Análise da rugosidade superficial de resinas acrílicas usadas em coroas provisórias submetidas à ação de enxaguatórios bucais: estudo in vitro

Objetivo: avaliar a influência de três enxaguatórios bucais na rugosidade superficial de três resinas acrílicas autopolimerizáveis utilizadas na confecção de coroas provisórias. Método: foi realizado um estudo in vitro, a amostra foi composta por 180 corpos de prova em forma de disco, de 3 marcas de resinas acrílicas autopolimerizáveis (Duralay, Dencor e TDV). Os espécimes de cada marca de resina acrílica (n=60) foram divididos em 5 grupos (n=12): um grupo sem tratamento e os demais grupos imergidos nas soluções: água destilada (grupo controle negativo), enxaguatório Listerine sem álcool, enxaguatório Oral-B sem álcool e enxaguatório Periogard sem álcool. A análise da rugosidade de superfície foi avaliada em rugosímetro (Ra). Resultados: Os dados obtidos no teste de rugosidade de superfície (μm) foram submetidos às medidas repetidas de duas vias (ANOVA) seguida do teste de Dunnett e teste de Tukey (p<0,05). Observou-se que as interações feitas entre resinas acrílicas e enxaguatórios bucais demostraram variância significante em determinados cruzamentos. Notou-se que o Listerine apresentou os maiores valores, provocando aumento estatisticamente significante na rugosidade superficial das resinas acrílicas Dencor e Duralay. A resina TDV apresentou menores valores quando comparada a Duralay, e a Dencor foi a que significativamente mais sofreu alteração intergrupos, especialmente sob ação do Periogard. Conclusão: As interações feitas entre resinas acrílicas e enxaguatórios bucais demostraram variância significante em determinados pares de grupos. As soluções antissépticas bucais aumentaram a rugosidade de superfície das resinas acrílicas autopolimerizáveis testadas

Green synthesis and characterization of silver nanoparticles reduced and stabilized by cashew tree gum

The advance in nanotechnology has enabled us to utilize particles in the size of the nanoscale. Among the most promising nanomaterials with antibacterial properties are metallic nanoparticles, which exhibit increased chemical activity due to their large surface to volume ratios. In the case of silver, the currently available data reveals the potential benefits and the wide range of applications. In this context, the application of green chemistry in the nano-science and technology is very important in the area of the preparation of various materials. The present study describes the development and the characterization of a rapid and low cost green synthesis of silver nanoparticles reduced and stabilized by exuded gum from Anacardium occidentale L. and evaluates in vitro their antibacterial activity. Characterization of cashew tree gumbased silver nanoparticles (AgNPs) was carried out based on UV-Vis spectroscopy, Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR). The main results revealed that the synthesized silver nanoparticles were spherical in shape, measuring about 4.5 to 6.5 nm in size with a uniform dispersal. AgNPs presented antibacterial activity, especially against Gram-negative bacteria

Green synthesis of silver nanoparticles using the seaweed Gracilaria birdiae and their antibacterial activity

AbstractThis work presents a simple method for the green synthesis of silver nanoparticles (AgNPs) using as reducing and stabilizing agent a polysaccharide extracted from red algae Gracilaria birdiae present in the coast of Piauí. The AgNPS were prepared using three polysaccharide concentrations (0.02, 0.03 and 0.05% v/v) and two pHs (10 and 11) at stirring for 30min at 90°C. The formation of silver nanoparticles was monitored by measurements of UV–vis and FTIR and characterized by size and zeta potential measurements using DLS and morphologically by TEM. The UV–vis absorption spectrum showed the surface plasmon peak at 410nm, which is characteristic peak of silver nanoparticles. The functional biomolecules present in the polysaccharide and the interaction between the nanoparticles were identified by the Fourier transform infrared spectroscopy (FTIR) analysis. The stability of the synthesized silver nanoparticles was analyzed during four months and no significant agglomeration was observed. The hydrodynamic diameter of the AgNPs varied between 20.2nm and 94.9nm. The AgNPs were tested for antimicrobial activity using Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) and all samples showed antimicrobial activity against E. coli. Using an environment-friendly, the AgNPs were synthesized in a simple, rapid and one-step process using natural sources as red algae with favorable characteristics such as spherical shape, small size and zeta potential negative. The results suggest that the polysaccharide mediated synthesized silver nanoparticles could be used as a model for future projects of nano-medicines or drug delivery systems

Thaulin-1: The first antimicrobial peptide isolated from the skin of a Patagonian frog Pleurodema thaul (Anura: Leptodactylidae: Leiuperinae) with activity against Escherichia coli

