Browsing by Subject "Chitosan"
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- PublicationOpen AccessAn infrared investigation in relation with chitin and chitosan characterization(Elsevier, 2001-01-12) Brugnerotto, J.; Lizardi, J.; Goycoolea Valencia, Francisco Martín; Argüelles Monal, Waldo; Desbrières, J.; Rinaudo, Marguerite; Biología Celular e HistologíaThe use of infrared spectroscopy for characterization of the composition of chitin and chitosan covering the entire range of degree of acetylation (DA) and a wide variety of raw materials is examined further. The ratio of absorbance bands selected was calibrated using 1H liquid and 13C CP-MAS solid-state NMR as absolute techniques. IR spectra of the structural units of these polymers validated the choice of baselines and characteristic bands. The bands at 1650 and 1320 cm-1 were chosen to measure the DA. As internal reference, the intensities at 3450 and 1420 cm-1 were evaluated. The absorption band ratios involving the reference at 3450 cm-1 had poorer fit. The absorption ratio A1320/A1420 shows superior agreement between the absolute and estimated DA-values (DA% = 31.92A1320/A1420 - 12.20; r = 0.990)
- PublicationEmbargoBactericidal efficacy of photodynamic therapy and chitosan in root canals experimentally infected with enterococcous faecalis: and in vitro study(Mary Ann Liebert, Inc., 2017-01-09) Camacho Alonso, Fabio; Julián Belmonte, Encarnación; Chiva García, Fernando; Martínez Beneyto, Yolanda; Dermatología, Estomatología, Radiología y Medicina FísicaObjective: To evaluate the antibacterial efficacy of photodynamic therapy (PDT) and chitosan against Enterococcus faecalis and assess the possible enhancive effect of chitosan on the photosensitizer methylene blue in experimentally infected root canals of extracted human teeth in vitro. Background data: E. faecalis is frequently found in persistent endodontic infections. In this context, the antimicrobial PDT or newer antibacterial alternatives such as chitosan could become modern alternatives to existing antibacterial treatment approaches. Methods: One hundred two single-rooted extracted teeth were used. The teeth were contaminated with 0.1 mL E. faecalis (3 × 108 cell/mL). These were randomized into six treatment groups (n = 17 teeth): Group 1 (2.5% NaOCl); Group 2 (PDT); Group 3 (chitosan 3 mg/mL); Group 4 (PDT+chitosan 3 mg/mL); Group 5 (positive control, no treatment); and Group 6 (negative control, no inoculation, no treatment). The canal content was sampled with sterile paper points. The samples were cultured on blood agar plates to determine the number of colony-forming units (CFU)/mL. Five teeth in each group were analyzed by scanning electron microscope (SEM) to determine the percentage of area with contamination and debris. Results: The positive control group showed the highest number of CFU/mL, with statistically significant differences in comparison with the other treatment groups (p ≤ 0.05). Group 4 (PDT+chitosan) showed the lowest CFU/mL count, followed by Group 2 (PDT alone), which obtained similar results to Group 1 (NaOCl), but there was no significance between the treated groups. SEM images showed that Group 4 (PDT+Chitosan) showed the lowest area of contamination. Conclusions: Combination of PDT and chitosan showed antibacterial potential against endodontic infection by E. faecalis.
- PublicationOpen AccessCharacterisation of the interaction among oil-in-water nanocapsules and mucin(MDPI, 2020-07-28) Collado-González, Mar; Kaur, Gurmeet ; González-Espinosa, Yadira ; Brooks, Rebecca ; Goycoolea, Francisco M.; Biología Celular e HistologíaMucins are glycoproteins present in all mucosal surfaces and in secretions such as saliva. Mucins are involved in the mucoadhesion of nanodevices carrying bioactive molecules to their target sites in vivo. Oil-in-water nanocapsules (NCs) have been synthesised for carrying N,N0-(di-m-methylphenyl)urea (DMTU), a quorum-sensing inhibitor, to the oral cavity. DMTU-loaded NCs constitute an alternative for the treatment of plaque (bacterial biofilm). In this work, the stability of the NCs after their interaction with mucin is analysed. Mucin type III from Sigma-Aldrich has been used as the mucin model. Mucin and NCs were characterised by the multi-detection symmetrical flow field-flow fractionation technique (AF4). Dynamic light scattering (DLS) and z-potential analyses were carried out to characterise the interaction between mucin and NCs. According to the results, loading DMTU changes the conformation of the NC. It was also found that the synergistic interaction between mucin and NCs was favoured within a specific range of the mucin:NC ratio within the first 24 h. Studies on the release of DMTU in vitro and the microbial activity of such NCs are ongoing in our lab.
