Optical microarray biosensing techniques

Microarrays provide a powerful analytical tool for the simultaneous analyses of thousands of parameters, be they DNA or proteins, in a single experiment. However, a number of challenges continue to hinder the widespread application of microarray assays for analytical and diagnostic purposes. Advances in detection methods can help overcome some of these challenges by improving sensitivity and reliability in signal detection and by enabling real-time detection of binding events. Thus, the aim of this review is to highlight the most promising optical microarray biosensing techniques. The principles of techniques making use of labels, including scanner type, total internal reflection type, fiber-optics-based, and SPR-enhanced fluorescence, are described, along with a brief summary of labeling strategies. State of the art label-free techniques, including imaging SPR and imaging ellipsometry, are also reviewed. Examples of microarray-based assays using each technique are given to illustrate both their usefulness and their limits of detection. Furthermore, the most competitive commercial microarray systems are presented and compared with one another in the context of their detection system. Finally, a discussion of the remaining challenges as well as trends and future applications of microarrays are presented in the context of optical sensing. Copyright © 2006 John Wiley & Sons, Ltd.