The growing demand for efficient chemotherapy in many cancers requires novel approaches in target... more The growing demand for efficient chemotherapy in many cancers requires novel approaches in target-delivery technologies. Nanomaterials with pH-responsive behavior appear to have potential ability to selectively release the encapsulated molecules by sensing the acidic tumor microenvironment or the low pH found in endosomes. Likewise, polyethylene glycol (PEG)- and poloxamer-modified nanocarriers have been gaining attention regarding their potential to improve the effectiveness of cancer therapy. In this context, DOX-loaded pH-responsive nanoparticles (NPs) modified with PEG or poloxamer were prepared and the effects of these modifiers were evaluated on the overall characteristics of these nanostructures. Chitosan and tripolyphosphate were selected to form NPs by the interaction of oppositely charged compounds. A pH-sensitive lysine-based amphiphile (77KS) was used as a bioactive adjuvant. The strong dependence of 77KS ionization with pH makes this compound an interesting candidate to...
Neutral hydrophobic β-hydroxyalkyl ethers of inulin have been prepared with varying molecular fea... more Neutral hydrophobic β-hydroxyalkyl ethers of inulin have been prepared with varying molecular features (the hydrophobic characteristics of the epoxide, length and nature, and the number of grafted groups per fructose units) in aqueous media under different ...
The encapsulation of antitumor drugs in nanosized systems with pH-sensitive behavior is a promiss... more The encapsulation of antitumor drugs in nanosized systems with pH-sensitive behavior is a promissing approach that may enhance the success of chemotherapy in many cancers. The nanocarrier dependence on pH might trigger an efficient delivery of the encapsulated drug both in the acidic extracellular environment of tumors and, especially, in the intracellular compartments through disruption of endosomal membrane. In this context, here we reported the preparation of chitosan-based nanoparticles encapsulating methotrexate as a model drug (MTX-CS-NPs), which comprises the incorporation of an amino acid-based amphiphile with pHresponsive properties (77KS) on the ionotropic complexation process. The presence of 77KS clearly gives a pH-sensitive behavior to NPs, which allowed accelerated release of MTX with decreasing pH as well as pH-dependent membrane-lytic activity. This latter performance demonstrates the potential of these NPs to facilitate cytosolic delivery of endocytosed materials. Outstandingly, the cytotoxicity of MTX-loaded CS-NPs was higher than free drug to MCF-7 tumor cells and, to a lesser extent, to HeLa cells. Based on the overall results, MTX-CS-NPs modified with the pH-senstive surfactant 77KS could be potentially useful as a carrier system for intracellular drug delivery and, thus, a promising targeting anticancer chemotherapeutic agent.
International journal of pharmaceutics, Jan 25, 2011
Surfactants are used as additives in topical pharmaceuticals and drug delivery systems. The bioco... more Surfactants are used as additives in topical pharmaceuticals and drug delivery systems. The biocompatibility of amino acid-based surfactants makes them highly suitable for use in these fields, but tests are needed to evaluate their potential toxicity. Here we addressed the sensitivity of tumor (HeLa, MCF-7) and non-tumor (3T3, 3T6, HaCaT, NCTC 2544) cell lines to the toxic effects of lysine-based surfactants by means of two in vitro endpoints (MTT and NRU). This comparative assay may serve as a reliable approach for predictive toxicity screening of chemicals prior to pharmaceutical applications. After 24-h of cell exposure to surfactants, differing toxic responses were observed. NCTC 2544 and 3T6 cell lines were the most sensitive, while both tumor cells and 3T3 fibroblasts were more resistant to the cytotoxic effects of surfactants. IC(50)-values revealed that cytotoxicity was detected earlier by MTT assay than by NRU assay, regardless of the compound or cell line. The overall resu...
