Browsing by Subject "Chitosan"

Now showing 1 - 7 of 7
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    Aggregation behaviour of gold nanoparticles in presence of chitosan
    (Springer, 2015-06-13) Fernández Espín, Vanesa ; Pamies, Ramón ; García de la Torre, José; García Montalbán, Mercedes; collado; Collado-González, Mar; Hernández Cifre, José Ginés; Díaz Baños, F. Guillermo; Víllora Cano, Gloria; Ingeniería Química
    Chitosan (CS) is a biocompatible polysaccharide with positive charge that is widely used as a coating agent for negatively charged nanoparticles. However, the types of structures that emerge by combining CS and anoparticles as well as their behaviour are still poorly understood. In this work, we characterize the nanocomposites formed by gold nanoparticles (AuNPs) and CS and study the influence of CS in the expected aggregation process that should experience those nanoparticles under the favourable conditions of low pH and high ionic strength. Thus, at the working CS concentration, we observe the existence of CS structures that quickly trap the AuNPs and avoid the formation of nanoparticle aggregates in environmental conditions that, otherwise, would lead to such an aggregation.
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    An 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 Histología
    The 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)
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    Bactericidal 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 Física
    Objective: 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.
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    Chitosan-nanoparticles effects on mucosal immunity: a systematic review
    (Elsevier, 2022-08-26) Collado-González, Mar; Esteban Abad, María de los Ángeles; Biología Celular e Histología
    Nanoparticles-based treatments is of utmost importance for aquaculture. In this scenario, chitosan-based nanoparticles have been proposed due to the properties of chitosan, which include mucoadhesiveness. Nevertheless, pivotal parameters of chitosan, such as degree of acetylation and molecular weight, are commonly underestimated in the available literature despite the influence they seem to have on the properties of chitosan-based nanoparticles. In this systematic review, the immunomodulator capacity of chitosan nanoparticles used as mucosal vaccines on teleost fish has been evaluated paying special attention to the chitosan properties. Four databases were used for literature search, yielding 486 documents, from which 14 meet the inclusion criteria. Only 21% of the available studies reported properly chitosan properties, which should be improved in future works to generate reproducible data as well as valuable information. To the best of our knowledge, this work objectively compares for the first time, by quantifying the mg of chitosan/g of fish applied in each study, the chitosan nanoparticle preparation and doses applied to fish, as well as the effects of the treatments applied on fish immune status.
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    Complex 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 Cano, Gloria; Veiga, Francisco; Ribeiro, Antonio; Carissimi, Guzmán; Química Física
    Polyelectrolyte 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.
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    Microencapsulation 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 Histología
    Synthetic 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
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    Synergistic 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 Animal
    Background: 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.