Enhanced low-cost lipopeptide biosurfactant production by Bacillus velezensis from residual glycerin.

Biosurfactants (BSFs) are molecules produced by microorganisms from various carbon sources, with applications in bioremediation and petroleum recovery. However, the production cost limits large-scale applications. This study optimized BSFs production by Bacillus velezensis (strain MO13) using residual glycerin as a substrate. The spherical quadratic central composite design (CCD) model was used to standardize carbon source concentration (30 g/L), temperature (34 °C), pH (7.2), stirring (239 rpm), and aeration (0.775 vvm) in a 5-L bioreactor. Maximum BSFs production reached 1527.6 mg/L of surfactins and 176.88 mg/L of iturins, a threefold increase through optimization. Microbial development, substrate consumption, concentration of BSFs, and surface tension were also evaluated on the bioprocess dynamics. Mass spectrometry Q-TOF-MS identified five surfactin and two iturin isoforms produced by B. velezensis MO13. This study demonstrates significant progress on BSF production using industrial waste as a microbial substrate, surpassing reported concentrations in the literature.

Assessment of spilled oil dispersion affected by dispersant: Characteristic, stability, and related mechanism.

Oil dispersion, a crucial process in oil transport, involves the detachment of oil droplets from slicks and their introduction into the water column, influencing subsequent oil migration and transformation. This study examines oil dispersion, considering characteristics, stability, and mechanisms, while evaluating the impact of dispersants and salinity. Results show the significant role of surfactant type in dispersants on oil dispersion characteristics, with anionic surfactants exhibiting higher sensitivity to salinity changes compared to nonionic surfactants. The dispersion efficiency varies with salinity, with anionic surfactants performing better in low salinity (<20‰) and nonionic surfactants showing superior performance at 30-35‰ salinities. Rheological analysis illustrates the breakup and coalescence of oil droplets within the shear rates of breaking waves. An increase in interfacial film rigidity impedes the coalescence of oil droplets, contributing to the dynamic stability of the oil-water hybrid system. The use of GM-2, a nonionic dispersant, results in the formation of a solid-like interface, characterized by increased elastic modulus, notably at 20‰ salinity. However, stable droplet size distribution (DSD) at 35‰ salinity for 60 h suggests droplets can remain dispersed in seawater. The enhancement of stability of oil dispersion is interpreted as the result of two mechanisms: stabilizing DSD and developing the strength of viscoelastic interfacial film. These findings offer insights into oil dispersion dynamics, highlighting the importance of surfactant selection and salinity in governing dispersion behavior, and elucidating mechanisms underlying dispersion stability.

Surfactant-based supramolecular dye assembly: A highly selective and economically viable platform for quantification of heparin antidote.

Herein, we have employed a supramolecular assembly of a cationic dye, LDS-698 and a common surfactant sodium dodecyl sulfate (SDS) as a turn-on fluorescent sensor for protamine (Pr) detection. Addition of cationic Pr to the solution of dye-surfactant complex brings negatively charged SDS molecules together through strong electrostatic interaction, assisting aggregation of SDS way before its critical micellar concentration (CMC). These aggregates encapsulate the dye molecules within their hydrophobic region, arresting non-radiative decay channels of the excited dye. Thus, the LDS-698•SDS assembly displays substantial enhancement in fluorescence intensity that follows a nice linear trend with Pr concentration, providing limit of detection (LOD) for Pr as low as 3.84(±0.11) nM in buffer, 124.4(±6.7) nM in 1% human serum and 28.3(±0.5) nM in 100% human urine. Furthermore, high selectivity, low background signal, large stokes shift, and emission in the biologically favorable deep-red region make the studied assembly a promising platform for Pr sensing. As of our knowledge it is the first ever Pr sensory platform, using a very common surfactant (SDS), which is economically affordable and very easily available in the market. This innovative approach can replace the expensive, exotic and specialized chemicals considered for the purpose and thus showcase its potential in practical applications.

Application of D-Optimal Mixture Design in the Development of Nanocarrier-Based Darifenacin Hydrobromide Gel.