International journal of peptide and protein research, 1994
In order to explore the ability of amphiphilic peptides to behave as surface-active agents with e... more In order to explore the ability of amphiphilic peptides to behave as surface-active agents with emulsifying properties, several short peptides of leucine and glutamine were synthesized with different periodicity, length and hydrophobic characteristics. The stepwise liquid-phase procedure using the N-hydroxysuccinimide ester was deployed in all chain-lengthening steps, and the same procedure was also used subsequently to modify some of the products by introducing a lipophilic moiety such as a palmitoyl residue. The surface-active properties of these products were evaluated by measuring the variation of surface (gamma s) and interfacial (gamma i) tensions and the formation of micelles as a function of concentration in aqueous solution. The alternating sequence (Leu-Gln)n showed good surface activity behaviour, similar to those of recognized surfactants, albeit with no emulsifying function. More hydrophobic compounds, such as lipopeptides, lowered the surface tension of water at concen...
... Bromide] and the Study of its Thermodynamic Properties Saliha Alehyen Fatima Bensajjay Mo... more ... Bromide] and the Study of its Thermodynamic Properties Saliha Alehyen Fatima Bensajjay Mohammed El Achouri Lourdes Pérez Aurora Pinazo Marıa Rosa Infante Received: 18 March 2009 / Accepted: 24 August 2009 / Published online: 24 October 2009 Ó AOCS 2009 ...
Synthesis of Glycero Amino Acid-Based Surfactants. Part 1. Enzymatic Preparation of rac-1-O-(N α-... more Synthesis of Glycero Amino Acid-Based Surfactants. Part 1. Enzymatic Preparation of rac-1-O-(N α-Acetyl-L-aminoacyl)glycerol Derivatives.-N α-Protected amino acids (I) are selectively esterified with one of the primary hydroxy groups of glycerol under optimized conditions using various enzymes. Since the enzymes can not differentiate between the two enantiotopic hydroxymethyl groups of glycerol, in all cases approximately 1:1 diastereomeric mixtures are obtained. Aspartic and glutamic acid derivatives (Ic) and (Id) are selectively esterified at the α-carboxylate group.-(MORAN,
The aim of this study was to find new biocompatible surfactants and mixtures with low ocular irri... more The aim of this study was to find new biocompatible surfactants and mixtures with low ocular irritant action for application in pharmaceutical formulations and to establish a relationship between their structure and their potential ocular irritant activity. An alternative method to the Draize in vivo test, based on the adverse effects of surfactants on the cytoplasmic membrane of red blood cell, was used to evaluate the potential ocular irritation of the surfactants. It was found that the hemolytic activity of arginine-based gemini surfactants increased with the aliphatic alkyl chain lengths of the hydrophobic tail. The addition of the surfactant with an alkyl chain length of 10 carbon atoms to cocoamidopropilbetaina (TB), decylglucoside (APG), and Nalpha-lauroyl-arginine ethyl ester (LAE) increases the hemolytic activity moderately for the mixtures with TB and LAE (1.1- and 1.5-fold, respectively) and strongly for APG (five-fold). The new arginine-based gemini surfactants constitut...
Page 1. 5 Amino Acids, Lactic Acid and Ascorbic Acid as Raw Materials for Biocompatible Surfactan... more Page 1. 5 Amino Acids, Lactic Acid and Ascorbic Acid as Raw Materials for Biocompatible Surfactants Carmen Moran1, Lourdes Perez2, Ramon Pons2, Aurora Pinazo2 and Maria Rosa Infante2 1Chemistry Department, Coimbra ...
The ultraviolet-A radiation damage effects on skin and eyes will be increased by phototoxic compo... more The ultraviolet-A radiation damage effects on skin and eyes will be increased by phototoxic compounds which could be present in pharmaceutical or cosmetic formulations. Great efforts have been made in the last years to find surfactants to replace those with phototoxic potential in commercial use. Series of different in vitro models for phototoxicity, included to validated neutral red uptake (NRU) 3T3 phototoxicity assay are useful screening tools. The phototoxic effects of a novel family of glycerol amino acid-based surfactant compounds were examined via these assays. Human red blood cells and two immortalised cell lines, murine fibroblast cell line 3T3, and one human keratinocyte cell line, HaCaT, were the in vitro models employed to predict potential photoirritation. The phototoxic end-points assessed were hemolysis (human red blood cell test) and resazurin transformation to resorufin and NRU in cell culture methods. The results suggest that no phototoxic effects by any new amino acid derived-surfactants, could be identified.
