Fisiología respiratoria: fisiología del surfactante pulmonar / Physiology of pulmonary surfactant

El proceso de respiración y el intercambio gaseoso requiere la interacción de variadas fuerzas en los distintos tejidos y órganos involucrados. La tensión superficial a nivel alveolar provocaría colapso de dichas estructuras de no ser por las características del surfactante que lo recubre. Revisaremos en este articulo la fisiología involucrada en su estructura física, producción y efectos pulmonares.

The process of breathing and gas exchange requires the interaction of various forces in the different tissues and organs involved. The surface tension at the alveolus would cause collapse of these structures without of the surfactant that covers it. We will review in this article the physiology involved in its physical structure, production, and pulmonary effects.

Fisiología respiratoria mecánica de la respiración / Mechanics breathing

El trabajo respiratorio se ejerce en una estructura cerrada donde se encuentran los pulmones, estos son sometidos a cambios de presiones determinados por la musculatura pulmonar en las diferentes fases del ciclo respiratorio, lo que generará gradientes y permite la entrada y salida de aire. Se suman a ello el calibre de las vías aéreas, el tipo de flujo, las características de las vías aéreas y del surfactante pulmonar, que determinan un menor o mayor trabajo respiratorio según la condición fisiológica.

The work of breathing is exerted in a closed structure where the lungs are located. These are subjected to pressure changes determined by the pulmonary musculature in the different phases of the respiratory cycle, which will generate gradients and allow the entry and exit of air. In addition to the aforesaid, airway calibre, type of flow, airway characteristics and pulmonary surfactant determine less or more work of breathing depending on the physiological condition.

Adjuvant interference on spray solution properties of 2, 4 - D and dicamba herbicides and their efficacy for Ipomoea SPP. control / Interferência de adjuvantes nas propriedades de calda dos herbicidas 2, 4 - D e dicamba e sua eficácia no controle de Ipomoea SPP

Synthetic auxin herbicides constitute major alternatives for managing tough-to-kill weeds such as Ipomoea spp. Adjuvant use is known to positively affect the biological efficacy of pesticides by modifying key spraying solution and droplet properties. Determining to what extent the use of adjuvants could change spray solution parameters and affect synthetic auxin herbicides' efficiency for Ipomoea spp. control were the research goals. The study was conducted in two phases: laboratory and field, respectively. In the laboratory, the pH, the surface tension, and the resources of the herbicide drops were measured. In the field, weed control was evaluated. All adjuvants modified spray solution properties, lowering surface tension values. Most adjuvants decreased pH values as well as number and density of droplets due to an increase in droplet size. Regardless of adjuvant usage, Ipomoea spp. control levels rose more rapidly following 2,4-D spraying rather than dicamba, resulting in lower biomass accumulation when the former was used. Dicamba-containing treatments displayed slightly but significantly lower Ipomoea spp. control levels at the end of the evaluation period. Herbicide efficacy for Ipomoea spp. control was not improved upon the addition to the spray solution of any of the tested adjuvants. Adjuvant use altered spraying solution and droplet properties. 2,4-D spraying allowed for lower Ipomoea spp. biomass and greater control levels relative to dicamba, suggesting it might constitute a better option for Ipomoea spp. control. Even though herbicide efficacy was not improved with adjuvants, their use should still be considered given favorable spraying solution alterations, mainly with some alteration in droplet sizes despite the use of similar spray nozzles tips - maintaining weed control efficacy.

