Alkaline/surfactant/polymer (ASP) flooding is of increasing interest and importance because of high oil prices and the need to increase oil production. The benefits of combining alkali with surfactant are well established. The alkali has very important benefits such as lowering interfacial tension and reducing adsorption of anionic surfactants that decrease costs and make ASP a very attractive enhanced oil recovery method provided the consumption is not too large and the alkali can be propagated at the same rate as a synthetic surfactant and polymer. However, the process is complex so it is important that new candidates for ASP be selected taking into account the numerous chemical reactions that occur in the reservoir. The reaction of acid and alkali to generate soap and its subsequent effect on phase behavior is the most crucial for crude oils containing naphthenic acids. Using numerical models, the process can be designed and optimized to ensure the proper propagation of alkali and effective soap and surfactant concentrations to promote low interfacial tension and a favorable salinity gradient. The first step in this investigation was to determine what geochemical reactions have the most impact on ASP flooding under different reservoir conditions and to quantify the consumption of alkali by different mechanisms. We describe the ASP module of UTCHEM simulator with particular attention to phase behavior and the effect of soap on optimum salinity and solubilization ratio. Several phase behavior measurements for a variety of surfactant formulations and crude oils were successfully modeled. The phase behavior results for sodium carbonate, blends of surfactants with an acidic crude oil followed the conventional Winsor phase transition with significant three-phase regions even at low surfactant concentrations. The solubilization data at different oil concentrations were successfully modeled using Hand's rule. Optimum salinity and solubilization ratio were correlated with soap mole fractions using mixing rules. New ASP corefloods were successfully modeled taking into account the aqueous reactions, alkali/rock interactions, and the phase behavior of soap and surfactant. These corefloods were performed in different sandstone cores with several chemical formulations, crude oils with a wide range of acid numbers, brine with a wide range of salinities, and a wide range of temperatures. 2D and 3D sector model ASP simulations were performed based on field data and design parameters obtained from coreflood history matches. The phenomena modeled included aqueous phase chemical reactions of the alkaline agent and consequent consumption of alkali, the in-situ generation of surfactant by reaction with the acid in the crude, surfactant/soap phase behavior, reduction of surfactant adsorption at high pH, cation exchange with clay, and the effect of co-solvent on phase behavior. Sensitivity simulations on chemical design parameters such as mass of surfactant and uncertain reservoir parameters such as kv/kh ratio were performed to provide insight as the importance of each of these variables in chemical oil recovery. Simulations with different permeability realizations provided the range for chemical oil recoveries. This study showed that it is very important to model both surface active components and their effect on phase behavior when doing mechanistic ASP simulations. The reactions between the alkali and the minerals in the formation depend very much on which alkali is used, the minerals in the formation, and the temperature. This research helped us increase our understanding on the process of ASP flooding. In general, these mechanistic simulations gave insights into the propagation of alkali, soap, and surfactant in the core and aid in future coreflood and field scale ASP designs. / text

Surfactant assisted solution exfoliation of expanded graphite by means of sonication was carried out in an attempt to produce non-covalent charge functionality on the surface of graphene for the directed self assembly of graphene films on patterned substrates via electrostatic interactions. This thesis includes the results of experimental research associated with: 1) quantifying the effectiveness of various di-functionalized dithienothiophene surfactant small molecules, 2) further understanding the surface affinity and interaction mechanism between these surfactant molecules and the surface of expanded graphite and graphene and 3) experimentally testing the feasibility of the directed self-assembly of graphene films by means of charge functionalization of graphene by the surfactant molecules adsorbed onto the surface of exfoliated graphene.