Monoacylglycerol amino acid conjugates constitute a novel class of specific biocompatible surfact... more Monoacylglycerol amino acid conjugates constitute a novel class of specific biocompatible surfactants that can be considered analogues to partial glycerides and lysophospholipids. They consist of one aliphatic chain and one polar head, i.e., the amino acid, linked through a glycerol moiety. In a previous work, we synthesized monolauroylated amino acid glyceride conjugates, 1-O-lauroyl-rac-glycero-3-O-(N R-acetyl-L-amino acid), changing the amino acid headgroup systematically: arginine (compound 2), aspartic acid (compound 3), glutamic acid (compound 4), asparagine (compound 5), glutamine (compound 6), and tyrosine (compound 7), to elucidate the structure-properties relationship governing the occurrence of their polymorphism. The thermotropism of the new compounds was measured with polarizing light microscopy, differential scanning calorimetry, and X-ray diffraction and compared with the classical monoglyceride rac-1-lauroylglycerol (compound 1). The experiments were performed for a sequence of heating, cooling, and reheating scans. The results showed that compounds 1-6 exhibit a thermotropic smectic phase. As a consequence, the substitution of the polar head did not engender any curvature into the system, which might lead to the formation of cubic or columnar phases. Interestingly, liquid crystalline phases were not found in the case of compound 7. Smallangle X-ray diffraction data in the gel phase revealed that the substitution of the polar head by the different amino acid structures did not modify significantly the lamellar repeat distance relative to that of the reference one. The observed area per molecule, however, was larger for the new compounds. Consequently, interdigitation was promoted in compounds 2-7. The diffraction patterns were analyzed in terms of electron density profiles, using a modified Caillé theory plus a Gaussian electron density representation (MCG method) on X-ray diffraction data.
ABSTRACT In search of more effective and lower impact surfactants, hydrophobic modification of po... more ABSTRACT In search of more effective and lower impact surfactants, hydrophobic modification of polymers has emerged as a promising strategy for the substitution of low molecular weight surfactants. Inulin, a polysaccharide obtained from chicory roots, has links with the sustainable chemistry model. Furthermore, hydrophobically modified inulins (HMI) can be synthesized in aqueous media. This article reports on the surface activity and aggregation of several compounds with differences in hydrophobic alkyl length and backbone linkage. HMI significantly reduces (down to 30 mN m(-1)) water surface tension while inulin does not. Both inulins and HMI are shown to aggregate hierarchically at three levels, namely aggregates (< 20 nm), flocks (< 100 nm) and precipitates (> 500 nm). The smaller aggregates, which in the case of inulins can be classified as monomers and in the case of HMI as micelles, have dimensions below 15 nm. The second level of aggregation corresponds to loose flocks with dimensions up to 100 nm and the third level corresponds to the precipitate constituted by aggregation of the flocks. Temperature and basic conditions affect the flock formation and kinetics without a strong influence on the smaller aggregates structure and size. Long term standing of both HMI and inulin solutions eventually precipitates. This precipitate may occupy a large volume but corresponds to a small amount of the solute. In the case of inulins, the precipitate has been found to have a degree of crystallinity that diminishes with increasing temperature.
