SciCombinator

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Concept: Light scattering

138

Two O/W forskolin-loaded nano-emulsions (0.075% wt.) based on medium chain triglycerides (MCT) and stabilized by a nonionic surfactant (Polysorbate 80 or Polysorbate 40) were studied as forskolin delivery systems. The nano-emulsions were prepared by the PIC method. The mean droplet size of the nano-emulsions with Polysorbate 80 and Polysorbate 40 with oil/surfactant (O/S) ratios of 20/80 and 80% water concentration, measured by Dynamic Light Scattering (DLS), was of 118 nm and 111 nm, respectively. Stability of the formulations, as assessed by light backscattering for 24 h, showed that both nano-emulsions were stable at 25ºC. Studies of forskolin in vitro skin permeation from the nano-emulsions and from a triglyceride solution were carried out at 32ºC, using Franz-type diffusion cells. A mixture of PBS/ethanol (60/40 v/v) was used as a receptor solution. The highest flux and permeability coefficient was obtained for the system stabilized with Polysorbate 80 (6.91±0.75 µg·cm-2·h-1 and 9.21·10-3±1.00·10-3 cm·h-1, respectively) but no significant differences were observed with the flux and permeability coefficient value of forskolin dissolved in oil. The obtained results showed that the nano-emulsions developed in this study could be used as effective carriers for topical administration of forskolin.

Concepts: Fatty acid, Surfactant, Colloidal chemistry, Light scattering, Dynamic light scattering, Polysorbate 80, Polysorbate, Polysorbate 20

55

Successful commercialization of wearable diagnostic sensors necessitates stability in detection of analytes over prolonged and continuous exposure to sweat. Challenges are primarily in ensuring target disease specific small analytes (i.e. metabolites, proteins, etc.) stability in complex sweat buffer with varying pH levels and composition over time. We present a facile approach to address these challenges using RTILs with antibody functionalized sensors on nanoporous, flexible polymer membranes. Temporal studies were performed using both infrared spectroscopic, dynamic light scattering, and impedimetric spectroscopy to demonstrate stability in detection of analytes, Interleukin-6 (IL-6) and Cortisol, from human sweat in RTILs. Temporal stability in sensor performance was performed as follows: (a) detection of target analytes after 0, 24, 48, 96, and 168 hours post-antibody sensor functionalization; and (b) continuous detection of target analytes post-antibody sensor functionalization. Limit of detection of IL-6 in human sweat was 0.2 pg/mL for 0-24 hours and 2 pg/mL for 24-48 hours post-antibody sensor functionalization. Continuous detection of IL-6 over 0.2-200 pg/mL in human sweat was demonstrated for a period of 10 hours post-antibody sensor functionalization. Furthermore, combinatorial detection of IL-6 and Cortisol in human sweat was established with minimal cross-talk for 0-48 hours post-antibody sensor functionalization.

Concepts: Spectroscopy, Scattering, PH, Ionic liquid, Sensors, Light scattering, Dynamic light scattering, Rayleigh scattering

28

Dynamic light scattering based sensor for glucose was developed with oligonucleotide functionalized gold nanoparticles (Oligo-AuNPs). Oligonucleotide 5'-SH-(A)(12)-AGACAAGAGAGG-3' (Oligo 1) modified AuNPs and oligonucleotide 5'-CAACAGAGAACG-(A)(12)-HS-3' (Oligo 2) modified AuNPs could hybridize with oligonulceotide 5'-CGTTCTCTGTTGCCTCTCTTGTCT-3' (Oligo 3), which resulted in the aggregation of Oligo-AuNPs probes, and triggered the increase of their average diameter. However, Oligo 3 could be cleaved into DNA fragments by the mixture of glucose, glucose oxidase (GOD) and Fe(2+), and the DNA fragments could not hybridize with Oligo-AuNPs probes. Under the conditions of 3.7 nM Oligo 1-AuNPs, 3.7 nM Oligo 2-AuNPs, 8.0 μg/mL GOD, 100 nM Oligo 3 and 900 nM Fe(2+), the average diameter of Oligo-AuNPs probes decreased linearly with the increasing concentration of glucose over the range from 50 pmol/L to 5.0 nmol/L, with a detection limit of 38 pmol/L (3σ/slope). Moreover, five sugars had no effect on the average diameter of mixture of Oligo-AuNPs probes, GOD and Fe(2+), which demonstrated the good selectivity of the assay.

