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Tunable solid-state fluorescence of a cationic dye acridine orange (AO) aggregates were triggered by introducing an anionic biosurfactant sodium deoxycholate (NaDC) as matrix. The NaDC/AO assembles with morphology of flabellate and dumbbell-shaped fiber bundles were formed via ionic self-assembly (ISA) strategy and both the ratio of NaDC to AO and temperature have influence on the morphology. Composition and driving force analysis of the microfibers have been investigated. The results revealed that the interaction between NaDC and AO was strongly influenced by direct electrostatic forces between the COO groups in NaDC and N + in AO, respectively. Besides the electrostatic interactions, which proved to be the main driving forces for the formation of the supramolecular aggregates, the π-π stacking and hydrogen bond interactions also makes some contribution. What’s more, the fluorescence have dramatically enhanced upon the formation of complex, and the wavelength and intensity of this solid-state aggregates fluorescence can be further controlled by the molar ratio of NaDC to AO which induced the fluorescence lifetime and fluorescence quantum yield both increase with the increased concentration of NaDC. Thus, it is expected that the facile design of tunable solid-state fluorescence material by the ISA strategy could be used to provide new insight for the development of solid luminescent materials. [ABSTRACT FROM AUTHOR]

Two-component hydrogels were formed by the supramolecular assembly of β-cyclodextrin (β-CD) and ionic liquid-type imidazolium gemini surfactants ([C 14 -4-C 14 im]Br 2 ) in water. The mechanism for the formation of hydrogels was studied by various methods including transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and rheological measurements. It can be revealed that in these hydrogels, β-CD is as the host and [C 14 -4-C 14 im]Br 2 is as the guest and they can form inclusion complexes. Moreover, the properties of the hydrogels of β-CD/[C 14 -4-C 14 im]Br 2 are responsive to external stimuli and can be controlled by changing the host/guest ratio or the temperature. For example, by increasing the temperature, the hydrogels change into solutions and this process is reversible and reproducible. Taken together and according to the previous study, it is suggested that the main driving forces are hydrogen bonding between β-CDs, β-CD and the imidazolium headgroup of [C 14 -4-C 14 im] 2+ , β-CD and the solvent, and the hydrophobic interaction between the hydrophobic chains of [C 14 -4-C 14 im]Br 2 . The properties of these hydrogels led them be useful in the field of biomedical applications such as injectable drug delivery systems. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (AuNCs) are a class of promising inorganic-organic hybrid nanomaterials with exceptional photoluminescent properties. The understanding of their photoluminescent mechanism is important for developing functional AuNCs-based materials. In this work, thiobarbituric acid-modified AuNCs (TBA-AuNCs) was prepared and its photoluminescent property was modulated through co-assembly with Ba2+. The emission intensity was sharply enhanced with the formation of TBA-AuNCs/Ba2+ complex. Structural characterization including transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy confirmed the hybridization of TBA-AuNCs with Ba2+. The pH-dependent photoluminescence as well as zeta potential measurements demonstrated that the ligand to metal charge transfer (LMCT) is crucial for the regulation of emission property of the TBA-AuNCs/Ba2+. Based on this special photoluminescent mechanism, the TBA-AuNCs/Ba2+ complex was employed as a chemical sensor for nitro-substituted aromatic compounds. The emission intensity of TBA-AuNCs/Ba2+ selectively displayed sharp quenching in response to 2-methyl-4-nitroimidazole among various imidazole derivatives. Simultaneously, the complex also showed high sensitivity toward p -nitroaniline and 2-nitrophenol. Therefore, the developed TBA-AuNCs/Ba2+ assemblies are potential in detecting the nitro-containing compounds, which will find applications in pharmaceutical analysis, environmental protection and other related fields. [Display omitted] • The emission of TBA-AuNCs is enhanced through the co-assembly with Ba2+. • The emission of TBA-AuNCs/Ba2+ complex is sensitive to pH value. • It is confirmed that the LMCT is crucial for the emission. • The TBA-AuNCs/Ba2+ complex can be used as a sensor for nitro-substituted compounds. [ABSTRACT FROM AUTHOR]

