Weihong Qiao

Synthesis and characterization of a series of carbamate-linked cationic lipids for gene delivery

A series of pH-sensitive lipids, 1a-h [(2,3-bis-alkyl-carbamoyloxy-propyl)-trialkylammonium halide] and 2a-d (1-dimethylamino-2,3-bis-alkylcarbamoyloxy-propane), with carbamate linkages between the hydrocarbon chains and an ammonium or tertiary amine head, were synthesized for liposome-mediated gene delivery. The variable length of the carbon chains and the quaternary ammonium or neutral tertiary amine heads allowed us to identify the structure-function relationship showing how these factors would affect cationic lipid in gene delivery performance.

Structure–Function Relationship Research of Glycerol Backbone-Based Cationic Lipids for Gene Delivery

Transfection activities of two series of synthetic glycerol backbone‐based cationic lipids were studied as gene delivery carriers. The variable length of hydrocarbon chains, diverse quaternary ammonium heads, different linkage, as well as alternative anion combined with them allowed to find how these factors affect cationic lipids on their gene delivery performance. The structure–function relationship of the synthetic glycerol backbone‐based cationic lipids was discussed, and the transfection efficiency of some of the cationic liposomes was superior or parallel to that of two commercial transfection agents.

Dynamic Interfacial Tension Between Crude Oil and Novel Surfactant Flooding Systems Without Alkali

Abstract The surface tensions of tetradecylmethylnaphthalene sulfonate (TMNS) surfactant aqueous solution and the dynamic interfacial tension (DIT) between crude oil, from Shandong Shengli oil field of China, and the surfactant solution without alkaline, was measured. Results indicate that the TMNS surfactant had great capability and efficiency of lowering the solution surface tension. The critical micelle concentration (cmc) is 0.001 mass% and the surface tension at this concentration is 28.19 mN.m−1. It was also found that the TMNS surfactant is greatly effective in reducing the interfacial tensions and can lower the tension of crude oil-water interface to ultra-low at very low concentration, 0.002 mass%, without alkali and other additives. Both chromatogram separation of flooding and breakage of stratum are avoided effectively. The lower salinity is favorable for the flooding systems, lowering the DIT. The synthesized TMNS surfactant flooding systems without alkali and sodium chloride, decreasing the cost of oil recovery and avoiding the stratum being destroyed, would have a great prospect for enhanced oil recovery (EOR).

Synthesis and Properties of Three Series Amino Acid Surfactants

Abstract Three series of surfactants with different amino acid moieties (glycine, glutamic acid and lysine) were synthesized with octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid and glycine, glutamic acid, lysine respectively. The reaction conditions and their properties including surface activity, emulsibility and foamability were studied. For the surfactants with glycine moiety and glutamic acid moiety respectively, cmc (critical micelle concentration) and γcmc (surface tension at cmc) decreased and surface activity enhanced as the length of carbon chain increased. The surfactants with glycine moiety exhibited the best emulsibility and foamability in the three series. The surfactants with glutamic acid moiety showed disappointing emulsibility, but their foamability was good. The surfactants with lysine moiety did not display favorable emulsibility and foamability due to the length of their double-chain.

Synthesis and Surface Activity of Guerbet Betaine Surfactants with Ethylene Oxide Groups

Abstract Three series of Guerbet betaine surfactants with ethylene oxide groups were synthesized by Guerbet alkyl polyoxyethylene ether surfactants, epichlorohydrin, dimethylamine and sodium chloro-acetate. Their structures were confirmed by MS. The critical micelle concentrations (CMC) and surface tension at CMC (γCMC) of all prepared Guerbet betaine surfactants were determined by K100C processor tensiometer with the Wilhelmy-plate method at 25°C. It is found that synthesized surfactants exhibit great efficiency of reducing surface tension. As the number of ethylene oxide groups increases, the γCMC gradually increases. As the length of the hydrophobic chain of Guerbet betaine surfactants increases, the γCMC increases firstly and then decreases.

Dynamic Interfacial Behavior of Decyl Methylnaphthalene Sulfonate Surfactants for Enhanced Oil Recovery

Abstract The high purity decyl methylnaphthalene sulfonate (DMNS) was synthesized, the purity was determined by HPLC and the structure was confirmed by IR, UV and ESI-MS. Dynamic interfacial tensions (DIT) between DMNS flooding systems and crude oil were measured and the effects of sodium carbonate concentration, surfactant concentration and sodium chloride concentration on the DIT behaviors were investigated. Its found that the surfactant concentration, alkali concentration and the salinity have obvious influences on DIT behaviors. DMNS possessed outstanding capacity and efficiency of lowering the DIT between oil and water. The minimum dynamic interfacial tension could reach 6.35×10−6 mNm−1 at a lowconcentration for added surfactant. DMNS might be used in Enhanced Oil Recovery with lowcosts and high efficiency.

Synthetic Diether‐linked Cationic Lipids for Gene Delivery

Quaternary ammonium lipids 2a–p, with diether linkages between hydrocarbon chains and their ammonium headgroups, were synthesized as potential vectors for cationic liposome‐mediated gene delivery. Varying the length of carbon chains and quaternary ammonium heads as well as different anionic complexes will enable the study of the structure–function relationships of these cationic lipids in terms of gene delivery properties.

Studies on the Correlation Between Dynamic Interfacial Tension Behaviors and the Composition of Petroleum Sulfonates

Abstract Three fractions with different average molecular mass were isolated from petroleum sulfonates by Soxhlet extraction. The molecular mass distribution was examined by electrospry ionization-mass spectra. The dynamic interfacial tension behaviors of the petroleum sulfonates and three fractions were investigated respectively. The results indicated that fraction extracted with benzene produced a greater decrease of the dynamic interfacial tension than other fractions, so the former plays a vital role in reducing interfacial tension. But petroleum sulfonates before separation exhibit better interfacial activity than all the fractions, which indicates that there exists obvious synergism between these different fractions.

Synthesis of Cationic Surfactant Intermediates 3-(dimethylamino)- propane-1,2-di-alkylcarbamate

Abstract Two cationic surfactant intermediates were synthesized by improved method. The alkyl isocyanates, dodecyl isocyanate (1a) and tetradecyl isocyanate (1b), were synthesized by corresponding alkyl amines and bis(trichloromethyl) carbonate (BTC) in anhydrous toluene. The yield of 1a–b reached 86%, the product was colorless liquid and the purity was measured more than 98% by GC. The target products, 3-(dimethylamino)propane-1,2-di-dodecylcarbamate (2a) and 3-(dimethylamino)propane-1,2-di-tetradecylcarbamate (2b) were synthesized by 1-dimethylamino-2,3-propanediol and alkyl isocyanates with triethylamine as catalyst, the yield of 2a–b was 65%.

Synthesis and Interfacial Tension Behavior of Heavy Alkyl Benzene Sulfonates

Abstract Heavy alkyl benzene sulfonates (HABS) were synthesized, and their interfacial tensions were measured and compared with those of petroleum sulfonates ORS-41. Effects of their coupling with lignosulfonate were also studied. The results showed that HABS exhibited good interfacial activities and the system of HABS blending with LS displayed better interfacial activities than ORS-41 and therefore reduced the prime cost. Their best proportions of synergism were from 3:1 to 4:1. HABS might be a more promising alkali-surfactant-polymer (ASP) flooding agent.