Caracterização e avaliação da atividade antimicrobiana de nanomateriais engenheirados com propriedade anti-incrustante sobre microrganismos isolados de ambiente marinho
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2021-06-25
Autores
Santos, Vithória Carolyna Trindade dos
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Universidade Estadual Paulista (Unesp)
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A bioincrustação marinha (BI) é um processo natural de extrema importância para a biodiversidade, onde ocorre o crescimento sucessivo de organismos em uma superfície submersa. No entanto, quando ocorre em estruturas construídas pelo homem, causam diversos problemas socioeconômicos e ambientais. A principal solução para a BI consiste na aplicação de tintas que contêm biocidas anti-incrustantes (BANIN) que impedem a adesão e crescimento destes organismos a uma superfície. Devido às leis ambientais cada vez mais restritivas, as empresas da área têm se dedicado no desenvolvimento de formulações que sejam menos nocivas ao meio ambiente. O objetivo do trabalho foi caracterizar nanomateriais (NM) com propriedades anti-incrustantes e determinar a sua toxicidade em microrganismos isolados da zona costeira brasileira. Os NM constituídos pelo biocida orgânico 4,5-dicloro-2-noctil-4-isotiazolin3-ona (DCOIT), encapsulado em nanocontentores mesoporosos de sílica (SiNC) e revestidos pela prata (Ag), foram caracterizados por Microscopia Eletrônica de Transmissão (MET), Espectroscopia de energia dispersiva (Energy Dispersive Spectroscopy - EDS ou EDX), Espalhamento de luz dinâmico (Dynamic Light Scattering - DLS), Potencial Zeta (Pζ) e Índice de polidispersão (Polydispersion Index - PDI). A toxicidade dos NM foi determinada a partir da Concentração mínima inibitória (CIM) e Concentração Mínima Biocida (CBM) em bactérias (Bacillus subtillis, Vibrio aestuarianus, V. parahaemolyticus), fungos (Penicillium citrinum IB-CLP11, P. sclerotigenum IB-CLP17, Aspergillus niger IBCLP20 e P. polonicum IB-CLP22) e microalga (Chlorella minutíssima BMAK26a). Os NM apresentaram estabilidade e monodispersão de tamanhos como verificado pelas análises de DLS, PDI e Pζ. As micrografias obtidas por MET revelaram a forma esférica com diâmetros de 112, 136, 139 e 133 nm para SiNC, SiNC-DCOIT, SiNC-Ag e SiNCDCOIT-Ag, respectivamente e a análise de EDS confirmou a presença dos elementos presentes nas amostras. O ensaio antimicrobiano em bactérias e fungos mostrou que SiNC apresentou ação antimicrobiana apenas para B. subtillis (CIM = 10 mg·L -1 ). DCOIT foi tóxico para todas as espécies de bactérias e fungos (CIM = 1 mg·L -1 ; CBM ≤ 10 mg·L - 1 ) e Ag sendo o que apresentou maior toxicidade (CBM ≤ 1 mg·L -1 ). SiNC-DCOIT, SiNCAg e SiNC-DCOIT-Ag apresentaram ação antimicrobiana para todas as espécies de bactérias e fungos (CIM = 1 mg·L -1 e CBM ≤ 10 mg·L -1 ). O ensaio de densidade celular em C. minutissima apresentou menor toxicidade para SiNC (EC50 = 2,24 mg·L -1 ), SiNCDCOIT (EC50 = 0,625 mg·L -1 ), SiNC-Ag (EC50 = 0,584 mg·L -1 ), quando comparados aos valores estimados para DCOIT (EC50 = 0,040 mg·L -1 ), Ag (EC50= 0,021 mg·L -1 ). A análise da clorofila total apresentou um aumento de 133%, 122% e 120% (SiNC, SiNC-Ag e SiNC-DCOIT, respectivamente) na concentração de 0,001 mg·L-1 em comparação com o controle. SiNC na concentração de 0,01 e 0,1 mg·L-1 apresentou uma umento de 130% para as duas concentrações. Enquanto que SiNC, SiNC-DCOIT, SiNC-Ag e SiNCDCOIT-Ag na concentração de 1 mg·L-1 apresentou uma diminuição de 28,9%, 81,3%, 85,5% e 92,4% no teor de clorofila total. DCOIT e Ag apresentaram uma maior influência no teor de clorofila, reduzindo em 17,3% e 23,2% em comparação com o controle, respectivamente a 0,01 mg·L-1 . O encapsulamento do biocida comprovou ser uma abordagem inovadora e promissora para o desenvolvimento de tintas anti-incrustantes.
