Good's buffers as a basis for developing self-buffering and biocompatible ionic liquids for biological research


This work reports a promising approach to the development of novel self-buffering and biocompatible ionic liquids for biological research in which the anions are derived from biological buffers (Good's buffers, GB). Five Good's buffers (Tricine, TES, CHES, HEPES, and MES) were neutralized with four suitable hydroxide bases (1-ethyl-3-methylimidazolium, tetramethylammonium, tetraethylammonium, and tetrabutylammonium) producing 20 Good's buffer ionic liquids (GB-ILs). The presence of the buffering action of the synthesized GB-ILs was ascertained by measuring their pH-profiles in water. Moreover, a series of mixed GB-ILs with wide buffering ranges were formulated as universal buffers. The impact of GB-ILs on bovine serum albumin (BSA), here used as a model protein, is discussed and compared with more conventional ILs using spectroscopic techniques, such as infrared and dynamic light scattering. They appear to display, in general, a greater stabilizing effect on the protein secondary structure than conventional ILs. A molecular docking study was also carried out to investigate on the binding sites of GB-IL ions to BSA. We further used the QSAR-human serum albumin binding model, log K(HSA), to calculate the binding affinity of some conventional ILs/GB-ILs to HSA. The toxicity of the GB and GB-ILs was additionally evaluated revealing that they are non-toxic against Vitro fischeri. Finally, the GB-ILs were also shown to be able to form aqueous biphasic systems when combined with aqueous solutions of inorganic or organic salts, and we tested their extraction capability for BSA. These systems were able to extract BSA with an outstanding extraction efficiency of 100% in a single step for the GB-IL-rich phase, and, as a result, the use of GB-IL-based ABS for the separation and extraction of other added-value biomolecules is highly encouraging and worthy of further investigation.



subject category

Chemistry; Science & Technology - Other Topics


Taha, M; Silva, FAE; Quental, MV; Ventura, SPM; Freire, MG; Coutinho, JAP

our authors


The authors are thankful to FCT - Fundacao para a Ciencia e a Tecnologia for financial support through the post-doctoral grants of M. Taha and S. P. M. Ventura, SFRH/BPD/78441/2011 and SFRH/BPD/79263/2011, respectively. CICECO is being funded by FCT through the Pest-C/CTM/LA0011/2013 project. The authors are also grateful to FCT under the scope of the project PTDC/AAC-AMB/119172/2010. M. G. Freire acknowledges the European Research Council (ERC) for the Grant ERC-2013-StG-337753.

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