BACKGROUND: Darifenacin hydrobromide, a BCS Class II drug, is poorly bioavailable due to extensive first-pass metabolism. The present study is an attempt to investigate an alternative route of drug delivery by developing a nanometric microemulsion-based transdermal gel for the management of an overactive bladder. METHODS: Oil, surfactant, and cosurfactant were selected based on the solubility of the drug, and surfactant: cosurfactant in surfactant mixture (Smix) was selected at a 1:1 ratio as inferred from the pseudo ternary phase diagram. The D-optimal mixture design was used to optimize the o/w microemulsion wherein the globule size and zeta potential were selected as dependable variables. The prepared microemulsions were also characterized for various physico-chemical properties like transmittance, conductivity, and TEM. The optimized microemulsion was gelled using Carbopol 934 P and assessed for drug release in vitro and ex vivo, viscosity, spreadability, pH, etc. RESULTS: Drug excipient compatibility studies showed that the drug was compatible with formulation components. The optimized microemulsion showed a globule size of less than 50 nm and a high zeta potential of -20.56 mV. The ME gel could sustain the drug release for 8 hours as reflected in in vitro and ex vivo skin permeation and retention studies. The accelerated stability study showed no significant change in applied storage conditions. CONCLUSION: An effective, stable, non-invasive microemulsion gel containing darifenacin hydrobromide was developed. The achieved merits could translate into increased bioavailability and dose reduction. Further confirmatory in vivo studies on this novel formulation, which is a cost-effective & industrially scalable option, can improve the pharmacoeconomics of overactive bladder management.

Comparative life cycle assessment for the manufacture of bio-detergents.

The increasing consumption of cleaning products deteriorates water resources due to harmful components such as phosphorus (P) and nitrogen (N) compounds, oils, bleach, and acids, typical compounds in traditional detergents. The use of biodegradable detergents as an environmentally friendly alternative has been proposed in different regions. In Colombia, resolution 1770/2018 sets a minimum biodegradability rate of 60% for the surfactants present in liquid detergents, which would reduce to a similar extent the impacts on water after their use. However, the environmental impacts of the supply chain of these detergents and their raw materials have not been evaluated so far. This study presents an environmental life cycle assessment of petroleum-based liquid detergents and a comparison to traditional solid detergents, based on the ISO 14040 standard and the ReCiPe-2016 impacts assessment method. A novel bio-detergent containing anionic plant-based surfactants was proposed in this analysis. The impacts of packaging and the distribution of the product to consumers were also considered. Raw materials contributed to 91% of the total of 314 g of CO2 eq generated per liter of liquid detergent, where the production of fatty alcohol sulfate and PET packaging shared 78.8% and 12.2% of the total impact, respectively. It was also determined that 5.4 L of water are consumed and 0.09 g of P eq and 0.1 g of N eq are emitted per liter of detergent. This liquid detergent presented better environmental performance than traditional detergents in all the impact categories, except for the fossil resource scarcity category. The evaluated detergent would significantly mitigate the generation of negative effects on ecosystems. Moreover, the substitution of PET for HDPE packaging could reduce the impacts on freshwater eutrophication by 10%, although the carbon footprint can slightly increase, which could be compensated due to its higher recyclability rate. In contrast, the proposed bio-detergent would not have significant benefits and would negatively affect water consumption and land use in its supply chain.

Biomolecules from Serratia sp. CS1 indigenous to Ethiopian natural alkaline lakes: biosurfactant characteristics and assessment of compatibility in a laundry detergent.

In this study, the biosurfactants (Bio-SFs) producing bacteria are screened from the selected alkaline lake of Ethiopia, and the potential bacterial strain and their produced Bio-SFs are further characterized. In an initial screening, 25 bacterial isolates were isolated, and among those, the bacterial isolate assigned as CS1 was identified as the most potent producer of Bio-SFs using a subsequent characterization process. The CS1 strain was identified as Serratia sp. via biochemical and molecular methods. An emulsion index (E24) of 69.06 ± 0.11% was obtained for CS1 after 5 days of incubation time at 30 °C. The CS1-extracted Bio-SFs were characterized by Fourier transform infrared (FTIR), and it indicated that the type of biosurfactant produced was a glycolipid. The stability of the crude Bio-SFs was characterized, and the optimal conditions were found to be 80 °C, pH 8, and 3% NaCl, respectively. The extracted Bio-SFs were compatible with tested commercial detergents, and its efficiency increased from 12.2 ± 0.1% to 67.1 ± 0.17% and 70.43 ± 0.11% when combined with commercially available detergent brands in Ethiopia such as Taza and Largo, respectively. This study suggests that the isolated S. marcescens CS1 strain has the potential to produce Bio-SFs that are viable competence to replace the use of synthetic chemicals in the production of commercial detergents.

