3. You were just hired at a biotech company working to develop a physiological system for precisely modeling cytokine transport in tissues. To launch the project, you have been tasked with characterizing diffusion of the cytokine interleukin-6 (IL-6) in a novel hydrogel the company is using to model tissue in the engineered fluidic culture device depicted below. This device consists of a central channel filled with hydrogel (orange) that acts as a diffusion barrier between the two liquid channels (labeled loading channel and collection channel in the diagram). The liquid in the channels and hydrogel are in direct contact (no intervening membrane). Assume transport in the hydrogel is purely by 1-D diffusion. The height and length of the interface between the hydrogel and liquid channels are 1 mm and 20 mm, respectively. The width of the hydrogel is 3 mm. Loading channel (IL-6 source) total volume = 20 ul Top-down view IL-6 molecules of the device. 20 mm Diffusion across hydrogel 3 mm Hydrogel Collection channel - total volume = 20 l Fick's 1st Law with applicable units for the flux and diffusion coefficient: (Hint: the units are the key to the finding the solution) J = Mass Flux [g/cm2.s] dC D = Diffusion Coef. (cm2/s] J = -D C = Concentration dx x= Position A. (6 pts) You designed an experiment to measure mass flux in the system and filled the loading channel with a 100 ng/ml IL-6 solution. You filled the collection channel with the same liquid buffer devoid of IL-6 (0 ng/ml IL-6). Assume that transport within the hydrogel is purely by static diffusion. You measured 555 pg/ml IL-6 in the collection channel after 10 minutes. Ignoring the slight decrease in the concentration gradient that would occur during this time, calculate an estimated IL-6 diffusion coefficient in the company's novel hydrogel. B. (4 pts) Use the IL-6 diffusion coefficient you calculated to determine the mass flux of IL-6 (i.e., the total amount transported) after 24 hours if you reduced the loading channel concentration to a physiological 1 ng/ml and operated the device with flow conditions in each channel tha maintained a steady-state concentration gradient across the hydrogel