The simultaneous removal of organic and inorganic pollutants from water requires multifunctional adsorbents. Cryogels of carboxymethyl cellulose (CMC) and sugarcane bagasse (BG) were modified with ...cetyltrimethylammonium bromide (CTAB) micelles for the adsorption of methylene blue (MB), Cr(VI) ions and bisphenol A (BPA) separately, in binary or ternary aqueous mixtures. Batch adsorption studies of MB and Cr(VI) and BPA on the CMCBG-CTAB adsorbents indicated removal capacities of 100%, 70% and 95%, respectively. MB adsorbed as multilayers on the CMCBG walls by electrostatic interaction, whereas Cr(VI) and BPA adsorbed on the cationic CTAB micelles surface and hydrophobic core of CTAB micelles, respectively. The breakthrough curves obtained for pure adsorbates and their mixtures showed that the adsorption of Cr(VI) ions increased (i) ~ 3.5 times in binary mixture with BPA or in the ternary mixture, in comparison to pure Cr(VI) solution, and (ii) 1.4 times in binary mixture with MB molecules, due to synergistic effects. In the presence of Cr(VI) ions in binary or ternary mixtures, the adsorption of MB was dramatically reduced due to screening effects. The adsorption of BPA was not significantly affected by the presence of MB or Cr(VI). The adsorbents were recycled five times without significant efficiency loss.
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•Bagasse particles increased the dimensional and mechanical stability of CMC adsorbents•Bagasse-CMC-CTAB adsorbents removed simultaneously BPA, MB and Cr(VI) ions•Cr(VI) ions adsorbed electrostatically on the CTAB cationic shell•BPA dissolved in the hydrophobic core of CTAB micelles•The presence of BPA or MB in the mixture increased the removal of Cr(VI)
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hydrogels of poly(vinyl alcohol) (PVA)/sodium alginate (SA), and magnetic nanoparticles (MNPs) were prepared by solvent casting in the absence and in the presence of magnets, in order to obtain MNPs ...distributed randomly (PVA/SA-rMNP) and magnetically oriented MNPs (PVA/SA-gMNP) in the polymer matrix. Atomic force microscopy (AFM) and magnetic force microscopy (MFM) techniques were used to evaluate the topography and to map the distribution of magnetic domains in the polymer matrix, respectively. The tip-surface distance (lift distance) of 50 nm during the MFM analyses facilitated the mapping of magnetic domains because the van der Waals forces were minimized. The magnetic signal stemming from clusters of MNPs were more easily identified than that from isolated MNPs. PVA and SA, PVA/SA, PVA/SA-rMNP, and PVA/SA-gMNP coatings with surface roughness (
R
a
) values of 3.8 nm, 28.7 nm, and 49.8 nm, respectively, were tested for the proliferation of mouse hippocampal HT-22 cells. While PVA/SA, PVA/SA-rMNP, and PVA/SA-gMNP coatings preserved cell viability >70% in comparison to the control (plastic plate) over 48 h, cell proliferation tended to decrease on surfaces with higher
R
a
values (PVA/SA-gMNP). These findings showed that the orientation of magnetic domains led to an increase of surface roughness, which decreased the viability of HT-22 cells. Thus, these results might be interesting for situations, where the control of cell proliferation is necessary.
Magnetic domains in dried magnetic hydrogels were analyzed through magnetic force microscopy. These magnetic domains can be detected under different MNPs arrangements when inserted in hydrogels.
► Xanthan was crosslinked by heating esterification, forming hydrogels. ► Tensiometry allowed understanding the swelling mechanism of xanthan hydrogels. ► Quasi-Fickian, Fickian and Anomalous ...Diffusion were observed for hydrogels. ► Swelling degree increased at high pH values due to ester linkages rupture. ► Swelling degree was affected by salts, depending on gel composition and salt.
