curcumin carriers. Films prepared with Van 20 % yielded gel content of 70 %, swelling degree of ~23 g water /g, bound water and capillary water, as revealed by Time-Domain Nuclear Magnetic Resonance measurements. Films prepared with higher Van contents showed small swelling degree (< 1.6 g water /g) and hydrophobicity, making them inadequate for drug loading. UV-Vis and fluorescence spectroscopic studies indicated that Van 20 % combined with SDS and SDS/βCD presented the highest CUR uptake (~3.0 mg/g), favored by electrostatic interactions and hydrophobic interactions. CHI and Van 20 % films did not present any cytotoxicity in human neuroblastoma SH-SY5Y cells. At pH 1.0 the films were completely soluble, pointing to their potential application as gastric delivery systems for hydrophobic drugs. Chemical compounds studied in the manuscript: Chitosan, vanillin, curcumin, β-cyclodextrin, sodium dodecyl sulfate, polyethylene glycol sorbitan monolaurate., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Alginate (Alg) beads are low-cost adsorbents used for wastewater remediation. In this work, alginate (Alg) and alginate/xanthan (Alg/XG) blend beads were synthesized by gelation method into calcium chloride and freeze-dried to improve the porosity. Their adsorption efficiency was tested for methylene blue (MB) dye in batch, recirculating and column adsorption systems. The blend beads were characterized using by SEM, FTIR-ATR and X-ray microcomputer tomography (Micro-CT) analyzes. Freeze-dried Alg and Alg/XG beads presented porosity of 46 ± 5% and 77 ± 3%, respectively. Adsorption isotherms of MB on freeze-dried Alg/XG beads indicated better adsorption capacity in comparison to the air-dried ones. Adsorption kinetics and breakthrough curves based on recirculating and vertical column adsorption processes of MB on freeze dried Alg/XG and air-dried Alg/XG beads indicated higher efficiency for the vertical column system packed with freeze dried Alg/XG beads. The removal efficiency of 91% MB by the freeze-dried Alg/XG beads in vertical column remained even after four consecutive adsorption-desorption cycles, disclosing these beads as potential systems for the wastewater treatment., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The mechanical and thermal properties of cryogels depend on their microstructure. In this study, the microstructure of hydroxypropyl methylcellulose (HPMC) cryogels was modified by the addition of ionic (bis (2-ethylhexyl) sodium sulfosuccinate, AOT) and non-ionic (Kolliphor ® EL) surfactants to the precursor hydrogels (30 g/L). The surfactant concentrations varied from 0.2 mmol/L to 3.0 mmol/L. All of the hydrogels presented viscous behavior (G″ > G'). Hydrogels containing AOT (c > 2.0 mmol/L) led to cryogels with the lowest compressive modulus (13 ± 1 kPa), the highest specific surface area (2.31 m 2 /g), the lowest thermal conductivity (0.030 W/(m·°C)), and less hygroscopic walls. The addition of Kolliphor ® EL to the hydrogels yielded the stiffest cryogels (320 ± 32 kPa) with the lowest specific surface area (1.11 m 2 /g) and the highest thermal conductivity (0.055 W/(m·°C)). Density functional theory (DFT) calculations indicated an interaction energy of -31.8 kcal/mol due to the interaction between the AOT sulfonate group and the HPMC hydroxyl group and the hydrogen bond between the AOT carbonyl group and the HPMC hydroxyl group. The interaction energy between the HPMC hydroxyl group and the Kolliphor ® EL hydroxyl group was calculated as -7.91 kcal/mol. A model was proposed to describe the effects of AOT or Kolliphor ® EL on the microstructures and the mechanical/thermal properties of HPMC cryogels.

