Research Article: Aggregation and interfacial phenomenon of amphiphilic drug under the influence of pharmaceutical excipients (green/biocompatible gemini surfactant)

Date Published: February 6, 2019

Publisher: Public Library of Science

Author(s): Malik Abdul Rub, Bing Xu.


In the current study, we have examined the interaction amongst an antidepressant drug amitriptyline hydrochloride (AMH) and ethane-1, 2-diyl bis(N,N-dimethyl-N-cetylammoniumacetoxy) dichloride (16-E2-16, a green gemini surfactant) through tensiometric and fluorimetric techniques in aqueous/electrolyte/urea solutions. Significant variations are observed in the various evaluated parameters in the present study. Gemini 16-E2-16 has outstanding surface properties along with a much lower cmc value, demonstrating very little toxicity as well as considerable antimicrobial activity. The cmc values of mixtures decrease through increase in mole fraction (α1) of 16-E2-16, which specifies the nonideality of the solution mixtures, along with demonstrating the occurrence of mixed micellization too. Negative βRub values signify on the whole attractive force of interaction between constituents of mixed micelles. Owing to the incidence of electrolyte NaCl (50–1), lowering of the micelles’ surface charge happens, resulting in aggregation taking place at lower concentration while the presence of urea (NH2CONH2) halts micellization taking place, which means the cmc value increases in the attendance of urea. The ΔGmo values for all systems were negative along with the presence of electrolyte/urea. The excess free energy (Gex) of studied mixed systems was also estimated and found to be negative for all the systems. Using the fluorescence quenching method, the micelle aggregation number (Nagg) was evaluated and it was found that the contribution of gemini surfactant was always more than that of the AMH and their value enhances in the existence of electrolyte while decreasing in the attendance of NH2CONH2 in the system. In addition, other fluorescence parameters such as micropolarity (I1/I3), dielectric constant (Dexp) as well as Stern–Volmer binding constants (Ksv) of mixed systems were evaluated and the results showed the synergistic performance of the AMH + 16-E2-16 mixtures. Along with tensiometric and fluorimetric techniques, FT-IR spectroscopy was also engaged to reveal the interaction among constituents.

Partial Text

Amphiphiles such as surfactants have been receiving consideration due to their extraordinary properties as well as numerous overlay uses as a part of pharmaceutics, drug delivery, emulsification, nanomaterial preparation, vesicle development, oil recuperation and so on [1–5]. Above a particular concentration, amphiphile molecules form micelles in aqueous as well as nonaqueous solution [5–8]. The concentration beyond which the formation of micelles starts is labeled the critical micelle concentration (cmc) [5–8]. It is important for most reasonable applications to select a mixture of amphiphiles to achieve the desired characteristics [5]. Mixed amphiphile mixtures are also be helpful for the environment because the amount of amphiphiles discharged and therefore their impact could probably be reduced considerably [5,9]. In the pharmaceutical industry, the absorption of several drugs in human beings is enhanced by way of micelles [10].

Detailed tensiometric and fluorescence studies of the interaction between the antidepressant drug AMH and the green gemini surfactant, 16-E2-16 were executed in three dissimilar solvents (water/electrolyte/urea (two different concentrations)) at 298.15 K. Owing to the existence of salt cmc values of the studied system in various ratios were found to decrease whereas in the existence of NH2CONH2 their value rises. In the presence and absence of electrolyte/urea the interfacial as well as micellar conduct in the mixed systems were examined where cmc values of mixtures were found below ideal cmc (cmcid), that demonstrates the attractive interaction amongst the studied constituents (drug and gemini). The X1Rub values in all cases were achieved negative, also viewing interaction in solution mixture and their negative value increases through raising the mole fraction of 16-E2-16 owing to an increase in hydrophobic interactions. The Nagg value for individual in addition to all studied mixtures in various solvents increases through raising the proportion of 16-E2-16 in solution mixtures. The experimentally evaluated and calculated apparent dielectric constants in all studied solutions were found to be less than their ideal value owing to attractive interactions within the micelle. Shifts in stretching along with bending frequencies of studied systems were found, suggesting an interaction among the constituents.




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