Modified Oligonucleotides for Biosensing Applications

There is a large interest in the use of the self assembling properties of biomolecules to fabricate new types of biosensors. In this work we describe the synthesis of a base analogue of cytosine bearing a thiol group. This group may be used to attach molecules of interest at internal positions of an oligonucleotide sequence and also to attach oligonucleotides to gold surfaces. Moreover we described the synthesis of an oligonucleotide with a photolabile linker at the loop of an intramolecular hairpin and an amino group at the T-end. The hairpin photolabile oligonucleotide when immobilized on a glass slide acts as a form of photo-resist: photolysis of an area results in the formation of single-stranded DNA that can direct the hybridization of a labeled complementary oligonucleotide.