The effect of inorganic salt on the morphology and nucleation of polyaniline nanofibers synthesized via self-assembly

Polyaniline (PANI), due to the various and controllable shapes, the environmental stability, the excellent physical and chemical property, has gained significant attention. PANI with abundant morphologies were successfully prepared through adjusting and controlling the state of the initial micelle-like in the micelle-like system composed by aniline and organic acids with relatively weak intermolecular interaction. Although the influence of the inorganic salts on their morphology, including the surface and the diameter, was investigated, the influence of salt on the nucleation of PANI was still unclear. Therefore, PANI nanofibers were fabricated through the addition of inorganic salt such as NaCl, MgSO4 and AlCl3 into the micelle-like composed of aniline and D-camphor-10-sulfonic acid. The influence of types and concentration of inorganic salts, doped acids and temperature on PANI was studied by Transmission Electron Microscope (TEM), UV-vis and Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy. In addition, in situ UV-vis and 1H Nuclear Magnetic Resonance technology (NMR) were applied to observe the process of aniline polymerization, and it was indicated the polymerization rate of aniline changed after the addition of inorganic salt NaCl into the initial solution.</p

Effects of Cationic Ammonium Gemini Surfactant on Micellization of PEO–PPO–PEO Triblock Copolymers in Aqueous Solution

Effects of cationic ammonium gemini surfactant hexamethylene-1,6-bis­(dodecyldimethylammonium bromide) (12–6–12) on the micellization of two triblock copolymers of poly­(ethylene oxide)–poly­(propylene oxide)–poly­(ethylene oxide), F127 (EO₉₇PO₆₉EO₉₇) and P123 (EO₂₀PO₇₀EO₂₀), have been studied in aqueous solution by differential scanning calorimetry (DSC), dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and NMR techniques. Compared with traditional single-chain ionic surfactants, 12–6–12 has a stronger ability of lowering the CMT of the copolymers, which should be attributed to the stronger aggregation ability and lower critical micelle concentration of 12–6–12. The critical micelle temperature (CMT) of the two copolymers decreases as the 12–6–12 concentration increases and the ability of 12–6–12 in lowering the CMT of F127 is slightly stronger than that of P123. Moreover, a combination of ITC and DLS has shown that 12–6–12 binds to the copolymers at the temperatures from 16 to 40 °C. At the temperatures below the CMT of the copolymers, 12–6–12 micelles bind on single copolymer chains and induce the copolymers to initiate aggregation at very low 12–6–12 concentration. At the temperatures above the CMT of the copolymers, the interaction of 12–6–12 with both monomeric and micellar copolymers leads to the formation of the mixed copolymer/12–6–12 micelles, then the mixed micelles break into smaller mixed micelles, and finally free 12–6–12 micelles form with the increase of the 12–6–12 concentration

Preparation and Characterization of GX-50 and Vitamin C Co-encapsulated Microcapsules by a Water-in-Oil-in-Water (W₁/O/W₂) Double Emulsion–Complex Coacervation Method

Co-encapsulated xanthoxylin (GX-50) and vitamin C (Vc) microcapsules (GX-50-Vc-M) were prepared by the combination of a water-in-oil-in-water (W1/O/W2) double emulsion with complex coacervation. The W1/O/W2 double emulsion was prepared by two-step emulsification, and it has a uniform particle size of 8.388 μm and high encapsulation efficiencies of GX-50 (85.95%) and Vc (67.35%) under optimized process conditions. Complex coacervation occurs at pHs 4.0–4.7, which has the highest encapsulation efficiency of GX-50 and Vc at pH 4.5. The complex coacervate with tannic acid solidifying (namely, wet microcapsules) has better mechanical properties and also enhances the ability of co-encapsulation of active ingredients. The resulting microcapsules by freeze-drying of wet microcapsules were characterized by UV–vis absorbance spectroscopy (UV–vis), Fourier infrared spectroscopy (FI-IR), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), X-ray diffraction (XRD), 2,2-diphenyl-1-picrylhydrazyl (DPPH·) radical scavenging, and in vitro permeation measurements. Under optimal conditions, the encapsulation efficiency and drug loading of GX-50-Vc-M for GX-50 and Vc are, respectively, 78.38 ± 0.51 and 59.34 ± 0.56%, and 35.6 ± 0.68 and 29.8 ± 0.92%. A slight shift in the FTIR peak between single GX-50 or Vc and GX-50-Vc-M confirmed the successful co-encapsulation of GX-50 and Vc in microcapsules. GX-50-Vc-M has bridged irregular spherical aggregates, while GX-50 and Vc are, respectively, encapsulated in hydrophobic and hydrophilic cavities of microcapsules in an amorphous dissolved state. GX-50-Vc-M has the highest DPPH· radical scavenging rate of 62.51%, and the scavenging process of GX-50-Vc-M on DPPH· radicals is more in line with the pseudo-second-order kinetic equation model. Moreover, the in vitro permeation of GX-50 and Vc in GX-50-Vc-M can reach maximum values of 40 and 60%, respectively. This concludes that GX-50-Vc-M is a promising delivery system for the penetration of the antioxidant into the deeper layers of the skin for the antioxidant effect

