Comparison of Physicochemical Studies of Single Tailed and Gemini Cyclohexanoxy Carbonyl Pyridinium Cationic Amphiphiles

Abstract

In the present research work, the physicochemical studies of surface active Cyclohexanoxy carbonyl Pyridinium single tailed and Gemini amphiphiles had been compared. Thermal stability, size of aggregates in aqueous system and interaction with a globular protein, Bovine Serum Albumin (BSA), was done by using TGA analysis, DLS, UV-visible, steady-state fluorescence and synchronous fluorescence and TEM respectively. On the basis of the experiments, it had been concluded that the Gemini amphiphile possessed less cytotoxicity, high thermally stability, form small sized compact aggregates and stable complex with BSA. The results have further been supported by higher value of Stern-Volmer quenching constant (K SV ) and a higher binding constants for Gemini amphiphiles as compared to single tailed amphiphiles. Moreover, on the basis of synchronous fluorescence spectra and UV spectra, it has been concluded that both the amphiphiles mainly interact with tryptophan residues. The less cytotoxicity values and stabilization of secondary structure of BSA in low concentration of ionic liquids implies that these ionic liquids can replaced the conventional surfactants in the detergent industries and used as a potential vehicles for the drug and gene delivery.the change in the wavelength of emission maximum (λ max ) and intensity parameters found to be sensitive to protein conformation and can be used to investigate the interactions between BSA and ionic liquids. DLS and TEM studies are used to see the change in conformation of the amphiphiles in the presence of BSA. Materials and Methods MaterialsGemini Amphiphiles (GA) and Single Tailed amphiphiles (ST) ( Figure 1) were synthesized in our lab by an earlier reported procedure [18,19]. Bovine Serum Albumin (BSA) (MW=66 kDa) was purchased from Central drug house (New Delhi, India) and was used as received. 0.01 M buffer, pH 7.2, was made from 0.01 M KH 2 PO 4 and 0.01 M sodium hydroxide. Potassium dihydrogen phosphate and sodium hydroxide were purchased from Merck, India. Millipore water was used in all experiments. Thermal gravimetric analysisThermal stability of both the amphiphiles had been investigated by Perkin Elmer Pyris 1 Thermal Gravimetric Analyzer (TGA). Both the samples were completely dried by rotatory vaccum pump. Both the samples were added in to the aluminum pans under the inert atmosphere at a heating rate of 10°C/min. Dynamic Light Scattering (DLS)The size of the studied cationic amphiphiles has been measured by the Zetasizer Nano ZS (Malvern Instrument Ltd.) UK. The inbuilt peltier device controls the temperature with an accuracy of ±0.1 K. The 1.0 mM aqueous solution of both amphiphiles has been filtered through 0.45 μM pore sized filter before measurement. CytotoxicityThe cytotoxicity of, 1.0 mM aqueous solution, both synthesized amphiphiles was carried out on C 6 glioma (cancerous brain cell line, passage number 65) by using MTT assay to calculate the IC 50 value of both the synthesized ionic liquids. Cells were seeded at a density of 10 × 10 3 cells/m...