Em contraste com a vasta descrição na literatura científica dos biofilmes bacterianos, poucos trabalhos focam o estudo da formação e as estratégias de inibição da constituição do biofilme fúngico. Este trabalho objetiva a caracterização do potencial antifúngico e antibiofilme do sal imidazólico 1-metil-3-octilimidazol cloreto (C16MImCl), e das frações (F70 e F90) purificadas de saponinas mate (Ilex paraguariensis A. st. Hil.), frente a células de biofilme de seis isolados clínicos de Candida tropicalis. A Concentração Inibitória Mínima (CIM) do C16MImCl foi de 0,014μg/mL frente às células planctônicas, ao passo que as Frações de Saponinas da Erva Mate (FSEM) não apresentaram atividade antifúngica. Utilizando o cateter traqueal (CT) como corpo de prova, foi utilizado para avaliar a capacidade de inibição e remoção do biofilme. Avaliou-se também a Concentração Mínima de Erradicação do Biofilme (CMEB) para remoção do biofilme pré-formado pelo método da microplaca. Para a atividade antibiofilme foi observado que o C16MImCl, apresentou melhor resultado quando comparado ao fluconazol. As FSEM também apresentaram atividade antibiofilme quando comparados ao fluconazol, entretanto menores do que o tensoativo sintético Pela análise dos resultados de CMEB, o C16MImCl foi o composto com maior capacidade de erradicar o biofilme pré-formado, na concentração de 0,9 μg/mL (92% a 100% de remoção do biofilme). Os demais compostos testados (fluconazol, FEM e a água) não apresentaram atividade removedora, observando-se valores menores que 80% de remoção. Tanto as concentrações nas quais C16MImCl inibiu as células planctônicas (0,014 μg/mL) como as de biofilme (0,028 -0,225 μg/mL) foram mais baixas que as obtidas pelo fluconazol. Os resultados obtidos demonstram a potencialidade destes tensoativos, principalmente o C16MImCl, que demonstrou baixa toxicidade e provável mecanismo de ação sobre a síntese do ergosterol. Assim, é possível afirmarmos que estes tensoativos representam uma potencial alternativa para o controle químico de fungos leveduriformes, especialmente as ocasionadas por células de biofilme por C. tropicalis. / In contrast to the extensive description in the literature of bacterial biofilms, few works focus on the study of the formation and strategies for inhibiting the formation of fungal biofilms. This work aims to characterize the antifungal potential and antibiofilm the imidazole salt 1 - methyl - 3 - octilimidazol chloride (C16MImCl), and fractions (F70 and F90) purified saponins mate (Ilex paraguariensis A. st. Hil.), against to biofilm cells of six clinical isolates of Candida tropicalis. The Minimum Inhibitory Concentration (MIC) of C16MImCl was 0.014 mg / mL to planktonic cells, whereas the Saponin Fractions of Yerba Mate (SFYM) showed no antifungal activity. Using the tracheal catheter (CT) as a specimen was used to evaluate the ability of the biofilm inhibition and removal. We also assessed the Minimum Biofilm Eradication Concentration (MBEC) to remove the preformed biofilms by the microplate method. For antibiofilm activity was observed that C16MImCl, showed better results when compared to fluconazole. The SFYM also had antibiofilm activity when compared to fluconazole, however smaller than the synthetic surfactant. By analyzing the results MBEC, the compound C16MImCl was capacity to eradicate pre- formed biofilm in a concentration of 0.9 mg / mL (92% to 100% biofilm removal) The other tested compounds (fluconazole, SFYM and water) showed no activity remover, observing less than 80 % removal values. Both concentrations at which they inhibit planktonic cells C16MImCl (0.014 μg/mL) and the biofilm (0.028 -0.225 μg/ml) were lower than those obtained by fluconazole. The results obtained demonstrate the potential of these surfactants, especially C16MImCl, which demonstrated low toxicity and probable mechanism of action on the synthesis of ergosterol. Thus, it is possible to assert that these surfactants are a potential alternative to chemical control of yeasts, especially those caused by biofilm cells of C. tropicalis.

