Hexadecyl Dimethyl Ammonium Chloride Research Articles

Recombinant VAR2CSA malaria protein-targeted exosome-mediated DACT2 gene therapy for effective glioma treatment

A good non-viral vector is the key to the success of gene delivery and therapy; hence, modified exosomes may overcome the physiological barrier in the delivery in vivo. This study aims to design a novel non-viral vector and verify its gene delivery function in vitro and in vivo for dapper homolog 2 (DACT2) genes. In this study, amphipathicity cationic exosomes with receptor targeted function and DACT2 gene loading function were constructed by exosomes, PEG, glycidyl hexadecyl dimethylammonium chloride, and recombinant VAR2CSA malaria protein (RVP) antibody. Characterizations of RVP antibody and PEG modified cationic lipid exosome (RVP-CL) nanocomplexes were evaluated by dynamic light scattering, atomic force microscopy, FTIR, and so on. The DNA condensation ability and stability were assessed by agarose gel electrophoresis. Cellular uptake efficiency and cytotoxicity in glioma cells were investigated. Furthermore, the tumor suppressive effect was evaluated in vitro and in vivo. The results indicated that RVP-CL had a uniform size of 100–200 nm and positive zeta potential. With high uptake efficiency, RVP-CL can rapidly target, recognize, and enter the glioma cell (KNS-42 and U118 mg) and release the gene. Moreover, RVP-CL/DACT2 can effectively inhibit the growth of glioma cells in vitro and in vivo. The modified cationic exosomes may offer a promising strategy for gene delivery in the treatment of RVP-positive gliomas or other tumors.

A Mesopore-Dependent Catalytic Cracking of n-Hexane Over Mesoporous Nanostructured ZSM-5.

Herein, pore size, crystalinity, and Si/Al ratio of mesoporous ZSM-5 (MFI) nanocrystals was controlled by synthesis parameters, such as surfactant concentration ([3-(trimethoxysilyl)propyl] hexa-decyl dimethyl ammonium chloride), sodium hydroxide concentrations, synthesis temperature and time. The morphology, surface structure and composition of the MFI particles was systematically investigated. More notably, the mesopore-dependent catalytic activity of ZSM-5 was evaluated by studying the cracking of n-hexane. The findings suggest the porosity has pronounced impact on the catalytic activity, selectivity and stability of ZSM-5 nanocrystals. Critical surface attributes such as nature of acid sites (Brønsted and Lewis), concentration, and strength are obtained by the infrared study of adsorbed probe molecules (pyridine) and the temperature programmed desorption. In spite of being weaker in Si/Al ratio or acidic strength, mesoporous catalysts showed more stable and efficient cracking of n-hexane suggesting that acidity seems not the predominant factor operative in the activity, selectivity and stability.

Catanionic AOT/BDAC micelles on gold {111} surfaces

A sodium dioctyl sulfosuccinate (AOT)/benzyl hexadecyl dimethyl ammonium chloride (BDAC) mixed micelle self-organization and adsorption on gold Au(111) surfaces have been investigated using a molecular dynamics approach. The spherical AOT/BDAC mixed micelle is strongly adsorbed on the gold surface and is disoriented to a cylinder-like shape.

Interaction between quaternary ammonium surfactants with coal pitch and analysis surfactants effects on preparing coal pitch water slurry

The wetting behavior, adsorption amount and Zeta potential of aqueous solutions of the octadearyl dimethyl ammonium chloride (OTAC), cetyl trimethyl ammonium chloride (CTAC) and benzyl hexadecyl dimethyl ammonium chloride (HDBAC) on coal pitch surface were investigated. When the content of surfactant was constant, along with the growing of slurry concentration, the apparent viscosity of coal pitch water slurry (CPWS) increased. On the other side, it declined when shear rate grew. There was a liner relationship between contact angle and surface tension, so Zisman theory was well agreed with this wetting system. The adsorption amount of dispersants on coal pitch surface increased with the growing of solution concentration. The Zeta potential grew at first, and then stayed the constant.

