Browsing by Author "Sarmento, Bruno"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Chitosan/sulfated locust bean gum nanoparticles: In vitro and in vivo evaluation towards an application in oral immunizationPublication . Braz, L.; Grenha, Ana; Ferreira, Domingos; Rosa Da Costa, Ana; Gamazo, Carlos; Sarmento, BrunoThis work proposes the design of nanoparticles based on locus bean gum (LBG) and chitosan to be used as oral immunoadjuvant for vaccination purposes. LBG-based nanoparticles were prepared by mild polyelectrolyte complexation between chitosan (CS) and a synthesized LBG sulfate derivative (LBGS). Morphological characterization suggested that nanoparticles present a solid and compact structure with spherical-like shape. Sizes around 180-200 nm and a positive surface charge between +9 mV and +14 mV were obtained. CS/LBGS nanoparticles did not affect cell viability of Caco-2 cells after 3 h and 24h of exposure when tested at concentrations up to 1.0 mg/mL. Two model antigens (a particulate acellular extract HE of Salmonella enterica serovar Enteritidis, and ovalbumin as soluble antigen) were associated to CS/LBGS nanoparticles with efficiencies around 26% for ovalbumin and 32% for HE, which resulted in loading capacities up to 12%. The process did not affect the antigenicity of the associated antigens. BALB/c mice were orally immunized with ovalbumin-loaded nanoparticles (100 mu g), and results indicate an adjuvant effect of the CS/LBGS nanoparticles, eliciting a balanced Th1/Th2 immune response. Thus, CS/LBGS nanoparticles are promising as antigen mucosal delivery strategy, with particular interest for oral administration. (C) 2017 Elsevier B.V. All rights reserved.
- Multifunctional magnetic iron oxide nanoparticles: diverse synthetic approaches, surface modifications, cytotoxicity towards biomedical and industrial applicationsPublication . Natarajan, Subramanian; Harini, Kannan; Gajula, Gnana P; Sarmento, Bruno; Neves-Petersen, Maria Teresa; Thiagarajan, ViruthachalamMagnetic iron oxide nanoparticles (MIONPs) play a major role in the emerging fields of nanotechnology to facilitate rapid advancements in biomedical and industrial platforms. The superparamagnetic properties of MIONPs and their environment friendly synthetic methods with well-defined particle size have become indispensable to obtain their full potential in a variety of applications ranging from cellular to diverse areas of biomedical science. Thus, the broadened scope and need for MIONPs in their demanding fields of applications required to be highlighted for a comprehensive understanding of their state-of-the-art. Many synthetic methods, however, do not entirely abolish their undesired cytotoxic effects caused by free radical production and high iron dosage. In addition, the agglomeration of MIONPs has also been a major problem. To alleviate these issues, suitable surface modification strategies adaptive to MIONPs has been suggested not only for the effective cytotoxicity control but also to minimize their agglomeration. The surface modification using inorganic and organic polymeric materials would represent an efficient strategy to utilize the diagnostic and therapeutic potentials of MIONPs in various human diseases including cancer. This review article elaborates the structural and magnetic properties of MIONPs, specifically magnetite, maghemite and hematite, followed by the important synthetic methods that can be exploited for biomedical approaches. The in vivo cytotoxic effects and the possible surface modifications employed to eliminate the cytotoxicity thereby enhancing the nanoparticle efficacy are also critically discussed. The roles and applications of surface modified MIONPs in medical and industrial platforms have been described for the benefits of global well-being.
- Protective effects of Lavandula viridis L'Hér extracts and rosmarinic acid against H2O2-induced oxidative damage in A172 human astrocyte cell linePublication . Costa, Patrícia; Sarmento, Bruno; Gonçalves, Sandra; Romano, AnabelaWe investigated the neuroprotective effect of Lavandula viridis extracts (infusion, water:ethanol and methanol) and rosmarinic acid, the major compound present in the extracts, against oxidative damage induced by hydrogen peroxide (H2O2) in A172 human astrocyte cell line regarding the neurotoxic effect, intracellular reactive oxygen species (ROS) production and the activity of the antioxidant enzyme catalase (CAT). We found that L. viridis extracts and rosmarinic acid protected A172 astrocytes against H2O2 and reduced intracellular ROS accumulation. Furthermore, the protection effect was not caused by modulation of CAT suggesting that other intracellular mechanisms are involved in the neuroprotective effect. Our results highlight that L. viridis extracts and rosmarinic acid have beneficial effects against oxidative damage associated with neurodegenerative diseases. © 2013.
- Synthesis and characterization of Locust Bean Gum derivatives and their application in the production of nanoparticlesPublication . Braz, Luis; Grenha, Ana; Corvo, Marta C.; Lourenço, João P.; Ferreira, Domingos; Sarmento, Bruno; Costa, Ana M. Rosa daThe development of LBG-based nanoparticles intending an application in oral immunization is presented. Nanoparticle production occurred by mild polyelectrolyte complexation, requiring the chemical modification of LBG. Three LBG derivatives were synthesized, namely a positively charged ammonium derivative (LBGA) and negatively charged sulfate (LBGS) and carboxylate (LBGC) derivatives. These were characterized by Fourier-transform infrared spectroscopy, elemental analysis, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and x-ray diffraction. As a pharmaceutical application was aimed, a toxicological analysis of the derivatives was performed by both MTT test and LDH release assay. Several nanoparticle formulations were produced using LBGA or chitosan (CS) as positively charged polymers, and LBGC or LBGS as negatively charged counterparts, producing nanoparticles with adequate properties regarding an application in oral immunization.