Em contraste com a vasta descrição na literatura científica dos biofilmes bacterianos, poucos trabalhos focam o estudo da formação e as estratégias de inibição da constituição do biofilme fúngico. Este trabalho objetiva a caracterização do potencial antifúngico e antibiofilme do sal imidazólico 1-metil-3-octilimidazol cloreto (C16MImCl), e das frações (F70 e F90) purificadas de saponinas mate (Ilex paraguariensis A. st. Hil.), frente a células de biofilme de seis isolados clínicos de Candida tropicalis. A Concentração Inibitória Mínima (CIM) do C16MImCl foi de 0,014μg/mL frente às células planctônicas, ao passo que as Frações de Saponinas da Erva Mate (FSEM) não apresentaram atividade antifúngica. Utilizando o cateter traqueal (CT) como corpo de prova, foi utilizado para avaliar a capacidade de inibição e remoção do biofilme. Avaliou-se também a Concentração Mínima de Erradicação do Biofilme (CMEB) para remoção do biofilme pré-formado pelo método da microplaca. Para a atividade antibiofilme foi observado que o C16MImCl, apresentou melhor resultado quando comparado ao fluconazol. As FSEM também apresentaram atividade antibiofilme quando comparados ao fluconazol, entretanto menores do que o tensoativo sintético Pela análise dos resultados de CMEB, o C16MImCl foi o composto com maior capacidade de erradicar o biofilme pré-formado, na concentração de 0,9 μg/mL (92% a 100% de remoção do biofilme). Os demais compostos testados (fluconazol, FEM e a água) não apresentaram atividade removedora, observando-se valores menores que 80% de remoção. Tanto as concentrações nas quais C16MImCl inibiu as células planctônicas (0,014 μg/mL) como as de biofilme (0,028 -0,225 μg/mL) foram mais baixas que as obtidas pelo fluconazol. Os resultados obtidos demonstram a potencialidade destes tensoativos, principalmente o C16MImCl, que demonstrou baixa toxicidade e provável mecanismo de ação sobre a síntese do ergosterol. Assim, é possível afirmarmos que estes tensoativos representam uma potencial alternativa para o controle químico de fungos leveduriformes, especialmente as ocasionadas por células de biofilme por C. tropicalis. / In contrast to the extensive description in the literature of bacterial biofilms, few works focus on the study of the formation and strategies for inhibiting the formation of fungal biofilms. This work aims to characterize the antifungal potential and antibiofilm the imidazole salt 1 - methyl - 3 - octilimidazol chloride (C16MImCl), and fractions (F70 and F90) purified saponins mate (Ilex paraguariensis A. st. Hil.), against to biofilm cells of six clinical isolates of Candida tropicalis. The Minimum Inhibitory Concentration (MIC) of C16MImCl was 0.014 mg / mL to planktonic cells, whereas the Saponin Fractions of Yerba Mate (SFYM) showed no antifungal activity. Using the tracheal catheter (CT) as a specimen was used to evaluate the ability of the biofilm inhibition and removal. We also assessed the Minimum Biofilm Eradication Concentration (MBEC) to remove the preformed biofilms by the microplate method. For antibiofilm activity was observed that C16MImCl, showed better results when compared to fluconazole. The SFYM also had antibiofilm activity when compared to fluconazole, however smaller than the synthetic surfactant. By analyzing the results MBEC, the compound C16MImCl was capacity to eradicate pre- formed biofilm in a concentration of 0.9 mg / mL (92% to 100% biofilm removal) The other tested compounds (fluconazole, SFYM and water) showed no activity remover, observing less than 80 % removal values. Both concentrations at which they inhibit planktonic cells C16MImCl (0.014 μg/mL) and the biofilm (0.028 -0.225 μg/ml) were lower than those obtained by fluconazole. The results obtained demonstrate the potential of these surfactants, especially C16MImCl, which demonstrated low toxicity and probable mechanism of action on the synthesis of ergosterol. Thus, it is possible to assert that these surfactants are a potential alternative to chemical control of yeasts, especially those caused by biofilm cells of C. tropicalis.