Tryptophan (Trp) decorated hydroxypropyl methylcellulose (HPMC) cryogels were prepared by a one-step reaction with citric acid. The increase of Trp content in the 3D network from 0 to 2.18 wt% increased the apparent density from 0.0267 g.cm -3 to 0.0381 g.cm -3 and the compression modulus from 94 kPa to 201 kPa, due to hydrophobic interactions between Trp molecules. The increase of Trp content in HPMC-Trp hydrogels increased the amount of non-freezing water, estimated from differential scanning calorimetry, and the amount of freezing water, which was determined by time-domain nuclear magnetic resonance. The adsorption capacity of methylene blue (MB) and rhodamine B (RB) on HPMC-Trp hydrogels increased with Trp content and the amount of freezing water. HPMC-Trp hydrogels could be recycled 6 times keeping the original adsorptive capacity. The diffusional constants of MB and RB tended to increase with Trp content. RB adsorbed on HPMC-Trp hydrogels presented a bathochromic shift of fluorescence., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Hypervalent tellurium compounds have a particular reactivity towards thiol compounds which are related to their biological properties. In this work, this property was assembled to tellurium-functionalized surfaces. These compounds were used as linkers in the immobilization process of thiolated biomolecules (such as DNA) on microcantilever surfaces. The telluride derivatives acted as reversible binding agents due to their redox properties, providing the regeneration of microcantilever surfaces and allowing their reuse for further biomolecules immobilizations, recycling the functional surface. Initially, we started from the synthesis of 4-((3-((4-methoxyphenyl) tellanyl) phenyl) amino)-4-oxobutanoic acid, a new compound, which was immobilized on a silicon surface. In nanomechanical systems, the detection involved a hybridization study of thiolated DNA sequences. Fluorescence microscopy technique was used to confirm the immobilization and removal of the telluride-DNA system and provided revealing results about the potentiality of applying redox properties to chalcogen derivatives at surfaces., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Xanthan gum (XG) was applied for the creation of hydrophilic, hydrophobic and layered cryogels. Firstly, the correlation among synthesis parameters, such as solvent composition and polymer concentration (C p ) in the precursor gel and mold diameter (Φ), with physicochemical properties and morphological parameters of resulting hydrophilic XG cryogels was investigated. The addition of acetic acid to the precursor led to stiffer XG cryogels. The reduction of C p and Φ promoted the increase in the cryogels surface area and porosity. Then, XG cryogels were silanized in order to produce hydrophobic cryogels, which presented sorption capacities for diesel, mineral and sunflower oils of 28 ± 2 g/g, 16 ± 2 g/g and 5.2 ± 0.3 g/g, respectively. The hydrophobic XG cryogels were considerably more efficient to remove ethinyl estradiol, an estrogenic pollutant, from liquid media than the hydrophilic cryogels. Hydrophilic and hydrophobic XG cryogels presented similar capacity to remove bisphenol A, another estrogenic pollutant, from liquid media. A new family of alternated hydrophobic/hydrophilic "Janus" like and multilayered cryogels was created and applied in mixtures of diesel oil and water or oil/water emulsions. The "Janus" like and multilayered cryogels remained at the interface, where the hydrophobic and hydrophilic layers adsorbed oil and water selectively., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This work was motivated by the need of stimuli responsive drug carriers, which can be activated by low cost non-invasive stimuli such as external magnetic field (EMF). Thus, novel antimicrobial materials based on xanthan gum (XG), magnetic nanoparticles (MNP), bovine serum albumin (BSA) and amoxicillin (Amox) were designed in order to promote the release of Amox under magnetic stimuli. Firstly, surfaces with different functionalities were prepared by sequential deposition of thin layers on Si wafers and characterized by means of ellipsometry and atomic force microscopy. Amox adsorbed preferentially onto XG or BSA films. In solution, favorable interactions between Amox and BSA were evidenced by substantial changes in the BSA secondary structure, as revealed by circular dichroism. Patches of XG and XG/MNP/BSA were immersed in 2 g L -1 Amox, yielding 10 ± 3 and 17 ± 4 μg/cm 3 Amox loading, respectively. The inclusion of 0.2 wt% Fe 3 O 4 in the patches and their exposure to EMF enabled in vitro release of Amox, at pH 5.5 and 0.02 mol L -1 NaCl, following the quasi-Fickian behavior. Amox diffused from XG/MNP/BSA patches in agar medium containing Staphylococcus aureus and Escherichia coli, inhibiting their growth. The inhibition of E. coli growth was particularly efficient under EMF., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Magnetic scaffolds with different charge densities were prepared using magnetic nanoparticles (MNP) and xanthan gum (XG), a negatively charged polysaccharide, or hydroxypropyl methylcellulose (HPMC), an uncharged cellulose ether. XG chains were crosslinked with citric acid (cit), a triprotic acid, whereas HPMC chains were crosslinked either with cit