Metabonomics analysis of liver in rats administered with chronic low-dose acrylamide

The current study aimed to investigate the hepatotoxicity of rats administered with chronic low-dose acrylamide (AA) by using metabonomics technology on the basis of ultraperformance liquid chromatography–mass spectrometry (UPLC-MS). A total of 40 male Wistar rats were randomly divided into the following four groups: control, low-dose AA (0.2 mg/kg bw, non-carcinogenic end-point based on the induction of morphological nerve changes in rats), middle-dose AA (1 mg/kg bw), and high-dose AA (5 mg/kg bw). The rats continuously received AA by administering it in drinking water daily for 16 weeks. After the treatment, rat livers were collected for metabonomics analysis and histopathology examination. Principal components analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) were used to investigate the metabonomics profile changes in rat liver tissues and screen the potential biomarkers.Fourteen metabolites were identified with significant changes in intensities (increased or decreased compared with the control group) as a result of treatment (p p b-muricholic acid, docosapentaenoic acid, sphingosine 1-phosphate, taurodeoxycholic acid, lysoPE(20:5), cervonyl carnitine, linoleyl carnitine, docosahexaenoic acid, lysoPC(20:4), lysoPE(18:3), PA(20:4), stearidonyl carnitine, alpha-linolenic acid, and lysoPA(18:0).Results showed that chronic exposure to AA at NOAEL (0.2 mg/kg bw) exhibited no toxic effect in rat livers at the metabolic level. AA induced oxidative stress to the liver and disrupted lipid metabolism. The results of liver histopathology examination further supported the metabonomic results. The current study aimed to investigate the hepatotoxicity of rats administered with chronic low-dose acrylamide (AA) by using metabonomics technology on the basis of ultraperformance liquid chromatography–mass spectrometry (UPLC-MS). A total of 40 male Wistar rats were randomly divided into the following four groups: control, low-dose AA (0.2 mg/kg bw, non-carcinogenic end-point based on the induction of morphological nerve changes in rats), middle-dose AA (1 mg/kg bw), and high-dose AA (5 mg/kg bw). The rats continuously received AA by administering it in drinking water daily for 16 weeks. After the treatment, rat livers were collected for metabonomics analysis and histopathology examination. Principal components analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) were used to investigate the metabonomics profile changes in rat liver tissues and screen the potential biomarkers. Fourteen metabolites were identified with significant changes in intensities (increased or decreased compared with the control group) as a result of treatment (p p b-muricholic acid, docosapentaenoic acid, sphingosine 1-phosphate, taurodeoxycholic acid, lysoPE(20:5), cervonyl carnitine, linoleyl carnitine, docosahexaenoic acid, lysoPC(20:4), lysoPE(18:3), PA(20:4), stearidonyl carnitine, alpha-linolenic acid, and lysoPA(18:0). Results showed that chronic exposure to AA at NOAEL (0.2 mg/kg bw) exhibited no toxic effect in rat livers at the metabolic level. AA induced oxidative stress to the liver and disrupted lipid metabolism. The results of liver histopathology examination further supported the metabonomic results.</p

Surfactant Selection Principle for Reducing Critical Micelle Concentration in Mixtures of Oppositely Charged Gemini Surfactants

