Controlling Nanoparticles in Biological Systems

Nano- and microscale particle systems have become a key component in biomedical applications such as drug-delivery systems. Their small size and potential for modification and functionalization make them suitable for performing specific tasks in the body. Yet, controlling these materials at the structural level to create particles capable of complex interactions with biological systems remains a challenge.Joerg Lahann, associate professor in the chemical engineering department at the University of Michigan (Ann Arbor), and his team of researchers are rising to that challenge. Using a microscale fluid manipulation system dubbed electrohydrodynamic cojetting, an electrospinning process in which thin fibrous strands are drawn from a liquid using high voltage, they believe that they can control nanoparticles' interactions with biological systems.As reported in the materials science journal Advanced Materials, Lahann's team utilizes this system to synthesize dual-compartment, biologically compatible polymer particles with the ability to selectively self-associate with human endothelial cells found in the lining of blood vessels. When they are incubated with these cells, the particles display a strongly specific binding pattern because one of their compartments has been modified with the protein streptavidin, which interacts strongly in biological systems. As a result of this selective funcationalization process, one hemisphere of a particle exhibits strong affinity with a cell surface while another does not, leading to spatial control at the cellular level. Since only one side of each particle is attracted to the cells, they form into layers, just one particle thick, on the cell surface.Having demonstrated the fundamental concept of selective particle control, Lahann and his cothinkers hope to build more-sophisticated multicompartmented building blocks suitable for use in more-complex biohybrid designs. Finer control over the particle architecture, they believe, will allow for the creation of different particle morphologies and functionalities, paving the way for the design of novel, complex systems for use in areas such as regenerative medicine, medical imaging, and diagnostics.