Patagonia's biodiversity has been explored from many points of view, however, skin secretions of native amphibians have not been evaluated for antimicrobial peptide research until now. In this sense, Pleurodema thaul is the first amphibian specie to be studied from this large region of South America. Analysis of cDNA-encoding peptide in skin samples allowed identification of four new antimicrobial peptides. The predicted mature peptides were synthesized and all of them showed weak or null antimicrobial activity against Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli with the exception of thaulin-1, a cationic 26-residue linear, amphipathic, Gly- and Leu-rich peptide with moderate antimicrobial activity against E. coli (MIC of 24.7 M). AFM and SPR studies suggested a preferential interaction between these peptides and bacterial membranes. Cytotoxicity assays showed that thaulin peptides had minimal effects at MIC concentrations towards human and animal cells. These are the first peptides described for amphibians of the Pleurodema genus. These findings highlight the potential of the Patagonian region's unexplored biodiversity as a source for new molecule discovery.This work was partially supported by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (PIP N° 11220120100050CO), and the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) (PICT N° 1199). M.M.M., L.O.P., S.A.C. and N.G.B. are researchers at CONICET. Work in AMT laboratory was supported by Project “NORTE-07-0124-FEDER-000002-Host-Pathogen Interactions” cofunded by Programa Operacional Regional do Norte under QREN, through FEDER (NORTE-07-0124-FEDER-000002-Host-Pathogen Interactions) and FCT. (SFRH/BD/97995/2013, SFRH/BD/93766/2013 and UID/MULTI/04378/2013) A.P. and A.G.G.A. are gratefully to FCT by their grants SFRH/BD/97995/2013 and SFRH/BD/93766/2013 respectively, financed by POPH–QREN–Tipologia 4.1–Formação Avançada, subsidized by Fundo Social Europeu and Ministério da Ciência, Tecnologia e Ensino Superior. The authors thank N.L. Olivera for logistic support and helpful discussions regarding the article. P.E. thanks CNPq for PVE grant no. 400398/2014-1, and is supported by FCTvia the project UID/MULTI/04378/2013

Antibacterial application of natural and carboxymethylated cashew gum-based silver nanoparticles produced by microwave-assisted synthesis

© 2019 Published by Elsevier Ltd.This study presents a green synthesis route to silver nanoparticles (AgNPs) stabilized with cashew gum (CG) or carboxymethylated cashew gum (CCG) using microwave-assisted synthesis and evaluates their antibacterial activity. The antimicrobial activity was measured by determining the minimum inhibitory concentration (MIC) with Staphylococcus aureus and Escherichia coli. In both cases of the presence of CG and CCG, it was found that higher pH lead to more efficient conversion of silver nitrate to AgNPs with well dispersed, spherical and stable particles as well as low crystallinity. CCG-capped AgNPs were slightly smaller (137.0 and 96.3 nm) than those coated with non-modified gum (144.7 and 100.9 nm). The samples presented promising antibacterial activity, especially on Gram-negative bacteria, resulting in significant membrane damage on treated bacteria in comparison to the untreated control, observed by atomic force microscopy. Thus, a quick and efficient synthesis route was applied to produce CGAgNPs and CCGAgNPs with antimicrobial potential.The authors gratefully acknowledge financial support from CAPES and FAPEPI; ACM are grateful to FAPESP (2014/02282-6 AND 2016/18023-5). YPM is grateful to CAPES (AUX-PERM-705/2009). The authors also acknowledge the CNPq and Capes for scholarship and financial aid. The authors are grateful to Fundação para a Ciência e a Tecnologia (MCTES funds) and European Union (European Social Fund and European Regional Development Fund), for financial support through project UID/QUI/50006/2013–POCI-01-0145-FEDER-007265 (LAQV-REQUIMTE), in the context of the COMPETE program from QREN, project NORTE-01-0145-FEDER-000011, in the context of the NORTE 2020 program, and fellowships SFRH/BD/97995/2013 (AP) and SFRH/BD/95983/2013 (MPdA), in the context of the POCH program, both from Portugal 2020 partnership agreement.info:eu-repo/semantics/publishedVersio

Characterization and Biological Activities of Ocellatin Peptides from the Skin Secretion of the Frog Leptodactylus pustulatus