Marine biofouling (BI) is a natural process of extreme importance for biodiversity, where successive growth of organisms occurs on a submerged surface. However, when it occurs on man-made structures, it causes several socioeconomic and environmental problems. The main solution for BI is the application of paints containing anti-fouling biocides (BANIN) that prevent these organisms from adhering and growing on a surface. Due to increasingly restrictive environmental laws, companies in the area have been dedicated to the development of formulations that are less harmful to the environment. The objective of this work was to characterize nanomaterials (NM) with anti-fouling properties and to determine their toxicity on microorganisms isolated from the Brazilian coastal zone. The NM consisting of the organic biocide 4,5-dichloro-2-noctyl-4- isothiazolin3-one (DCOIT), encapsulated in mesoporous silica nanocontainers (SiNC) and coated by silver (Ag), were characterized by Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS or EDX), Dynamic Light Scattering (DLS), Zeta Potential (Pζ) and Polydispersion Index (PDI). The toxicity of NMs was determined from the Minimum Inhibitory Concentration (MIC) and Minimum Biocidal Concentration (MBC) on bacteria (Bacillus subtillis, Vibrio aestuarianus, V. parahaemolyticus), fungi (Penicillium citrinum IB-CLP11, P. sclerotigenum IB-CLP17, Aspergillus niger IB-CLP20 and P. polonicum IB-CLP22) and microalgae (Chlorella minutíssima BMAK26a). The NMs showed stability and size monodispersity as verified by DLS, PDI and Pζ analyses. Micrographs obtained by TEM revealed spherical shape with diameters of 112, 136, 139 and 133 nm for SiNC, SiNC-DCOIT, SiNC-Ag and SiNC-DCOIT-Ag, respectively and EDS analysis confirmed the presence of the elements present in the samples. The antimicrobial assay on bacteria and fungi showed that SiNC showed antimicrobial action only for B. subtillis (MIC = 10 mg·L-1 ). DCOIT was toxic to all species of bacteria and fungi (MIC = 1 mg·L-1 ; MBC ≤ 10 mg·L-1 ) and Ag showing the highest toxicity (MBC ≤ 1 mg·L1 ). SiNC-DCOIT, SiNC-Ag and SiNC-DCOIT-Ag showed antimicrobial action for all species of bacteria and fungi (MIC = 1 mg·L-1 and MBC ≤ 10 mg·L-1 ). Cell density assay on C. minutissima showed lower toxicity for SiNC (EC50 = 2.24 mg·L-1 ), SiNC-DCOIT (EC50 = 0.625 mg·L-1 ), SiNC-Ag (EC50 = 0.584 mg·L-1 ), when compared to the estimated values for DCOIT (EC50 = 0.040 mg·L-1 ), Ag (EC50 = 0.021 mg·L-1 ). Total chlorophyll analysis showed an increase of 133%, 122% and 120% (SiNC, SiNC-Ag and SiNCDCOIT, respectively) at the concentration of 0.001 mg·L-1 compared to the control. SiNC at the concentration of 0.01 and 0.1 mg-L-1 showed an increase of 130% for both concentrations. While SiNC, SiNC-DCOIT, SiNC-Ag and SiNC-DCOIT-Ag at the concentration of 1 mg·L-1 showed a decrease of 28.9%, 81.3%, 85.5% and 92.4% in total chlorophyll content. DCOIT and Ag showed a greater influence on chlorophyll content, reducing by 17.3% and 23.2% compared to the control, respectively at 0.01 mg·L-1 . Encapsulation of the biocide has proven to be an innovative and promising approach for the development of anti-fouling paints.
