Imaging of Protein Fouling

FIGURE 19.11 Scanning electron microscopy image of sintered membrane surface fouled with whey protein concentrate deposits. (From Bird, M.R. and Barttlett, M., J. Food Engr., 53, 143, 2002. With permission.)... 

Rajesh S, Jayalakshmi A, Senthilkumar S, Sankar HSH, Mohan DR. Performance evaluation of poly(amide-imide) incorporated cellulose acetate ultrafiltration membranes in the separation of proteins and its fouling propensity by AFM imaging. Ind Eng Chem Res 2011 50(24) 14016-29. 

Can the two-stage mechanism for protein fouling (that has been proposed in the literature as a result of filtration data analysis) be verified through multiphoton images ... 

Multi-photon microscopy for in situ characterization is a fluorescence laser scanning technique (see Chapter 8). This technique can produce 3D images, which can be stacked to get time series for different interesting phenomena in UF and MF. Fouling inset can be characterized and thus also the critical flux can be measured. Fouling of membranes, especially by proteins, has been studied with this technique. Because the target substance needs to be fluorescent, not all kinds of filtration processes can be monitored in this way. 

From a top-down image it is impossible to ascertain whether the initial fouling occurs within the membrane pores, or at the openings of the pores. This can only be achieved using profile or side-on images. A side view of an internally fouled cylindrical pore membrane would consist of alternating vertical bands of fluorescence and darkness. The fluorescence bands are pores with protein deposited within them and the dark bands are nonporous areas, or pores that do not have any protein deposited within them. When a significant cake has formed on top of the membrane this is visible. 

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