The present invention relates to a device for interfacing nanofluidic and microfluidic components suitable for use in performing high throughput macromolecular analysis. Diffraction gradient lithography (DGL) is used to form a gradient interface between a microfluidic area and a nanofluidic area. The gradient interface area reduces the local entropic barrier to nanochannels formed in the nanofluidic area. In one embodiment, the gradient interface area is formed of lateral spatial gradient structures for narrowing the cross section of a value from the micron to the nanometer length scale. In another embodiment, the gradient interface area is formed of a vertical sloped gradient structure. Additionally, the gradient structure can provide both a lateral and vertical gradient.