Cisplatin, as a significant chemotherapeutic drug for the treatment of cancers, was combined with rapamycin (RAPA), an autophagy inducer, or 3-methyladenine (3-MA), an autophagy inhibitor, and these cisplatin combination drugs were tested with HeLa cells to explore their specific effects on autophagy by cell viability assay, mitochondria membrane potential (MMP) determination, transmission electron microscopic (TEM) observation, dansylcadaverine (MDC) staining, and western blotting analysis. Results revealed that cisplatin combination drugs enhanced formation of autophagosomes, and morphological and biochemical markers of autophagy in HeLa cells can be clearly determined with the formation of enlarged acidic vesicles and conversion of light chain 3 (LC3) protein. Cisplatin combination drugs induce stronger effects on autophagy than either of the components does. Combination drug-induced autophagy inhibits the growth of HeLa cell in a dose-dependent manner and subsequently sensitizes the cells to apoptosis and cell death. Furthermore, interactions between cisplatin combination drugs and human serum albumin (HSA) were investigated under fluorescence, synchronous fluorescence, and circular dichroism analysis. Results suggest that cisplatin combination drugs can bind to HSA and induce conformation and microenvironmental changes of HSA via electrostatic binding affinity. These investigations can provide useful and fundamental information, which could be used in cytotoxic chemotherapy to dramatically increase efficacy in pharmaceutical and biotechnology fields.

•Interactions of human serum albumin (HSA) with eight quaternary ammonium surfactants are investigated by various measurements.•Complexes with larger size can be detected in gemini surfactant-HSA systems than in single-chain surfactant-HSA systems.•Gemini surfactants have much strong binding ability to induce the unfolding of HSA in comparison with the single-chain surfactants.The interactions of human serum albumin (HSA) with four cationic gemini surfactants and four single-chain surfactants have been investigated from the measurements of fluorescence spectroscopy, dynamic lights scattering (DLS), zeta potential, and circular dichroism (CD). The fluorescence results show the binding strength of surfactants to HSA, along with the blue shift under the maximum emission wavelength (λmax) which is sensitive to the protein conformations. It has been found that the hydrodynamic diameters of the protein aggregates are enlarged and the electrokinetic potentials of them get positive with increasing the concentration of the surfactants. The conformational transformation of the secondary structures of surfactant–HSA aggregates has been confirmed through the quantitative analysis of the CD spectra. The isothermal titration microcalorimetry (ITC) has been employed to further analyze the binding process of single-chain surfactants to HSA. The comprehensive results obtained from various approaches have shown that both hydrophobic and electrostatic interactions are present in the cationic surfactant–HSA systems. Compared with the corresponding single-chain surfactants, the gemini ones have much stronger binding ability to induce the unfolding of HSA. These investigations on the interactions between HSA and surfactants with the altered chain architecture in different concentration regimes can facilitate the application of surfactant-protein systems in pharmaceutical, biotechnology and related fields.

•Fractal surfaces were prepared by the solid–solid phase transformation method.•C6 cells were cultured on the PPP surface which imitate the fractal environment.•Hydrophobic surfaces have significant effects on cell proliferation and morphology.To provide a biomimic environment for glial cell culture, glycerol tripalmitate (PPP) has been used as a raw material to prepare fractal surfaces with different degrees of hydrophobicity. The spontaneous formation of the hydrophobic fractal surfaces was monitored by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The surface morphologies were observed by a scanning electron microscope (SEM), and then the fractal dimension (FD) values of the surfaces were determined with the box-counting method. C6 glioma cells were cultured and compared on different hydrophobic PPP surfaces and poly-L-lysine (PLL)-coated surface. The cell numbers as a function of incubation time on different surfaces during the cell proliferation process were measured, and the cell morphologies were observed under a fluorescence microscope. Influences of hydrophobic fractal surfaces on the cell number and morphology were analyzed. The experimental results show that the cell proliferation rates decrease while the cell morphology complexities increase with the growth of the fractal dimensions of the PPP surfaces.

