Light Scattering Measurements of Hemoglobin Critical Fluctuation and the Energy Landscape For Polymerization

We have developed a novel method for measuring light scattering to observe critical fluctuations in hemoglobin (Hb) solutions. A small rectangular cell (0.2 x 4.0 x 30 mm) is filled with 24 μL of Hb solution. An optical fiber with outer diameter of 125 μm (62.5 μm core) is sealed into the cell in contact with the solution, and light scattering is measured at 90°. The flat faces of the cell permit measuring absorbance spectra to ensure sample integrity. The scattering source is a 785 nm laser diode that delivers 1.5 mW to the sample. Scattered light is detected by a Hamamatsu GaAs(Cs) PMT via a LWD microscope objective. Measured scattered light intensity agrees (±10%) with scattered intensit…