JORGE GABRIEL DOS SANTOS BATISTA
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Artigo IPEN-doc 30910 Advances in silver nanoparticles2024 - RODRIGUES, ADRIANA S.; BATISTA, JORGE G.S.; RODRIGUES, MURILO A.V.; THIPE, VELAPHI C.; MINARINI, LUCIENE A.R.; LOPES, PATRICIA S.; LUGAO, ADEMAR B.Nanoparticles play a crucial role in the field of nanotechnology, offering different properties due to their surface area attributed to their small size. Among them, silver nanoparticles (AgNPs) have attracted significant attention due to their antimicrobial properties, with applications that date back from ancient medicinal practices to contemporary commercial products containing ions or silver nanoparticles. AgNPs possess broad-spectrum biocidal potential against bacteria, fungi, viruses, and Mycobacterium, in addition to exhibiting synergistic effects when combined with certain antibiotics. The mechanisms underlying its antimicrobial action include the generation of oxygen-reactive species, damage to DNA, rupture of bacterial cell membranes and inhibition of protein synthesis. Recent studies have highlighted the effectiveness of AgNPs against various clinically relevant bacterial strains through their potential to combat antibiotic-resistant pathogens. This review investigates the proteomic mechanisms by which AgNPs exert their antimicrobial effects, with a special focus on their activity against planktonic bacteria and in biofilms. Furthermore, it discusses the biomedical applications of AgNPs and their potential non-preparation of antibiotic formulations, also addressing the issue of resistance to antibiotics.Resumo IPEN-doc 30275 Silver nanoparticles reduced by tannic acid and sodium citrate2023 - RODRIGUES, ADRIANA S.; BATISTA, JORGE G.S.; MINARINI, LUCIENE A.R.; LOPES, PATRICIA; LUGAO, ADEMAR B.Introduction and objective: Green nanotechnology aims to reduce hazardous chemical waste in the environment through sustainable development. Phytochemicals are proposed to minimize environmental impacts and produce safe biological applications. Silver nanoparticles (AgNPs) have effective antimicrobial properties against Gram-positive and Gram-negative bacterias, fungi and viruses, being promising to reduce the microbial load. Antimicrobial systems based on AgNPs shows promise in combating bacteria. Methodology: Confirmation of the formation of silver nanoparticles was evaluated by UV-Vis spectrophotometry. The hydrodynamic size and polydispersion index were evaluated by dynamic light scattering. The zeta potential was used to assess stability through surface charge. The obtained morphology and average size were evaluated by transmission electronic microscopy. The cytotoxicity assay was performed to assess cellular viability of silver nanoparticles in HUVEC cells. The antimicrobial activity was analyzed by minimum inhibitory concentration through microdilution in broth and later the inoculum was performed in plates. Results and discussion: Characterization by spectrophotometry of AT_AgNPs and CT_AgNPs showed absorption bands at 430 nm. Hydrodynamic size analyzes revealed diameters of 57.87-97.45 nm, with polydispersion indices (PdI) ranging between 0.289 and 0.392. The zeta potential was determined between - 4.41 and -10.3 mV. Transmission electron microscopy (TEM) images revealed spherical morphology with sizes between 20-50 nm. AgNPs have been tested as a treatment against hospital microorganisms with risk classification level 2, including Gram-negative (Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. The Minimum Inhibitory Concentration (MIC) was determined to evaluate the lowest concentration that inhibits the growth of microorganisms. The MIC values obtained with the AT_AgNPs were: 4.18 ug/mL (AB14 and EC23), 8.36 ug/mL (EC26 and KP43), 16.72 ug/mL (PA17), 66.9 ug/mL (PA3) and 133.8 ug/mL (SA). For CT_AgNPs, they were: 51.8 ug/mL (AB14, EC26 and PA17), without inhibition in EC23, KP43, PA3 and SA strains. Synergism was evaluated by mixing suspensions of the two nanoparticles (ATCT_AgNPs), resulting in MIC values of 1.48 ug/mL (PA3 and SA), 2.96 ug/mL (EC23, KP43 and PA17) and 5.93 ug/mL (AB14 and EC26). Conclusions: The results suggest that AT_AgNPs and the synergistic combination with CT_AgNPs have potential as effective antimicrobial agents against nosocomial bacteria. These AgNPs may represent a promising alternative for the development of new therapeutic strategies to combat bacterial infections. However, further studies are needed to investigate its activity in other contexts and its safety in clinical use.Artigo IPEN-doc 27201 Comparison between gold nanoparticles synthesized by radiolysis and by EGCG-driven gold reduction2020 - FREITAS, LUCAS F. de; CRUZ, CASSIA P.C. da; CAVALCANTE, ADRIANA K.; BATISTA, JORGE G. dos S.; VARCA, GUSTAVO H.C.; MATHOR, MONICA B.; LUGAO, ADEMAR B.Radiolytic synthesis and phytochemical-driven gold reduction for the generation of nanoparticles are successful examples of Green Chemistry applied for nanomaterials. The present work compares these two green approaches focusing on hydrodynamic size, stability over time, optical properties and toxicity in NIH 3T3 (ATCC® CRL- 1658™) cells and Danio rerio (Zebra Fish). The radiolytic synthesis was performed by mixing 1 mM NaAuCl4; polyvinyl pyrrolidone 0.5%, AgNO3 6×10−5 M, propan-2-ol 0.2 M and acetone 0.06 M, followed by irradiation at 15 kGy (5 kGy h−1, 60Co source). The EGCG-functionalized nanoparticles were synthesized by mixing 1.6 mM of Au with 0.8 mM of EGCG in phosphate buffer (10 mM) for 2 h. Both methods yield the formation of gold nanoparticles featuring plasmon resonance bands at 520–530 nm, polydispersity above 0.3 was relevant only for the radiolytic protocol. Regarding stability over time, after 30 days, the nanoparticles synthesized radiolytically presented no relevant size changes, while some aggregation was observed for the EGCG-particles. The same nanoparticles demonstrated a lack of stability in high ionic strength medium. Slight toxicity was observed for the EGCG-nanoparticles in Danio rerio, with an IC50 calculated as 40.49%, while no IC50 was established within the concentration range of radiolysis-AuNPs used in this study. In conclusion, both green methods generated nanoparticles with good control of size and optical properties, especially via reduction by EGCG. However, the stability and toxicity results were found to be more promising for the radiolytically synthesized gold nanoparticles.Artigo IPEN-doc 25206 An overview of the synthesis of gold nanoparticles using radiation technologies2018 - FREITAS, LUCAS F. de; VARCA, GUSTAVO H.C.; BATISTA, JORGE G. dos S.; LUGAO, ADEMAR B.At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems.