Carbohydrate-based aqueous biphasic systems for biomolecules extraction

Abstract

Any potential of new biotechnological processes would be assuredly canceled in the absence of efficient separation strategies. This work comprehensively addresses the solutes partitioning behavior in biocompatible carbohydrate-polymer aqueous biphasic systems (ABSs) to explore the separation performance of these systems. The complete liquid–liquid phase diagrams were determined for sucrose/glucose-polypropylene glycol (PPG) ABSs at 25 °C and atmospheric pressure. Then, the partitioning pattern of four biomolecules, including caffeine, codeine, vanillin, and curcumin, was investigated in the carbohydrate-PPG ABSs. The obtained results show that caffeine, vanillin, and curcumin are mostly electrically neutral in the medium of the studied ABSs and preferentially concentrate in the more hydrophobic PPG-rich phase with the maximum partition coefficients (K) of 2.05, 19.75, and 246.37, respectively. However, codeine, being present mainly in the cationic form in the ABSs investigated, has a high tendency for the more hydrophilic carbohydrate-rich phase with the highest K−1 = 16.85. The magnitude of log K values for all the target biomolecules linearly increases by decreasing the water content ratio of the coexisting phases. The maximum value of the caffeine/codeine selectivity index was estimated to be 34.5 at optimum conditions. The best value of K did not necessarily correspond to the maximum recovery percentage (R) because the volume ratio of phases is another factor that can affect the R values. The curcumin partitioning behavior in carbohydrate-propanol ABSs was also investigated to provide a competitive platform. The gathered results indicate that although both carbohydrate-PPG and carbohydrate-propanol ABSs provide satisfactory partitioning performance for vanillin and curcumin, carbohydrate-PPG ABSs own a higher selectivity index for the alkaloids studied.