This paper presents an environmentally improved procedure for the preparative purification of a s... more This paper presents an environmentally improved procedure for the preparative purification of a series of arginine-based gemini surfactants. The technique used was cation-exchange chromatography. Mixtures of boric-borate buffer, co-solvent (ethanol), and sodium chloride were tested as eluents. The influence of the buffer pH and the amount of co-solvent on the chromatographic process was studied for the model compound bis(Nalpha-lauroyl-L-arginine) 1,3-propanediamide dihydrochloride, C3(LA)2, and purification conditions were established. The method was scaled-up to the multigram level for C3(LA)2 and the rest of the series. The proposed preparative procedure involves simple equipment, low cost materials, and minimal amounts of solvent (water/ethanol), with low toxicity.
... of 1.5 nm. 3.4. Conductivity Measurements. Conductances G were measured usingJones cells (Met... more ... of 1.5 nm. 3.4. Conductivity Measurements. Conductances G were measured usingJones cells (Metrohm Models EA-655-5 and EA-655−50) in conjunction with a Radiometer CDM3 conductivity meter. The cell constants were ...
... Pérez, † Aurora Pinazo, † Milton J. Rosen, ‡ and M a Rosa Infante* †. Department of Surfactan... more ... Pérez, † Aurora Pinazo, † Milton J. Rosen, ‡ and M a Rosa Infante* †. Department of Surfactant Technology, CID (CSIC), J. Girona 18-26, 08034 Barcelona, Spain, and Surfactant Research Institute, Brooklyn College of the City University of New York, Brooklyn, New York 11210. ...
Journal of Dispersion Science and Technology, 1999
ABSTRACT New monodisperse nonionic surfactant molecules based on lysine with two different fatty ... more ABSTRACT New monodisperse nonionic surfactant molecules based on lysine with two different fatty acid chains in the hydrophobic part and one or two polyoxyethylene methoxy capped chain s (EOn-Me) in the hydrophilic head group were synthesized and their physicochemical and toxicity properties were compared to the symmetrical homologs with the same number of methylene groups in the acyl fatty chains. Our findings indicate that the asymmetry studied results in higher surface active properties and in a greater capacity for micellization when compared with their symmetrical analogs, albeit with a slight increase in toxicity.
The growing demand for efficient chemotherapy in many cancers requires novel approaches in target... more The growing demand for efficient chemotherapy in many cancers requires novel approaches in target-delivery technologies. Nanomaterials with pH-responsive behavior appear to have potential ability to selectively release the encapsulated molecules by sensing the acidic tumor microenvironment or the low pH found in endosomes. Likewise, polyethylene glycol (PEG)- and poloxamer-modified nanocarriers have been gaining attention regarding their potential to improve the effectiveness of cancer therapy. In this context, DOX-loaded pH-responsive nanoparticles (NPs) modified with PEG or poloxamer were prepared and the effects of these modifiers were evaluated on the overall characteristics of these nanostructures. Chitosan and tripolyphosphate were selected to form NPs by the interaction of oppositely charged compounds. A pH-sensitive lysine-based amphiphile (77KS) was used as a bioactive adjuvant. The strong dependence of 77KS ionization with pH makes this compound an interesting candidate to...
Neutral hydrophobic β-hydroxyalkyl ethers of inulin have been prepared with varying molecular fea... more Neutral hydrophobic β-hydroxyalkyl ethers of inulin have been prepared with varying molecular features (the hydrophobic characteristics of the epoxide, length and nature, and the number of grafted groups per fructose units) in aqueous media under different ...
The encapsulation of antitumor drugs in nanosized systems with pH-sensitive behavior is a promiss... more The encapsulation of antitumor drugs in nanosized systems with pH-sensitive behavior is a promissing approach that may enhance the success of chemotherapy in many cancers. The nanocarrier dependence on pH might trigger an efficient delivery of the encapsulated drug both in the acidic extracellular environment of tumors and, especially, in the intracellular compartments through disruption of endosomal membrane. In this context, here we reported the preparation of chitosan-based nanoparticles encapsulating methotrexate as a model drug (MTX-CS-NPs), which comprises the incorporation of an amino acid-based amphiphile with pHresponsive properties (77KS) on the ionotropic complexation process. The presence of 77KS clearly gives a pH-sensitive behavior to NPs, which allowed accelerated release of MTX with decreasing pH as well as pH-dependent membrane-lytic activity. This latter performance demonstrates the potential of these NPs to facilitate cytosolic delivery of endocytosed materials. Outstandingly, the cytotoxicity of MTX-loaded CS-NPs was higher than free drug to MCF-7 tumor cells and, to a lesser extent, to HeLa cells. Based on the overall results, MTX-CS-NPs modified with the pH-senstive surfactant 77KS could be potentially useful as a carrier system for intracellular drug delivery and, thus, a promising targeting anticancer chemotherapeutic agent.