Os herbicidas mimetizadores da auxina constituem alternativas importantes para o manejo de plantas daninhas de difícil controle, como Ipomoea spp. Sabe-se que o uso de adjuvante afeta positivamente a eficácia biológica dos pesticidas, modificando as principais propriedades da solução e do espectro de gotas da pulverização. Os objetivos desse trabalho foram determinar em que medida o uso de adjuvantes pode alterar os parâmetros da solução de pulverização e afetar a eficiência dos herbicidas mimetizadores da auxina para Ipomoea spp. Os estudos foram conduzidos em duas fases: em laboratório e em campo. Em laboratório foi avaliado o pH, tensão superficial e características das gotas dos herbicidas. Em campo foi avaliado o controle da planta daninha. Todos os adjuvantes modificaram as propriedades da solução de pulverização, diminuindo os valores de tensão superficial. A maioria dos adjuvantes diminuiu os valores de pH, bem como o número e a densidade de gotas. Independentemente do uso de adjuvante, os níveis de controle de Ipomoea spp. aumentaram mais rapidamente após a pulverização com 2,4-D do que com o dicamba, resultando em menor acúmulo de biomassa quando o primeiro foi usado. Os tratamentos contendo dicamba apresentaram ligeiramente menor controle de Ipomoea spp. A aplicação de 2,4-D promoveu menor biomassa e maiores níveis de controle em relação ao dicamba de Ipomoea spp., sugerindo que possa constituir uma opção melhor de controle. Embora a eficácia do herbicida não tenha sido melhorada com adjuvantes, seu uso ainda deve ser considerado com alterações favoráveis da solução de pulverização, principalmente tamanhos de gotas em qualquer uso de pontas de pulverização - mantendo a eficácia do controle de plantas daninhas.

Biosurfactant and bioemulsifier as promising molecules produced by Mucor hiemalis isolated from Caatinga soil

BACKGROUND: The present study describes the production of biosurfactant (BS) and emulsifier (BE) by the filamentous fungus Mucor hiemalis UCP 0039, as well as the characterization and stability of the both biomolecules for environmental or industrial applications. RESULTS: Biosurfactants and bioemulsifiers are amphiphilic compounds and are produced as extracellular molecules. The results showed that bioproduct obtained by shaker condition reduced the water surface tension of 72 to 32 mN/m and reached an emulsification index of 96%, while the static cultivation resulted in a biomolecule with a surface tension of 40 mN/m and an emulsification index of 96%, suggesting the production of a biosurfactant and bioemulsifier, respectively. The compounds showed glycolipid nature but the biosurfactant presented cationic charge, while the bioemulsifier, anionic charge. Thus, the results confirmed that M. hiemalis produced two distinct biomolecules under different parameters and in the same culture medium. CONCLUSIONS: It is the first time that biosurfactant and emulsifier production has been described in the same medium and under different physical conditions by Mucor hiemalis. Both biomolecules showed thermal stability, as well as have significant effect on the viscosity of hydrophobic compounds, indicating the excellent potential for environmental safety or industrial applications to improve the efficiency of sustainable and economic technologies.

Clinical Significance and Method of Measuring Lung Fluid Viscosity and Surface Tension / 医用生物力学

Pulmonary fluid refers to a thin and continuous liquid layer mainly consisting of airway mucus and lining liquid on the inner surface of alveoli, which is essential for maintaining a healthy lung. The clinical significance of rheological properties of pulmonary fluid in airway stability, pulmonary barrier and clearance functions, ventilator induced lung injury and surfactant replacement therapy in infant respiratory distress syndrome was introduced in this paper. Furthermore, a variety of classical methods for measuring surface tension and liquid viscosity, such as Langmuir-Wilhelmy balance, captive bubble method, glass capillary viscometer and rotational viscometer, and emerging techniques (e.g. particle tracking microrheometer and axisymmetric drop shape analysis) were reviewed, and their advantages and drawbacks were also compared, in order to provide an important reference for the assisted diagnosis and treatment of lung diseases in clinical practice.

Produção de biossurfactantes: manoproteínas intracelulares e soforolipídios extracelulares por Saccharomyces cerevisiae / Biosurfactant production: intracellular manoproteins and extracellular sophorolipids by Saccharomyces cerevisiae