Two novel aqueous two-phase systems (ATPSs) involving protic piperazinium-based ionic liquids (ILs) and anionic surfactants were found in the 1-ethylpiperazinium tetrafluoroborate ([C2pi][BF4]) + sodium dodecyl sulfate (SDS) + H2O system and the 1-phenylpiperazinium tetrafluoroborate ([Phpi][BF4]) + sodium dodecyl benzenesulfonate (SDBS) + H2O system. The ATPS regions in the ternary phase diagrams were determined, and the compositions and the microstructures of the conjugated phases were analyzed by UV–vis, 1H NMR, DLS, and cryogenic TEM measurements. The results demonstrate size-enhanced micelles for both ATPSs. The strong electrostatic interactions between the cationic moiety of IL and the anionic surfactant play a very important role in the assembly of the large aggregates, and the cation−π interactions are involved in the [Phpi][BF4] + SDBS + H2O ATPS. In addition, the small cationic moiety of [C2pi][BF4] can be packed in the micelles, while the larger hydrophilic cationic moiety of [Phpi][BF4] makes it difficult to get into the micelles, leading to the different size enhancement effects. The driving force of phase separation is the formation and distribution of the large aggregates in the aqueous solutions. This work presents a novel nonaromatic ATPS formed by a piperazinium-based IL and an anionic surfactant, in which considerable size enhancement of aggregates takes place without the assistance of aromaticity in contrast to the other aromatic ATPSs.

Twelve gemini quaternary ammonium surfactants have been employed to evaluate the antibacterial activity and in vitro cytotoxicity. The antibacterial effects of the gemini surfactants are performed on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with minimum inhibitory concentrations (MIC) ranging from 2.8 to 167.7 μM. Scanning electron microscopy (SEM) analysis results show that these surfactants interact with the bacterial cell membrane, disrupt the integrity of the membrane, and consequently kill the bacteria. The data recorded on C6 glioma and HEK293 human kidney cell lines using an MTT assay exhibit low half inhibitory concentrations (IC50). The influences of the gemini surfactants on the cell morphology, the cell migration ability, and the cell cycle are observed through hematoxylin-eosin (HE) staining, cell wound healing assay, and flow cytometric analyses, respectively. Both the values of MIC and IC50 decrease against the growth of the alkyl chain length of the gemini surfactants with the same spacer group. In the case of surfactants 12-s-12, the MICs and IC50s are found to decrease slightly with the spacer chain length changing from 2 to 8 and again to increase at higher spacer length (s = 10–12). All of the gemini surfactants show great antibacterial activity and cytotoxicity, and they might exhibit potential applications in medical fields.

Investigation of conformational isomerism of ring compounds can help us get a clear comprehension of the ring structure and reveal significant structure–activity relationship. In this study, conformational isomerism of the cationic moiety of ionic liquid 1-ethyl-1,4-dimethylpiperazinium bis(trifluoromethylsulfonyl)imide ([C2C1C14pi][NTf2]) has been investigated by means of 1H nuclear magnetic resonance spectra. The energy levels for different conformations of the cationic moiety [C2C1C14pi]+ are obtained via density functional theory calculations. The predominant cis-conformer in [C2C1C14pi][NTf2] at its liquid state is observed under ambient conditions, where the ethyl group locates at the equatorial position of quaternary nitrogen atom, consistent with the calculated results. The trans-conformer minorities in the IL convert to the cis-conformers when [C2C1C14pi][NTf2] is well crystallized. Besides, the addition of polar solvents, such as ethanol, leads to a convenient and complete transformation from the trans-form to the recognizable cis-form. The phase-transition behaviors have been measured by means of differential scanning microcalorimetry (DSC), and the DSC results can be highly affected by the initial state of the IL. Density and viscosity measurements for mixtures of [C2C1C14pi][NTf2] with ethanol or 1-propanol at different temperatures T = (293.15 to 323.15) K are performed. Conformational isomerism affects the excess molar volumes of [C2C1C14pi][NTf2] + alcohol systems more significantly than the viscometric property. The behaviors, as comparison, for the mixtures of 1-n-pentyl-1,4-dimethyl-piperazinium bis(trifluoromethylsulfonyl)imide ([C5C1C14pi][NTf2]) with ethanol are observed with the same phenomena as the common binary systems. On the basis of the experimental and calculated results of the ILs, it can be concluded that conformational isomerism in the cation of [C2C1C14pi][NTf2] is quite significant, and it should be taken into account when sensitive properties are evaluated.

