Improving the extraction and purification of immunoglobulin G by the use of ionic liquids as adjuvants in aqueous biphasic systems

- Novel aqueous biphasic systems (ABS) formed by ionic liquids as adjuvants were investigated.
- The performance of the studied ABS for the extraction and purification of Immunoglobulins G (IgG) was evaluated.
- Extraction efficiencies of 100% of IgG were achieved in a single-step.
- An enhancement of 37% in the IgG purity of IgG was obtained with systems formed by ionic liquids.
- The stability and structural integrity of IgG in presence of ionic liquids was evaluated.

Immunoglobulins G (IgG) could become widespread biopharmaceuticals if cost-efficient processes for their extraction and purification are available. In this work, aqueous biphasic systems (ABS) composed of polyethylene glycols and a buffered salt, and with ionic liquids (ILs) as adjuvants, have been studied as alternative extraction and purification platforms of IgG from a rabbit serum source. Eleven ILs were investigated to provide insights on the chemical features which maximize the IgG partitioning. It is shown that in polymer-salt systems pure IgG preferentially partitions to the polymer-rich phase; yet, the complete extraction was never attained. Remarkably, after the addition of 5 wt% of adequate ILs to polymer-salt ABS, the complete extraction of pure IgG in a single-step was accomplished. The best systems and conditions were then applied to the extraction and purification of IgG directly from rabbit serum samples. The complete extraction of IgG in a single-step was maintained while its purity in the polymer-rich phase was enhanced by ca. 37% as compared to the IL-free ABS. The antibody stability was also evaluated revealing that appropriate ILs are able to maintain the IgG stability and can be used as phase-forming components of ABS when envisaging the purification of high-cost biopharmaceuticals.

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