Formulation Design, Characterization and In-Vivo Assessment of Cefixime Loaded Binary Solid Lipid Nanoparticles to Enhance Oral Bioavailability.

Cefixime; widely employed cephalosporin antibiotic is unfortunately coupled to poor water solubility with resultant low oral bioavailability issues. To solve this problem micro-emulsion technique was used to fabricate binary SLNs using blend of solid and liquid lipids, surfactant as well as co-surfactant. The optimized nano suspension was characterized followed by modification to solidified dosage form. During characterization, optimized nano-suspension (CFX-4) produced particle size 189±2.1 nm with PDI 0.310±0.02 as well as -33.9±2 mV zeta potential. Scanning electron microscopy (SEM) presented nearly identical and spherical shaped particles. Differential scanning calorimetry and X-ray powder diffraction analysis ascertained decrease in drug's crystallinity. In-vitro release of drug pursued zero-order characteristics and demonstrated non-fickian pattern of diffusion. The freeze dried nano suspension (CFX-4) was transformed to capsule dosage form to perform comparison based In-Vivo studies. In-Vivo evaluation corresponded to 2.20-fold and 2.11-fold enhancement in relative bioavailability of CFX nano-formulation (CFX-4) as well as the prepared capsules respectively in contrast to the commercialized product (Cefiget®). In general; the obtained results substantiated superior oral bioavailability along with sustained pattern of drug release for CFX loaded binary nano particles. Thus, binary SLNs could be employed as a resourceful drug carrier for oral CFX delivery.

A detailed assessment on the interaction of sodium alginate with a surface-active ionic liquid and a conventional surfactant: a multitechnique approach.

An investigation has been made on the interaction of a biodegradable anionic polyelectrolyte, sodium alginate (NaAlg), with two oppositely charged cationic surfactants, 1-hexadecyl-3-methyl imidazolium chloride (C16MImCl) and 1-hexadecyl triphenylphosphonium bromide (C16TPB), the former is a surface active ionic liquid (SAIL) and the latter a conventional surfactant over a wide concentration regime of the polyelectrolyte. Dual influence of electrostatic and hydrophobic interactions plays in this investigation when mixing surfactants with an oppositely charged polyelectrolyte. A number of different experimental techniques, e.g., conductometry, tensiometry, steady state and time resolved spectrofluorimetry, turbidimetry, isothermal titration calorimetry (ITC), dynamic light scattering (DLS), attenuated total reflection (ATR), high resolution transmission electron microscopy (HR-TEM) and fluorescence microscopy, have been implemented to get comprehensive information about the interaction of the oppositely charged polyelectrolyte and surfactants. Tensiometry study reveals the existence of several conformations of NaAlg influenced by different concentrations of surfactants titrated to it and these are abbreviated as critical aggregation concentration (cac), saturated concentration of polymer-surfactant complex (Cs) and finally extended critical micelle concentration due to the aggregation of the surfactant itself, appearing in chronological order from low to high concentrations of surfactants. Apart from tensiometry, these above concentrations have been well found and the values are well comparable when investigating polyelectrolyte-surfactant interaction by other physicochemical techniques as well. Irreversible phase separation of the oppositely charged polyelectrolyte-surfactant complex (PS-complex) occurs at higher polyelectrolyte concentration investigated here for both the surfactants in the vicinity of cac for C16MImCl and near for C16TPB and finally persists after further addition of surfactants above the formation of free micelles. Several bulk and interfacial parameters, viz., Gibbs free energy of micellization , enthalpy of micellization , entropy of micellization , degree of counterion binding (ß), surface excess at cmc (Γmax), area minimum (Amin), surface pressure at cmc (πcmc), pC20, packing parameter (P), hydrodynamic radius (r) and aggregation number (Na) of two surfactants both in the presence and absence of NaAlg, have been calculated for these investigated systems. Characterization of NaAlg, both surfactants and their individual complexes was performed using FTIR-ATR. DLS shows the distribution of size of polymer surfactant complexes over a wide range of surfactant concentrations at a fixed polyelectrolyte concentration, while HR-TEM study reveals not only the size of agglomerated clusters of the PS-complex but also its shapes. Images of NaAlg-surfactant complexes were also captured using fluorescence microscopy in solution phase. A strong PS-complex in the presence of C16MImCl has been reported here over C16TPB.

