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A micelle-vesicle transition induced by n-octanol C(8)OH was observed in an aqueous cetyltrimethylammonium bromide (CTAB)/potassium bromide (KBr) system. This transition was investigated by viscosity, rheology, dynamic light scattering (DLS), and direct imaging technique, cryo-transmission electron microscopy (cryo-TEM). Viscometry shows that the system underwent several morphological transitions with the increase in concentration of C(8)OH (regions I-IV). At low octanol concentration (region I), DLS analysis showed an increase in the apparent hydrodynamic diameter of the micelles with the addition of C(8)OH which was supported by cryo-TEM and rheology. With further addition of C(8)OH, transition of the elongated micelles occurred to a viscoelastic fluid comprising entangled wormlike micelles (region II), for which rheological data can be described by the Maxwell model. Further, the wormlike micelles transform to vesicles at [C(8)OH] ≈ 0.020 M (region III). This transition and the consequent changes in the fluid response can be explained in terms of vesicle formation caused by further addition of C(8)OH. Beyond this concentration (region IV), vesicles are the predominant microstructures in the system which shows unusual temperature response.

The effect of long chain alcohols (C9OH–C12OH) on the micellar properties of CTAB in the presence of an inorganic salt, KBr, has been systematically studied by viscometry, rheology, DLS and the direct imaging technique,i.e.cryo-TEM.

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The interaction of SDS/SDBS in aqueous gelatin solutions is studied above the gelation temperature by viscosity and circular dichroism (CD) measurements. The steep rise observed in the relative viscosity can be due the structural transitions leading to micellar growth of higher order. Circular dichroism spectra indicated that gelatin helped in inducing the sphere?rod transition, without suffering any conformational changes within it. The findings are particularly significant in terms of the head group contribution, hydrophobic interaction and the formation of formulated complexes.

Scaffolds fabricated from polymers have imprinted its wide applicability in the field of tissue engineering. The surface of electrospun poly(lactic acid) (PLA) nanofibers was modified to improve their compatibility with living medium. PLA film were treated with alkali solution to introduce carboxyl groups on the surface followed by covalent grafting of gelatin using Xtal Fluoro-E as coupling agent. The gelatin g-PLA polymer synthesized via 'graft-onto' method exhibit fascinating properties as studied by contact angle measurement, fourier transformed infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, water vapor transmission rate(WVTR), swelling studies and differential scanning calorimetry. The fabricated gelatin g-PLA scaffolds were further characterized to conduct the study on hydrolytic degradation, and extent of biodegradation at ambient temperature. It was observed from the in-vitro analysis that the gelatin g-PLA nanofiber (with hemolytic percentage, 0.56 6 0.13%) was cytocompatible with fibroblast cell and does not impair cell growth. The WVTR obtained for the electrospun mat around 2900 6 100 g/m 2 . 24 h signifies the optimal moist environment required for tissue engineering especially wound healing. Notably, many of these strategies resulted in porous hydrophilic scaffolds with human cell growth and proliferation for medical applications of various types. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46056. INTRODCTIONPoly(L-lactic acid) (PLA) is one of the most important biodegradable, biocompatible, environment-friendly, and recyclable thermoplastic polyester with extensive biomedical applications. 1 However, due to the hydrophobic nature of the PLA, cell adhesion is not possible in a straight forward way. 2 The most convenient method to improve the cytocompatibility is by grafting PLA with some hydrophilic and bio-compatible components, such as chitosan, 3 gelatin, 4 alginate, 5 RGD peptide, 6 arginine, 7 lysine, PEG, 8 collagen and other extracellular matrix (ECM) proteins. In order to increase the cytocompatibility of PLA, modifications can be done by several processes such as polymerization grafting, 9 oxygen plasma modification, 10 hydrolysis, 11 entrapment, 12 aminolysis, 13 and so on. The employment of ECM proteins or RGD peptide for surface coating of PLA is one of the facile and favorable method to achieve cytocompatibility. Alternatively, the feasibility of swollen PLA surface entrapped with bio macro-molecules, such as chitosan, gelatin, and poly(L-lysine) increases when exposed to the solvent/non-solvent mixture, where most of the solvents for PLA are nonbiocompatible.Alkaline hydrolysis is one of the efficient and common pretreatment method to create active functional group on PLA backbone. 14 Most promising outcome has been established on treatment of the natural fibers with alkaline solution (e.g., with 2% sodium hydroxide aqueous solution). The improvement in the surface hydrophilicity can be confirmed by the decreasing contact angle of ...

Structural transitions triggered by pH in an aqueous micellar system comprising of a cationic surfactant (cetylpyridinium chloride) and an aromatic dibasic acid (phthalic acid) was investigated. Reversible switching between liquid-like and gel-like states was exhibited by the system on adjusting the solution pH. Self-assembled structures, responsible for the changes in flow properties were identified using rheology, light scattering techniques and cryogenic Transmission Electron Microscopy (cryo-TEM). High-viscosity, shear-thinning behavior and Maxwell-type dynamic rheology shown by the system at certain pH values suggested the growth of spheroidal/short cylindrical micelles into long and entangled structures. Light scattering profiles also supported the notion of pH-induced microstructural transitions in the solution. Cryo-TEM images confirmed the presence of spheroidal/short cylindrical micelles in the low-viscosity sample whereas very long and entangled thread-like micelles in the peak viscosity sample. pH-dependent changes in the micellar binding ability of phthalic acid is proposed as the key factor regulating the morphological transformations and related flow properties of the system.

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