RESUMEN
Aromatic hydrocarbons are extensive environmental pollutants occurring in both water and air media, and their removal is a priority effort for a healthy environment. The use of adsorbents is among the several strategies used for the remediation of these compounds. In this paper, we aim the synthesis of an amphiphilic hydrogel with the potential for the simultaneous sorption of a set of monocyclic and polycyclic aromatic hydrocarbons associated with toxicity effects in humans. Thus, we start by the synthesis of a copolymer-based in chitosan and ß-cyclodextrin previously functionalized with the maleic anhydride. The presence of ß-cyclodextrin will confer the ability to interact with hydrophobic compounds. The resulting material is posteriorly incorporated in a cryogel of poly(vinyl alcohol) matrix. We aim to improve the amphiphilic ability of the hydrogel matrix. The obtained hydrogel was characterized by swelling water kinetics, thermogravimetric analysis, rheological measurements, and scanning electron microscopy. The sorption of aromatic hydrocarbons onto the gel is characterized by pseudo-first-order kinetics and Henry isotherm, suggesting a physisorption mechanism. The results show that the presence of maleic anhydride-ß-cyclodextrin and chitosan into hydrogels leads to an increase in the removal efficiency of the aromatic compounds. Additionally, the capacity of this hydrogel for removing these pollutants from a fossil fuel sample has also been tested.
RESUMEN
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 2â¯gâ¯L-1 Amox, yielding 10⯱â¯3 and 17⯱â¯4⯵g/cm3 Amox loading, respectively. The inclusion of 0.2â¯wt% Fe3O4 in the patches and their exposure to EMF enabled in vitro release of Amox, at pHâ¯5.5 and 0.02â¯molâ¯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.
Asunto(s)
Amoxicilina/química , Portadores de Fármacos/química , Liberación de Fármacos , Óxido Ferrosoférrico/química , Campos Magnéticos , Polisacáridos Bacterianos/química , Albúmina Sérica Bovina/química , Adsorción , Amoxicilina/farmacología , Animales , Antibacterianos/química , Antibacterianos/farmacología , Bovinos , Escherichia coli/efectos de los fármacos , Concentración de Iones de Hidrógeno , Staphylococcus aureus/efectos de los fármacosRESUMEN
Petroleum comprises the monoaromatic and polycyclic aromatic hydrocarbons, which exhibit acute toxicity towards living animals. Consequently, their removal from natural environment is a priority challenge. On the other hand, biomaterials are increasingly being used as adsorbents. Pectin and chitosan are well-known polysaccharides able to form coacervate hydrogels. Aiming an increase of sorption ability by hydrophobic compounds, pectin was also functionalized with two amphiphilic compounds: ß-cyclodextrin (ß-CD) and poly(vinyl alcohol) (PVA). Both the modified pectin and the hydrogels were evaluated using nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The hydrogels were further characterized in terms of thermogravimetric analysis (TGA) and swelling kinetics. The interaction between the hydrogel and mix solutions containing six different aromatic compounds (BTXs and the following PAHs: pyrene, benzo(b)fluoranthene and benzo(a)pyrene) has been evaluated through sorption isotherms and kinetics. The mechanism of sorption interaction and the selectivity of the adsorbents towards different aromatic compounds were discussed. The results clearly show that the presence of ß-CD and PVA into gel leads to an increase in the removal efficiency of both, BTXs and PAHs. The gels were subjected to two sorption/desorption cycles to have an assessment of the capability of adsorbents for re-use. Finally, the sorption quantification of those six aromatic compounds from a real gasoline sample onto gels has been tested.
RESUMEN
Nanoparticles (NPs) based on N,N-dimethyl chitosan (DMC) and N,N,N-trimethyl chitosan (TMC), physical crosslinked with sodium tripolyphosphate (TPP) were successful obtained, using water/benzyl alcohol emulsion system. NPs morphologies were evaluated by Scanning Electron Microscopy and Transmission Electron Microscopy. NPs were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis, Zeta Potential, Differential Scanning Calorimetry and Wide-angle X-ray Scattering. Curcumin (CUR) was loaded onto NPs and controlled release studies were evaluated in simulated intestinal fluid and in simulated gastric fluid. Cytotoxicity assays showed only loaded TMC/TPP particles containing CUR were slightly cytotoxic on human cervical tumor cells (SiHa cells), concerning unloaded TMC/TPP particles. Conversely, loaded NPs (TMC/TPP/CUR and DMC/TPP/CUR), especially TMC/TPP/CUR sample presented greater biocompatibility toward healthy VERO cells than unloaded NPs (TMC/TPP and DMC/TPP).
