Microcontact Printing of Poly (L-lysine) Using PDMS Stamps for the Adhesion and Patterning of Neurons

One method that facilitates the high throughput of microcontact printing arrays of proteins for the adhesion of neurons is a micropatterning technique using Polydimethylsiloxane (PDMS) stamps.  This technique was used as an aid to achieve patterning of neurons and growth of neural extensions (dendrites and axons). The PDMS was made from a mixture of Sylgard 184 PDMS base and PDMS curing agent in a ratio of 10:1 by mass. These stamps were cured in a polyurethane master mold with pillar relief patterns of the desired arrays on a hot plate at 70 degrees Celsius. The stamp included raised circular pillars, in 32x32 array patterns that varied in pitch and diameter. Once the stamps were cured, they were cut out and treated with Poly (L-lysine) (PLL), a cell adhesion promoter solution, pillar side up. Once dried, a residual layer of PLL remained and was then deposited on a glass substrate by applying force to the PDMS stamp on the substrate pillar side down. A glass-backed PDMS stamp proved to achieve the best deposited patterns of PLL. Also, in conjunction with the glass backing, 50-200 gram weights were used as the stamping forces to allow for a more even distribution of force in an attempt to prevent stamp deformation. Stamped substrates were then placed in culture wells, and hippocampal rat neurons were introduced with media into each well. After an incubation period, neurons preferentially anchored to the stamped PLL spots on the substrates. Neurite growth between neurons appeared between 5-10 DIV.