A review of the chemistry of poly(lactic acid) was carried out with a focus on techniques and applications of PLA polymer and copolymers with reference to some of the work that has been accomplished over the last 20 years or so. A review of the characterisation techniques used to analyse PLA polymers and copolymers was also carried out giving reference to the equipment and methods used herein. An investigation into the potential of PLA as the hydrophilic portion of a polymeric surfactant was carried out. To develop PLA based surfactants, the ring opening polymerisation of lactide was carried out in a melt in the presence of a long chain alcohol (C₇ to C₂₀) or diol (C₄ & C₆) to produce AB or ABA type polymers that follow the traditional surfactant template. Stannous octanoate and 4-dimethylaminopyridine were typically used as catalysts due to their high activity and relative cheapness. PLA only shows good hydrophilicity with up to 12 lactic acid units in the chain. Above this the electrostatic interactions between polymer chains reduced water solubility. It was also noted that D,L-lactide produced more water soluble polymers (syndiotactic) than the enantiomerically pure L-lactide (isotactic polymer chains). An investigation of the hydrophobic properties of PLA was carried out to evaluate their usefulness for other biodegradable surfactant applications. To this end an investigation of sugars as the hydrophilic portion of the molecule was carried out. Due to problems with solubilising sugars, they were deemed unsuitable for use as initiatiors within the scope of this research. Choline chloride was then investigated as a potential hydrophilic initiator and indeed has produced some of the most water soluble of PLA polymers. Choline chloride presented several challenges as an initiator, its high melting point resulted in polar solvents such as t-butanol being employed. Alternatively, more success was achieved by preparation of a choline chloride eutectic mixture prior to the polymerisation. It was discovered that a choline chloride/urea eutectic mixture was capable of self initiation, thus required no further addition of catalyst, this result shows a potential step forward in PLA green chemistry. A final investigation into producing surface-active PLA in a one-pot process that required only a hydroxycarboxylate initiator was carried out. The production of PLA sodium or potassium salts was carried out in a melt polymerisation and the results show some promise. Initiators that have been employed include a range of a, b and g-hydroxycarboxylic acids. These work through tautomerisation to the alkoxide, which then initiates a living type polymerisation of lactide to produce surface-active polymers. As well as the synthesis of these polymers some analysis of the physical and aqueous properties of these materials was carried out. PLA sodium salts were shown to have reasonable surfactant ability (~45 mNm⁻¹) and low CMC values of around 5x10⁻⁹ mol cm⁻³. They were also shown to have some properties as emulsifiers, and in some cases showed non-Newtonian fluid behaviour such as shear-thinning (thixotropy) and shear-thickening (dilatant). The thermal characteristics of the polymers such as T[subscript]g and stability were assessed as well as their ability to retain water.

Orientador: Lúcia Regina Durrant / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-22T11:02:32Z (GMT). No. of bitstreams: 1 Pescumo_FernandaFranzoni_M.pdf: 1387373 bytes, checksum: baa6cd7b83f29182ab90172ebb03c248 (MD5) Previous issue date: 2013 / Resumo: Biossurfactantes e bioemulsificantes são compostos ativos de superfícies (CAS) produzidos por micro-organismos. Desempenham várias funções biológicas, e sua característica anfifílica, juntamente com baixa toxicidade, biodegradabilidade e resistência a extremos de pH, temperatura e salinidade, tem despertado o interesse para a aplicação dessas moléculas em processos biotecnológicos. Porém, o alto custo aliado à baixa produção ainda são impedimentos para a utilização em larga escala. Os desafios para se implementar a produção são: desenvolvimento de estratégias para tornar a produção economicamente viável e o isolamento de moléculas e microorganismos mais eficientes. Neste trabalho, foi estudada a produção, isolamento, extração