@article {Ongo001305, author = {Grant Ongo and S{\'e}bastien G. Ricoult and Timothy E. Kennedy and David Juncker}, title = {Ordered, Random, Monotonic, and Non-monotonic Digital Nanodot Gradients}, elocation-id = {001305}, year = {2013}, doi = {10.1101/001305}, publisher = {Cold Spring Harbor Laboratory}, abstract = {Cell navigation is directed by inhomogeneous distributions of extracellular cues. It is well known that noise plays a key role in biology and is present in naturally occurring gradients at the micro- and nanoscale, yet it has not been studied with gradients in vitro. Here, we introduce novel algorithms to produce ordered and random gradients of discrete nanodots {\textendash} called digital nanodot gradients (DNGs) {\textendash} according to monotonic and non-monotonic density functions. The algorithms generate continuous DNGs, with dot spacing changing in two dimensions along the gradient direction according to arbitrary mathematical functions, with densities ranging from 0.02\% to 44.44\%. The random gradient algorithm compensates for random nanodot overlap, and the randomness and spatial homogeneity of the DNGs were confirmed with Ripley{\textquoteright}s K function. An array of 100 DNGs, each 400 {\texttimes} 400 {\textmu}m2, comprising a total of 57 million 200 {\texttimes} 200 nm2 dots was designed and patterned into silicon using electron-beam lithography, then patterned as fluorescently labeled IgGs on glass using lift-off nanocontact printing. DNGs will facilitate the study of the effects of noise and randomness at the micro- and nanoscales on cell migration and growth.}, URL = {https://www.biorxiv.org/content/early/2013/12/10/001305}, eprint = {https://www.biorxiv.org/content/early/2013/12/10/001305.full.pdf}, journal = {bioRxiv} }