Concepts: Nanoparticle, Scattering, Nanotechnology, Gold, Light scattering, Dynamic light scattering, Rayleigh scattering, Static light scattering

28

Pluronic F127/poly(aspartic acid) mixtures were investigated in dilute solutions by viscometry and dynamic light scattering. The two polymers were chosen due to well known applications in biomedical field, taking into account the final purpose (the use of the complex structure as drug delivery systems). The central item was to identify the possibility of complexation between the poly(carboxylic acid) and a non-ionic polymer and to investigate the conditions of the interpolymer complex formation. The ability of Pluronic F127 to form micelle is well known. Poly(aspartic acid), as a polycarboxylic acid with resemblance with polyacrylic acid, can act as dispersant, antiscalant, superabsorber, being also able to form micelles. Due to its functional groups, COOH and NH(2), poly(aspartic acid) can make physical and/or chemical bonds with other macromolecular compounds. The intrinsic viscosity and the dynamic light scattering data obtained for PLU/PAS mixtures at 25°C have shown that interpolymer complex formation occurs around 1/1wt. ratio between the two polymers.

Concepts: Concentration, Chemistry, Chemical compound, Colloidal chemistry, Light scattering, Dynamic light scattering, Rayleigh scattering, Polymers

28

The time-evolutions of nanoparticle hydrodynamic radius and aggregate fractal dimension during the aggregation of fullerene (C(60)) nanoparticles (FNPs) were measured via simultaneous multiangle static and dynamic light scattering. The FNP aggregation behavior was determined as a function of monovalent (NaCl) and divalent (CaCl(2)) electrolyte concentration, and the impact of addition of dissolved natural organic matter (humic acid) to the solution was also investigated. In the absence of humic acid, the fractal dimension decreased over time with monovalent and divalent salts, suggesting that aggregates become slightly more open and less compact as they grow. Although the aggregates become slightly more open, the magnitude of the fractal dimension suggests intermediate aggregation between the diffusion- and reaction-limited regimes. We observed different aggregation behavior with monovalent and divalent salts upon the addition of humic acid to the solution. For NaCl-induced aggregation, the introduction of humic acid significantly suppressed the aggregation rate of FNPs at NaCl concentrations lower than 150mM. In this case, the aggregation was intermediate or reaction-limited even at NaCl concentrations as high as 500mM, giving rise to aggregates with a fractal dimension of 2.0. For CaCl(2)-induced aggregation, the introduction of humic acid enhanced the aggregation of FNPs at CaCl(2) concentrations greater than about 5mM due to calcium complexation and bridging effects. Humic acid also had an impact on the FNP aggregate structure in the presence of CaCl(2), resulting in a fractal dimension of 1.6 for the diffusion-limited aggregation regime. Our results with CaCl(2) indicate that in the presence of humic acid, FNP aggregates have a more open and loose structure than in the absence of humic acid. The aggregation results presented in this paper have important implications for the transport, chemical reactivity, and toxicity of engineered nanoparticles in aquatic environments.

Concepts: Chemistry, Soil, Aggregate, Aggregate data, Light scattering, Humus, Natural organic matter, Fractal

28

This research mainly deals with a novel flame-retardant and UV-protection for cellulosic fabrics using ZnO nanoparticles. We present the preparation and application of ZnO nanoparticles. The size of the prepared nanoparticles was analysed using dynamic light scattering (DLS). The application of nano ZnO on cellulosic fabrics (cotton 100% and cotton/cotton polyester 65/35%) was achieved by using different polycarboxilic acids (succinic acid [SA] and 1,2,3,4-butane tetracarboxilic acids [BTCA]) with sodium hypophosphite (SHP) as catalyst through conventional pad-dry-cure method. The effect of concentration of SHP on the physical properties, flammability and UV-protection of cross-linked fabrics are investigated. The effect of concentration of zinc oxide nanoparticles and the effect of curing temperature were also investigated. The results revealed the importance of SHP in increasing the flame-redundancy of the treated cellulosic fabrics.

Concepts: Ultraviolet, Zinc, Titanium dioxide, Zinc oxide, Textile, Sunscreen, Light scattering, Dynamic light scattering

28

In the present work ethanol, methanol, petroleum ether and water extracts of the leaves of Ocimum sanctum were screened for their anti-microbial activity by using the agar diffusion method. The minimum inhibitory concentration of the extracts was also measured. The methanol extracts O. sanctum proved to have the maximum antimicrobial effect were loaded inside the sodium alginate chitosan nanoparticles by cation induced controlled gelification method and finished on cotton fabric by pad dry cure method. The average particle size of the nanoparticles was calculated using dynamic light scattering technique. The antimicrobial activity of the fabrics was assessed by using the standard AATCC technique (AATCC 100). The quantitative tests proved that cotton fabrics finished with the methanol extract of O. sanctum loaded nanoparticles possessed remarkable antibacterial activities with excellent wash durability. The study revealed that the herb encapsulated nanoparticle could act as a biocontrol agent against bacteria in fabrics.