- PublicationOpen AccessChitosan as stabilizing agent for negatively charged nanoparticles(Elsevier, 2016-12-24) Collado-González, Mar; Montalbán, Mercedes G.; Peña-García, Jorge; Pérez-Sánchez, Horacio; Víllora, Gloria; Díaz Baños, F. Guillermo; Biología Celular e HistologíaChitosan is a biocompatible polysaccharide with positive Z potential which can stabilize negative charged nanoparticles. Silk fibroin nanoparticles and citrate gold nanoparticles, both with negative Z potential, but they form aggregates at physiological ionic strength. In this work, we study the behavior of chitosan in solution when the ionic strength of the medium is increased and how the concentration of chitosan and the proportion of the two components (chitosan and AuNP or SFN) significantly affect the stability and size of the nanocomposites formed. In addition to experimental measurements, molecular modeling were used to gain insight into how chitosan interacts with silk fibroin monomers, and to identify the main energetic interactions involved in the process. The optimum values for obtaining the smallest and most homogeneous stable nanocomposites were obtained and two different ways of organization through which chitosan may exert its stabilizing effect were suggested.
- PublicationOpen AccessComparison of sulfamethoxazole removal efficiency using polyethersulfone ultrafiltration membrane modified by various methods(MDPI, 2024-12-20) Hidalgo, Asunción María ; Murcia, María Dolores; Gómez, María ; Collado-González, Mar ; Montiel, María Claudia ; Martínez, Marta; Ingeniería Química ; Biología Celular e HistologíaNowadays, there is a growing interest in membrane modification processes to improve their characteristics and the effectiveness of their treatments and reduce the possible fouling. In this sense, in this work, a modification of an ultrafiltration membrane with three different materials has been carried out: reduced graphene oxide (rGO), chitosan and MgCl2. For both the native and the modified membranes, a study has been carried out to remove the emerging contaminant sulfamethoxazole (SMX). SEM and SEM-EDX analyses have been performed to confirm membrane surface modifications. In the characterisation of the membranes, it is noteworthy that the values of the permeability coefficient, Aw, have been lower in the modified membranes, which is unexpected. Regarding the pollutant removal tests, the influence of pressure and initial concentration on permeate flux and rejections has been studied. Native membrane shows the highest permeate flux values. Comparing the modified membranes, the highest rejection values are obtained with the rGO-modified membrane, which can be explained by its greater hydrophilic character. Finally, a fouling study was carried out, verifying that in almost all cases, fouling occurs after the passage of the pollutant due to the blockage of the membrane pores.
- PublicationOpen AccessComplex polysaccharide-based nanocomposites for 2 oral insulin delivery(MDPI (Basel, Switzerland), 2020-01-15) Collado-González, Mar; Freitas, Alessandra R.; Santos, Ana Claudia; Ferreira, Nuno F.; Ferreri, Maria Cristina; Sequeira, Joana A.D.; Díaz Baños, F. Guillermo; Víllora, Gloria; Veiga, Francisco; Ribeiro, Antonio; Carissimi, Guzmán; Química FísicaPolyelectrolyte nanocomposites rarely reach a stable state and aggregation often occurs. Here, we report the synthesis of nanocomposites for the oral delivery of insulin composed of alginate, dextran sulfate, poly-(ethyleneglycol) 4000, Poloxamer 188®, chitosan, and BSA. Chitosan seems to be essential for the final size of the nanocomposites. When the chitosan concentration used in the synthesis is 10-4 gcm-3, nanocomposites, microcomposites and milimetric composites are obtained. Reducing the chitosan concentration to 10-5 or 10-7 gcm-3 yields nanocomposites of 400-600 nm or 800-900 nm hydrodynamic diameter, respectively, measured by DLS. According to our results, the molecular weight of chitosan has little influence on the size of the composites. The enhanced stability of the newest nanocomposites synthesized was assessed with LUMiSizer®. The rounded shapes of the nanocomposites were confirmed by scanning electron microscopy. Analysis by HPLC revealed that, after loaded with insulin, about 80% of the drug was released from our nanocomposites.
