Mechanism of the Extraction of Proteins into Tween 85 Nonionic Microemulsions

Abstract

Protein extraction into Tween 85 nonionic microemulsions is characterized. Apparently, a weak electrostatic interaction is the underlying extraction mechanism. The extraction of several proteins is examined as a function of protein size and net charge. The proteins that extracted successfully are positively charged. A size-exclusion limit (60 kDa) is also evident in these extractions. Tween 85 and several other nonionic surfactants possess a net negative charge at neutral pH. Titration measurements are an effective means of quantifying charge on these surfactants. In Tween 85 microemulsion separations, both the sign and the magnitude of surfactant charge play a role in extraction. Blends of Neodol 91−2.5 (capable of extracting 0% protein) and Tween 85 (capable of extracting 100% protein) indicate that a minimum net surfactant charge of 15 mequiv/mol is required for extraction.

Protein separation by affinity extraction with reversed micelles of Span 85 modified with Cibacron Blue F3G-A

“…The result is in agreement with the effect of pH on lysozyme adsorption to CB-modified membranes [29]. In addition, previous publications have reported that non-ionic surfactants such as Tween 85, Span 20 and Span 60 are negatively charged at neutral pH [12,30], so weak electrostatic attractions between Span 85 and lysozyme (isoelectric point, pI = 11.1) might contribute somewhat to lysozyme extraction at the neutral pH range. In contrast, the extraction yield of ovalbumin decreased from 49% to 36% with increasing pH value.…”

Inclusion Extraction of Alkali Metals by Emulsion Liquid Membranes and Nano-baskets of p-tert-Calix[4]arene Bearing Di-[N-(X)sulfonyl Carboxamide] and Di-(1-propoxy) in ortho-cone Conformation

“…This step is associated with the recovery of the membrane phase. Some of the ELM's applications include separation of sugars, 15 organic acids, 16,17 amino acids, 18-21 proteins 22 and antibiotics.…”

Inclusion separation of alkali metals in emulsion liquid membranes by nanobaskets of calix[4]crown-3

“…This step is associated with the recovery of the membrane phase. ELM applications include separation of sugars (Ikeda et al 2003), organic acids (Yordanov and Boyadzhiev, 2007;Demirci et al, 2003), amino acids (Kaghazchia et al, 2006;Mohagheghi et al, 2008;Oshima et al, 2003;Bayraktar, 2001), proteins (Vasudevan and Wiencek, 1996) and antibiotics (Habaki et al, 2008;Lee, 2002).…”