Cationic quaternary ammonium gemini surfactants C_<i>n</i>H_2<i>n</i>+1­(CH₃)₂N⁺­CH₂CH­CHCH₂(CH₃)₂­N⁺C_<i>n</i>­H_2<i>n</i>+12Br^– (C_<i>n</i>C₄C_<i>n</i>, <i>n</i> = 12, 8, 6) with alkyl spacers, C_<i>n</i>H_2<i>n</i>+1(CH₃)₂­N⁺CH₂CHO­HCH­OHCH₂(CH₃)₂­N⁺C_<i>n</i>­H_2<i>n</i>+12Br^– (C_<i>n</i>C₄(OH)₂C_<i>n</i>, <i>n</i> = 12, 8, 6, 4) with two hydroxyl groups in alkyl spacers, and cationic ammonium single-chain surfactants C_<i>n</i>H_2<i>n</i>+1(CH₃)₂N⁺Br^– (C_<i>n</i>TAB, <i>n</i> = 12, 8, 6) have been chosen to fabricate oppositely charged surfactant mixtures with anionic sulfonate gemini surfactant C₁₂H₂₅N­(CH₂CH₂­CH₂SO₃^–)­CH₂CH₂­CH₂(CH₃)₂­N­(CH₂­CH₂CH₂­SO₃^–)­C₁₂H₂₅­2Na (C₁₂C₃C₁₂(SO₃)₂). Surface tension, electrical conductivity, and isothermal titration microcalorimetry (ITC) were used to study their surface properties, aggregation behaviors, and intermolecular interactions. The mixtures of C₁₂C₃C₁₂(SO₃)₂/C_<i>n</i>C₄(OH)₂C_<i>n</i> (<i>n</i> = 12, 8) and C₁₂C₃C₁₂(SO₃)₂/C₁₂C₄C₁₂ show anomalous larger critical micelle concentration (CMC) than C₁₂C₃C₁₂(SO₃)₂, while the mixtures of C₁₂C₃C₁₂(SO₃)₂/C_<i>n</i>C₄(OH)₂C_<i>n</i> (<i>n</i> = 6, 4), C₁₂C₃C₁₂(SO₃)₂/C_<i>n</i>C₄(OH)₂C_<i>n</i> (<i>n</i> = 6, 4), and C₁₂C₃C₁₂(SO₃)₂/C_<i>n</i>TAB (<i>n</i> = 12, 8, 6) exhibit much lower CMC than C₁₂C₃C₁₂(SO₃)₂. The results indicate that strong hydrophobic interactions between the alkyl chains assisted by strong electrostatic attractions between the headgroups and hydrogen bonds between the spacers lead to the formation of less surface active premicellar aggregates in bulk solution, resulting in the increase of CMC. If these interactions are weakened or inhibited, less surface active premicellar aggregates are no longer formed in the mixtures, and thus the CMC values are reduced. The work reveals that the combination of two surfactants with great self-assembling ability separately may have strong intermolecular binding interactions; however, their mixtures do not always generate superior synergism properties. Only moderate intermolecular interaction can generate the strongest synergism in CMC reduction

Nucleation of Polyaniline Nano-/Macrotubes from Anilinium Composed Micelles

A mechanistic study on the nucleation of polyaniline nanotubes (PANI-NT) through template-free method is explored by in situ solution-state ¹H NMR experiments via a careful analysis of the spectral evolution of the major species in the course of the reaction. Before polymerization, aniline and salicylic acid have assembled into loosely packed micelles due to electrostatic interactions and the proton exchange reaction between aniline and anilinium. A three-stage polymerization with a formation, accumulation of aniline dimers, as well as a generation of phenazine-like oligomers is observed, which can be attributed to the monomer transformation from neutral aniline molecules to anilinium cations and the significantly lowered pH in the reaction. Strong π–π stacking interactions from the phenazine-like oligomers facilitate the intermolecular aggregation which initiates the formation of PANI-NT. At first, such aggregates, locating at the outermost layer of anilinium composed micelles, shield in situ formed protons from releasing into the aqueous bulk but into the micelle instead. Due to the continuously increased charge in the micelle, a sphere-to-rod structural transition occurs which leads the oligomer aggregates to be sheathed at the exterior of the rod. Further consumption of anilinium in the micelle leaves the internal cavity while the fusion between the micelles elongates the length of the tubes. Our work demonstrates that (i) loosely packed anilinium composed micelles, highly mobile monomers within the micelle, and efficient blockage of the proton-releasing to the aqueous bulk are three key factors for the generation of tubular structures; and (ii) dynamic NMR line shape analysis provides a new perspective for resolving the formation profile of nanostructured polymers

Electrochemical Determination of Imidacloprid Using an Electrosynthesized Hexa-Peri-Hexabenzocoronene Modified Glassy Carbon Electrode (GCE) by Differential Pulse Voltammetry (DPV)

Hexa-peri-hexabenzocoronene (HBC) modified glassy carbon electrodes (HBC/GCEs) was fabricated by an electrochemical synthesis, solving the difficulty of the preparation of HBC films because of its poor solubility. HBC/GCE was used as a sensing electrode for the voltammetric investigation of imidacloprid (IDP). The presence of HBC increased the conductivity of GCE, and showed good electrocatalytic activity toward the reaction of IDP. Therefore, the HBC enhanced the electrochemical signal of IDP, which increased the sensitivity of the sensor. The best performance was obtained by optimizing the electrochemical synthesis time, pH and enrichment time. The linear response range and the limit of detection were 5 to 750 μmol·L−1 and 1.5 μmol·L−1, respectively. Moreover, the proposed sensor also exhibited good repeatability, selectivity and stability, and promising applications for real sample.</p

Solubility Measurement and Correlation of 2‑Amino-3-chloropyrazine and 2‑Amino-3,5-dibromopyrazine in a Series of Mixed Solvent Systems at <i>T</i> = (278.15 to 323.15) K