- PublicationOpen AccessEffect of chemical crosslinking on the swelling and shrinking properties of thermal and pH-responsive Chitosan hydrogels(Wiley, 2003-10-07) Goycoolea Valencia, Francisco Martín; Heras, Ángeles; Aranaz, Inmaculada; Galed, Gemma; Fernández Valle, María E.; Argüelles Monal, Waldo; Biología Celular e HistologíaThe ability to form a gel through the physical or chemical crosslinking of chitosan has been well documented. In an attempt to mimic biological systems, thermal and pH-sensitive chitosan cylindrical hydrogels were produced by a combination of physical and chemical crosslinking processes. To this end, chitosan hydrogels prepared from alkali chitin were molded in cylinders and, once washed, were further crosslinked with glutaraldehyde at stoichiometric ratios, R (-[–CH=O]/[–NH2]), of 1.61 and 3.22 x10^-2. Variation in swelling as a result of stepwise changes in temperature between 40 and 2 °C at pH values of 7.0, 7.6, and 8.0 revealed that the system responds in markedly different manners dependent upon the pH. At pH 7.0, cooling from 40 to 2 °C results in contraction of the gel network structure. While raising the temperature from 2 to 40 °C leads to a rapid swelling response (i.e., ca. a twofold increase in the amount of solvent uptake). Subsequent cooling to 2 °C is accompanied by a new contraction cycle. At pH 7.6 the temperature dependence of the swelling–contraction behavior is exactly the opposite of that observed at pH 7.0.Very similar trends were observed for the gels at both degrees of crosslinking. The swelling–shrinking behavior observed in gels of pH 7.6, is similar in kind to that of uncrosslinked gels and is interpreted in terms of a lower critical solution temperature (LCST) volume phase transition, driven by hydrophobic association, presumably involving residual acetyl groups in the chitin. The results at pH 7.0 suggest that the slight ionization of the –NH3+ groups leads to the destruction of the hydrophobic hydration thus effectively reversing the negative thermal shrinking.
PublicationRestrictedMembrane fluidity determines sensitivity of filamentous fungi to chitosan(2010) López Jiménez, José Ángel; Palma Guerrero, J.; Pérez Berná, A. J.; Huang, I. C.; Jansson, H.B.; Salinas, J.; Villalaín, J.; Read, N.D.; López Llorca, L. V.; Filosofía- PublicationOpen AccessMicroencapsulation of astaxanthin in a chitosan matrix(Elsevier, 2004-02-06) Higuera Ciapara, I.; Felix Valenzuela, L.; Goycoolea Valencia, Francisco Martín; Argüelles Monal, W.; Biología Celular e HistologíaSynthetic astaxanthin was microencapsulated in a chitosan matrix cross-linked with glutaraldehyde by using the method of multiple emulsion/solvent evaporation. A powdered product containing microcapsules with a diameter of 5–50 mm was obtained. The stability of the pigment in the microcapsules was studied under storage at 25, 35 and 45 8 °C for 8 weeks by measuring isomerization and loss of concentration of pigment. Pigments were extracted from the microcapsules with a mixture of dichloromethane/methanol (50:50) and the astaxanthin was analyzed by HPLC with a diode array detector (480 nm). Results showed that the microencapsulated pigment did not suffer isomerization nor chemical degradation under the investigated storage conditions
- PublicationEmbargoMultimodal biomedical implant with plasmonic and simulated body temperature responses(Wiley, 2023-04-28) Mingot, Júlia; Benejam, Nícolas; Víllora, Gloria; Alemán, Carlos; Armelin, Elaine; Lanzalaco, Sonia; Ingeniería QuímicaThis work presents a novel nanoparticle-based thermosensor implant able to reveal the precise temperature variations along the polymer filaments, as it contracts and expands due to changes in the macroscale local temperature. The multimodal device is able to trace the position and the temperature of a polypropylene mesh, employed in abdominal hernia repair, by combining plasmon resonance and Raman spectroscopy with hydrogel responsive system. The novelty relies on the attachment of the biocompatible nanoparticles, based on gold stabilized by a chitosan-shell, already charged with the Raman reporter (RaR) molecules, to the robust prosthesis, without the need of chemical linkers. The SERS enhanced effect observed is potentiated by the presence of a quite thick layer of the copolymer (poly(N-isopropylacrylamide)-co-poly(acrylamide)) hydrogel. At temperatures above the LCST of PNIPAAm-co-PAAm, the water molecules are expulsed and the hydrogel layer contracts, leaving the RaR molecules more accessible to the Raman source. In vitro studies with fibroblast cells reveal that the functionalized surgical mesh is biocompatible and no toxic substances are leached in the medium. The mesh sensor opens new frontiers to semi-invasive diagnosis and infection prevention in hernia repair by using SERS spectroscopy. It also offers new possibilities to the functionalization of other healthcare products.
