Collado-González,  Mar

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Collado-González, Mar

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Collado-González, Mar

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Universidad de Murcia. Departamento de Biología Celular e Histología

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Open Access
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.
Open Access
Modification of chicha gum: antibacterial activity, ex vivo mucoadhesion, antioxidant activity and cellular viability
(Elsevier, 2022-12-21) Freitas, Alessandra R.; Ribeiro, António J.; Ribeiro, Alessandra B.; Collado-González, Mar; Silva, Luís R.; Alves, Luís; Melro, Elodie; Antunes, Filipe E.; Veiga, Francisco; Morais, Alan I. S.; Bezerra, Roosvelt D. S.; Soares-Sobrinho, José L.; Osajima, Josy A.; Silva-Filho, Edson C.; Biología Celular e Histología
The aim of the present work was to modify the exuded gum of Sterculia striata tree by an amination reaction. The viscosity and zero potential of the chicha gum varied as a function of pH. The modification was confirmed by Xray diffraction (XRD), infrared spectroscopy (FTIR), size exclusion chromatography (SEC), zeta potential, thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Furthermore, the chemical modification changed the molar mass and surface charge of the chicha gum. In addition, the gums were used in tests for ex vivo mucoadhesion strength, antibacterial activity against the standard strain of Staphylococcus aureus (ATCC 25923), inhibitory activity of α-glucosidase, antioxidant capacity, and viability of Caco-2 cells. Through these tests, it was found that amination caused an increase in the mucoadhesive and inhibitory activity of chicha gum against the bacterium Staphylococcus aureus. In addition, the gums (pure and modified) showed antioxidant capacity and an inhibitory effect against the α-glucosidase enzyme and did not show cytotoxic potential.
Open Access
Comparison of sulfamethoxazole removal efficiency using polyethersulfone ultrafiltration membrane modified by various methods
(MDPI, 2024-12-20) Hidalgo Montesinos, Asunción María; Murcia Almagro, María Dolores; Gómez Gómez, María; Collado-González, Mar; Montiel Morte, María Claudia; Martínez Morga, Marta; Martínez, Marta; Ingeniería Química ; Biología Celular e Histología
Nowadays, 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.
Open Access
Chitosan/albumin coating factorial optimization of alginate/dextran sulfate cores for oral delivery of insulin
(Multidisciplinary Digital Publishing Institute (MDPI), 2023-03-14) Pessoa, Bruno ; Sandri, Giuseppina ; Ribeiro, António ; Collado-González, Mar; Biología Celular e Histología
The design of nanoparticle formulations composed of biopolymers, that govern the physicochemical properties of orally delivered insulin, relies on improving insulin Stability and absorption through the intestinal mucosa while protecting it from harsh conditions in the gastrointestinal (GI) tract. Chitosan/polyethylene glycol (PEG) and albumin coating of alginate/dextran sulfate hydrogel cores are presented as a ultilayer complex protecting insulin within the nanoparticle. This study aims to optimize a anoparticle formulation by assessing the relationship between design parameters and experimental data using response surface methodology through a 3-factor 3-level optimization Box–Behnken design. While the selected independent variables were the concentrations of PEG, chitosan and albumin, the dependent variables were particle Size, polydispersity index (PDI), zeta potential, and insulin release. Experimental results showed a nanoparticle size ranging from 313 to 585 nm, with PDI from 0.17 to 0.39 and zeta potential ranging from 􀀀29 to 􀀀44 mV. Insulin bioactivity was maintained in simulated GI media with over 45% cumulative release after 180 min in a simulated intestinal medium. Based on the experimental responses and according to the criteria of desirability on the experimental region’s constraints, solutions of 0.03% PEG, 0.047% chitosan and 1.20% albumin provide an optimum nanoparticle formulation for insulin oral delivery.
Open Access
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.
Open Access
Size-exclusion chromatography of macromolecules: a brief tutorial overview on fundamentals with computational tools for data analysis and determination of structural information
(MDPI, 2025-02-22) Henández-Cifre, José Ginés; Collado-González, Mar; Díaz Baños, F. Guillermo; García de la Torre, José; Química Física; Ingeniería Química; Biología Celular e Histología
Size-exclusion chromatography (SEC) is presently a widely used and very informative technique for the characterization of macromolecules in solution. Beyond the first implementations of SEC—which required cumbersome column calibrations and were mainly intended for the determination of molecular weights—the modern SEC approach involving multiple detectors (md-SEC) is based on solution properties such as intrinsic viscosity and light scattering. Thus, md-SEC enables the direct and more efficient determination of molecular weights, as well as the determination of relationships between property and molecular weight, which can be quite useful in structural studies. Here, we first present a review of the fundamental aspects of the dilute-solution properties of macromolecules—particularly the differential refractive index, intrinsic viscosity, and scattering-related properties—on which the various detectors involved in md-SEC are based. Then, we developed SECtools, a suite of public-domain, open-source computer programs, which allow for the full analysis of md-SEC chromatograms. These analyses range from just the recorded raw signals (mV) of the detectors to a full determination of molecular weight averages and distributions. The use of these programs is illustrated through experimental studies using various samples.