e caracterização de um CAS por Gordonia amicalis. O micro-organismo foi cultivado em meio GYP (glucose, extracto de levedura, peptona) por 7 dias, e a extração foi feita por precipitação com sulfato de amônio, que resultou em uma concentração de 0,5 g/L do extrato bruto em meio líquido. O CAS não reduziu significativamente a tensão superficial do meio GYP, e apresentou um balanço hidrofílico-lipofílico (HBL) de caráter lipofílico, apresentando mais emulsões do tipo água em óleo (A/O) do que óleo em água (O/A). A molécula apresentou estabilidade a temperaturas de 25ºC a 100ºC, pH de 2 a 10 e salinidades de 5% a 15% quando cultivado por 7 dias, e foi capaz de modificar a interface água/superfície na análise de ângulo de contato. O extrato de 14 dias apresentou Atividade Emulsificante em 24 horas (AE24) reduzida em temperaturas acima de 50ºC, e ausente em pH ácido e salinidades de 5% e 10%. Análises de Cromatografia de Camada Delgada (CCD) revelaram presença de aminoácidos e açúcares na molécula e a análise do potencial zeta revelou que o CAS é um surfactante aniônico. Nas análises de Espectrometria no Infravermelho com Transformadas de Fourier (IR-TF) foram observados estiramentos indicativos de agrupamentos O-H e C-O, que podem indicar presença de grupos éter ou ésteres. O CAS produzido por Gordonia amicalis em meio sintético GYP mostrou-se um eficiente agente emulsificante, com potencial para aplicações biotecnológicas futuras / Abstract: Biosurfactants and bioemulssifiers are surface active compounds (SACs) produced by microorganisms. They have a wide variety of biological functions. Its amphiphilic characteristic, with low toxicity, biodegradability and resistance to extremes of pH, temperature and salinity, has increased the interest of these molecules for application biotechnological process. However, high costs and low production rates are restrictions to their widespread use. The challenges for implementing production are: developing strategies to turn the production economically feasible and isolating more efficient molecules and microorganisms. In this work, we studied the production, isolation, extraction and characterization of a SAC by a Gordonia amicalis. The microrganism was grown in GYP (Glucose, Yeast extract, Peptone) medium for 7 days, and the isolation was carried out by precipitation with ammonium sulfate, which resulted in 0.5 g / L of crude extract. The SAC did not significantly reduce the surface tension of GYP medium, and showed an hydrophilic-lipophilic balance (HLB) with lipophilic character, showing more water in oil (W/O) emulsions than oil in water (O/W) emulsions. The molecule extracted at 7 days was stable at temperatures ranging from 25 to 100 ° C, pH of 2-10 and salinities of 5-15%, and can modify the water/surface contact by the angle of contact analysis. The 14-day isolated extract showed EA24 reduced at temperatures above 50 ºC, and had no Emulsification Activity in 24 hours (EA24) in acid pH and salinity of 5% and 10%. Thin Layer Chromatography (TLC) analysis revealed the presence of sugars and amino acids in the molecule and the zeta potential analysis revealed the compound is an anionic surfactant. In the Fourier Transformed Infrared Spectrometry (FTIV) it were observed stretches indicatives of O-H and C-O groups, that might indicate ether or ester groups. The SAC produced by Gordonia amicalis in GYP medium proved to be an efficient emulsifier, with potential for biotechnological applications / Mestrado / Ciência de Alimentos / Mestra em Ciência de Alimentos

<p>Surfaktanti imaju značajnu primenu u farmaciji i medicini. Ove supstance se primenjuju u farmakoterapiji, koriste se za solubilizaciju hidrofobnih lekova, a pojedina ispitivanja pokazuju da mogu unaprediti bioraspoloživost određenih aktivnih supstanci. U poslednje vreme se sve vi&scaron;e pažnje posvećuje ispitivanju sme&scaron;a surfaktanata, po&scaron;to je utvrđeno da sistemi dva ili vi&scaron;e surfaktanta često pokazuju poželjnija svojstva od pojedinačnih surfaktanata za aplikaciju u farmaciji i medicini. U ovoj disertaciji su ispitivani binarni sistemi osam anjona žučnih kiselina i dva nejonska surfaktanta (polisorbat 40 i polisorbat 80). Ciljevi su određivanje vrednosti kritičnih micelarnih koncentracija ispitivanih sme&scaron;a