Characterization of aqueous two phase systems by combining lab-on-a-chip technology with robotic liquid handling stations

Over the last decade, the use of design of experiment approaches in combination with fully automated high throughput (HTP) compatible screenings supported by robotic liquid handling stations (LHS), adequate fast analytics and data processing has been developed in the biopharmaceutical industry into a strategy of high throughput process development (HTPD) resulting in lower experimental effort, sample reduction and an overall higher degree of process optimization. Apart from HTP technologies, lab-on-a-chip technology has experienced an enormous growth in the last years and allows further reduction of sample consumption. A combination of LHS and lab-on-a-chip technology is highly desirable and realized in the present work to characterize aqueous two phase systems with respect to tie lines. In particular, a new high throughput compatible approach for the characterization of aqueous two phase systems regarding tie lines by exploiting differences in phase densities is presented. Densities were measured by a standalone micro fluidic liquid density sensor, which was integrated into a liquid handling station by means of a developed generic Tip2World interface. This combination of liquid handling stations and lab-on-a-chip technology enables fast, fully automated, and highly accurate density measurements. The presented approach was used to determine the phase diagram of ATPSs composed of potassium phosphate (pH 7) and polyethylene glycol (PEG) with a molecular weight of 300, 400, 600 and 1000 Da respectively in the presence and in the absence of 3% (w/w) sodium chloride. Considering the whole ATPS characterization process, two complete ATPSs could be characterized within 24 h, including four runs per ATPS for binodal curve determination (less than 45 min/run), and tie line determination (less than 45 min/run for ATPS preparation and 8 h for density determination), which can be performed fully automated over night without requiring man power. The presented methodology provides a cost, time and material effective approach for characterization of ATPS phase diagram on base on highly accurate and comprehensive data. By this means the derived data opens the door for a more detailed description of ATPS towards generating mechanistic based models, since molecular approaches such as MD simulations or molecular descriptions along the line of QSAR heavily rely on accurate and comprehensive data. (C) 2014 Elsevier B.V. All rights reserved.