Asunto(s)
Quitosano/química , Quitosano/toxicidad , Curcumina/química , Portadores de Fármacos/química , Portadores de Fármacos/toxicidad , Nanopartículas , Animales , Chlorocebus aethiops , Liberación de Fármacos , Estabilidad de Medicamentos , Humanos , Temperatura , Células VeroRESUMEN
Polysaccharide-based device for oral delivery of heparin (HP) was successfully prepared. Previously synthesized N,N-dimethyl chitosan (DMC) (86% dimethylated by (1)H NMR spectroscopy) was complexed with HP by mixing HP and DMC aqueous solutions (both at pH 3.0). The polyelectrolyte complex (PEC) obtention was confirmed by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG) and wide-angle X-ray scattering (WAXS). In vitro controlled release assays of HP from PEC were investigated in the simulated intestinal fluid (SIF) and simulated gastric fluid (SGF). The PEC efficiently protected the HP in SGF condition in which HP is degraded. On the other hand, in SIF PEC promoted the releasing of 80 ± 1.5% of loaded HP. The promissory results indicated that the PEC based on DMC/HP presented potential as drug-carrier matrix, since biological activity of HP was improved at pH close to physiological condition.
Asunto(s)
Quitosano/análogos & derivados , Quitosano/química , Portadores de Fármacos/química , Sistemas de Liberación de Medicamentos , Electrólitos/química , Heparina/química , Heparina/farmacología , Líquidos Corporales/química , Quitosano/síntesis química , Modelos Teóricos , Espectroscopía de Protones por Resonancia Magnética , Espectroscopía Infrarroja por Transformada de Fourier , Termogravimetría , Difracción de Rayos XRESUMEN
N-trimethyl chitosan of two quaternization degrees, DQ=20 and 80mol% and labeled as TMC20 and TMC80, were synthesized and characterized by (1)H NMR. Polyelectrolyte complexes (PECs) of TMC/alginate (TMC/ALG) were prepared at pHs 2, 7 and 10 by mixing the aqueous solutions of unlike polymers. The PECs were characterized through infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG) and wide-angle X-ray scattering (WAXS). Using the TMC of DQ=20 mol% and following the same methodology for preparing the PECs, beads of TMC20/ALG were obtained at pH 2 and loaded with curcumin (CUR) at pH 6.0-6.5. The morphology of the beads was evaluated by scanning electron microscopy (SEM). Studies in vitro of the controlled release of CUR from beads were investigated in simulated intestinal fluid (SIF) and simulated gastric fluid (SGF) and treated using conventional and partition-diffusion models. Results indicated that the beads based on TMC20 and ALG presented potential as drug-carrier to improve the solubility and biological activity of CUR at pH close to physiological one.
Asunto(s)
Alginatos , Quitosano , Curcumina , Alginatos/síntesis química , Alginatos/química , Alginatos/farmacocinética , Alginatos/farmacología , Quitosano/síntesis química , Quitosano/química , Quitosano/farmacocinética , Curcumina/química , Curcumina/farmacocinética , Preparaciones de Acción Retardada/síntesis química , Preparaciones de Acción Retardada/química , Preparaciones de Acción Retardada/farmacocinética , Ácido Glucurónico/síntesis química , Ácido Glucurónico/química , Ácido Glucurónico/farmacocinética , Ácido Glucurónico/farmacología , Ácidos Hexurónicos/síntesis química , Ácidos Hexurónicos/química , Ácidos Hexurónicos/farmacocinética , Ácidos Hexurónicos/farmacología , Concentración de Iones de HidrógenoRESUMEN
N-trimethyl chitosan-graft-poly(vinyl alcohol) (TMC-g-PVA) copolymers were prepared. The grafting reactions were conducted in water changing the feed ratios of poly(vinyl alcohol)/6-O-succinate-N-trimethyl chitosan (PVA/STMC). The structure of TMC-g-PVA copolymers was characterized through (1)H NMR spectroscopy, thermogravimetric analysis (TGA/DTG), wide-angle X-ray scattering (WAXS) and scanning electron microscopy (SEM). The quaternization degree (DQ) and substitution degree (DS) of N-trimethyl chitosan (TMC) and 6-O-succinate-N-trimethyl chitosan (STMC) were determined by (1)H NMR, being the spectroscopy 14.0 and 5.5mol-% found, respectively. The viability of HCT-116 cancerous cells was investigated at different concentrations. The effect of PVA/STMC ratios on the cytotoxicity of the TMC-g-PVA copolymers was examined and the CC50 values determined for every case.