Forward and backward extraction of BSA using mixed reverse micellar system of CTAB and alkyl halides

Abstract

The forward and backward extraction of bovine serum albumin (BSA) has been studied using mixed reverse micellar systems of cetyl trimethyl ammonium bromide (CTAB) and alkyl halides (including 1-chlorobutane (R 4Cl), 1-bromooctane (R 8Br) and 1-iodobutane (R 4I)). The addition of alkyl halide R 8Br to 50 mmol/l CTAB/20% (v/v) hexanol/petroleum ether reverse micellar system could improve the BSA transfer from the aqueous phase to reverse micellar phase, while the addition of R 4Cl or R 4I had almost no effect on the BSA transfer. The mixed reverse micelles formed with CTAB and alkyl halides exhibit excellent backward extraction behavior for BSA. The mixed reverse micelles formed with CTAB and R 4I can realize the recovery of BSA effectively in a wide range of pH up to or higher than the isoelectric point of BSA. The mixed reverse micelles formed with CTAB and R 4Cl, R 8Br or R 4I can obviously enhance the BSA backward transfer at low ionic strength with addition of KBr or KCl as electrolyte. The mixed reverse micellar system indicates that it requires less time to reach the mass transfer equilibrium in comparison with the reverse micellar system with CTAB only. The mechanism of backward extraction proposed that with the addition of alkyl halides to CTAB reverse micelles, the hydrophobic interaction between the reverse micelles decreased.