In this work xanthan chains were crosslinked by esterification reaction at 165°C either in the absence or in the presence of citric acid. Higher crosslinking density was obtained using citric acid, as evidenced by its lower swelling degree. Tensiometry, a very precise and sensitive technique, was applied to study swelling rates and diffusion mechanisms of water, which was initially quasi-Fickian, controlled by wicking properties, changing to Fickian or Anomalous, depending on hydrogel composition. Hydrogels swelling degree increased at high pH values, due to electrostatic repulsion and ester linkages rupture. Equilibrium swelling degree was affected by salts, depending on gel composition and kind of salt. Effects could be explained by interaction between ions and polymeric chains, EPA/EPD ability of water or osmotic gradient.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this study, coatings of polydopamine (PDA) in the presence of caffeine were investigated upon their deposition on substrates with different surface energies. The physicochemical properties and ...stability of PDA coatings deposited in the absence and presence of caffeine (C/PDA) on Si/SiO
2
(high surface energy), cellulose acetate butyrate (CAB) (intermediate surface energy) and polystyrene (PS) (low surface energy) surfaces were investigated by means of ellipsometry, contact angle measurements and X-ray photoelectron spectroscopy. In order to gain insight about the interactions between caffeine and PDA at molecular level, Raman and infrared (FTIR-ATR) spectroscopy measurements were performed for PDA and C/PDA, and the results were supported by density functional theory calculations. In comparison with bare PDA, the C/PDA system displayed an increase in the deposition rate on all substrates, indicating co-deposition of caffeine and PDA. PDA and C/PDA coatings turned hydrophobic substrates into hydrophilic surfaces and vice versa. PDA coatings on CAB and PS films were the most stable systems. CAB/PDA microbeads were created and tested as new adsorbents for caffeine, presenting removal capacity of 40%.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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•Magnetic xanthan/alginate films presented good mechanical and swelling properties.•The content of levodopa loaded into magnetic hydrogels amounted to 18 wt%.•Under external magnetic ...field, the Fickian release of levodopa reached 64% after 30 h.•Magnetically released LD favored proliferation and differentiation of neural cells.
Magnetic responsive hydrogels composed of alginate (Alg) and xanthan gum (XG), crosslinked with Ca2+ ions, were modified by in situ magnetic nanoparticles (MNP) formation. In comparison to magnetic Alg hydrogels, magnetic Alg-XG hydrogels presented superior mechanical and swelling properties, due to the high charge density and molecular weight of XG. The loading efficiency of levodopa (LD), an important antiparkinson drug, in the Alg-XG/MNP hydrogels was the highest (64%), followed by Alg/MNP (56%), Alg-XG (53%) and Alg (28%). A static external magnetic field (EMF) of 0.4 T stimulated the release of LD from Alg-XG/MNP hydrogels achieving 64 ± 6% of the initial loading after 30 h. The viability, proliferation and expression of dopaminergic markers of human neuroblastoma SH-SY5Y cell on the LD loaded magnetic hydrogels were successful, particularly under EMF, which stimulated the release of LD. Overall, the results of this study provided the rational design of magnetic hydrogels for the delivery of drugs, which combined with external magnetic stimulus, might improve cell proliferation and specific differentiation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Crosslinked xanthan chains in the presence of citric acid presented disordered conformation.•Crosslinked xanthan chains in the presence of citric acid presented high charge density.•Proteins loading ...and releasing are controlled by hydrogels and proteins net charge.•Lysozyme loaded xanthan hydrogels showed substantial bactericidal activity.
In this article the molecular conformation of xanthan chains in hydrogel films was investigated by means of circular dichroism, showing substantial differences between xanthan hydrogel prepared in the absence (XNT) and in the presence of citric acid (XCA). The xanthan chains in XNT hydrogels films presented ordered conformation (helixes), while in XCA they were in the disordered conformation (coils), exposing a larger number of carboxylate groups than XNT. The large charge density in XCA hydrogels was evidenced by their behavior under variable ionic strength. Studies about the application of XNT and XCA for loading and delivering of bovine serum albumin (BSA) and lysozyme (LYZ) showed that both events are controlled by hydrogels and proteins net charge, which can be triggered by pH. The preservation of LYZ native conformation after hydrogel loading explained the substantial bactericidal activity of LYZ loaded hydrogels and enables their use as active wound dressings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Adsorbents made of hydroxypropyl methylcellulose (HPMC) and sugarcane bagasse (BG) microparticles were applied for the separation of 17α-ethinylestradiol (EE2) from aqueous solution in batch, and ...from aqueous solution and freshwater in fixed-bed columns. HPMC chains and BG microparticles were crosslinked by the esterification with citric acid. The adsorbents presented compression modulus values that increased from 208 ± 20 kPa (pure HPMC) to 917 ± 90 kPa, when the content of BG particles added to HPMC was 50 wt% (HPMC50BG). The porosity (~ 97%), specific surface area (1.16 ± 0.10 m
