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Percorrer por autor "Gamazo, Carlos"

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  • Chitosan/sulfated locust bean gum nanoparticles: In vitro and in vivo evaluation towards an application in oral immunization
    Publication . Braz, L.; Grenha, Ana; Ferreira, Domingos; Rosa Da Costa, Ana; Gamazo, Carlos; Sarmento, Bruno
    This 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.
    2017-03Artigo científico Acesso aberto Ver mais
  • Repurposing bacterial lysates: Engineering inhalable locust bean gum microparticles for respiratory infection prevention
    Publication . da Silva, Joana Pinto; Berzosa, Melibea; Chiarentin, Lucas; Delgado-López, Alberto; Almeida, Maria Patricia; Vitorino, Carla; Figueiras, Ana; Rosa da Costa, Ana M; Gamazo, Carlos; Grenha, Ana
    This study explores the development of inhalable microparticles containing bacterial lysates (BL) from multiple relevant bacterial species that include Staphylococcus aureus, Streptococcus pyogenes and Klebsiella pneumoniae, and locust bean gum (LBG) for pulmonary immunization against respiratory infections. LBG, a galactomannan, was chosen for its mucoadhesive properties and affinity for antigen-presenting cells. Microparticles were prepared by spray-drying, testing different LBG:BL ratios. The morphological analysis revealed convoluted microparticles, and BL association efficiency up to 81 % was determined. Antigenic assays confirmed that bacterial antigens of S. pyogenes, used as reference, remained preserved on the microparticles despite the applied processing conditions. The aerodynamic analysis showed that lower BL content (LBG:BL = 10:0.2, w/w) produced more suitable particles for pulmonary delivery, with 4.6 μm mass median aerodynamic diameter (MMAD) and 29 % fine particle fraction (FPF). Fluorescence microscopy confirmed uniform distribution of BL within the LBG matrix and LBG microparticles demonstrated superior adhesive properties compared to controls. Sustained release of BL from microparticles was observed in vitro, reaching around 80 % after 6 h, which increased to around 85 % after 24 h. Cytotoxicity studies showed appropriate cell viability at physiologically relevant concentrations (around 70 % or more). These findings suggest that LBG-based microparticles loaded with BL have potential to be explored as inhalable formulation for prevention of respiratory infections, offering targeted delivery and prolonged antigen presentation to enhance immune responses.
    2025-12Artigo científico Acesso aberto Ver mais