Marine biofouling (BI) is a natural process of extreme importance for biodiversity, where successive growth of organisms occurs on a submerged surface. However, when it occurs on man-made structures, it causes several socioeconomic and environmental problems. The main solution for BI is the application of paints containing anti-fouling biocides (BANIN) that prevent these organisms from adhering and growing on a surface. Due to increasingly restrictive environmental laws, companies in the area have been dedicated to the development of formulations that are less harmful to the environment. The objective of this work was to characterize nanomaterials (NM) with anti-fouling properties and to determine their toxicity on microorganisms isolated from the Brazilian coastal zone. The NM consisting of the organic biocide 4,5-dichloro-2-noctyl-4- isothiazolin3-one (DCOIT), encapsulated in mesoporous silica nanocontainers (SiNC) and coated by silver (Ag), were characterized by Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS or EDX), Dynamic Light Scattering (DLS), Zeta Potential (Pζ) and Polydispersion Index (PDI). The toxicity of NMs was determined from the Minimum Inhibitory Concentration (MIC) and Minimum Biocidal Concentration (MBC) on bacteria (Bacillus subtillis, Vibrio aestuarianus, V. parahaemolyticus), fungi (Penicillium citrinum IB-CLP11, P. sclerotigenum IB-CLP17, Aspergillus niger IB-CLP20 and P. polonicum IB-CLP22) and microalgae (Chlorella minutíssima BMAK26a). The NMs showed stability and size monodispersity as verified by DLS, PDI and Pζ analyses. Micrographs obtained by TEM revealed spherical shape with diameters of 112, 136, 139 and 133 nm for SiNC, SiNC-DCOIT, SiNC-Ag and SiNC-DCOIT-Ag, respectively and EDS analysis confirmed the presence of the elements present in the samples. The antimicrobial assay on bacteria and fungi showed that SiNC showed antimicrobial action only for B. subtillis (MIC = 10 mg·L-1 ). DCOIT was toxic to all species of bacteria and fungi (MIC = 1 mg·L-1 ; MBC ≤ 10 mg·L-1 ) and Ag showing the highest toxicity (MBC ≤ 1 mg·L1 ). SiNC-DCOIT, SiNC-Ag and SiNC-DCOIT-Ag showed antimicrobial action for all species of bacteria and fungi (MIC = 1 mg·L-1 and MBC ≤ 10 mg·L-1 ). Cell density assay on C. minutissima showed lower toxicity for SiNC (EC50 = 2.24 mg·L-1 ), SiNC-DCOIT (EC50 = 0.625 mg·L-1 ), SiNC-Ag (EC50 = 0.584 mg·L-1 ), when compared to the estimated values for DCOIT (EC50 = 0.040 mg·L-1 ), Ag (EC50 = 0.021 mg·L-1 ). Total chlorophyll analysis showed an increase of 133%, 122% and 120% (SiNC, SiNC-Ag and SiNCDCOIT, respectively) at the concentration of 0.001 mg·L-1 compared to the control. SiNC at the concentration of 0.01 and 0.1 mg-L-1 showed an increase of 130% for both concentrations. While SiNC, SiNC-DCOIT, SiNC-Ag and SiNC-DCOIT-Ag at the concentration of 1 mg·L-1 showed a decrease of 28.9%, 81.3%, 85.5% and 92.4% in total chlorophyll content. DCOIT and Ag showed a greater influence on chlorophyll content, reducing by 17.3% and 23.2% compared to the control, respectively at 0.01 mg·L-1 . Encapsulation of the biocide has proven to be an innovative and promising approach for the development of anti-fouling paints.
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Palavras-chave
Nano-anti-incrustante, DCOIT, Bacillus subtillis, Aspergillus niger, Chlorella minutissima