RESUMO Os biossurfactantes apresentam inúmeras aplicações ambientais e são produzidos por diversos microrganismos. Os provenientes da levedura Saccharomyces cerevisiae são pouco estudados para fins ambientais, sendo atóxicos. Objetivou-se o estudo da produção de biossurfactantes intra e extracelular por essa levedura, desenvolvida em meio de cultivo contendo 0,5% de extrato de levedura e 1% de peptona, além de concentrações variadas de sacarose e indutores oleosos - glicerol e óleos de soja e diesel. Os experimentos foram realizados durante 96 horas, e a produção de biossurfactantes foi avaliada diariamente, por meio da redução da tensão superficial e de estabilização de emulsões. O biossurfactante extracelular foi extraído da biomassa obtida, com posterior precipitação e caracterização química por intermédio de espectrometria de massa. As maiores produtividades de emulsificantes extracelulares foram obtidas com glicerol (0,20 UE.h-1) e óleo de soja (0,21 UE.h-1), em 48 horas de cultivo. Em ensaios posteriores, realizados com aumento da concentração de indutor, foi verificado um aumento das produtividades extracelulares para 0,45 UE.h-1 para o glicerol e 0,30 UE.h-1 para o óleo de soja. A maior redução da tensão superficial foi de 9,89%, em 72 horas, para o indutor óleo diesel. A diminuição dessa tensão, aliada ao aumento das atividades emulsificantes, é um importante indicativo da utilização do substrato hidrofóbico pelo microrganismo. O estudo comprova aumento na produção de biossurfactantes extracelulares quando realizada otimização de cultivo. Para a produção dos intracelulares, a necessidade de processo de rompimento celular aumenta os custos do bioprocesso.

ABSTRACT Biosurfactants implicate many environmental applications, being produced by a wide range of microorganisms. Those from the Saccharomyces cerevisiae yeast are still poorly studied for environmental purposes and are non-toxic. The aim of the study was the production of intra- and extracellular biosurfactants by the Saccharomyces cerevisiae yeast. The yeast was grown in cultured medium containing 0.5% yeast extract, 1% peptone and variable concentrations of sucrose and oily inducers. Inducers used were glycerol, soybean oil and diesel oil. Experiments were conducted for 96 h, and the daily production of biosurfactants was evaluated by reducing surface tension and stabilizing emulsions. Extracellular biosurfactant was extracted from the obtained biomass, with subsequent precipitation and chemical characterization by mass spectrometry. The highest extracellular emulsifier yields were achieved with glycerol inductor (0.20 UE h-1) and soybean oil (0.21 UE h-1) in 48h of cultivation. In later tests performed with increasing concentration of inducer, an increase in extracellular yields was noticed in these experiments (0.45 UE h-1 for glycerol and 0.30 UE h-1 for the soybean oil). The greatest reduction in surface tension was 9.89% in 72 h for diesel oil inducer. The reduction of surface tension combines with the increase of emulsifying activities in an important indicator of the use of hydrophobic substrate by the microorganism. The study confirms an increase in the production of extracellular biosurfactants when optimizing cultivation. The production of intracellular biosurfactants has also been verified, however the process of cellular disruption increases the cost of the bioprocess.

Application Status of Properties of Surface and Interface in Research on Pharmaceutical Preparations / 中国实验方剂学杂志

The surface and interface,as the transition region between two phases,belongs to the category of physical chemistry.At present,it is widely used in materials and other scientific fields.Meanwhile,this property also plays an important role in pharmaceutical research.The interface layer involved in the progress of pharmaceutical preparations is connected with the two-phase or three-phase between gas,liquid and solid closely.The interface effect will affect the final shaping of pharmaceutical preparations and the dissolution and absorption of drugs in the human body.In this paper,the surface and interface characteristics(specific surface area,surfacial and interfacial tension and surface Gibbs free energy) were compared,and the application of interface phenomena(wetting,solubilization and emulsification) in pharmaceutical research were introduced.From the points of view of the progress control of pharmaceutical preparations and the effectiveness of their products,the article expounds the important role of properties of surface and interface in the field of pharmaceutical preparations.Therefore,it is necessary to pay attention to the properties of surface and interface,one of the key physical properties of drugs,and to apply them in the pharmaceutical research.