International journal of pharmaceutics, Jan 25, 2011
Surfactants are used as additives in topical pharmaceuticals and drug delivery systems. The bioco... more Surfactants are used as additives in topical pharmaceuticals and drug delivery systems. The biocompatibility of amino acid-based surfactants makes them highly suitable for use in these fields, but tests are needed to evaluate their potential toxicity. Here we addressed the sensitivity of tumor (HeLa, MCF-7) and non-tumor (3T3, 3T6, HaCaT, NCTC 2544) cell lines to the toxic effects of lysine-based surfactants by means of two in vitro endpoints (MTT and NRU). This comparative assay may serve as a reliable approach for predictive toxicity screening of chemicals prior to pharmaceutical applications. After 24-h of cell exposure to surfactants, differing toxic responses were observed. NCTC 2544 and 3T6 cell lines were the most sensitive, while both tumor cells and 3T3 fibroblasts were more resistant to the cytotoxic effects of surfactants. IC(50)-values revealed that cytotoxicity was detected earlier by MTT assay than by NRU assay, regardless of the compound or cell line. The overall resu...
International journal of peptide and protein research, 1994
In order to explore the ability of amphiphilic peptides to behave as surface-active agents with e... more In order to explore the ability of amphiphilic peptides to behave as surface-active agents with emulsifying properties, several short peptides of leucine and glutamine were synthesized with different periodicity, length and hydrophobic characteristics. The stepwise liquid-phase procedure using the N-hydroxysuccinimide ester was deployed in all chain-lengthening steps, and the same procedure was also used subsequently to modify some of the products by introducing a lipophilic moiety such as a palmitoyl residue. The surface-active properties of these products were evaluated by measuring the variation of surface (gamma s) and interfacial (gamma i) tensions and the formation of micelles as a function of concentration in aqueous solution. The alternating sequence (Leu-Gln)n showed good surface activity behaviour, similar to those of recognized surfactants, albeit with no emulsifying function. More hydrophobic compounds, such as lipopeptides, lowered the surface tension of water at concen...
... Bromide] and the Study of its Thermodynamic Properties Saliha Alehyen Fatima Bensajjay Mo... more ... Bromide] and the Study of its Thermodynamic Properties Saliha Alehyen Fatima Bensajjay Mohammed El Achouri Lourdes Pérez Aurora Pinazo Marıa Rosa Infante Received: 18 March 2009 / Accepted: 24 August 2009 / Published online: 24 October 2009 Ó AOCS 2009 ...