The effects of alkaline amino acids l -Lysine ( l -Lys) and l -Arginine ( l -Arg) on the lyotropic liquid crystal (LLC) behavior of ionic liquid-type imidazolium surfactant (1-tetradecyl-3-methylimidazolium bromide, C 14 mimBr) were investigated systematically. The corresponding properties were investigated by polarized optical microscopy (POM), small angle X-ray scattering (SAXS), field emission-scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy and rheological measurements. The results indicated that with the introduction of l -Lys, LLC phase of C 14 mimBr gradually undergoes the transition to an isotropic homogeneous phase, which demonstrated to be worm-like micelles (WLMs). While for C 14 mimBr/ l -Arg system, it remained the hexagonal phases and merely induced the variation of the mechanical strength of C 14 mimBr LLCs. It can be speculated that the balance between electrostatic interaction, H-bond interaction, and hydrophobic interaction plays an important role in the phase transition of C 14 mimBr/amino acids. Our work can contribute to a better understanding of the effect of the additions especially amino acids on the influence of the surfactant aggregates and their macroscopic properties, which maybe open the door for wide applications in the biological system. [ABSTRACT FROM AUTHOR]

Supramolecular hydrogels were facilitated by α-cyclodextrin (α-CD) and three silicone surfactants named S1E8, S1E19 and S2E38, respectively. Influences of the molecular structure and concentration of the silicone surfactants on the formation of hydrogels and their stabilities were investigated. The hydrogels were characterized by phase behavior study and various techniques. The results indicated that the balance between the hydrophilicity and the hydrophobicity of the silicone surfactants is crucial for the formation and high stability of the hydrogels. S2E38, which has two poly-(ethylene oxide) chains, exhibits a stronger ability to form hydrogels than S1E8 and S1E19 do. Moreover, in vitro study using doxorubicin (DOX) as a model anticancer drug shows that α-CD/silicone surfactant hydrogels can be used as injectable carriers for controlled drug release. [ABSTRACT FROM AUTHOR]

A water-in-oil (W/O) microemulsion was prepared by mixing cyclohexane and HAuCl 4 aqueous solution at the presence of a nonionic surfactant Triton X-100 and 1-hexanol. By successively adding sodium borohydride (NaBH 4 ), ammonium hydroxide (NH 3 ·H 2 O) and tetraethyl orthosilicate (TEOS) to this microemulsion, Au@SiO 2 hybrid nanoparticles were produced which have been fully characterized by transmission electron microscopy (TEM) and high resolution TEM (HR-TEM) observations, UV–vis measurements and thermo gravimetric analysis (TGA). It was found that in each Au@SiO 2 hybrid nanoparticle, the silica shell can encapsulate multiple Au nanodots. The parameters of the Au@SiO 2 hybrid nanoparticles including the thickness of the silica shell, the number of encapsulated Au nanodots and the size of the nanoparticles can be easily tuned by changing the volume of TEOS and the reaction time before adding TEOS, respectively. These interesting core–shell nanoparticles provide ideal candidates for a variety of applications in materials science, biology and catalysis. [ABSTRACT FROM AUTHOR]

Sodium deoxycholate/graphene oxide (NaDC/GO) composite hydrogels were prepared in varying salinity. The hydrogels were characterized in detail by phase behavior study, transmission electron microscopy (TEM) observations, scanning electron microscopy (SEM) observations, X-ray powder diffraction (XRD) mesurements, Fourier transform infrared (FT-IR) spectra and rheological measurements. It was found that the introduction of GO to NaDC hydrogel enhances the mechanical strength of the composite hydrogel. When contacted with methylene blue solution, methylene blue can be absorbed inside the gel accompanied with a swelling of the gel. On the contrary, the hydrogel forms by NaDC only dissolves in methylene blue solution, forming a homegeous solution. Further study reveals that the gelation of NaDC/GO composite gel can be accelerated by an increase in salinity. This work may open the door for a variety of applications of NaDC/GO composite hydrogels such as in biotechnology, drug delivery and sewage treatment. [ABSTRACT FROM AUTHOR]