Visible light photopolymerization in BHDC reverse micelles. Laser flash photolysis study of the photoinitiating mechanism

Abstract The photopolymerization of acrylamide (AA) in reverse micelles (RMs) of benzyl hexadecyl dimethylammonium chloride (BHDC) was investigated. The polymerization was performed by irradiation in the 500 nm region of the spectrum, employing as photoinitiating system the synthetic dye safranine-O and triethanolamine (TEOA) as co-initiator. The characterization of the nanoparticles of polyacrylamide was done by dynamic light scattering. Molecular weight determinations were carried out by viscosimetry. Small nanoparticles of polyacrylamide are formed with a low polydispersity and a molecular weight close to 10 6 . The results were compared with those in AOT (sodium bis(2-ethylhexyl) sulfosuccinate) RMs. Laser flash photolysis was used to investigate the photoinitiating mechanism. The maximum of the T – T absorption spectra in RMs confirms that, in spite of its positive charge, the dyes remain at the interface co-micellizing with BHDC. The triplet lifetime is much longer in the RMs than in homogeneous organic solvents. The triplet quenching by TEOA was very much more effective in the RMs than in a homogeneous solvent. The quantum yield of formation of active radicals was evaluated from the transient absorption spectra. It was concluded that they are generated by an intermicellar electron transfer process followed by an intramicellar proton transfer reaction. The quantum yield was found to be 0.2 ± 0.02. A similar radical yield in a homogeneous solvent requires an amine concentration near 50 times higher.

Spectroscopic and time-resolved fluorescence emission properties of a cationic and an anionic porphyrin in biomimetic media and Candida albicans cells

Abstract Spectroscopic and time-resolved fluorescence emission techniques were used to provide information for the interaction of 5,10,15,20-tetrakis(4- N , N , N -trimethylammoniumphenyl) porphyrin (TMAP 4+ ) and 5,10,15,20-tetrakis(4-sulphonatophenyl) porphyrin (TPPS 4− ) with different biomimetic media and with Candida albicans cells. In n -heptane/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water and benzene/benzyl- n -hexadecyldimethylammonium chloride (BHDC)/water reverse micelles interactions were dependent on the micellar interface and the amount of water dispersed in the microemulsion. It was also observed that the DNA binding of cationic porphyrin TMAP 4+ led to two lifetimes. In vitro investigations showed that TMAP 4+ is bound to C. albicans . Fluorescence lifetime measurements and fluorescence microscopic images provided additional insight into the effects of porphyrin uptake by cells. The results reveal a double localization of TMAP 4+ inside of C. albicans cells. Thus, a redistribution of TMAP 4+ was observed in unwashed cells, probably due to a relocalisation of molecules that were weakly bound to the cells or remained in solution. However, this effect was not found with molecules tightly bound in the cells, after one washing step.

Latexes with Hexadecyl Group on Their Quaternary Ammonium Ions as Catalytic Media for the Hydrolysis of Paraoxon by o-Iodosobenzoate

The micelle-mimetic poly[(styrylmethyl)hexadecyldimethylammonium chloride] latexes were used as media and supports for o-iodosobenzoate (IBA) catalyst in the hydrolysis of paraoxon (PO). The latex particles contained 16–67 mol% hexadecyl group in their repeating units. The kinetics of the hydrolysis of PO by IBA was investigated in the presence of these latexes at pH 8.0 and 25°C. As the quaternization percentage of the latexes increased, the rates of the hydrolysis increased. The pseudo-first-order rate constants (k obsd) of the hydrolysis were determined and the highest k obsd values were obtained for reactions carried out in the medium of the QL-67 latex which contains 67% quaternization in its repeating unit. (Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.)

