Researchers in Bioengineering Associate Professor Dan Fletcher’s laboratory have pioneered a new method for encapsulating proteins in cell-like lipid vesicles, according to a study published in the March 25, 2008 issue of the Proceedings of the National Academy of Sciences. Compartmentalization of biomolecules within lipid membranes is a fundamental requirement of living systems and an essential feature of many pharmaceutical therapies.
Created vesicles encapsulating biologically active compounds are useful as chemical microreactors, delivery vehicles for pharmaceuticals, and platforms for synthetic biological systems. However, applications of membrane-enclosed solutions of proteins, DNA, or biologically active compounds have been limited by the difficulty of forming unilamellar vesicles with controlled contents in a repeatable manner.
Current formation methods fall short of ideal in simultaneously controlling several important vesicle qualities, including size, membrane unilamellarity (single-layered), and internal solution concentration. Also highly desired has been a high-throughput process with high encapsulation efficiency to minimize needed solution volume, the ability to great giant unilamellar vesicles (diameters greater than 10 micrometers), and the ability to examine the vesicle and any associated reactions immediately after loading.
The Fletcher lab team created a method for simultaneously creating and loading giant unilamellar vesicles (GUVs) using a pulsed microfluidic jet. Like blowing a bubble, the microfluidic jet forms a planar lipid bilayer into a vesicle that is filled with solution from the jet and separates from the planar bilayer. A technological advance, their method rapidly generates multiple vesicles containing solutions of any composition and molecular weight. They demonstrated repeatable encapsulation of 500-nm particles into GUVs and show that functional pore proteins can be incorporated into the vesicle membrane to mediate transport.
The research, done by Mechanical Engineering graduate students Jeanne Stachowiak and Thomas Li, Biophysics graduate students David Richmond and Allen Liu, and Bioengineering graduate student Sapun Parekh, should open up new opportunities for forming, studying, and applying multicomponent biomolecular systems in fields such as in vitro biochemistry, synthetic biology, and pharmaceutical sciences. The Fletcher lab has extensive experience with microfluidic jetting, including their work with the MicroJet needleless jet injector.
Read the full article at PNAS