Influence of surfactants addition on the properties of calcium hypochlorite solutions

Abstract Objectives The aim of this study was to evaluate the influence of surfactants 0.2% or 0.1% cetrimide (Cet) or 0.008% benzalkonium chloride (BAK) on 2.5% calcium hypochlorite (Ca(OCl)2), and compare to sodium hypochlorite (NaOCl), regarding the properties of pH, free chlorine content, surface tension, contact angle, pulp dissolution and antimicrobial activity. Material and Methods The pH and free chlorine content were evaluated by digital pHmeter and by titration, respectively. Surface tension was measured by the platinum ring technique with a Du Noüy tensiometer. The solution's contact angle in human dentin surfaces was checked by Drop Shape Analyzer software. Bovine pulps were used for pulp dissolution analysis and the dissolving capacity was expressed by percent weight loss. Antimicrobial activity over Enterococcus faecalis was evaluated by the agar diffusion method. Results Surfactants addition to Ca(OCl)2 and NaOCl did not alter the pH, free chlorine content and pulp dissolution properties. Ca(OCl)2 had the highest surface tension among all tested solutions. When surfactants were added to Ca(OCl)2 and NaOCl, there was a significant reduction of surface tension and contact angle values. The addition of 0.2% or 0.1% Cet enhanced antimicrobial activity of both Ca(OCl)2 and NaOCl. Conclusion Surfactant addition to 2.5% Ca(OCl)2 has shown acceptable outcomes for pH, free chlorine content, surface tension, contact angle, pulp dissolution and antimicrobial activity. Furthermore, the addition of 0.2% Cet showed better results for all tested properties.

Study of relationship among solution concentration-boiling point-saturation vapor pressure for glycyrrhizic acid solution / 中草药

Objective Based on the theory of dynamic method for measuring the boiling point-saturated vapor pressure, the functional relationship between the boiling point and saturation vapor pressure was studied for the glycyrrhizic acid solution. To build the relationship among the mass fraction of glycyrrhizic acid solution, boiling point and saturation vapor pressure, in order to provide the experimental data and theoretical basis for the related studies of traditional Chinese medicine concentration process. Methods The concentration of glycyrrhizic acid was determined by UPLC for different concentration of glycyrrhizic acid solution. Also, the surface tension of glycyrrhizic acid solution was measured by platinum plate method. Based on dynamic method, the boiling point was measured with the changing saturated vapor pressure at the different mass fractions of solution. Results The concentration of glycyrrhizin in the original extract was 99.25 mg/mL, which accounted for 21.5% of the total solid soluble substance. The dilution process is fully even and conforms to the gradient ratio. When the solution mass fraction was more than 18%, the micelle was formed gradually in the liquid, reducing the surface tension of the solution. It can be found that the boiling point showed the downward trend with increasing solution concentration of glycyrrhizic acid, while the pressure was maintained constant in the environment. When the temperature of solution was hold constant, the saturation vapor pressure of the solution increased with increasing solution concentration of glycyrrhizic acid, but the trend of this interaction was not obvious between the temperature range (313.0—343.0 K). Conclusion According to the experimental results, the functional relationship among the concentration, boiling point and saturated vapor pressure of glycyrrhizic acid solution was constructed. While maintaining the concentration vacuum and the heating energy consumption unchanged in the production process, the glycyrrhizic acid solution temperature should slowly decrease and the evaporation rate should be moderately accelerated with the increasing mass fraction of solution.

First report of the production of a potent biosurfactant with ,-trehalose by Fusarium fujikuroi under optimized conditions of submerged fermentation

Abstract Biosurfactants have many advantages over synthetic surfactants but have higher production costs. Identifying microorganisms with high production capacities for these molecules and optimizing their growth conditions can reduce cost. The present work aimed to isolate and identify a fungus with high biosurfactant production capacity, optimize its growth conditions in a low cost culture medium, and characterize the chemical structure of the biosurfactant molecule. The fungal strain UFSM-BAS-01 was isolated from soil contaminated with hydrocarbons and identified as Fusarium fujikuroi. To optimize biosurfactant production, a PlackettBurman design and a central composite rotational design were used. The variables evaluated were pH, incubation period, temperature, agitation and amount of inoculum in a liquid medium containing glucose. The partial structure of the biosurfactant molecule was identified by nuclear magnetic resonance spectrometry. F. fujikuroi reduced surface tension from 72 to 20 mN m1 under the optimized conditions of pH 5.0, 37 °C and 7 days of incubation with 190 rpm agitation. The partial identification of the structure of the biosurfactant demonstrated the presence of an ,-trehalose. The present study is the first report of the biosynthesis of this compound by F. fujikuroi, suggesting that the biosurfactant produced belongs to the class of trehalolipids.