Synthesis of Glycero Amino Acid-Based Surfactants. Part 1. Enzymatic Preparation of rac-1-O-(N α-... more Synthesis of Glycero Amino Acid-Based Surfactants. Part 1. Enzymatic Preparation of rac-1-O-(N α-Acetyl-L-aminoacyl)glycerol Derivatives.-N α-Protected amino acids (I) are selectively esterified with one of the primary hydroxy groups of glycerol under optimized conditions using various enzymes. Since the enzymes can not differentiate between the two enantiotopic hydroxymethyl groups of glycerol, in all cases approximately 1:1 diastereomeric mixtures are obtained. Aspartic and glutamic acid derivatives (Ic) and (Id) are selectively esterified at the α-carboxylate group.-(MORAN,
The aim of this study was to find new biocompatible surfactants and mixtures with low ocular irri... more The aim of this study was to find new biocompatible surfactants and mixtures with low ocular irritant action for application in pharmaceutical formulations and to establish a relationship between their structure and their potential ocular irritant activity. An alternative method to the Draize in vivo test, based on the adverse effects of surfactants on the cytoplasmic membrane of red blood cell, was used to evaluate the potential ocular irritation of the surfactants. It was found that the hemolytic activity of arginine-based gemini surfactants increased with the aliphatic alkyl chain lengths of the hydrophobic tail. The addition of the surfactant with an alkyl chain length of 10 carbon atoms to cocoamidopropilbetaina (TB), decylglucoside (APG), and Nalpha-lauroyl-arginine ethyl ester (LAE) increases the hemolytic activity moderately for the mixtures with TB and LAE (1.1- and 1.5-fold, respectively) and strongly for APG (five-fold). The new arginine-based gemini surfactants constitut...
Page 1. 5 Amino Acids, Lactic Acid and Ascorbic Acid as Raw Materials for Biocompatible Surfactan... more Page 1. 5 Amino Acids, Lactic Acid and Ascorbic Acid as Raw Materials for Biocompatible Surfactants Carmen Moran1, Lourdes Perez2, Ramon Pons2, Aurora Pinazo2 and Maria Rosa Infante2 1Chemistry Department, Coimbra ...
The ultraviolet-A radiation damage effects on skin and eyes will be increased by phototoxic compo... more The ultraviolet-A radiation damage effects on skin and eyes will be increased by phototoxic compounds which could be present in pharmaceutical or cosmetic formulations. Great efforts have been made in the last years to find surfactants to replace those with phototoxic potential in commercial use. Series of different in vitro models for phototoxicity, included to validated neutral red uptake (NRU) 3T3 phototoxicity assay are useful screening tools. The phototoxic effects of a novel family of glycerol amino acid-based surfactant compounds were examined via these assays. Human red blood cells and two immortalised cell lines, murine fibroblast cell line 3T3, and one human keratinocyte cell line, HaCaT, were the in vitro models employed to predict potential photoirritation. The phototoxic end-points assessed were hemolysis (human red blood cell test) and resazurin transformation to resorufin and NRU in cell culture methods. The results suggest that no phototoxic effects by any new amino acid derived-surfactants, could be identified.
Monoacylglycerol amino acid conjugates constitute a novel class of specific biocompatible surfact... more Monoacylglycerol amino acid conjugates constitute a novel class of specific biocompatible surfactants that can be considered analogues to partial glycerides and lysophospholipids. They consist of one aliphatic chain and one polar head, i.e., the amino acid, linked through a glycerol moiety. In a previous work, we synthesized monolauroylated amino acid glyceride conjugates, 1-O-lauroyl-rac-glycero-3-O-(N R-acetyl-L-amino acid), changing the amino acid headgroup systematically: arginine (compound 2), aspartic acid (compound 3), glutamic acid (compound 4), asparagine (compound 5), glutamine (compound 6), and tyrosine (compound 7), to elucidate the structure-properties relationship governing the occurrence of their polymorphism. The thermotropism of the new compounds was measured with polarizing light microscopy, differential scanning calorimetry, and X-ray diffraction and compared with the classical monoglyceride rac-1-lauroylglycerol (compound 1). The experiments were performed for a sequence of heating, cooling, and reheating scans. The results showed that compounds 1-6 exhibit a thermotropic smectic phase. As a consequence, the substitution of the polar head did not engender any curvature into the system, which might lead to the formation of cubic or columnar phases. Interestingly, liquid crystalline phases were not found in the case of compound 7. Smallangle X-ray diffraction data in the gel phase revealed that the substitution of the polar head by the different amino acid structures did not modify significantly the lamellar repeat distance relative to that of the reference one. The observed area per molecule, however, was larger for the new compounds. Consequently, interdigitation was promoted in compounds 2-7. The diffraction patterns were analyzed in terms of electron density profiles, using a modified Caillé theory plus a Gaussian electron density representation (MCG method) on X-ray diffraction data.
