Surfactant-mediated water transport at gelatin gel/oil interfaces

Size tunable mesoporous carbon microspheres using Pluronic F127 and gelatin as co-template for removal of ibuprofen

Size tunable mesoporous carbon microspheres, MCMs were obtained using Pluronic F127 and gelatin in co-templating method via hydrothermal and pyrolysis treatments. The presence of gelatin increased the mechanical strength of Pluronic F127 which can sustain the uniform microspherical structure of carbon following pyrolysis at 950 °C. The diameter of MCMs were controlled by variation of weight ratios between Pluronic F127 to gelatin from 1:0.01 to 1:1. MCMs exhibited inter-particulate mesoporous structure with high thermal stability (<500 °C). The MCMs were used as adsorbent for removal of ibuprofen and the kinetic studies using linear regression analysis revealed the adsorption fits pseudo second-order kinetic. The rate of adsorption and the amount of adsorbed ibuprofen were correlated well with the surface area and the crystallite size of MCMs. The efficiencies of ibuprofen adsorption on MCMs were also investigated when ibuprofen was dissolved at different concentration of water and hexane mixtures, the effect temperature variation and the amount MCMs to the volume of ibuprofen solution.

Nanoencapsulation improved water solubility and color stability of carotenoids extracted from Cantaloupe melon (Cucumis melo L.)

Cantaloupe melon carotenoids were encapsulated in porcine gelatin, whey protein isolate and concentrate by emulsification O/W to evaluate which agent could promote an increase in water solubility, and color stability in yogurt. The average particle size obtained was 59.3 (2.60) nm-161.0 (27.30) nm. Encapsulated crude extract in porcine gelatin presented the smallest size and polydispersity index [0.4 (0.04)], and showed sphericity, smooth surface and low agglomeration in SEM. These results associated to the good chemical interaction between the raw materials shown by FTIR, justify the increase in water solubility [0.072 (0.007) mg.mL^-1] compared to the crude extract [0.026 (0.003) mg.mL^-1]. The yogurt added with this nanoencapsulate remained stable for 60 days, unlike the crude extract. The results show that the nanoencapsulation using gelatin increased water solubility and the potential of application of melon carotenoids in food as natural dyes.

Spontaneous Microstructure Formation at Water/Paraffin Oil Interfaces

An experimental investigation of spontaneous emulsification is proposed with a water drop pendant in a paraffin oil (PO) solution loaded with a surfactant (SPAN80). Optical microscopy in a transmission mode is employed for high-spatial-resolution image recording. The kinetics of spontaneous emulsification is studied. It is shown to generate a darkening of the drops because of interface modification with a characteristic time that depends upon the SPAN80 concentration. For low concentrations, spontaneous emulsification is slow and produces micrometer-sized droplets, whereas for large concentrations, it is fast and bush-like microstructures are observed. These microstructures increase in size and progressively invade the complete water/PO interfaces, detach, and finally migrate into the PO phase. This transport phenomenon withdraws water from the drops and leads to a gradual shrinking of their volume. At the end of this process, they appear as deformed objects surrounded by a loose membrane.

Electrowetting of complex fluids: perspectives for rheometry on chip

We explore the possibilities of electrowetting (EW) as a tool to assess the elastic properties of aqueous jellifying materials present in the form of a small droplet on a hydrophobic substrate. We monitored the EW response of aqueous solutions of gelatin (2-10 wt %) in ambient oil for various temperatures (8-40 degrees C) below and above the gel point. Whereas the drops remained approximately spherical cap-shaped under all conditions, the voltage-induced reduction of the contact angle became progressively less pronounced upon entering the gel state at lower temperatures. We modeled the decrease in contact angle by minimizing the total energy of the drops consisting of interfacial energies, electrostatic energy, and the elastic energy due to the deformation of the drop, which was taken into account in a modified Hertz model. This allowed fitting the data and extracting the elastic modulus G, which were found to agree well with macroscopic storage moduli G' obtained with oscillatory shear rheometry. These results show that EW can be used as a tool for characterizing soft materials with the elastic moduli ranging (at least) from 10 to 1000 Pa. Our observations also create interesting perspectives for performing in situ rheological measurement inside microfluidic chips.