Concepts: Alcohol, Ethanol, Scattering, Cell wall, Cotton, Textile, Antimicrobial, Light scattering

28

The influence of shape on nanomaterial aggregation and deposition was systematically studied with poly-acrylic acid (PAA) coated uniform-sized gold nanospheres (AuNSs) and nanorods (AuNRs). Time resolved dynamic light scattering was employed to study their aggregation kinetics in a wide range of mono- and di-valent electrolyte conditions. Results indicated that PAA coated AuNSs have higher aggregation propensity compared to anisotropic PAA coated AuNRs, as observed through critical coagulation concentration (CCC). The CCC values were estimated as 50mM NaCl and 1.8mM CaCl(2) for AuNS, which showed substantial increase to 250mM NaCl and 7mM CaCl(2) for anisotropic AuNRs. Though electrokinetic behavior showed similar surface potential for the spherical and rod-shaped materials, the geometric differences between the samples have likely resulted in unique conformation of the PAA coatings, leading to different magnitudes of steric hindrances and hence yielding the observed aggregation behavior. The deposition kinetics was monitored using the quartz crystal microbalance with dissipation technique. AuNRs showed relatively slower deposition compared to AuNSs for low electrolytes concentrations. With the increase in electrolyte concentration, the differences in deposition rates between spheres and rods diminished. The results from this study showed that the shape of nanomaterials can influence interfacial properties and result in unique aggregation and deposition behavior under typical aquatic conditions.

Concepts: Nanoparticle, Electrochemistry, Nanotechnology, Nanomaterials, Electrolyte, Quartz, Light scattering, Dynamic light scattering

28

The terminal hydroxyl groups of amphiphilic multiarm star copolymers with a hydrophilic hyperbranched polyethylenimine (PEI) core and hydrophobic poly(ε-caprolactone) (PCL) arms were partially or completely transformed into the radical-crosslinkable methacrylate (MA) groups (PEI-b-PCL-MA). The resulting PEI-b-PCL-MA polymers with 100% MA substitution self-assembled in water into simple vesicles, whereas those with partial MA substitution aggregated into complex vesicles. These structures could be proved by transmission electron microscopy and dynamic light scattering only after crosslinking the intra-vesicular MA groups that generated the covalently stabilized vesicles (CSVs). The obtained CSVs could be used as host for the formation of gold nanoparticle (AuNP) cluster, and the AuNP clusters stabilized by the CSVs were stable under a wider range of CSV/AuNP feed ratio than those stabilized by the uncrosslinked precursors. The diameter of AuNPs in the clusters was in the range of 4-6 nm, and the distance of adjacent AuNPs could be modulated through altering the feed ratio of CSV/AuNP. The color of the solutions of AuNPs with CSV could be tuned from brown to red, purple, even blue. The composites of CSV and AuNPs could be further used as nanocarriers to accommodate hydrophobic guest of pyrene, and a higher amount of AuNPs in the nanocarriers led to a lower encapsulation capacity for pyrene guests.

Concepts: Electron, Nanoparticle, Nanotechnology, Gold, Scientific techniques, Light scattering, Dynamic light scattering, Rayleigh scattering

28

Concanavalin A (Con A) binding fraction of human seminal plasma is vital as it shows decapacitating activity and contains proteins which have critical roles in fertility related processes. Con A binding proteins were isolated by lectin affinity chromatography. These proteins form high molecular weight aggregates at near physiological pH (7.0) as inferred by gel filtration. Aggregation analysis was performed by dynamic light scattering (DLS). DLS analysis was also performed at different pH values and in presence of various additives including NaCl, EDTA, cholesterol and sugars, such as D-glucose, D-fructose and D-mannose to identify their effect on aggregation size. The results indicate that degree of aggregation was highly reduced in presence of D-fructose, EDTA and at lower and higher pH values as depicted by lowering of hydrodynamic radii. This aggregation behaviour might be decisive for fertility related events with a suggestive role towards inhibition of premature capacitation.

Concepts: Proteins, Molecular biology, Glucose, PH, Light scattering, Dynamic light scattering, Concanavalin A, Lectin