Characterization and cytotoxicity assessment of biosurfactant derived from Lactobacillus pentosus NCIM 2912.

Noteworthy properties of biosurfactant (BS) are fascinating scientific fraternity to explore them for food, medicinal, cosmetic, or pharmaceutical etc. applications. Newer products intended for pharmaceutical purposes are mandatory to go through pragmatic evaluation protocols. BS, being less cytotoxic, offers an ideal candidature for widespread applications in the healthcare sector. The goal of the current study was the isolation, physico-chemical characterization, and safety assessment of cell-associated biosurfactant (CABS) from Lactobacillus pentosus NCIM 2912. The culture was grown in a 3-L fermentor to produce CABS from the cell pellets through procedures like centrifugation, filtration, dialysis, column chromatography, and freeze-drying. Further, physical properties like surface tension (ST), critical micelle concentration (CMC), contact angle (CA), emulsification activity, stability of emulsion (height of emulsion, the extent of coalescence, and appearance), and ionic character of CABS were evaluated. Analytical characterization through TLC, FTIR, NMR, and GC-MS was carried out. The physico-chemical characterization revealed CABS as an anionic, multicomponent glycolipopeptide having a hydrophobic chain comprising butanoic acid (C4), decanoic acid (C10), undecanoic acid (C11), tridecanoic acid (C13), hexadecenoic acid (C16), and octadecanoic acid (C18). The oil-in-water (O/W) emulsions formed by CABS with various oils (olive, sesame, soybean, coconut) were stabilized up to the 7th day of storage and were analogous with polysorbate 80 (emulsifier/defoamer used in food industries). The O/W emulsions are quite stable at room temperature with no evidence of coalescence of droplets around 1 week. The cytotoxicity of CABS was evaluated through MTT (3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cytotoxicity study performed on the human embryonic kidney (HEK 293), mouse fibroblast ATCC L929 and human epithelial type (HEP-2) cell lines recorded viability of 90.3 ± 0.1%, 99.2 ± 0.43, and 94.3 ± 0.2% respectively. The toxicity of the BS was comparable to that of the commercially used rhamnolipid sample. Thus, CABS derived from L. pentosus NCIM 2912 pose promising applications in the pharmaceutical, food industries acquiescently. The multifunctional potential of the incredibly versatile microbial product like BS from lactic acid bacteria (LAB) certainly contributes to wider avenues for varied industries.

Single-Molecule Study of Thermomyces lanuginosus Lipase in a Detergency Application System Reveals Diffusion Pattern Remodeling by Surfactants and Calcium.

Lipases comprise one of the major enzyme classes in biotechnology with applications within, e.g., baking, brewing, biocatalysis, and the detergent industry. Understanding the mechanisms of lipase function and regulation is therefore important to facilitate the optimization of their function by protein engineering. Advances in single-molecule studies in model systems have provided deep mechanistic insights on lipase function, such as the existence of functional states, their dependence on regulatory cues, and their correlation to activity. However, it is unclear how these observations translate to enzyme behavior in applied settings. Here, single-molecule tracking of individual Thermomyces lanuginosus lipase (TLL) enzymes in a detergency application system allowed real-time direct observation of spatiotemporal localization, and thus diffusional behavior, of TLL enzymes on a lard substrate. Parallelized imaging of thousands of individual enzymes allowed us to observe directly the existence and quantify the abundance and interconversion kinetics between three diffusional states that we recently provided evidence to correlate with function. We observe redistribution of the enzyme's diffusional pattern at the lipid-water interface as well as variations in binding efficiency in response to surfactants and calcium, demonstrating that detergency effectors can drive the sampling of lipase functional states. Our single-molecule results combined with ensemble activity assays and enzyme surface binding efficiency readouts allowed us to deconvolute how application conditions can significantly alter protein functional dynamics and/or surface binding, both of which underpin enzyme performance. We anticipate that our results will inspire further efforts to decipher and integrate the dynamic nature of lipases, and other enzymes, in the design of new biotechnological solutions.