Production and characterization of a biosurfactant produced by Streptomyces sp. DPUA 1559 isolated from lichens of the Amazon region

Surfactants are amphipathic compounds containing both hydrophilic and hydrophobic groups, capable to lower the surface or interfacial tension. Considering the advantages of the use of biosurfactants produced by microorganisms, the aim of this paper was to develop and characterize a biosurfactant produced by Streptomyces sp. DPUA1559 isolated from lichens of the Amazon region. The microorganism was cultured in a mineral medium containing 1% residual frying soybean oil as the carbon source. The kinetics of biosurfactant production was accompanied by reducing the surface tension of the culture medium from 60 to values around 27.14 mN/m, and by the emulsification index, which showed the efficiency of the biosurfactant as an emulsifier of hydrophobic compounds. The yield of the isolated biosurfactant was 1.74 g/L, in addition to the excellent capability of reducing the surface tension (25.34 mN/m), as observed from the central composite rotational design when the biosurfactant was produced at pH 8.5 at 28°C. The critical micelle concentration of the biosurfactant was determined as 0.01 g/mL. The biosurfactant showed thermal and pH stability regarding the surface tension reduction, and tolerance under high salt concentrations. The isolated biosurfactant showed no toxicity to the micro-crustacean Artemia salina, and to the seeds of lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L.). The biochemistry characterization of the biosurfactant showed a single protein band, an acid character and a molecular weight around 14.3 kDa, suggesting its glycoproteic nature. The results are promising for the industrial application of this new biosurfactant.

First report of the production of a potent biosurfactant with α, ß-trehalose by Fusarium fujikuroi under optimized conditions of submerged fermentation

Abstract Biosurfactants have many advantages over synthetic surfactants but have higher production costs. Identifying microorganisms with high production capacities for these molecules and optimizing their growth conditions can reduce cost. The present work aimed to isolate and identify a fungus with high biosurfactant production capacity, optimize its growth conditions in a low cost culture medium, and characterize the chemical structure of the biosurfactant molecule. The fungal strain UFSM-BAS-01 was isolated from soil contaminated with hydrocarbons and identified as Fusarium fujikuroi. To optimize biosurfactant production, a Plackett-Burman design and a central composite rotational design were used. The variables evaluated were pH, incubation period, temperature, agitation and amount of inoculum in a liquid medium containing glucose. The partial structure of the biosurfactant molecule was identified by nuclear magnetic resonance spectrometry. F. fujikuroi reduced surface tension from 72 to 20 mN m−1 under the optimized conditions of pH 5.0, 37 °C and 7 days of incubation with 190 rpm agitation. The partial identification of the structure of the biosurfactant demonstrated the presence of an α,β-trehalose. The present study is the first report of the biosynthesis of this compound by F. fujikuroi, suggesting that the biosurfactant produced belongs to the class of trehalolipids.

Kinetic study and modeling of biosurfactant production using Bacillus sp

Background: Surfactants are one of the most important raw materials used in various industrial fields as emulsifiers, corrosion inhibitors, foaming agents, detergent products, and so on. However, commercial surfactant production is costly, and its demand is steadily increasing. This study aimed to evaluate the performance of typical strains of Bacillus sp. to produce biosurfactants through fermentation. It also included the investigation of the effect of initial glucose concentration and the carbon to nitrogen ratio. Results: The biosurfactant yield was in the range of 1­2.46 g/L at initial glucose concentrations of 10­70 g/L. The optimum fermentation condition was achieved at a carbon to nitrogen ratio of 12.4, with a decrease in surface tension of up to 27 mN/m. Conclusions: For further development and industrial applications, the modified Gompertz equation is proposed to predict the cell mass and biosurfactant production as a goodness of fit was obtained with this model. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension.

