Formation of diazoketo-functionalized self-assembled monolayer and it's applications for biomolecular patterning

Abstract

A novel micropatterning technique is proposed here that combines a top down approach based on photolithography and a bottom-up strategy through self-organization of multifunctional molecules. In this study, a diazoketo-functionalized self-assembled monolayer (SAM) is formed on silicon wafer/glass substrate. The covalent nature of the assembly process results in them displaying superior stability, which allows extensive handling and further modification steps without deterioration of the monolayer. Moreover, these SAMs are compatible with silicon technology and permit the use of optical techniques, such as fluorescence spectroscopy, as read-out methods. Selective UV light irradiation (λ=200~250nm) on the diazoketo-functionalized SAM would results in the formation of carboxylic acid groups on the UV light exposed regions. These carboxylic groups would be further utilized for the immobilization of active biomolecules such as DNA, proteins, etc. Such selective immobilization of biomolecules are highly useful for the biosensor and high throughput array applications. The major advantage of this process is that it does not require the addition of photoacid generator (PAG) and the post-exposure bake (PEB) steps to generate patterns. In addition, during the UV light irradiation, only a molecular nitrogen is released as a byproduct. Thereby the overall process is non-toxic which makes it highly suitable for the immobilization of biomolecules and cells. Also, using the well-established lithographic tools, the process can be easily applied for the large scale production.