Amended Safety Assessment of Fatty Acyl Sarcosines and Sarcosinate Salts as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 5 acyl sarcosines and 9 sarcosinate salts as used in cosmetics; all of these ingredients are reported to function in cosmetics as hair conditioning agents and most also can function as surfactants-cleansing agents. The ingredients reviewed in this assessment are composed of an amide comprising a fatty acyl residue and sarcosine and are either free acids or simple salts thereof. The Panel relied on relevant new data, including concentration of use, and considered data from the previous Panel report, such as the reaction of sarcosine with oxidizing materials possibly resulting in nitrosation and the formation of N-nitrososarcosine. The Panel concluded that these ingredients are safe as used in cosmetics when formulated to be non-irritating, but these ingredients should not be used in cosmetic products in which N-nitroso compounds may be formed.

A systematic assessment of the relationship between synthetic surfactants and mucosal adjuvanticity.

Intranasal immunization with surfactants as vaccine adjuvants enhances protective immunity against invasive mucosal pathogens. However, the effects of surfactants and their adjuvanticity on mucosal immune responses remain unclear. Comparison of the mucosal adjuvanticity of 20 water-soluble surfactants from the four classes based upon the polarity composition of the hydrophilic headgroup revealed that the order of mucosal adjuvanticity was as follows: amphoteric > nonionic > cationic > anionic. Within the same class, each surfactant displayed different adjuvanticity values. Analysis of the diameter and ζ-potential of amphoteric surfactant-OVA complexes and their surface physicochemical properties revealed that the diameter was approximately 100 nm, which is considered suitable for immune induction, and that the ζ-potential of the anionic surfactant-OVA complexes was exceedingly negative. The increase in the number of carbon atoms in the hydrophobic tailgroups of the amphoteric surfactant resulted in an increase in the OVA-specific Ab titers. Our findings demonstrate that amphoteric surfactants exhibit potent mucosal adjuvanticity and highlight the importance of the number of carbon atoms in the tailgroups and the diameter and ζ-potential of the complexes when designing mucosal adjuvants.

Kinetic modeling and quasi-economic analysis of fermentative glycolipopeptide biosurfactant production in a medium co-optimized by statistical and neural network approaches.

This study presents the kinetics of production of a glycolipopeptide biosurfactant in a medium previously co-optimized by response surface and neural network methods to gain some insight into its volumetric and specific productivities for possible scale-up towards industrial production. Significant kinetic parameters including maximum specific growth rate, µmax, specific substrate consumption rate, qs and specific biosurfactant yield, Yp/x were determined from logistic model parameters after comparison with other kinetic models. Results showed that bio-catalytic rates of lipase and urease reached exponential values within the first 12 h of fermentation leading to high specific rates of substrate consumption and bacterial growth. Volumetric biosurfactant production reached significantly high levels during prolonged stationary growth and specific urease activity. This suggests that glycolipopeptide biosynthesis may proceed through stationary phase transpeptidation of the glycolipid base. A high cross-correlation coefficient of 0.950 confirmed that substrate consumption and glycolipopeptide production occurred contemporaneously during the 66-h fermentation. The maximum biosurfactant concentration of 132.52 g/L, µmax of 0.292 h-1, qp of 1.674 g/gDCW/h, rp of 2.008 g/(Lh) and Yp/x of 4.413 g/g predicted by the selected logistic model and a unit cost of €0.57/g glycolipopeptide in the optimized medium may lead to technical and economic benefits.

Lipid-based nano-formulation platform for eplerenone oral delivery as a potential treatment of chronic central serous chorioretinopathy: in-vitro optimization and ex-vivo assessment.

