title: Measuring the interaction forces between protein inclusion bodies and an air bubble using an atomic force microscope.
abstract: Interaction forces between protein inclusion bodies and an air bubble have been quantified using an atomic force microscope (AFM). The inclusion bodies were attached to the AFM tip by covalent bonds. Interaction forces measured in various buffer concentrations varied from 9.7 nN to 25.3 nN (+/- 4-11%) depending on pH. Hydrophobic forces provide a stronger contribution to overall interaction force than electrostatic double layer forces. It also appears that the ionic strength affects the interaction force in a complex way that cannot be directly predicted by DLVO theory. The effects of pH are significantly stronger for the inclusion body compared to the air bubble. This study provides fundamental information that will subsequently facilitate the rational design of flotation recovery system for inclusion bodies. It has also demonstrated the potential of AFM to facilitate the design of such processes from a practical viewpoint.
authors.affiliation: Cooperative Research Centre for Tissue Growth and Repair, Department of Chemical Engineering, University of Adelaide, South Australia 5005, Australia.
authors.forename: N D
authors.initials: ND
authors.lastname: Wangsa-Wirawan
authors.forename: A
authors.initials: A
authors.lastname: Ikai
authors.forename: B K
authors.initials: BK
authors.lastname: O'Neill
authors.forename: A P
authors.initials: AP
authors.lastname: Middelberg
mesh_terms: D000388:Air; D002021:Buffers; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D002479:Inclusion Bodies / Q000737:chemistry / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000302:isolation & purification; D018625:Microscopy, Atomic Force; D009994:Osmolar Concentration; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification*; D013048:Specimen Handling; D055672:Static Electricity
chemical_list: D002021:Buffers; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I