Optical protein patterning

BeHsle JM, Kunik D, Costantino S (2009) Rapid multicomponent optical protein patterning. Lab Chip 9 3580-3585... 

A drawback of the MD-class BioCD is the microfabrication required to pattern gold spokes on the disc to set the quadrature condition. To remove the microfabrication, an alternative means to establish a quadrature condition uses adaptive optical mixers in the far field to establish and lock phase quadrature. In this case, the disc can be a high-reflectance antinode surface with protein patterned directly on the disc surface without any need for surface structuring. As the disc spins, the immobilized protein causes phase modulation that is detected in the quadrature condition set up by the adaptive mixer. 

In order to quantitatively analyze the protein patterns, the gels were scanned, and the relative optical density of the bands was plotted against the distance from the start of the gel. 

Rla. Rees, V. H., and Laurence, D. J. R., The correspondence with Beer s Law for the optical density of stained protein patterns on filter paper as a function of surface protein concentration. Clin. Chem. 1, 329 (1955). 

Fig. 11.5 Differential phase contrast detection of patterned protein in a 10 mm by 30 mm region, (a) Protein height signal showing ridges of protein in a checker board pattern, (b) Side band demodulated signal image in which the carrier frequency of the ridges is removed to show only the protein envelope. Reprinted from Ref. 21. with permission. 2008 Optical Society of America...

Fig. 12. Diagram of elution pattern of red cell acid phosphatase and various markers on Biogel P 60. The position of the various protein markers was determined both by optical density determination and by starch gel electrophoresis of the individual fractions (83). The experiment was carried out using a polyacrylamide gel (Biogel P 60, 50-150 mesh exclusion limit >60,000 Bio-Rad Laboratories, California) in 0.05 M tris buffer, pH 8.0, containing 0.08% (v/v) Tween 80 and 0.1% (v/v) 2-mercaptoethanol to stabilize the enzyme. Column 60 X 4 cm. Flow rate 20 ml/hr, 4 ml fractions. (A) OD at 280 nm, ( ) OD at 540 nm, ( ) LDH assay with p-nitrophenyl phosphate for AcP. From Hopkinson and Harris (85).

---