Antimicrobial Effect and Surface Tension of Some Chelating Solutions with Added Surfactants

Abstract This study assessed the antimicrobial efficacy and surface tension of established irrigating solutions with a new experimental chelating solution in infected dentin tubes. Twenty-five specimens were randomly assigned to each of the irrigating solutions. Twenty specimens were used as negative and positive controls. After 21 days of contamination with E. faecalis, the irrigating solutions MTAD, QMiX and Tetraclean NA were delivered into each infected root canal. The solutions were removed and dentin samples were withdrawn from the root canals with sterile low-speed round burs with increasing ISO diameters. The dentin powder samples obtained with each bur were immediately collected in separate test tubes containing 3 mL of BHI broth. After that, 100 μL from each test tube was cultured on blood agar. The grown colonies were counted and recorded as colony-forming units (CFU). The surface tension of the irrigants was measured using a Cahn DCA-322 Dynamic Contact Angle Analyzer. A Kruskal Wallis nonparametric ANOVA and a Friedman test were used (p<0.05). Tetraclean NA showed lower surface tension and CFU values than MTAD and QMiX. Better antibacterial action and low surface tension were observed for Tetraclean NA, probably due to the improved penetration into the root canal and dentinal tubes

Resumo Este estudo avaliou a eficácia antimicrobiana e tensão superficial de soluções irrigadoras e uma nova solução quelante em tubos de dentina infectada. Vinte e cinco espécimes foram aleatoriamente distribuídos conforme as soluções irrigantes. Decorrifdos 21 dias de contaminação com E. faecalis, a soluções de irrigação MTAD, QMiX e Tetraclean NA foram distribuídas em cada canal radicular infectado. As soluções foram removidas e as amostras de dentina foram retiradas dos canais radiculares com brocas esféricas de baixa velocidade com diâmetros ISO sucessivamente maiores. As amostras do pó de dentina obtidas com cada broca foram imediatamente colocadas em tubos de ensaio separados contendo 3 mL de caldo BHI. A seguir, 100 μL de cada amostra do tubo de teste foi cultivada em agar de sangue. As colônias crescidas foram contadas e registadas como unidades formadoras de colônias (UFC). A tensão superficial das soluções irrigantes foi medida utilizando o método de Wilhelmy. A análise não paramétrica de Kruskal-Wallis e o teste de Friedman foram utilizados (p<0,05). Tetraclean NA apresentou menor tensão de superfície e menores valores de UFC do que MTAD e QMiX. A melhor ação antibacteriana e baixa tensão superficial foram observadas para Tetraclean NA, provavelmente devido à melhor penetração no canal radicular e túbulos dentinários.

Development of a Synthetic Surfactant Using a Surfactant Protein-C Peptide Analog: In Vitro Studies of Surface Physical Properties

PURPOSE: Pulmonary surfactant (PS) replacement has been the gold standard therapy for neonatal respiratory distress syndrome; however, almost all commercial PSs contain animal proteins. We prepared a synthetic PS by using a human surfactant protein (SP) analog and evaluated its in vitro properties. MATERIALS AND METHODS: A peptide sequence (CPVHLKRLLLLLLLLLLLLLLLL) of human SP-C was chosen to develop the peptide analog (SPa-C). The new synthetic SP-C PS (sSP-C PS) was synthesized from SPa-C, dipalmitoyl phosphatidylcholine, phosphatidyl glycerol, and palmitic acid. Physical properties of the sSP-C PS were evaluated by measuring the maximum and minimum surface tensions (STs), surfactant spreading, and adsorption rate. In addition, we recorded an ST-area diagram. The data obtained on sSP-C PS were subsequently compared with those of purified natural bovine surfactant (PNBS), and the commercial product, Surfacten(R). RESULTS: The sSP-C PS and Surfacten(R) were found to have maximum ST values of 32-33 mN/m, whereas that of PNBS was much lower at 19 mN/m. The minimum ST values of all three products were less than 10 mN/m. The values that were measured for the equilibrium ST of rapidly spreading sSP-C PS, Surfacten(R), and PNBS were 27, 27, and 24 mN/m, respectively. The surface adsorptions were found to be the same for all three PSs (20 mN/m). ST-area diagrams of sSP-C PS and Surfacten(R) revealed similar properties. CONCLUSION: In an in vitro experiment, the physical properties exhibited by sSP-C PS were similar to those of Surfacten(R). Further study is required to evaluate the in vivo efficacy.