surfaktanta, utvrđivanje međudejstva između različitih surfaktanta u njihovim me&scaron;ovitim micelama, kao i ispitivanje uticaja stukture ispitivanih surfaktanata na fizičko-hemijske karakteristike me&scaron;ovitih micela. Rezultati pokazuju da ispitivane sme&scaron;e imaju znatno niže vrednosti kritičnih micelarnih koncentracija od anjona žučnih kiselina. Sme&scaron;e anjona žučnih kiselina i polisorbata 40 imaju manje vrednosti eksperimentalnih kritičnih micelarnih koncentracija, od izračunatih, idealnih, vrednosti, &scaron;to ukazuje na postojanje sinergističkih interakcija u me&scaron;ovitim micelama. Sme&scaron;e anjona žučnih kiselina i polisorbata 80 imaju uglavnom veće vrednosti kritičnih micelarnih koncentracija od idealnih vrednosti, &scaron;to može biti posledica postojanja antagonističkih interakcija između gradivnih jedinica me&scaron;ovitih micela. Vrednosti interakcija, koje dovode do neidealnog pona&scaron;anja sistema surfaktanata, su određene računanjem vrednosti interakcionog parametra, &beta;_1,2, prema regular solution theory. Sistemi anjona žučnih kiselina i polisorbata 40 imaju negativne vrednosti interakcionog parametra, dok sistemi anjona žučnih kiselina i polisorbata 80 imaju uglavnom pozitivne vrednosti interakcionog parametra. Poređenjem fizičko-hemijskih parametara me&scaron;ovitih micela je utvrđeno da postojanje privlačnih međudejstava između hidrofilnih delova različitih surfaktanata najverovatnije potiče od vodoničnih veza koje se formiraju između hidrofilnih grupa anjona žučnih kiselina i polioksietilenskih delova. Pozitivne vrednosti &beta;_1,2 parametra su najverovatnije posledica sterno krute cis dvostruke veze oleinske kiseline u molekulu polisorbata 80, usled čega se lipofilni deo ovog nejonskog surfaktanta teže pakuje u jezgru me&scaron;ovitih micela. Pretpostavlja se da zbog toga dolazi do formiranja dimera anjona žučnih kiselina u me&scaron;ovitim micelama u kojima se javljaju odbojne interakcije između negativno naelektrisanih karboksilatnih grupa.</p> / <p>Surfactants have important application in pharmacy and medicine. These substances are applied in pharmacotherapy, they are used for hydrophobic drug solubilisation, and certain investigations indicate they can improve bioavailability of certain active substances. Lately, investigations of surfactant mixtures have gained a lot of attention, since it was found that systems of two or more surfactants often show more desirable properties than the individual surfactants, for application in pharmacy and medicine. In this dissertation, binary systems of eight bile acid anions and two nonionic surfactants (polysorbate 40 and polysorbate 80) were investigated. The aims were to determine values of critical micelle concentrations of investigated surfactant mixtures, interactions between different surfactants in their mixed micelles, and to investigate the influence of the structure of investigated surfactants on physico-chemical characteristics of mixed micelles. The results indicate that investigated mixtures have significantly lower values of critical micelle concentrations than bile acid anions. Mixtures of bile acid anions and polysorbate 40 have&nbsp; lower values of experimentally obtained critical micelle concentrations than the calculated, ideal, values, indicating the existence of synergistic interactions in mixed micelles. Mixtures of bile acid anions and polysorbate 80 have mainly higher values of critical micelle concentrations than the ideal values, what could be due to the existence of antagonistic interactions between building units of mixed micelles. The values of the interactions, attributing to the nonideal behaviour of the surfactant systems were obtained by calculating the values of the interaction parameter, &beta;1,2 , according to the regular solution theory. Systems of bile acid anions and polysorbate 40 have negative values of the interaction parameter, while systems of bile acid anions and polysorbate 80 have mainly positive values of interaction parameter. By comparing the physico-chemical parameters of mixed micelles, it was determined that existence of attractive interactions between hydrophilic parts of different surfactants most probably originates from the hydrogen bonds, which are formed between hydrophilic groups of bile acid anions and polyoxyethylene parts. Positive values of &beta;1,2 parameter are most probably due to sterically rigid cis double bond of oleic acid in polysorbate 80 molecule, causing the lipophilic tail of this nonionic surfactant to pack less easily in the core of mixed micelles. It is hypothesised that this influences formation of dimers of bile acid anions in mixed micelles, where repulsive interactions emerge between negatively charged carboxylate groups.</p>