PURPOSE: Eplerenone (EPL) is a selective mineralocorticoid receptor antagonist used for treatment of chronic central serous chorioretinopathy which characterized by accumulation of subretinal fluid causing a localized area of retinal detachment. unfortunately, EPL suffers from poor oral bioavailability due to poor aqueous solubility in addition to high hepatic first pass metabolism. METHOD: Aiming to improve its oral bioavailability, EPL-loaded nanostructured lipid carriers (NLCs) were prepared by the emulsification solvent evaporation method and in-vitro evaluated for particle size (PS), polydispersity index (PDI), zeta potential (ZP), and entrapment efficiency (EE%). A D-optimal design was used for study the effect of liquid lipid to solid lipid ratio, surfactant type and percentage on PS, PDI, EE%, and for data optimization. The optimized EPL-loaded NLCs system was further evaluated using in-vitro drug release and ex-vivo permeation studies through rabbit intestine in comparison to EPL aqueous suspension. The physicochemical properties of the drug in the optimized system were further examined using FT-IR and X-ray diffraction studies. RESULTS: The resultant NLCs showed small PS (100.85-346.60 nm), homogenous distribution (0.173-0.624), negatively charged particles (ZP -20.20 to -36.75 mV), in addition to EE% (34.31-70.64%). The optimized EPL-loaded NLCs system with a desirability value of 0.905 was suggested through the Design expert® software, containing liquid to solid lipid ratio (2:1) in presence of 0.43%w/v Pluronic® F127 as a surfactant. The optimized EPL-loaded NLCs system showed a PS of 134 nm and PDI of 0.31, in addition to high EE% (76 ± 6.56%w/w), and ZP (-32.37 mV). The ex-vivo permeation study showed two-fold higher drug permeation through rabbit intestine compared to that from the aqueous drug suspension after 24 h, confirming the ability of optimized EPL-loaded NLCs system as successful oral targeting delivery carrier. CONCLUSION: Our results pave the way for a new oral nanotherapeutic approach toward CSCR treatment. In-vivo study is currently under investigation.

Stability of Biologics and the Quest for Polysorbate Alternatives.

Most biopharmaceutical formulations use polysorbates: surfactants that are highly efficient but difficult to manage in terms of compositional variability, quality, and stability. Alternatives, such as poloxamers, albumin, and cyclodextrin, are becoming popular and are being explored for their potential to protect biopharmaceuticals against physical and mechanical stresses.

Characterization of low-cost glycolipoprotein biosurfactant produced by Lactobacillus plantarum 60 FHE isolated from cheese samples using food wastes through response surface methodology and its potential as antimicrobial, antiviral, and anticancer activities.

Considering the need of new lactic acid bacteria (LAB) for the production of novel biosurfactant (BS) molecules, the current study brings out a new insight on the exploration of cheese samples for BS producers and process optimization for industrial applications. In view of this, Lactobacillus plantarum 60FHE, Lactobacillus paracasei 75FHE, and Lactobacillus paracasei 77FHE were selected as the most operative strains. The biosurfactants (BSs) described as glycolipoproteins via Fourier-transform infrared spectroscopy (FTIR) exhibited antimicrobial activity against the food-borne pathogens. L. plantarum 60FHE BS showed an anticancer activity against colon carcinoma cells and had a week antiviral activity against Hepatitis A virus. Furthermore, glycolipoprotein production was enhanced by 1.42-fold through the development of an optimized process using central composite design (CCD). Emulsifying activities were stable after 60-min incubation from 4 to 120 °C, at pH 2-12, and after the addition of NaCl (2-14%). Characterization by nuclear magnetic resonance spectroscopy (1H NMR) revealed that BS produced from strain 60FHE was glycolipoprotein. L. plantarum produced mixed BSs determined by Liquid Chromatography/Mass Spectrometry (LC-MS). Thus, indicating that BS was applied as a microbial food prevention and biomedical. Also, L. plantarum 60FHE BS was achieved with the use of statistical optimization on inexpensive food wastes.

Safety Assessment of PEGylated Alkyl Glycerides as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of 60 PEGylated alkyl glycerides. PEGylated alkyl glycerides are mono-, di-, and/or triglycerides that have been modified with ethylene glycol repeat units (in the starting material form as epoxide). Most of the PEGylated alkyl glycerides are reported to function as skin-conditioning agents or surfactants. The Panel reviewed the available animal and clinical data as well as data from the 1999 report for the 5 polyethylene glycol (PEG) glyceryl cocoates and the 2012 report of PEGylated oils, to determine the safety of these ingredients. The Panel concluded these ingredients are safe in the current practices of use and concentration when formulated to be nonirritating; this conclusion supersedes the 1999 conclusion issued on 5 PEG glyceryl cocoate ingredients.