Biophysics and Surface Chemistry in Physiology.

Even though the physiology deals with the study of normal functions of the body the various physiological processes can be explained better with the help of underlying physical and chemical changes. The scientific progresses and advances in the subjects like physics, chemistry and biology gave us opportunity to apply principles of these sciences to understand the working of living organisms better. The underlying physical properties of lipids, water and their surface interaction led to the discovery of cell membrane. The use of vegetable oil to calm the sea waves was known to mankind since 4000 BC since the time from Akkadian ruler Hammurabi, but the more scientific experiments in this area were done by Benjamin Franklin, Lord Rayleigh, Agnes Pockels and Irving Langmuir. In this review we trace back the history of surface chemistry of lipids on water surface and their application in physiology.

Effect of an Alcohol-Based Caries Detector on the Surface Tension of Sodium Hypochlorite Preparations

The purpose of this study was to evaluate the effect of an alcohol-based caries detector (Kurakay) on the surface tension of a conventional sodium hypochlorite (NaOCl) preparation, and a product containing a surface-active agent (Chlor-XTRA). The surface tensions of the following solutions were tested: NaOCl, a mixture of NaOCl and Kurakay 9:1 w/w, Chlor-XTRA, a mixture of Chlor-XTRA and Kurakay 9:1 w/w. Ten measurements per test solution were made at 20 C, using an optical method called the "Pendant drop method", with a commercially available apparatus. The addition of Kurakay reduced the surface tension for NaOCl (p<0.05) whilst no significant difference was detected for Chlor-XTRA (p>0.05). Statistically significant differences between the NaOCl and Chlor-XTRA groups were found (p<0.05). The addition of an alcohol-based caries detector resulted in a reduction of the original surface tension values for NaOCl only. Taking into account the fact that mixtures of NaOCl and Kurakay have been used to assess the penetration of root canal irrigants in vitro, the related changes in surface tension are a possible source of bias.

O objetivo deste estudo foi avaliar o efeito de um detector de cárie com álcool (Kurakay) sobre a tensão superficial de um preparado convencional de hipoclorito de sódio (NaOCl) e um produto contendo um agente surfactante (Chlor-XTRA). Foram testadas as tensões superficiais das seguintes soluções: NaOCl, uma mistura de NaOCl e Kurakay na proporção de 9:1 em peso, Chlor-XTRA e um mistura de Chlor-XTRA e Kurakay na proporção de 9:1 em peso. Dez medidas foram feitas com cada solução, a 20 °C, utilizando um método óptico chamado "Método da gota pendente" (Pendant drop method) usando aparelhos disponíveis. Adição do Kurakay reduziu a tensão superficial do NaOCl (p<0,05), mas não houve diferença significante para Chlor-XTRA (p>0,05). Foram encontradas diferenças estatisticamente significantes entre os grupos NaOCl e Chlor-XTRA (p<0,05). Adição de um detector de cárie com álcool resultou na diminuição do valor original da tensão superficial apenas para NaOCl. Considerando que as misturas de NaOCl e Kurakay tem sido usadas para estudar a penetração in vitro dos irrigantes radiculares, as diferenças acima são uma possível fonte de desvio nos resultados.

Mosquitocidal Bacillus amyloliquefaciens: Dynamics of growth & production of novel pupicidal biosurfactant.