Photophysics of safranine-O and phenosafranine in reverse micelles of BHDC

The photophysics of safranine-O (3,7-diamino-2,8-dimethyl-5 phenyl phenazinium chloride, SF) and phenosafranine (3,7-diamino-5-phenyl phenazinium chloride, PSF) was investigated in reverse micelles (RMs) of the cationic surfactant benzyl hexadecyl dimethylammonium chloride (BHDC). The excited singlet state properties were measured by absorption and fluorescence spectroscopy. All the measurements indicate that both dyes are localized in the interface, sensing a medium of lower polarity than water. Stokes’ shift increases and fluorescence quantum yield decreases with increasing the water content, but never reach the values or pure water. The triplet state properties of the dyes in RMs were investigated by laser flash photolysis. The maximum of the T–T absorption spectra in RMs confirms that, in spite of their positive charge, the dyes remain at the interface co-micellizing with BHDC. The triplet lifetime is much longer in the RMs than in homogeneous organic solvents. The two dyes present a different dependence of their photophysical properties with the water content. The two methyl groups in the ring of SF produce a stronger preference of the dye for a hydrophobic environment, and consequently a deeper location in the interface closer to the organic phase. A remarkable difference is observed in the triplet quenching by aliphatic amines. While the quenching by hydrophobic tributylamine is much lower in BHDC/benzene RMs than in a homogeneous solvent, the hydro soluble triethanolamine is near two orders of magnitude more effective in the RMs than in homogeneous solution. This is explained by the different local concentration of the amines in the interface.

Enhanced catalytic activity of o-iodosobenzoate in poly[(styrylmethyl)hexadecyldimethylammonium chloride] latexes for the hydrolysis of p-nitrophenyl diphenyl phosphate

Six 5.0 mol% crosslinked poly[(styrylmethyl)hexadecyldimethylammonium chloride] latexes containing 8–67% quaternization were synthesized via two-stage process and used as supports for o-iodosobenzoate (IBA) catalyst in the hydrolysis of model organophosphate compound p-nitrophenyl diphenyl phosphate (PNPDPP). The hydrodynamic diameters of the cationic latexes were less than 200 nm. The rate of the hydrolysis of PNPDPP greatly increased in the presence of the cationic latex particles and strongly depended on the degree of quaternization and amount of the latex as well as pH, type of buffer, and ionic strength of the medium. As the quaternization percentage of the latexes increased, the rates of the hydrolysis increased. The pseudo-first-order and second-order-rate constants of the hydrolysis reaction carried out with different amounts and type of cationic latexes at pH 7.0, 8.0 and 9.0 in different buffer solutions at 25 °C were determined. 1.0 × 10 −5 M IBA in 0.25 mg/mL of QL-67 latex enhanced the rate of the hydrolysis of 1.0 × 10 −5 M PNPDPP about 5670 times in TAPS buffered solution at pH 8.0 compared to the one in buffered solution and 1590 times in the presence of IBA alone in TAPS buffered solution. The highest second-order-rate constant k cat of 21200 ± 1100 M −1 s −1 was obtained when 0.25 mg/mL of QL-67 was employed in the hydrolysis reaction at pH 8.0.

Synthesis and Desulfurization Performance of Nanocrystal-Assembled Zeolite L with a Hierarchical Pore Structure

Zeolite MeLTL with a micro-mesoporous composite pore structure was synthesized by using nanocrystal clusters of zeolite L prepared by the crystallization nurturing method as a precursor and [3-(trimethoxysilyl)propyl] hexadecyldimethylammonium chloride (TPHAC) as the organic mesopore directing surfactant. Several techniques including X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Al-27 magic angle spinning nuclear magnetic resonance (Al-27 MAS NMR), and Fourier transform infrared spectroscopy of pyridine adsorption (Py-FTIR) were used to characterize the samples. Results show that zeolite MeLTL is formed by the self-assembly of zeolite L nanocrystals, and it has bimodal pore distributions with a stepwise mesoporous structure and the microporous structure of zeolite L. The BET surface area and the pore volume increased significantly and were 611 m(2).g(-1) and 0.696 cm(3).g(-1), respectively. Zeolite MeLTL was composed of zeolite L units and this was responsible for the adequate surface acid amount and acid strength. As a result, the pore diffusion ability and the catalytic performance of zeolite MeLTL are enhanced by the improvement in textural properties. For diesel hydrodesulfurization, the catalyst introduced zeolite MeLTL gave better hydrodesulfurization activity compared to the catalysts introduced zeolite L or Al-MCM-41 or used bare gamma-Al2O3 as a support. The sulfur content of diesel oil after hydrotreatment was 9.3 mu g.g(-1) and the desulfurization rate was 99.3%.

