Baocai Xu

Light and host–guest inclusion mediated salmon sperm DNA/surfactant interactions

DNA/cationic surfactant interaction is relevant from the viewpoint of gene therapy, where the complexation and resulting compaction are essential to protect DNA from nuclease, and to allow entry of DNA into cells. In this work, light input and host-guest inclusion controlled DNA complexation by a novel cationic surfactant 1-[6-(4-phenylazo-phenoxy)-hexyl]-3-methylimidazolium bromide (AzoC6Mim) is reported. The surfactant is covalently attached with an azobenzene group, which undergoes reversible photoisomerizations by changing light input. Under visible light, trans-AzoC6Mim can bind to salmon sperm DNA through electrostatic attraction and hydrophobic interaction, resulting into DNA compaction. Under UV light, although cis-AzoC6Mim still binds to DNA chain, DNA/surfactant complex is decompacted owing to the decrease of surfactant hydrophobicity. On the other hand, azobenzene group can form an inclusion complex with α-CD through host-guest interaction, which removes AzoC6Mim from DNA chain and decompacts the DNA/surfactant complex.

A surfactant type fluorescence probe for detecting micellar growth.

We report on the detection of micellar growth in anionic, cationic, and catanionic surfactant systems using a novel surfactant type fluorescence probe, sodium 12-(N-dansyl)amino-dodecanate (12-DAN-ADA). The fluorescent group was incorporated in the tail of the surfactant which tethers the fluorescent group deep inside the apolar micellar cores. The fluorescence anisotropy of 12-DAN-ADA was found to be very sensitive for directly detecting the micellar growth in micelles containing oppositely charged surfactants, including cationic CTAB systems and mixed systems of oppositely charged surfactants (DEAB/SDS); in regard to the like charged SDS micellar systems, the sensitivity can be greatly enhanced by addition of a water soluble quencher which quenches the background fluorescence from the equilibrium population of free 12-DAN-ADA.

Lauryl Trimethyl Ammoniums with New Type Counteranions

Abstract The interfacial properties of a new family of lauryl trimethyl ammonium salts of the general formula CH3(CH2)11N+(CH3)3X− (X = CH3OCOO, HCOO, CH3COO, CH3CHOHCOO) were studied. The physicochemical parameters of these quaternary ammonium salts were discussed. The effect of the counteranion on the behavior of these surfactants was analyzed.

A Surface Rheological Study of a Glucosamide-Based Trisiloxane Gemini Surfactant at the Air/Water Interface

The dilational viscoelastic properties of a glucosamide-based trisiloxane gemini surfactant at the air/water interface were investigated. Aqueous solutions of the glucosamide-based trisiloxane gemini surfactant were spread onto a pendant drop and the dynamic surface tensions were measured by means of axisymmetric drop shape analysis. The surface dilatational elasticity, viscosity, and phase angle of the adsorption monolayer were also determined by the oscillating drop technique. The influences of frequency and concentration on the surface dilational properties were expounded. It is showed that the surface dilational modulus and elastic modulus increased with the increase of frequency, the viscous modulus was complex, while the phase angle decreased with the increase of frequency. Surface dilational modulus, elastic modulus, and viscous modulus passed through the maximum with the increase of bulk concentration and the phase angle increased with the increase of concentration.

A Surface Rheological Study of Silwet L-77 Surfactant at the Air/Water Interface

The dilational viscoelastic properties of Silwet L-77, a trisiloxane surfactant of the general formula (Me3SiO)2SiMe(CH2)3(OCH2CH2)7.5OH, at the air/water interface were investigated. Aqueous solutions of Silwet L-77 were spread onto a pendant drop and the dynamic surface tensions were measured by means of axisymmetric drop shape analysis. The surface dilatational elasticity, viscosity, and phase angle of the adsorption monolayer were also determined using the oscillating drop technique. The influences of frequency and concentration on the surface dilational properties were expounded. It is shown that the surface dilational modulus and elastic modulus increased with the increase of frequency, the viscous modulus was complex, while the phase angle decreased with the increase of frequency. Surface dilational modulus, elastic modulus, and viscous modulus passed through the maximum with the increase of bulk concentration and the phase angle increased with the increase of concentration.

