We report an unusual phenomena of attraction between DNA and the sidewall of a two-dimensional (2d) glass nanoslit with height, h, less than the Kuhn length l(K). The DNA molecules are stretched and diffuse along the wall. The scaling analysis reveals that the wall-bound DNA molecules exhibit one-dimensional (1d) diffusion. A modified blob model is able to predict the chain extension down to 30 nm, well into the subpersistence length regime where the chain deflection length should be considered. This discrepancy may be due to the partially bound confinement of chains near the sidewall. In contrast, the scaling analysis of DNA molecules far from the sidewall exhibit 2d dynamics that can be described by de Gennes and Odijk model for h > l(K) and h < l(K) respectively. We further apply the unusual wall attraction to trap and stretch DNA molecules around posts in a nanoslit. We demonstrate that the DNA molecules exhibit trapping-escaping movement, and they can be transported from post to post with an electric field.