Water intrusion-extrusion in silicalite-1 with tunable mesoporosity prepared in fluoride medium

Experimental water intrusion–extrusion isotherms were performed at room temperature on mesoporous silicalite-1 samples, prepared in fluoride medium and using carbon black or surfactant, [3-(trimethoxysilyl)propyl]hexadecyldimethylammonium chloride, as porogen and templating agents, respectively. The increase of the porous volume observed for the silicalite-1 sample prepared in the presence of carbon black leads to an increase of the water intruded volume at high pressure (100 MPa). Therefore, the amount of stored energy in this water–zeolite system is greater than for a conventional “water–silicalite-1” system. However, the fluoride route appears to be a less effective method than the alkaline route.

Water intrusion in mesoporous silicalite-1: An increase of the stored energy

In silicalite-1 (pure silica MFI-type zeolite), the water adsorption is extremely weak when the pressure is lower than the water saturation vapor pressure. The water condensation (intrusion) is obtained by applying a high hydraulic pressure, approximately of 100 MPa. Extrusion of water occurring at the similar pressure, the “water–silicalite-1” system constitutes thus a real molecular spring, which can store and restore mechanical energy. In order to increase the stored energy in this system, the porous volume of this zeolite was increased by the creation of additional micro-, meso- and macropores using carbon black or surfactant [3-(trimethoxysilyl)propyl]hexadecyldimethylammonium chloride, as porogen and templating agents, respectively. The presence of meso- and macropores modifies the water condensation behavior in silicalite-1. Indeed, the water intrusion takes place in two stages. The first one, from 3 to 7 MPa, corresponds to the filling of meso- and macropores but the amount of stored energy is very low. The second one, at 100 MPa, corresponds to the filling of micropores. The increase of the microporous volume leads to an increase of the intruded water volume at high hydraulic pressure. Consequently, the stored energy is greater than for a conventional silicalite-1 zeolite.

Critical behavior of a ternary microemulsion studied by turbidity, density, and refractive index.

A detailed study of turbidity, density, and refractive index in the critical region of two samples of a water in an oil ternary microemulsion system, water plus benzene plus benzyl hexadecyl dimethylammonium chloride (BHDC), is presented. Special care is taken to determine the criticality of the samples. The critical point is approached from the homogeneous phase by varying the temperature at fixed concentrations of the components. Along this path Fisher-renormalized Ising exponents are expected. The critical exponents for the correlation length (\ensuremath{\nu}) and osmotic susceptibility (\ensuremath{\gamma}) are determined through the turbidity. The critical exponent \ensuremath{\alpha} can be deduced from the (1-\ensuremath{\alpha}) behavior of the density and the refractive index. From mere numerical analysis alone turbidity behavior cannot be distinguished between Ising and Fisher-renormalized Ising exponents. However, physical arguments suggest the latter values for the exponents \ensuremath{\nu} and \ensuremath{\gamma}. We do not see any anomaly in the density within a resolution of \ifmmode\pm\else\textpm\fi{}3\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$. This is consistent with the renormalization of \ensuremath{\alpha} [${\mathrm{\ensuremath{\alpha}}}^{\mathrm{*}}$=-\ensuremath{\alpha}/(1-\ensuremath{\alpha})]. A very weak anomaly in the refractive index is detected which is better described by a function of the exponential type, which has been discussed for a quaternary microemulsion near the critical end point, than the (1-\ensuremath{\alpha}) power behavior.