7 research outputs found
Dual Action of Hydrotropes at the Water/Oil Interface
Hydrotropes are substances
containing small amphiphilic molecules, which increase solubility
of nonpolar (hydrophobic) substances in water. Hydrotropes may form
dynamic clusters (less or about 1 ns lifetime) with water molecules;
such clusters can be viewed as “pre-micelles” or as
“micellar-like” structural fluctuations. We present
the results of experimental and molecular dynamics (MD) simulation
studies of interfacial phenomena and liquid–liquid equilibrium
in the mixtures of water and cyclohexane with the addition of a typical
nonionic hydrotrope, tertiary butanol. The interfacial tension between
the aqueous and oil phases was measured by Wilhelmy plate and spinning
drop methods with overlapping conditions in excellent agreement between
techniques. The correlation length of the concentration fluctuations,
which is proportional to the thickness of the interface near the liquid–liquid
critical point, was measured by dynamic light scattering. In addition,
we studied the interfacial tension and water–oil interfacial
profiles by MD simulations of a model representing this ternary system.
Both experimental and simulation studies consistently demonstrate
a spectacular crossover between two limits in the behavior of the
water–oil interfacial properties upon addition of the hydrotrope:
at low concentrations the hydrotrope acts as a surfactant, decreasing
the interfacial tension by adsorption of hydrotrope molecules on the
interface, while at higher concentrations it acts as a cosolvent with
the interfacial tension vanishing in accordance with a scaling power-law
upon approach to the liquid–liquid critical point. It is found
that the relation between the thickness of the interface and the interfacial
tension follows a scaling law in the entire range of interfacial tensions,
from a “sharp” interface in the absence of the hydrotrope
to a “smooth” interface near the critical point. We
also demonstrate the generic nature of the dual behavior of hydrotropes
by comparing the studied ternary system with systems containing different
hydrocarbons and hydrotropes
Dual Action of Hydrotropes at the Water/Oil Interface
Hydrotropes are substances
containing small amphiphilic molecules, which increase solubility
of nonpolar (hydrophobic) substances in water. Hydrotropes may form
dynamic clusters (less or about 1 ns lifetime) with water molecules;
such clusters can be viewed as “pre-micelles” or as
“micellar-like” structural fluctuations. We present
the results of experimental and molecular dynamics (MD) simulation
studies of interfacial phenomena and liquid–liquid equilibrium
in the mixtures of water and cyclohexane with the addition of a typical
nonionic hydrotrope, tertiary butanol. The interfacial tension between
the aqueous and oil phases was measured by Wilhelmy plate and spinning
drop methods with overlapping conditions in excellent agreement between
techniques. The correlation length of the concentration fluctuations,
which is proportional to the thickness of the interface near the liquid–liquid
critical point, was measured by dynamic light scattering. In addition,
we studied the interfacial tension and water–oil interfacial
profiles by MD simulations of a model representing this ternary system.
Both experimental and simulation studies consistently demonstrate
a spectacular crossover between two limits in the behavior of the
water–oil interfacial properties upon addition of the hydrotrope:
at low concentrations the hydrotrope acts as a surfactant, decreasing
the interfacial tension by adsorption of hydrotrope molecules on the
interface, while at higher concentrations it acts as a cosolvent with
the interfacial tension vanishing in accordance with a scaling power-law
upon approach to the liquid–liquid critical point. It is found
that the relation between the thickness of the interface and the interfacial
tension follows a scaling law in the entire range of interfacial tensions,
from a “sharp” interface in the absence of the hydrotrope
to a “smooth” interface near the critical point. We
also demonstrate the generic nature of the dual behavior of hydrotropes
by comparing the studied ternary system with systems containing different
hydrocarbons and hydrotropes
Rapid Optimization of Metal Nanoparticle Surface Modification with High-Throughput Gel Electrophoresis
The ability to effectively control and optimize surface modification of metal nanoparticles is paramount to the ability to employ metal nanoparticles as diagnostic and therapeutic agents in biology and medicine. Here we present a high-throughput two-dimensional-grid gel electrophoresis cell (2D-GEC)-based method, capable of optimizing the surface modification of as many as 96 samples of metal nanoparticles in approximately 1 h. The 2D-GEC method determines not only the average zeta-potential of the modified particles but also the homogeneity of the surface modification by measuring the distance between the front of the sample track and the area where the maximum optical density is achieved. The method was tested for optimizing pH and concentration of the modifiers (pM) for functionalizing gold nanorod thiol-containing acidic agents
Table_3_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.docx
The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p
Table_2_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.docx
The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p
Table_1_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.DOCX
The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p
Data_Sheet_1_Epinephrine extensively changes the biofilm matrix composition in Micrococcus luteus C01 isolated from human skin.DOCX
The importance of the impact of human hormones on commensal microbiota and microbial biofilms is established in lots of studies. In the present investigation, we continued and extended the research of epinephrine effects on the skin commensal Micrococcus luteus C01 and its biofilms, and also the matrix changes during the biofilm growth. Epinephrine in concentration 4.9 × 10–9 M which is close to normal blood plasma level increased the amount of polysaccharides and extracellular DNA in the matrix, changed extensively its protein, lipid and polysaccharide composition. The Ef-Tu factor was one of the most abundant proteins in the matrix and its amount increased in the presence of the hormone. One of the glucose-mannose polysaccharide was absent in the matrix in presence of epinephrine after 24 h of incubation. The matrix phospholipids were also eradicated by the addition of the hormone. Hence, epinephrine has a great impact on the M. luteus biofilms and their matrix composition, and this fact opens wide perspectives for the future research.</p