Sukhprit Singh

Synthesis and Properties of Thioether Spacer Containing Gemini Imidazolium Surfactants

Twelve new gemini imidazolium surfactants have been synthesized, having dodecyl, tetradecyl, hexadecyl, and octadecyl chain lengths and three different spacers (i.e., -S-(CH(2))(n)-S-), where n = 2, 3, and 4 and their surface properties have been evaluated by surface tension and conductivity methods. The thermal degradation of these new gemini surfactants was determined by thermogravimetric analysis (TGA). These surfactants have low cmc values as compared to other categories of gemini cationic surfactants and exhibit peculiarities at sufficiently low concentration because they were able to form premicellar aggregates over a wide range of concentration below their cmc values. The DNA binding affinity of these gemini surfactants determined by agarose gel electrophoresis and ethidium bromide exclusion experiments established their strong interaction with DNA, thereby protecting it against enzymatic degradation.

Novel Gemini Pyridinium Surfactants: Synthesis and Study of Their Surface Activity, DNA Binding, and Cytotoxicity

New pyridinium gemini amphiphiles having ethane-1,2-dithiol spacer have been synthesized by regioselective electrophilic cobromination of alpha-olefins. Ethane-1,2-dithiol (1) and N-bromosuccinimide (6) on reaction with alpha-olefins (dodecene (2), tetradecene (3), hexadecene (4), and octadecene (5)) gave the respective 1,2-bis(2-bromoalkylthio)ethane (7-10). The bromoalkylthio ethers when reacted with pyridine (11) gave the respective gemini bispyridinium bromide (12-15). The surface properties of new geminis were evaluated by surface tension and conductivity measurements. These gemini surfactants have also been found to be having low cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on C6 glioma cells. The DNA binding capabilities of these amphiphiles have been determined below as well as above critical micelle concentration. The preliminary studies by agarose gel electrophoresis indicated chain length dependent DNA binding abilities which has further been proved by ethidium bromide exclusion experiments and transmission electron microscopy (TEM).

Gemini imidazolium surfactants: synthesis and their biophysiochemical study.

New gemini imidazolium surfactants 9-13 have been synthesized by a regioselective epoxy ring-opening reaction under solvent-free conditions. The surface properties of these new gemini surfactants were evaluated by surface tension and conductivity measurements. These surfactants have been found to have low critical micelle concentration (cmc) values as compared to other categories of gemini cationic surfactants and also showed the tendency to form premicellar aggregates in solution at sufficiently low concentration below their cmc values. The thermal degradation of these surfactants was determined by thermograviometry analysis (TGA). These new cationic surfactants have a good DNA binding capability as determined by agarose gel electrophoresis and ethidium bromide exclusion experiments. They have also been found to have low cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the C6 glioma cell line.

Micellization behavior of morpholinium-based amide-functionalized ionic liquids in aqueous media.

Morpholinium-based amide-functionalized ionic liquids (ILs) [C(n)AMorph][Br], where n = 8, 12, and 16, have been synthesized and characterized for their micellization behavior in aqueous medium using a variety of state of the art techniques. The adsorption and micellization behavior of [CnAMorph][Br] ILs at the air-solution interface and in the bulk, respectively, has been found to be much better compared to that observed for nonfunctionalized homologous ILs and conventional cationic surfactants, as shown by the comparatively higher adsorption efficiency, lower surface tension at the critical micelle concentraiton (γ(cmc)), and much lower critical micelle concentration (cmc) for [C(n)AMorph][Br] ILs. Conductivity measurements have been performed to obtain the cmc, degree of counterion binding (β), and standard free energy of micellization (ΔG(m)°). Isothermal titration calorimetry has provided information specifically about the thermodynamics of micellization, whereas steady-state fluorescence has been used to obtain the cmc, micropolarity of the cybotactic region, and aggregation number (N(agg)) of the micelles. Both dynamic light scattering and atomic force microscopy have provided insights into the size and shape of the micelles. 2D (1)H-(1)H nuclear Overhauser effect spectroscopy experiments have provided insights into the structure of the micelle, where [C16AMorph][Br] has shown distinct micellization behavior as compared to [C8AMorph][Br] and [C12AMorph][Br] in corroboration with observations made from other techniques.

Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.

Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles.

Effect of Sodium Lauryl Sulphate on the Texture of Sponge Cake

Sponge cake was prepared by adding sodium lauryl sulphate (SLS), an anionic surfactant, to egg albumen during the mixing stage at levels of 0, 0.05, 0.1 and 0.2% on flour weight basis. The rheology of the cake batter was studied and texture of sponge cake crumb was measured on an Instron universal testing machine. Increasing levels of SLS lowered the specific gravity, surface tension, consistency coefficient and air bubble diameter. The cake volume increased with increasing levels of SLS. Texture profile analysis of cake crumb revealed that increasing SLS levels lowered crumb firmness and cohesiveness. Storage of cake crumb for up to 10 days at room temperature revealed that crumb containing SLS remained softer and that SLS may be involved in preventing starch retrogradation.

14α-Methylzymosterol and other sterols from Wrightia tinctoria seeds

Abstract The structure of a new sterol isolated from the unsaponifiable lipid of Wrightia tinctoria seed lipid was shown to be 14α-methylzymosterol by comparison with a synthetic authentic compound. Four uncommon sterols, desmosterol, clerosterol, 24-methylene-25-methylcholesterol and 24-dehydropollinastanol, in addition to several usual phytosterols, were isolated and identified.

Self-assembly, DNA binding and cytotoxicity trends of ether functionalized gemini pyridinium amphiphiles.

Six new ether functionalized gemini pyridinium amphiphiles have been synthesized having dodecyl, tetradecyl alkyl chain lengths and three different spacers (i.e. -(CH2)n-, where n is 4, 5 and 6) and investigated for their self-assembling behavior by state of the art techniques such as tensiometry, conductivity and spectrofluorometry. These new pyridinium gemini surfactants exhibit lower cmc values as compared to other gemini surfactants reported in literature. These amphiphiles form stable complexes with DNA as established by agarose gel electrophoresis and ethidium bromide exclusion experiments. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was carried out in vitro on C6 glioma cell line for cytotoxicity assessment of new pyridinium geminis. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) have been used to measure the micellar size of gemini surfactants. Further, thermal stability of these amphiphiles has been evaluated by thermogravimetric analysis (TGA). The dependence of self-assembly behavior and other properties on spacer as well as alkyl chain length has been established.

Structural diversity, physicochemical properties and application of imidazolium surfactants: Recent advances

The current review covers recent advances on development and investigation of cationic surfactants containing imidazolium headgroup, which are being extensively investigated for their self-aggregation properties and are currently being utilized in various conventional and non-conventional application areas. These surfactants are being used as: soft template for synthesis of mesoporous/microporous materials, drug and gene delivery agent, stabilizing agent for nanoparticles, dispersants for single/multi walled carbon nanotubes, antimicrobial and antifungal agent, viscosity modifiers, preparing nanocomposite materials, stabilizing microemulsions, corrosion inhibitors and catalyst for organic reactions. Recently several structural derivatives of these surfactants have been developed having many interesting physicochemical properties and they have demonstrated enormous potential in the area of nanotechnology, material science and biomedical science.

Synthesis and self aggregation properties of ester-functionalized heterocyclic pyrrolidinium surfactants

Linear fatty alcohols on reaction with chloro/bromo acetic acid in the presence of catalytic amount of p-toluene sulphonic acid monohydrate under solvent-free conditions are converted into alkyl-2-haloacetate which on reaction with N-methyl pyrrolidine gives ester-functionalized pyrrolidinium surfactants. Thus, new series of ester-functionalized heterocyclic pyrrolidinium head group containing cationic surfactants have been synthesized by green approach via energy saving and cost effective methodology. These new surfactants have been investigated for their surface properties by surface tension, conductivity, and fluorescence method. Surface properties of these surfactants have been found to be far better compared to conventional heterocyclic cationic surfactants having similar hydrophobic alkyl chain length.