Can the Isothermal Calorimetric Curve Shapes Suggest the Structural Changes in Micellar Aggregates?

Inspired by the unusual shapes of the titration curve observed for many surfactants and mixed colloidal systems, we decided to extend the analysis to isothermal titration calorimetric curves (ITC) by paying special attention to potential structural changes in micellar aggregates. In this paper, we used isothermal titration calorimetry in conjunction with Scanning Transmission Electron Microscopy (STEM), Small-Angle Neutron Scattering (SANS) and X-ray Scattering (SAXS) methods support by Monte Carlo and semiempirical quantum chemistry simulations to confirm if the isothermal calorimetric curve shape can reflect micelle transition phenomena. For that purpose, we analysed, from the thermodynamic point of view, a group of cationic gemini surfactants, alkanediyl-α,ω-bis(dimethylalkylammonium) bromides. We proposed the shape of aggregates created by surfactant molecules in aqueous solutions and changes thereof within a wide temperature range. The results provide evidence for the reorganization processes and the relationship (dependence) between the morphology of the created aggregates and the conditions such as temperature, surfactant concentration and spacer chain length which affect the processes.

Biochemical characterization of a surfactant-stable keratinase purified from Proteus vulgaris EMB-14 grown on low-cost feather meal.

OBJECTIVES: The bioaccumulation of keratinous wastes from poultry and dairy industries poses a danger of instability to the biosphere due to resistance to common proteolysis and as such, microbial- and enzyme-mediated biodegradation are discussed. RESULTS: In submerged fermentation medium, Proteus vulgaris EMB-14 utilized and efficiently degraded feather, fur and scales by secreting exogenous keratinase. The keratinase was purified 14-fold as a monomeric 49 kDa by DEAE-Sephadex A-50 anion exchange and Sephadex G-100 size-exclusion chromatography. It exhibited optimum activity at pH 9.0 and 60 °C and was alkaline thermostable (pH 7.0-11.0), retaining 87% of initial activity after 1 h pre-incubation at 60 °C. The Km and Vmax of the keratinase with keratin azure were respectively 0.283 mg/mL and 0.241 U/mL/min. Activity of P. vulgaris keratinase was stimulated by Ca2+, Mg2+, Zn2+, Na+ and maintained in the presence of some denaturing agents, except ß-mercaptoethanol while Cu2+ and Pb2+ showed competitive and non-competitive inhibition with Ki 6.5 mM and 17.5 mM, respectively. CONCLUSION: This purified P. vulgaris keratinase could be surveyed for the biotechnological transformation of bioorganic keratinous wastes into valuable products such as soluble peptides, cosmetics and biodegradable thermoplastics.

Interfacial rheology for the assessment of potential health effects of inhaled carbon nanomaterials at variable breathing conditions.

Lung surface is the first line of contact between inhaled carbon nanomaterials, CNMs, and the organism, so this is the place where pulmonary health effects begin. The paper analyzes the influence of several CNMs (single- and multi-walled nanotubes with various surface area: 90-1,280 m2/g and aspect ratio: 8-3,750) on the surface-active properties of the lung surfactant, LS, model (Survanta). Effects of CNM concentration (0.1-1 mg/ml) and surface oscillation rate were determined using the oscillating drop method at simulated breathing conditions (2-10 s per cycle, 37 °C). Based on the values of apparent elasticity and viscosity of the interfacial region, new parameters: Sε and Sµ were proposed to evaluate potential effect of particles on the LS at various breathing rates. Some of tested CNMs (e.g., COOH- functionalized short nanotubes) significantly influenced the surfactant dynamics, while the other had weaker effects even at high particle concentration. Analysis of changes in Sε and Sµ provides a new way to evaluate of a possible disturbance of the basic functions of LS. The results show that the expected pulmonary effects caused by inhaled CNMs at variable breathing rate depend not only on particle concentration (inhaled dose) but also on their size, structure and surface properties.