<p>Binarne me&scaron;ovite micele su značajne u farmaceutsko-farmakolo&scaron;kim primenama, u kojima lek kao povr&scaron;inska aktivna supstanca može da bude gradivna jedinica binarne micelle (promena bioraspoloživosti, mehanizam resorpcije itd.). Takođe su važne i me&scaron;ovite micele kod kojih su gradivne jedinice biosurfaktanti (biokompatibilni solubilizatori lekova). U kozmetičkoj, prehrambenoj i industriji detergenata me&scaron;ovite micele su uveliko zastupljene. Važno je nalaženje binarnih sistema surfaktanata koji u me&scaron;ovitim micelama poseduju sinergističko međudelovanje (negativna vrednost interakcionog parametra). Takva binarna sme&scaron;a surfaktanata ima nižu vrednost kritične micelarne koncentracije od hidrofobnije komponente sme&scaron;e. U prvom delu rada je ispitivan uticaj dužine hidrofobnog segmenta homolognih Tween-ova iz me&scaron;ovitih micela sa Triton-om X100 na interakcioni parametra ( i, j &beta; ) i dodatnu Gibbs-ovu energiju (GE ), takođe ispitivao se i uticaj temperature na stabilnost proučavanih me&scaron;ovitih micela (273,15-328,115 K). Kritične micelarne koncentracije čistih surfaktanata i njihovih binarnih sme&scaron;a su određeni spektrofluorometrijski uz primenu pirena kao probnog molekula. Nađeno je da na svakoj ispitivanoj temperaturi povećanje dužine zasićenog alifatičnog niza polisorbata povećava stabilnost me&scaron;ovite micele ( , 0 i j &beta; &lt; i GE &lt; 0 ) u odnosu na idealnu me&scaron;ovitu micelu. Prisustvo C9 dvostruke veze u ostatku oleinske kiseline Tween-a 80 umanjuje sinergistički efekat ovog polisorbata u odnosu na Tween 60, koji ima hidrofobni segment sa istim brojem C atoma, ali bez olefinske veze. Dodatna slobodna entalpija ispod temperature 298.15 K određena je entropijskim doprinosem, a iznad 298.15 K entalpijskim doprinosom. U drugom delu rada ispitivane su binarne sme&scaron;e surfaktanata Tween 85/Triton X100 i Tween 85/Triton X165 u vodenom rastvoru u intervalu temperature od 273.15 K do 323.15 K. Pri temperaturama od 273.15 K i 283.15 K između različitih gradivnih jedinica binarnih me&scaron;ovitih micela postoje sinergističke interakcije na čiju veličinu ne utiče razlika u dužini polioksietlienskih nizova Triton-a X100 i Triton-a X165. Na većim vrednostima temperature duži polioksietilenski niz Triton-a X165 pokazuje stabilizirajuči efekat u me&scaron;ovitoj miceli sa Tween-om 85 u odnosu na me&scaron;ovite micele Tween 85/Triton X100. Kod ispitivanih binarnim me&scaron;ovitim micela ne može se prihvatiti aproksimacija regularnih sme&scaron;a o nula vrednosti dodatne entropije formiranja binarne me&scaron;ovite micele.</p> / <p>Binary micelles are important in pharmaceutical-pharmacological applications, in which drug as surface active substance can be building unit of binary micelle (influencing bioavailability change, change of resorption mechanism etc.). Mixed micelles in which building units are biosurfactants (biocompatible drug solubilizers) are also important. In cosmetics, food and detergent industry mixed micelles are widely present. It is important to find binary surfactant systems having synergistic interactions (negative value of interaction parameter). That binary surfactant mixture has lower critical micelle concentration value than more hydrophobic component of the mixture. In the first parth of this work, influence of hydrophobic segment length of homologues Tweens in mixed micelles with Triton X-100 on the interaction parameter value ( i, j &beta; ) and an excess Gibbs energy (GE ) was investigated. Also, influence of temperature on the stability of investigated mixed micelles has been investigated (273.15-328.15 K). Critical micelle concentration values of pure surfactants and their binary mixtures were determined spectrofluorimetrically using pyrene as a probe molecule. It