Foam and Rheological Properties of a Kind of Extended Surfactants

Abstract The foam and rheological properties of four extended surfactants C12–14PmE2S (m = 0, 3, 5, and 8) of four different concentrations were investigated in this paper. The foam properties, including, foamability, foam stability, liquid carrying ability, foam drainage and foam morphology were characterized. The rheological measurements were carried out through frequency sweep in the oscillation mode. The foamability and foam stability decreased with increasing numbers of PO groups embedded in those surfactants. At the same concentration, the longer the PO chain of the surfactant molecule, the larger the liquid carrying capacity of the foam. The foaming number decreases as the time increases, and longer PO chains were associated with faster foam number decline. The rheological measurements show that those surfactant solutions are “liquid-like”. With increasing surfactant concentration, the viscous modulus of C12–14P8E2S increases gradually, whereas that of C12–14E2S decreases.

The Preparation and Characterization of Water-Based Pigment Paste

The different water-based pigment paste was prepared using copper phthalocyanine blue pigment and dispersion resin, the influences of different pre-dispersion speed on dispersion of pigment paste were also investigated. And the characterization of the different pastes was investigated by rheology behavior, dynamic light scattering (DLS) and scanning electron microscopy (SEM) respectively. The results showed that the results measured by dynamic light scattering the best dispersion of the pigment paste was made when the pre-dispersion speed at 1000 rpm. But the results evaluated by rheology behavior showed that the best dispersion was when the pre-dispersion speed at 1500 rpm. Then the additional technique such as scanning electron microscopy was employed for proofing of pigment pastes. The SEM images of different samples are compared, and it is found that when the pre-dispersion speed at 1500 rpm, the pigment paste samples with good dispersion. Based on the results from different assessment methods, the pigment paste with best dispersion were prepared when pre-dispersion speed at 1500 rpm.

Synergistic interactions between zwitterionic surfactants derived from olive oil and an anionic surfactant

Abstract The surface properties of the mixtures of zwitterionic surfactants derived from olive oil (carboxylbetaine-OCB and sulfobetaine-OSB) and anionic surfactant-sodium dodecylbenzene sulfonate (SDBS) at different mole fractions were investigated by surface tension measurement. The influences of the addition of inorganic salts (NaCl, MgCl2) on the surface activities in OCB/SDBS and OSB/SDBS systems were also studied. The result shows that the two mixed systems possess lower CMC values and higher surface activities over all mole fractions studied than their individual components. Meanwhile, the noticeable synergistic interactions of OCB/SDBS and OSB/SDBS were determined by the micelle interaction parameter (βm) according to regular solution theory. It is observed that the mixed OCB/SDBS system at αOCB = 0.6 and the mixed OSB/SDBS system at αOSB = 0.6 exhibit the strongest synergism. In addition, the binary surfactant mixtures performed better surface activities upon addition of inorganic salts and the different valence state of mental ions of the inorganic salts had different surface ability effect on the mixed system: Mg2+ > Na+. Graphical Abstract

Synthesis, characterization, and surface properties of amide amine oxides based on natural vegetable oil

ABSTRACT Two types of novel amine oxide surfactants, castor oil amide amine oxide and cottonseed oil amide amine oxide, have been successfully synthesized via a two-step synthetic route with mild reaction conditions, the chemical structures of which were confirmed by mass spectra (MS) and FTIR spectra. Their surface activities have been measured. The results show that these synthesized amide amine oxide surfactants reduced the surface tension of water to a minimum value of approximately 32.48 mN/m at a concentration of 5.06 × 10−5 mol/L. It was also found that these novel amide amine oxide surfactants exhibited strong emulsifying power. GRAPHICAL ABSTRACT

Aggregation behaviors of amine-oxide gemini surfactants

ABSTRACT The micellar aggregation of a series of gemini surfactants [N, N’-dimethyl-N, N’-bis(2-alkylamideethyl)-ethylenediamine oxide (alkyl = C11H23, C13H27, C15H31)] in aqueous media has been investigated. The results show that there is an excellent agreement among the critical micelle concentration (CMC) values obtained by surface tension and steady-state fluorescence methods. Because of the occurrence of self-coiling or the formation of pre-micellization, the CMC values, the I1/I3 values, and the micelle aggregation numbers (Nagg) at CMC (Nm) increase with the hydrophobic alkyl chain length increasing. Besides, vesicles are observed above the CMC for all these surfactants. GRAPHICAL ABSTRACT