ABSTRACT In search of more effective and lower impact surfactants, hydrophobic modification of po... more ABSTRACT In search of more effective and lower impact surfactants, hydrophobic modification of polymers has emerged as a promising strategy for the substitution of low molecular weight surfactants. Inulin, a polysaccharide obtained from chicory roots, has links with the sustainable chemistry model. Furthermore, hydrophobically modified inulins (HMI) can be synthesized in aqueous media. This article reports on the surface activity and aggregation of several compounds with differences in hydrophobic alkyl length and backbone linkage. HMI significantly reduces (down to 30 mN m(-1)) water surface tension while inulin does not. Both inulins and HMI are shown to aggregate hierarchically at three levels, namely aggregates (< 20 nm), flocks (< 100 nm) and precipitates (> 500 nm). The smaller aggregates, which in the case of inulins can be classified as monomers and in the case of HMI as micelles, have dimensions below 15 nm. The second level of aggregation corresponds to loose flocks with dimensions up to 100 nm and the third level corresponds to the precipitate constituted by aggregation of the flocks. Temperature and basic conditions affect the flock formation and kinetics without a strong influence on the smaller aggregates structure and size. Long term standing of both HMI and inulin solutions eventually precipitates. This precipitate may occupy a large volume but corresponds to a small amount of the solute. In the case of inulins, the precipitate has been found to have a degree of crystallinity that diminishes with increasing temperature.
This paper presents an environmentally improved procedure for the preparative purification of a s... more This paper presents an environmentally improved procedure for the preparative purification of a series of arginine-based gemini surfactants. The technique used was cation-exchange chromatography. Mixtures of boric-borate buffer, co-solvent (ethanol), and sodium chloride were tested as eluents. The influence of the buffer pH and the amount of co-solvent on the chromatographic process was studied for the model compound bis(Nalpha-lauroyl-L-arginine) 1,3-propanediamide dihydrochloride, C3(LA)2, and purification conditions were established. The method was scaled-up to the multigram level for C3(LA)2 and the rest of the series. The proposed preparative procedure involves simple equipment, low cost materials, and minimal amounts of solvent (water/ethanol), with low toxicity.
... of 1.5 nm. 3.4. Conductivity Measurements. Conductances G were measured usingJones cells (Met... more ... of 1.5 nm. 3.4. Conductivity Measurements. Conductances G were measured usingJones cells (Metrohm Models EA-655-5 and EA-655−50) in conjunction with a Radiometer CDM3 conductivity meter. The cell constants were ...
... Pérez, † Aurora Pinazo, † Milton J. Rosen, ‡ and M a Rosa Infante* †. Department of Surfactan... more ... Pérez, † Aurora Pinazo, † Milton J. Rosen, ‡ and M a Rosa Infante* †. Department of Surfactant Technology, CID (CSIC), J. Girona 18-26, 08034 Barcelona, Spain, and Surfactant Research Institute, Brooklyn College of the City University of New York, Brooklyn, New York 11210. ...
Journal of Dispersion Science and Technology, 1999
ABSTRACT New monodisperse nonionic surfactant molecules based on lysine with two different fatty ... more ABSTRACT New monodisperse nonionic surfactant molecules based on lysine with two different fatty acid chains in the hydrophobic part and one or two polyoxyethylene methoxy capped chain s (EOn-Me) in the hydrophilic head group were synthesized and their physicochemical and toxicity properties were compared to the symmetrical homologs with the same number of methylene groups in the acyl fatty chains. Our findings indicate that the asymmetry studied results in higher surface active properties and in a greater capacity for micellization when compared with their symmetrical analogs, albeit with a slight increase in toxicity.
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Papers by Rosa Infante