The solubility of 2-amino-3-chloropyrazine (ACPY) in some binary cosolvent mixtures of (methanol, isopropyl alcohol, ethylene glycol (EG), N,N-dimethylformamide (DMF)) plus water and the experimental solubility of 2-amino-3,5-dibromopyrazine (ADPY) in (ethanol + water), (isopropyl alcohol + water), (EG + water), and (PG + water) were all determined by the isothermal saturation method from 278.15 K to 323.15 K at 101.2 kPa. The trend of the system temperature and the change of the solvent partner are both factors that affect the dissolution. As the temperature goes higher, the amount of dissolution follows, but the higher is the water content of the solvent, the less solute will be dissolved. The combination of DMF and water is best for the dissolution of ACPY, and the addition of ethanol to water shows an advantage of dissolving ADPY over other combinations. The experimentally obtained dissolution data were then calculated by using three models for the two miscible solvent systems. For ADPY, RAD and RMSD maximums were 2.63 × 10–2 and 2.10 × 10–5. For ACPY, RAD and RMSD were no greater than 6.55 × 10–2 and 6.83 × 10–4

Lecithin/Cholesterol/Tween 80 Liposomes for Co-Encapsulation of Vitamin C and Xanthoxylin

Co-encapsulated hydrophilic vitamin C (Vc) and hydrophobic xanthoxylin (GX-50) liposomes (L-Vc-GX-50) were prepared using ethanol injection and ultrasonic methods and characterized by dynamical light scattering, ζ-potential, cryogenic transmission electron microscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy, antioxidant capacity, tyrosinase activity, and in vitro permeation measurements. L-Vc-GX-50 are formed by the assembly of egg yolk lecithin, cholesterol, and tween 80, with Vc and GX-50 encapsulated in their hydrophilic and hydrophobic cavities, respectively. By considering the hydrodynamic radius (Rh), ζ-potential, and encapsulation efficiency (EE) of L-Vc-GX-50, the optimum formulation was determined to be egg yolk lecithin/cholesterol/tween 80/GX-50 or Vc (15:3:3:1, w/w) with phosphate buffer (pH 6.8, 0.01 M). The as-prepared L-Vc-GX-50 have an average Rh of 114 nm, a negative ζ-potential (−23.63 mV), a high EE of Vc (73.3%) and GX-50 (87.4%), and a unilamellar vesicle structure. Compared co-encapsulated L-Vc-GX-50 with single encapsulated Vc or GX-50 liposomes (L-Vc or L-GX-50), the EE of Vc in L-Vc-GX-50 is obviously higher than that of L-Vc, while the EE of GX-50 in L-Vc-GX-50 is similar to that in L-GX-50; the antioxidant capacity and tyrosinase inhibition activity of L-Vc-GX-50 are higher than those of L-GX-50 or L-Vc. The in vitro permeation data indicate that the final cumulative permeation amount of Vc and GX-50 in L-Vc-GX-50 can reach around 2.1 and 1.3 mg/cm2, respectively. The release kinetics fitting data show that the release kinetics of L-Vc-GX-50 follows the Korsmeyer–Peppas model and that the release of active ingredients is mainly dominated by the synergistic effect of diffusion release and rupture release. Moreover, L-Vc-GX-50 has good low-temperature storage stability, and the storage stability of GX-50 in L-Vc-GX-50 is significantly improved compared to L-GX-50. The main objective of this study is to improve the instability of Vc and the insolubility of GX-50 in cosmetics

P2/O3 Biphasic Cathode Material through Magnesium Substitution for Sodium-Ion Batteries

P2-type Fe–Mn-based oxides offer excellent discharge specific capacity and are as affordable as typical layered oxide cathode materials for sodium-ion batteries (SIBs). After Cu modification, though they can improve the cycling performance and air stability, the discharge specific capacity will be reduced. Considering the complementary nature of biphasic phases in electrochemistry, hybridizing P2/O3 hybrid phases can enhance both the storage performance of the battery and specific capacity. Herein, a hybrid phase composite with high capacity and good cycle performance is deliberately designed and successfully prepared by controlling the amount of Mg doping in the layered oxide. It has been found that the introduction of Mg can activate anion redox in the oxide layer, resulting in a significant increase in the specific discharge capacity of the material. Meanwhile, the dual-phase structure can produce an interlocking effect, thus effectively alleviating structure strain. The degradation of cycling performance caused by structural damage during the high-voltage charging and discharging process is clearly mitigated. The results show that the specific discharge capacity of Na0.67Cu0.2Mg0.1Fe0.2Mn0.5O2 is as high as 212.0 mAh g–1 at 0.1C rate and 186.2 mAh g–1 at 0.2C rate. After 80 cycles, the capacity can still maintain 88.1%. Moreover, the capacity and cycle performance as well as the stability can still remain stable even in the high-voltage window. Therefore, this work offers an insightful exploration for the development of composite cathode materials for SIBs