Challenges in the Design of Optical DNA Biosensors

The field of biosensors and biochips for nucleic acid diagnostics has developed significantly over the last decade. High-throughput techniques offering the advantages of sensitivity and selectivity combined with rapid analysis to provide reproducible and accurate results are highly sought after in the areas of medical diagnostics, forensics, environmental monitoring, and bioterrorism. This chapter gives a short review of the necessary considerations for the preparation of immobilized nucleic acid films on a solid sensor substrate and the development of techniques utilized for the detection of selective hybridization of target binding materials. The fundamentals of fibre optic and surface plasmon resonance optical sensor platforms are outlined, followed by key developments in the area of fluorescent particle labels and dyes used for the detection of nucleic acid hybridization. Recent advances in hybridization assays include fluorescent cationic polymer, molecular beacon, and duplex probe technologies. Finally, current methods used for the detection of interfacial DNA hybridization are described, including a discussion of limitations and possible strategies to enhance the key design priorities of sensitivity and selectivity.