or with oxalic acid (oxa), a diprotic acid. The scaffolds XG-cit, HPMC-cit and HPMC-oxa were characterized by scanning electron microscopy (SEM), inductively coupled plasma atomic emission spectroscopy (ICP-AES), superconducting quantum interference device (SQUID) magnetometry, contact angle and zeta-potential measurements. In addition, the flux of Ca 2+ ions through the scaffolds was monitored by using a potentiometric microsensor. The adhesion and proliferation of murine fibroblasts (NIH/3T3) on XG-cit, XG-cit-MNP, HPMC-cit, HPMC-cit-MNP, HPMC-oxa and HPMC-oxa-MNP were evaluated by MTT assay. The magnetic scaffolds presented low coercivity (<25Oe). The surface energy values determined for all scaffolds were similar, ranging from 43mJm -2 to 46mJm -2 . However, the polar component decreased after MNP incorporation and the dispersive component of surface energy increased in average 1mJm -2 after MNP incorporation. The permeation of Ca 2+ ions through XG-cit-MNP was significantly higher in comparison with that on XG-cit and HPMC-cit scaffolds, but through HPMC-cit-MNP, HPMC-oxa and HPMC-oxa-MNP scaffolds it was negligible within the timescale of the experiment. The adhesion and proliferation of fibroblasts on the scaffolds followed the trend: XG-cit-MNP>XG-cit>HPMC-cit, HPMC-cit-MNP, HPMC-oxa, HPMC-oxa-MNP. A model was proposed to explain the cell behavior stimulated by the scaffold charge, MNP and Ca 2+ ions permeation., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Hydroxypropyl methylcellulose (HPMC) E4M chains are crosslinked with citric acid and ethylenediaminetetraacetic acid (EDTA), resulting in adsorbent sponges (SpE4M), which are impregnated with magnetic nanoparticles (SpE4M-mag) for the adsorption of 17 α-ethinyl estradiol (EE). The characterization of SpE4M and SpE4M-mag characterization includes X-ray microcomputer tomography (Micro-CT), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) vibrational spectroscopy, elemental analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), and X-ray diffraction (XRD). SpE4M and SpE4M-mag present porosities of 72±6 % and 80±7 %, respectively, and outstanding stability in water, in the pH range 4 to 8, and in alcohols, alkanes, and acetone. The compressive moduli of SpE4M and SpE4M-mag amount to 2.75 and 4.37 MPa, respectively. The adsorption of 17 α-ethinyl estradiol (EE), an estrogenic pollutant, on SpE4M and SpE4M-mag follows the pseudo-first-order kinetic model. The EE removal capacity by SpE4M is 78±5 %, which is twice that presented by SpE4M-mag. The new sponges are recovered successfully either by flotation or by an external magnet, and can be recycled five times keeping 80 % of their initial removal capacity after the fifth cycle, disclosing their potential for environmental remediation., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hydroxypropyl methylcellulose (HPMC) E4M and J5MS samples with degrees of substitution of methyl groups (DS) 1.9 and 1.5, respectively, and molar substitutions of hydroxypropyl groups (MS) 0.25 and 0.75, respectively, were used to create aerogels in the presence of citric (cit), oxalic (oxa) or terephthalic (ter) acids, as crosslinkers. E4M-cit, J5MS-cit and J5MS-oxa aerogels presented outstanding stability in water, acid media, alcohols, acetone and hydrocarbons, density values of∼(0.020±0.002)g/cm 3 , compressive modulus ranging from (111±9)kPa to (133±11)kPa. On the other hand, E4M-oxa, E4M-ter and J5MS-ter aerogels were not adequate adsorbents because they collapsed in water. The adsorption behavior of 17α-ethinyl estradiol (EE) and methylene blue (MB) onto E4M-cit, J5MS-cit and J5MS-oxa aerogels were fitted to Freundlich model, indicating higher affinity of EE for J5MS-cit and J5MS-oxa and higher affinity of MB for E4M-cit aerogels. HPMC aeorogels could be successfully reused., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Analytical methods for the determination of rare earth elements (REE) in natural waters by plasma spectrochemical techniques often require sample preparation procedures for analytes preconcentration as well as for removing matrix constituents, that may interfere on the analytical measurements. In the present work, calcium alginate (CA) beads were used for the first time aiming at Ce, La and Nd preconcentration from groundwater samples for further determination by inductively coupled plasma optical emission spectrometry (ICP OES). Test samples were analyzed in batch mode by transferring a 40mL test portion (pH=5±0.2) into a 50mL polyethylene flask containing 125mg CA beads. After 15min contact, the analytes were quantitatively extracted from the loaded CA beads with 2.0mL of 1.0molL -1 HCl solution for further determination by ICP OES, using Ce (II) 456.236, La (II) 379.478 and Nd (II) 430.358nm emission lines. The proposed approach is a reliable alternative for REE single-stage preconcentration from aqueous samples, as it provided accurate results based on the addition and recovery analysis of groundwater. The results obtained by the proposed method were also compared with those from reference method based on inductively coupled plasma mass spectrometry (ICP-MS) and no significant differences were observed after applying the Student's t-test at 95% confidence level., (Copyright © 2016 Elsevier B.V. All rights reserved.)