Chip fab techniques help build living neural circuits

Researchers in Korea have taken a leaf out of the microengineer's book, and used lithographic techniques to build live neural circuits in a petri dish. They hope the technique could be exploited one day to build neural tissue scaffolds, to help regenerate neurons in damaged areas of the body, including the spinal cord.

The development is not strictly materials science, but fascinating nonetheless — especially in a world where there is an increasing interplay between biology and technology, with proteins being used as the building blocks for circuits, and graphene proving itself adept at protein detection.

The researchers printed a variety of single-cell-sized shapes — including triangles, circles, hexagons, squares and stars — onto a culture substrate using microcontact printing, a form of soft lithography, with a mixture of poly-L-lysine and laminin A chain synthetic peptide. Then they sprayed this surface with rat neurons that had been tagged with fluorescent dyes. This meant they could take pictures of the resulting growth patterns.

In microcontact printing, the master is typically created using techniques familiar to anyone in the microprocessor industry: a silicon wafer is painted with photoresist, and then patterned using UV light and a photomask to create the stamp.

The main thrust of the Korean research was to discover whether or not a shaped substrate might also be able to direct the form of neuron growth. A neuron is composed of three main parts: a cell body, or soma, dendrites and an axon, which extends from the soma and links to other cells, creating a network. The growth of an axon is guided by proteins, and there is a huge body of research trying to understand the mechanisms involved.

Triangles with small vertices worked best, according to the work published in the Institute of Physics Publishing's Journal of Neural Engineering. Co-author of the study Professor Yoonkey Nam notes in the announcement: "Based on our results, we are suggesting a new design principle for guiding axons in a dish. We can control the axonal growth in a certain direction by putting a sharp triangle pointing to a certain direction. Then, a neuron that adhered to the triangle will have an axon in the sharp vertex direction."

Nam added: "Eventually, we want to know if we can design a neural tissue model that biologically mimics some neural circuits in our brain."

The work could have a wide range of other applications, from drug screening, though to memory and learning studies.