ABSTRACT
O presente estudo avaliou o efeito de aplicações de vidro na zircônia, com e sem prata, na rugosidade, formação de biofilme, viabilidade celular e resistência flexural com objetivo de produzir um material cerâmico com prata efetivo contra microrganismos e eficiente mecanicamente. Foram confeccionadas amostras de zircônia T (VITA Zahnfabrik, Alemanha) divididas em: YZ polida (P); YZ com glaze (G); YZ com vidro de infiltração (INF); YZ com vidro de prata 5% (Ag5); YZ com vidro de prata 4% (Ag4); YZ com vidro de infiltração + vidro de prata 5% (INF-Ag5); YZ com vidro de infiltração + vidro de prata 4% (INF-Ag4). Os espécimes foram submetidos a testes de rugosidade média (Ra) (n=15) ; energia livre de superfície (n=5); contagem de unidades formadoras de colônia (log UFC/mL) (n=8); microscopia eletrônica de varredura (MEV) (n=2) e citotoxicidade (ensaio de MTT) (n=8). Além disso, foi avaliada a resistência à flexão de todos os grupos (n=30). O grupo Ag5 obteve maior rugosidade e menor aderência de biofilme comparado aos demais grupos. Através da ELS, observou-se que todos os grupos apresentaram comportamento parcialmente hidrofílico. Na UFC, os grupos contendo prata inibiram o crescimento de Candida albicans, o grupo Ag5 inibiu Streptococcus mutans e nenhum grupo foi efetivo contra o Streptococcus sanguinis. Na avaliação qualitativa feita através do MEV, houve menor crescimento de colônias no grupo Ag5 quando comparado aos grupos controles (Polido; Glaze; Vidro de Infiltração), tanto para C. albicans quanto para S. mutans. No MTT, os grupos Ag4 e INF-Ag4 obtiveram 49% e 35,4% de viabilidade celular, sendo semelhante significativamente ao glaze comercial que apresentou 47,13%; Ag5 apresentou 16,2% e INF-Ag5 21,39% (p<0,05). A aplicação do vidro de prata conduziu à menor resistência flexural quando comparada aos grupos sem prata, o que foi compensado pela infiltração de vidro na amostra pré-sinterizada que elevou a resistência do material pela formação de uma interfase zircônia-vidro. Concluiu-se que o grupo Ag5 obteve maior efeito antimicrobiano contra C. albicans e S. mutans, os grupos Ag4 e INF-Ag4 foram os menos citotóxicos e o grupo INF foi o mais resistente à fratura.
The present study evaluated the effect of glass applications on zirconia, with and without silver, on roughness, biofilm formation, cell viability and flexural strength aiming to produce a ceramic material with silver effective against microorganisms and mechanically efficient. Samples of T zirconia (VITA Zahnfabrik, Germany) were made, divided into: polished YZ (P); YZ with glaze (G); YZ with infiltration glass (INF); YZ with 5% silver glass (Ag5); YZ with 4% silver glass (Ag4); YZ with infiltration glass + 5% silver glass (INF-Ag5); YZ with infiltration glass + 4% silver glass (INF-Ag4). The specimens were submitted to medium roughness tests (Ra) (n = 15); free surface energy (n = 5); colonyforming units count (log CFU / mL) (n = 8); scanning electron microscopy (SEM) (n = 2) and cytotoxicity (MTT assay) (n = 8). In addition, the flexural strength of all groups was assessed (n = 30). The Ag5 group had greater roughness and less biofilm adherence compared to other groups. Through ELS, he observed that all groups showed partially hydrophilic behavior. In the CFU, groups containing silver inhibited the growth of Candida albicans, the Ag5 group inhibited Streptococcus mutans and no group was effective against Streptococcus sanguinis. In the qualitative evaluation made through SEM, there was less growth of colonies in the Ag5 group when compared to the control groups (Polished; Glaze; Infiltration glass) for both C. albicans and S. mutans. In the MTT, the Ag4 and INF-Ag4 groups obtained 49% and 35.4% cell viability, being significantly similar to the commercial Glaze, which presented 47.13%. Ag5 presented 16.2% and INF-Ag5 21.39% (p <0.05). The application of silver glass led to lower flexural strength when compared to groups without silver, which was compensated by the infiltration of glass in the pre-sintered sample which increased the material's resistance by the formation of a zirconia-glass interphase. It was concluded that the Ag5 group had the greatest antimicrobial effect against C. albicans and S. mutans, the Ag4 and INF-Ag4 groups were the least cytotoxic and the INF group was the most resistant to fracture.
Subject(s)
Silver , Zirconium , BiofilmsABSTRACT
Anthropogenic impacts are an increasing threat to the diversity of fishes, especially in areas around large urban centres, and many effective conservation actions depend on accurate species identification. Considering the utility of DNA barcoding as a global system for species identification and discovery, this study aims to assemble a DNA barcode reference sequence library for marine fishes from the coastal region of São Paulo State, Brazil. The standard 652 bp 'barcode' fragment of the cytochrome c oxidase subunit I (COI) gene was PCR amplified and bidirectionally sequenced from 678 individuals belonging to 135 species. A neighbour-joining analysis revealed that this approach can unambiguously discriminate 97% of the species surveyed. Most species exhibited low intraspecific genetic distances (0.31%), about 43-fold less than the distance among species within a genus. Four species showed higher intraspecific divergences ranging from 2.2% to 7.6%, suggesting overlooked diversity. Notably, just one species-pair exhibited barcode divergences of <1%. This library is a first step to better know the molecular diversity of marine fish species from São Paulo, providing a basis for further studies of this fauna - extending the ability to identify these species from all life stages and even fragmentary remains, setting the stage for a better understanding of interactions among species, calibrating the estimations about species composition and richness in an ecosystem, and providing tools for authenticating bioproducts and monitoring illegal species exploitation.