2
/g) and swelling degree (20 ± 1 g water/g) values were not affected by the addition of BG particles. The adsorption isotherms determined for EE2 on HPMC and on HPMC50BG fitted to the Langmuir and Freundlich models; the adsorption capacity of HPMC was slightly higher than that of composite HPMC50BG. Nevertheless, the addition of BG particles rendered outstanding mechanical reinforcement and dimensional stability to the adsorbents. The adsorption was driven by (i) hydrophobic interactions between EE2 methylene and aromatic groups and HPMC methyl groups, as evidenced by FTIR spectroscopy, and (ii) H bonds between HPMC and EE2 hydroxyl groups, as revealed by the adsorption enthalpy change (Δ
H
ads
) of − 45 kJ/mol. Column adsorption experiments of EE2 from aqueous solution on HPMC and HPMC50BG indicated adsorptive capacity (
q
0
) values of 8.06 mg/g and 4.07 mg/g, respectively. These values decreased considerably for the adsorption of EE2 from river water, probably due to the competition of EE2 with humic substances dissolved in natural water. The HPMC adsorbents could be recycled retaining up to 83% of the original efficiency.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This study aimed to describe the clinical, genetic, and epidemiological features of Charcot‐Marie‐Tooth disease (CMT) in Brazilian patients from a tertiary center, and to compare our data with ...previously published findings. This retrospective observational study conducted between February 2015 and July 2020 evaluated 503 patients (94 families and 192 unrelated individuals), diagnosed with CMT. Clinical and neurophysiological data were obtained from electronic medical records and blood samples were used for genetic analyses. Multiplex ligation‐dependent probe amplification was used to assess duplications/deletions in PMP22. Sanger sequencing of GJB1 was performed in cases of suspected demyelinating CMT. Targeted gene panel sequencing was used for the remaining negative demyelinating cases and all axonal CMT cases. The first decade of life was the most common period of disease onset. In all, 353 patients had demyelinating CMT, 39 had intermediate CMT, and 111 had axonal CMT. Pathogenic or likely pathogenic variants were identified in 197 index cases. The most common causative genes among probands were PMP22 (duplication) (n = 116, 58.88%), GJB1 (n = 23, 11.67%), MFN2 (n = 12, 6.09%), GDAP1 (n = 7, 3.55%), MPZ (n = 6, 3.05%), PMP22 (point mutation) (n = 6, 3.05%), NEFL (n = 3, 1.52%), SBF2 (n = 3, 1.52%), and SH3TC2 (n = 3, 1.52%). Other identified variants were ≤1% of index cases. This study provides further data on the frequency of CMT subtypes in a Brazilian clinical‐based population and highlights the importance of rarer and previously undiagnosed variants in clinical practice.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Magnetic alginate beads (Alg-MNP) were used as carriers for dopamine (DOPA), which was released in the absence and the presence of an external magentic field (EMF) of 0.4T; the release was more ...favored under magnetic stimulus.
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•Loading efficiency of DOPA into magnetic responsive Alg-MNP beads was 38% at pH 7.4.•DOPA release followed Fickian mechanism under external magnetic field (EMF).•DOPA release under external magnetic field amounted to 33% after 26h.•DOPA release followed anomalous diffusion mechanism in the absence of EMF.
Hybrid beads composed of magnetite nanoparticles (MNP) and alginate (Alg) were synthesized and coded as Alg-MNP. They were incubated in dopamine (DOPA) solution (5g/L), at pH 7.4 and 8°C, during 12h, promoting the DOPA loaded magnetic beads, coded as Alg-MNP/DOPA. The release of DOPA was further evaluated in the absence and the presence of external magnetic field (EMF) of 0.4T. The products Alg-MNP and Alg-MNP/DOPA were characterized by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared vibrational spectroscopy (FTIR), UV spectrophotometry, thermogravimetric analyses (TGA), inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses and superconducting quantum interference device (SQUID) magnetometer. The magnetic and chemical properties of Alg-MNP beads were not affected by DOPA loading. The incorporation of DOPA into the beads depended on the pH and on the negative charge density. At pH 7.4 38% of DOPA were loaded into Alg-MNP beads, whereas at pH 2 or using neat Alg beads (lower charge density than Alg-MNP) the loading efficiency decreased to one third or less. In the absence of EMF, 24% of the loaded DOPA was released from Alg-MNP at pH 7.4 over a period of 26h. The released amount increased to 33% under the stimulus of EMF. A model was proposed to explain the loading efficiency of charged drugs, as DOPA, into hybrid beads and the role played by EMF on delivery systems, where drug and matrix are oppositely charged. The results suggest that the alginate combined with magnetite nanoparticles is a promising system for release of DOPA in the presence of EMF.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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