Background & objectives: A strain of Bacillus amyloliquefaciens (VCRC B483) producing mosquito larvicidal and pupicidal biosurfactant was isolated from mangrove forest soil. The present study was aimed at studying the kinetics of growth and production of the mosquitocidal biosurfactant by this bacterium. Methods: Dynamics of growth, sporulation and production of mosquitocidal biosurfactant were studied by standard microbiological methods. The mosquitocidal biosurfactant was precipitated from the culture supernatant and bioassayed against immature stages of   mosquito vectors to determine lethal dose and lethal time. The activity, biological and biochemical properties of the biosurfactant have also been studied. Results: The pupal stages of mosquitoes were found to be more vulnerable to the biosurfactant produced by this bacterium with Anopheles stephensi being the most vulnerable species. The median lethal time (LT50) was found to be 1.23 h when the pupal stages of the above species were exposed to lethal concentration LC90 (9 μg/ml) dosage of the biosurfactant. Production of biosurfactant was found to increase with incubation time and maximum biomass, maximum quantity of biosurfactant (7.9 mg/ml), maximum biosurfactant activity (6 kBS unit/mg) and maximum mosquitocidal activity (5 μg/ml) were attained by 72 h of growth. The lipopeptide nature of the biosurfactant was confirmed by β-haemolysis, lipase activity, biofilm forming capacity, thermostability and biochemical analysis. Interpretation & conclusions: The mosquitocidal biosurfactant produced by B. amyloliquefaciens (VCRC B483) may be a prospective alternative molecule for use in mosquito control programmes involving bacterial biopesticides.

Production and Evaluation of Biosurfactant by Serratia marcescens UCP 1549 Using Industrial Wastes.

Aims: Biosurfactants are surface-active agents of microbial origin that have a property of lowering the surface tension between two liquids. This study aimed to the production of biosurfactant by Serratia marcescens UCP 1549 in medium containing agro-industrial wastes for making possible its industrial application in the near future and to propose its environmental applications. Place and Duration of Study: Center of Science and Technology from State University of Paraíba - UEPB, Campina Grande – PB, Brazil and Nucleus of Research in Environmental Sciences and Biotechnology (NPCIAMB), Catholic University of Pernambuco - UNICAP, Recife-PE, Brazil between June 2011 and July 2012. Methodology: According to the proposed factorial design, the culture medium was developed and used for the production of biosurfactant and incubated at 28ºC, 155 rpm during 48 h. The produced biosurfactant was evaluated by emulsifying index, emulsifying activity and surface tension using hydrophobic substrates as vegetable oils after frying, nhexadecane and diesel. Results: The best results for emulsification index were found between 79.92 and 100% of emulsification and for activity were values between 2.304 and 5.000 EA (emulsification activity) using vegetable oil after frying as substrate. In relation of the surface tension, the best value obtained was 33.10mN/m in the condition of the central point of the experimental design. Conclusion: The results show that Serratia marcescens UCP 1549 was capable of producing a biosurfactant with emulsifying property from industrial wastes in the studied conditions in this work.

Characterization and properties of the biosurfactant produced by Candida lipolytica UCP 0988

Background: Biotechnological processes are costly, especially for the production of biosurfactants. The successful production of a biosurfactant is dependent on the development of processes using low cost raw materials. Considering the importance of the characteristics of a biosurfactant to facilitate its industrial application, the properties of the biosurfactant produced by Candida lipolytica through previously optimized medium have been established. Results: The yeast was grown for 72 h to determine the kinetics of growth and production. The surface tension of the cell-free broth was reduced from 55 to 25 mN/m. The yield of biosurfactant was 8.0 g/l with a CMC of 0.03%. The biosurfactant was characterized as an anionic lipopeptide composed of 50% protein, 20% lipids, and 8% of carbohydrates. Conclusions: The isolated biosurfactant showed no toxicity against different vegetable seeds: Brassica oleracea, Solanum gilo and Lactuca sativa L. and the micro-crustacean Artemia salina. The properties of the biosurfactant produced suggest its potential application in industries that require the use of effective compounds at low cost.