was found for every investigated temperature that increase in length of saturated aliphatic side chain of a polisorbate increases the stability of investigated mixed micelles (&beta; &lt; and GE &lt; 0 ) compared to ideal mixed micelles. Presence of the C9 double bond in oleic acid residue of Tween 80 reduces synergistic effect of this polysorbate compared to Tween 60 which contains hydrophobic segment with the same number of C atoms but without olefin bond. Excess free enthalpy below the 298.15 K is determined with entropic contribution, but above 298.15 K with enthalpic contribution. In the second parth of this work, binary surfactant mixtures of Tween 85/Triton X100 and Tween 85/Triton X165 have been investigated in water solution in the temperature range from 273.15 K to 323.15 K. At the temperatures of 273.15 K and 283.15 K between different building units of binary mixed micelles synergistic interactions exist, which size is not affected by difference in length of the polyoxyethylene chains. At higher temperatures, longer polyoxyethylene chain of Triton X165 shows more stabilizing effect in mixed micelle with Tween 85 than in mixed micelles of Tween 85/Triton X100. For investigated binary mixed micelles, regular solution theory approximation about zero value of excess entropy of binary mixed micelle formation cannot be accepted.</p>

Charles University Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Consultant: PharmDr. Jan Marek, Ph.D. Supervisor: doc. PharmDr. Veronika Nováková, Ph.D. Student: Kateřina Pekařová Title of Thesis: Cationic surface active compounds and evaluation of its properties Quaternary ammonium salts are used as surfactants in many branches of the food, pharmaceutical and chemical industries. The basic properties of these substances were studied in the thesis. The critical micellar concentration of the homologous series of five substances was determined using the conductometric method. The theory of declining critical micellar concentration with the increasing length of the side alkyl chain has been verified. The hydrolytic activity of two commonly used cationic surfactants benzalconium chloride and benzoxonium chloride for the decomposition of the organophosphorus pesticide fenitrothion was tested. For these two substances, the effect of pH and temperature changes was evaluated. The influence of tenside concentration was also monitored. Benzoxonium chloride at 50 řC and pH 11was found as the most effective hydrolytic catalyst for the decomposition of the organophosphorus pesticide fenitrothione.

A pre-eminent emulsion-based micellar drug delivery system, "microemulsion", comprising drug in oil or water phase, stabilized by surfactants and co-surfactants, has been evidenced to have a phenomenal role in a number of applications. Oils play an important role in the formation of ME and increase the drug absorption at the site of action. Oils employed in microemulsion formulation solubilize lipophilic drug. As the concept of "natural" therapies is recently gaining importance amongst researchers all over the world, scientists are employing essential oil as an organic component in this system. The active components of essential oils include flavonoids, phenylpropanoids, monoterpenes and polyunsaturated mega-6-fatty acids. These oils are enriched with characteristic intrinsic properties such as anti-oxidant, anti-bacterial, anti-viral, etc., bestowing enhanced supremacy to the whole microemulsion system. This mini-review is the first to document various types of essential oils employed in microemulsion systems and highlight their therapeutic potential and applications as drug delivery vehicles. Key inferences from this study suggest: 1) Clove oil is the most explored oil for incorporation into a microemulsion based system, followed by peppermint and Tea Tree Oil (TTO). 2) Penetration enhancing effects of these oils are due to the presence of terpenic constituents. 3) Essential oil based microemulsions protect volatility of ethereal oils and protect them from degradation in the presence of light, air, temperature. 4) These systems may also be explored for their applications in different industries like aromatherapy, food, drink, fragrance, flavour, cosmeceutical, soap, petroleum and pharmaceutical industry.