The surface chemistry at the DNA recognition and binding interface plays an important role in determining the performance of DNA microarrays and DNA biosensors. Surface-initiated controlled radical polymerization (SI-CRP) reactions represent a powerful toolbox to generate microarray and biosensor surfaces with enhanced DNA recognition and binding properties or to amplify and transduce these events. Surface-initiated polymerizations generate thin films in which all polymer chains are tethered with one chain end to the underlying surface and are also referred to as polymer brushes. SI-CRP reactions possess a number of features that make them highly attractive to engineer the properties of biosensor interfaces. First of all, the thickness of the films can be precisely adjusted to match the requirements of the specific biosensor format. Secondly, the grafting density of these films can be tuned to optimize binding kinetics and capacity. Finally, being a bottom-up technique, SI-CRP can also be used to modify complex, patterned or structured biosensor substrates with a conformal DNA recognition and binding interface. This article provides an overview of the state-of-the-art on the use of SI-CRP techniques to enhance or facilitate DNA biosensing. On the one hand, SI-CRP techniques have been used to generate high binding capacity surface coatings. On the other hand, these reactions have also been demonstrated to be powerful tools to amplify DNA recognition and binding and allow visual detection. The examples discussed in this article not only underline the potential of SI-CRP reactions to engineer the properties of biosensor interfaces, but also, together with future advances in these polymerization techniques, provide exciting opportunities to further enhance the performance of DNA microarrays and DNA biosensors. (C) 2014 Elsevier Ltd. All rights reserved.