Figure 4.

Microfluidic chip used for protein refolding [15]. (a) Designed microfluidic chips. In MR1, the denaturant concentration around the protein rapidly decreases because of diffusion, which is expected to have a similar mechanism to one-step dialysis and dilution. In MR2, the denaturant concentration shows a step-wise decrease, which is a similar mechanism to step-wise dialysis. The denatured protein was injected into channel a. The diluting buffer was injected into channels b and c; (b) Confocal fluorescence microscope image at the junction in MR1 showing laminar flow of the urea stream through the diluting buffer streams. The focused urea stream contains N-(4-nitrobenzo-2-oxa-1,3-diazolyl)amine (NBD) as an indicator; (c) Relative fluorescence intensities of NBD in the urea stream as a function of the distance from the inlet (position a). Flow rates (μL/min) are shown in the graph.