Microfluidic Devices for Membrane Protein Nanoparticle Formation

Microfluidic devices, so-called BioMEMs, or Lab on a chip, have been widely used to improve the science and technology, especially in biological applications. The analysis of protein structure formation is currently one of the most interesting research areas in biology. The analysis of protein structure not only aid scientists in realizing the interaction of molecule biology but also can be applied to improve in the development of the drug design in pharmacology. Our main focus is on the membrane proteins that are estimated to be more than 30% of total protein number. These membrane proteins can be a transport channel for controlling molecule transportation, a sensor and a receptor to communicate between cells. The existing structures of membrane proteins are embedded with lipid bilayer structure where they are naturally formed by hydrophobic reaction. Consequently, the best way to analyze the single membrane protein structure is from the purified single membrane-detergent complex added with lipid and then removing the detergents to form a nature structure of membrane protein with lipid bilayer which is called a reconstitution, or membrane protein crystallization. The current method of membrane protein crystallization is using dialysis membrane in between protein-detergent-lipid solution and a buffer solution to dialyze and remove the detergents. The main drawbacks in the current methodology include time-consuming hand pipette, large volume of protein sample consumption (microliter), and slow diffusion of dialysis process (days). We present a new method of membrane protein crystallization by using microfluidic device to achieve the reconstitution. This microfluidic device is designed and fabricated by using a soft lithography which is one of MEMs techniques. Based on this new microfluidic device we can reach break-through improvements compared to the current method with dialysis membrane. First, hand pipette is no longer required because the input fluids are all driven by controllable syringe pumps. Secondly, micro channels allow a lower volume of protein sample consumption, nanoliter to picoliter. The third advantage is the diffusion process in microfluidic device can be completed in few seconds without dialysis membrane to form membrane protein crystals