- PublicationEmbargoSynergistic antimicrobial effect of photodynamic therapy and chitosan on the titanium-adherent biofilms of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa: An in vitro study(Wiley, 2022) Camacho Alonso, Fabio; Salinas, Jesús; Sánchez Siles, Mariano; Pato Mourelo, Jesús; Cotrina Veizaga, Brian Davis; Ortega, Nieves; Dermatología, Estomatología, Radiología y Medicina Física; Sanidad AnimalBackground: To date, no studies on the combined use of photodynamic therapy (PDT) and chitosan against peri-implantitis have been published. The aim of this study was to evaluate the possible synergistic antimicrobial effect of PDT and chitosan on the titanium-adherent biofilms of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Methods: A total of 60 titanium discs were included in this study. The discs were randomized into three bacterial contaminations (n = 20 discs per bacterium). After being cultured (incubated for 48 hours) they were randomized again into four different disinfection modalities (n = 5 discs per treatment): control (without treatment), PDT, chitosan 3 mg/mL, and PDT + chitosan 3 mg/mL. After the treatments, the colony forming units (CFU) were measured to determine antimicrobial effects, and field emission scanning electron microscopy (FESEM) was used to study cell morphology and titanium adherence. Results: For all the evaluated bacteria and all the variables studied the order from highest to lowest antimicrobial effectiveness was: PDT + chitosan 3 mg/mL > chitosan 3 mg/mL > PDT > control. Although, all disinfection methods were significantly effective when compared to control, the combined treatment of PDT + chitosan 3 mg/mL had the greatest antimicrobial effect against the three studied bacteria. Conclusions: The combination of PDT and chitosan has a synergistic antimicrobial effect against the bacteria S. aureus, E. coli, and P. aeruginosa, all closely related to peri-implantitis. However, further in vivo studies are needed because this study provides data based on an in vitro scenario that might not be extrapolated to patients with peri-implantitis.
- PublicationEmbargoUse of photodynamic therapy and chitosan for inactivacion of Candida albicans in a murine model(Wiley, 2016-09-03) Camacho Alonso, Fabio; Martínez Beneyto, Yolanda; Gallego, Mª Carmen; Cuello, Francisco; Buendía, Antonio Julián; Pérez Lajarín, Leonor; Salinas, Jesús; Dermatología, Estomatología, Radiología y Medicina FísicaBackground The wide use of topical and systemic antifungal agents as the conventional treatment for oral candidiasis has caused Candida albicans to develop resistance to these agents. The aims of this study were to evaluate the effects of photodynamic therapy (PDT) and chitosan on buccal candidiasis and study the possible enhancive effect of chitosan on the photosensitizer methylene blue. Methods Thirty-five DBA/2 immunosuppressed mice were orally inoculated with a suspension of Candida albicans. The animals were randomized into seven groups (n = 5 per group): Group 1 (control); Group 2 (nystatin); Group 3 (PDT); Group 4 (chitosan 1.5 mg/ml); Group 5 (chitosan 3 mg/ml); Group 6 (PDT + chitosan 1.5 mg/ml); and Group 7 (PDT + chitosan 3 mg/ml). The Candida albicans count was evaluated on days 3, 5, 7, and 11 after inoculation. At last, macroscopic and microscopic analyses of the tongue dorsa were performed. Results On day 7 after inoculation, the control group showed a greater number of Candida albicans (5.25 ± 0.41 log10 CFU/ml), with significant differences compared to all other groups (P ≤ 0.05). On day 11 after inoculation, animals treated with PDT showed lower CFU/ml count. Groups 2, 3, 4, 5, and 6 showed fewer microscopic candidiasis lesions than Groups 1 and 7. Conclusions PDT has an antifungal effect, even greater than nystatin. Chitosan has a powerful fungicide effect but did not possess any enhancive effect on methylene blue.