Measuring the Interaction Forces between Protein Inclusion Bodies and an Air Bubble Using an Atomic Force Microscope

• Published in: Biotechnology progress Vol. 17; no. 5; pp. 963 - 969
• Main Authors: Wangsa-Wirawan, N. D., Ikai, A., O'Neill, B. K., Middelberg, A. P. J.
• Format: Journal Article
• Language: English
• Published: USA American Chemical Society 01-09-2001; American Institute of Chemical Engineers
• Subjects: Air; atomic force microscopy; Biological and medical sciences; Biotechnology; Buffers; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Humans; Hydrogen-Ion Concentration; Inclusion Bodies - chemistry; Inclusion Bodies - metabolism; Insulin-Like Growth Factor I - biosynthesis; Insulin-Like Growth Factor I - isolation & purification; Methods. Procedures. Technologies; Microscopy, Atomic Force; Osmolar Concentration; Others; Recombinant Proteins - biosynthesis; Recombinant Proteins - isolation & purification; Specimen Handling; Static Electricity; Various methods and equipments; Atomic force microscopy; Separation method; Flotation; Interaction; Inclusion body; Measurement method; Air bubble; Application; Protein
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp010072+

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.