Eight new peptides were isolated from the skin secretion of the frog Leptodactylus pustulatus and their amino acid sequences determined by de novo sequencing and by cDNA cloning. Structural similarities between them and other antimicrobial peptides from the skin secretion of Leptodactylus genus frogs were found. Ocellatins-PT1 to -PT5 (25 amino acid residues) are amidated at the C-terminus, while ocellatins-PT6 to -PT8 (32 amino acid residues) have free carboxylates. Antimicrobial activity, hemolytic tests, and cytotoxicity against a murine fibroblast cell line were investigated. All peptides, except for ocellatin-PT2, have antimicrobial activity against at least one Gram negative strain. Ocellatin-PT8 inhibited the growth of Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Salmonella choleraesuis strains with MICs in the 60−240 μM range. No significant effect was observed in human erythrocytes and in a murine fibroblast cell line after exposure to the peptides at MICs. A comparison between sequences obtained by both direct HPLC-MS de novo sequencing and cDNA cloning demonstrates the secretion of mature peptides derived from a pre-pro-peptide structure

In Situ Synthesis of Silver Nanoparticles in a Hydrogel of Carboxymethyl Cellulose with Phthalated-Cashew Gum as a Promising Antibacterial and Healing Agent

Silver nanoparticles have been shown to possess considerable antibacterial activity, but in vivo applications have been limited due to the inherent, but low, toxicity of silver. On the other hand, silver nanoparticles could provide cutaneous protection against infection, due to their ability to liberate silver ions via a slow release mechanism, and their broad-spectrum antimicrobial action. Thus, in this work, we describe the development of a carboxymethyl cellulose-based hydrogel containing silver nanoparticles. The nanoparticles were prepared in the hydrogel in situ, utilizing two variants of cashew gum as a capping agent, and sodium borohydride as the reducing agent. This gum is non-toxic and comes from a renewable natural source. The particles and gel were thoroughly characterized through using rheological measurements, UV-vis spectroscopy, nanoparticles tracking analysis, and transmission electron microscopy analysis (TEM). Antibacterial tests were carried out, confirming antimicrobial action of the silver nanoparticle-loaded gels. Furthermore, rat wound-healing models were used and demonstrated that the gels exhibited improved wound healing when compared to the base hydrogel as a control. Thus, these gels are proposed as excellent candidates for use as wound-healing treatments

Novel Scaffold Based on Chitosan Hydrogels/Phthalated Cashew Gum for Supporting Human Dental Pulp Stem Cells

Hydrogels are structures that have value for application in the area of tissue engineering because they mimic the extracellular matrix. Naturally obtained polysaccharides, such as chitosan (CH) and cashew gum, are materials with the ability to form polymeric networks due to their physicochemical properties. This research aimed to develop a scaffold based on chitosan and phthalated cashew tree gum and test it as a support for the growth of human mesenchymal stem cells. In this study, phthalation in cashew gum (PCG) was performed by using a solvent-free route. PCG-CH scaffold was developed by polyelectrolyte complexation, and its ability to support adherent stem cell growth was evaluated. The scaffold showed a high swelling rate. The pore sizes of the scaffold were analyzed by scanning electron microscopy. Human dental pulp stem cells (hDPSCs) were isolated, expanded, and characterized for their potential to differentiate into mesenchymal lineages and for their immunophenotypic profile. Isolated mesenchymal stem cells presented fibroblastoid morphology, plastic adhesion capacity, and differentiation in osteogenic, adipogenic, and chondrogenic lineages. Mesenchymal stem cells were cultured in scaffolds to assess cell adhesion and growth. The cells seeded on the scaffold showed typical morphology, attachment, and adequate distribution inside the matrix pores. Thus, cells seeded in the scaffold may improve the osteoinductive and osteoconductive properties of these biomaterials

Characterization and Biological Activities of Ocellatin Peptides from the Skin Secretion of the Frog <i>Leptodactylus pustulatus</i>

Eight new peptides were isolated from the skin secretion of the frog <i>Leptodactylus pustulatus</i> and their amino acid sequences determined by de novo sequencing and by cDNA cloning. Structural similarities between them and other antimicrobial peptides from the skin secretion of <i>Leptodactylus</i> genus frogs were found. Ocellatins-PT1 to -PT5 (25 amino acid residues) are amidated at the C-terminus, while ocellatins-PT6 to -PT8 (32 amino acid residues) have free carboxylates. Antimicrobial activity, hemolytic tests, and cytotoxicity against a murine fibroblast cell line were investigated. All peptides, except for ocellatin-PT2, have antimicrobial activity against at least one Gram-negative strain. Ocellatin-PT8 inhibited the growth of <i>Escherichia coli</i>, <i>Staphylococcus aureus</i>, <i>Klebsiella pneumoniae</i>, and <i>Salmonella choleraesuis</i> strains with MICs in the 60–240 μM range. No significant effect was observed in human erythrocytes and in a murine fibroblast cell line after exposure to the peptides at MICs. A comparison between sequences obtained by both direct HPLC-MS de novo sequencing and cDNA cloning demonstrates the secretion of mature peptides derived from a pre-pro-peptide structure