•Temperature-induced phase inversion phenomena are observed.•Difference of density change rate is the direct reason for phase inversion.•Property differences are lowest around the phase-inversion temperature.•Transfers of ions make main contributions to the change of density difference.•Microstructures in the separated phases change along the temperature.Three quaternary ammonium surfactants, N-alkyl-N, N-2-dihydroxyethyl-N-methyl ammonium bromide (CnDHAB, n = 12, 14, and 16) and sodium dodecyl sulfate (SDS) have been used to form aqueous two-phase systems of cationic–anionic surfactant mixtures with cationic surfactant in excess (ATPS-C). Densities, viscosities, interfacial tensions and ion concentrations of/between the two separate phases were measured and microstructures were observed as a function of temperature to elucidate the temperature effect on ATPS-C and the phase inversion. The density of the surfactant-concentrated phase decreases against the temperature faster than that of the dilute phase, which can lead to the phase inversion at a certain temperature. The ultralow interfacial tension between the separated phases can be determined, which exhibits a minimum near the phase inversion temperature. It is followed that the property differences between the separated phases are the lowest around the phase-inversion temperature. Composition analyses manifest that the inorganic ions transferring from the concentrated phase to the dilute phase with increasing the temperature. These transformations make main contributions to the change of density difference between the separate phases. Combining the results of viscosity measurement, dynamic light scattering (DLS), and transmission electron microscopy (TEM), it is evident that network structures and large aggregates are destroyed and smaller spherical micelles or vesicles can be observed in the concentrated phase with increasing the temperature. In the dilute phase, vesicles can be observed and most of the aggregates are irregular micelles especially at lower temperatures before the phase inversion occurs.Phase inversion of C12DHAB/SDS/NaCl system (CT = 8.000 × 10−2 mol L−1, MRC12DHAB/SDS=1.963,MRC12DHAB/SDS=1.963,CNaCl = 6.000 × 10−2 mol L−1) with crystal violet as dye during the heating process. (A) 42.0 °C; (B) 45.5 °C; (C) 46.5 °C; (D) 47.5 °C; (E) 51.0 °C.

The micelle formations in aqueous solutions of a set of quaternary ammonium surfactants, N-alkyl-N-2-hydroxyethyl-N,N-dimethyl ammonium bromide (CnHDAB, n = 12, 14, and 16), N-alkyl-N,N-2-dihydroxyethyl-N-methyl ammonium bromide (CnDHAB, n = 12, 14, and 16), along with N-dodecyl-N,N,N-trimethyl ammonium bromide (DTAB), and N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB), were investigated by the isothermal titration calorimetry (ITC). The critical micellar concentrations (CMCs) and the enthalpies of micellization at six different temperatures were determined. The entropies and Gibbs free energies of micellization were then calculated by using the pseudophase separation model. The effects on the thermodynamic data of the temperature, the length of the alkane chain, and the number of hydroxyethyl substituents on the surfactant headgroup were discussed. The CMC value of each surfactant increases slightly with the temperature increase. At a given temperature, both the increases of the length of the alkane chain and the number of hydroxyethyl substituents lead to the decreases of the CMC values.

Combining with the 1H and 13C nuclear magnetic resonance (NMR) determinations, elemental analysis and molecular weight measurement, average molecular formula of the chemical unit for the asphaltenes from Chinese Daqing crude oil were calculated. Thermal pyrolysis kinetics of the asphaltenes had been studied using thermogravimetric analysis (TGA). The distributed activation energy model (DAEM) was used to analyze these complex systems. The results show that the peak activation energy for pyrolysis of the asphaltenes is 245 kJ mol−1 and the pre-exponential factor is 5.88 × 1014 s−1. The DAEM method presented reasonably good results of the prediction of the weight loss curves. A linear relationship can be found from the plots of logarithm of the pre-exponential factor against the activation energy at selected conversion values. This phenomenon known as the compensation effect was explained and it was in agreement with the estimated chemical structure determined by NMR.

On the basis of dissociation enthalpies from micro-calorimetric measurements by using LKB-2277 BioActivity Monitor, along with dissociation equilibrium constants, enthalpic and entropic contributions to substituent effects and solvent effects on the dissociation of acetic acid and three mono-substituted halogen–acetic acids (X–CH2COOH, X=H, Cl, Br, I) in binary mixtures of EtOH–H2O have been examined in terms of enthalpic and entropic reaction constants (ρH, ρS), and enthalpic and entropic substituent constants (σH, σS). A satisfactory linear free energy relationship (LFER) with the Hammett type equation has been obtained. The reaction constants have been calculated for the different EtOH–H2O mixtures and several reasonable quantitative equations have been obtained to relate them with the composition or dielectric constant of the mixed solvents.