The identification and application of bioaffinity interactions in a large scale array format has become an indispensable tool for modern biological research. Bioaffinity interactions such as DNA-DNA and antigen-antibody interactions are now employed in an array format to quickly ascertain the presence of a particular DNA sequence in a sample, to detect and identify microbial and viral species, and to verify efficacy and function in medical diagnostics. For example, the use of spotted or photolithographically produced DNA arrays for the detection of messenger RNA is becoming a standard tool in the study of the state of gene expression in an organism. In addition to the detection of biopolymers, the identification of new bioaffinity interactions such as DNA-protein binding and protein-protein binding is also being performed in a large scale array format in order to study protein function and interaction (proteomics), and in high throughput screening assays for the development of pharmaceuticals. For example, the identification and subsequent monitoring of sequence specific protein-DNA interactions is needed in order to the understand the regulatory networks that control gene expression in response to sensor kinase activity.

While the vast majority of array-based studies of bioaffinity interactions employ fluorescently labeled biopolymers, there is a need for the continued development of sensitive analytical methods that can be used to detect bioaffinity interactions in biological samples without the need of molecular labels or tags. This is especially true for the case of protein-protein interactions, where labeling is difficult and can interfere with protein function. The surface-sensitive optical technique of surface plasmon resonance (SPR) imaging is emerging as a "label free" measurement that can be used in an array format for the detection of bioaffinity interactions. SPR imaging detects the presence of a biopolymer on a chemically modified gold surface by the change in the local index of refraction that occurs upon adsorption. In the past few years, we have developed the technique of near infrared SPR imaging for the detection of DNA and RNA by hybridization to DNA microarrays. We have also used SPR imaging of DNA microarrays to study protein-DNA interactions.

Our recent papers in this area are:

• Hye Jin Lee, Yuling Yan, Gerard Marriott and Robert M. Corn,
  "Quantitative Functional Analysis of Protein Complexes on Surfaces,"
  J. Physiology (London), 563 61-71 (2005).



• Terry T. Goodrich, Hye Jin Lee, and Robert M. Corn,
  "Enzymatically Amplified Surface Plasmon Resonance Imaging Method Using RNase H and RNA Microarrays for the Ultrasensitive Detection of Nucleic Acids,"
  Analytical Chem., 76 6173-6178 (2004).



• Greta J. Wegner, Alastair W. Wark, Hye Jin Lee, Eric Codner, Tomonori Saeki, Shiping Fang, and Robert M. Corn,
  "Real-Time Surface Plasmon Resonance Imaging Measurements for the Multiplexed Determination of Protein Adsorption/Desorption Kinetics and Surface Enzymatic Reactions on Peptide Microarrays,"
  Analytical Chem., 76 5667-5684 (2004).



• Terry T. Goodrich, Hye Jin Lee, and Robert M. Corn,
  "Direct Detection of Genomic DNA by Enzymatically Amplified SPR Imaging Measurements of RNA Microarrays,"
  J. Am. Chem. Soc., 126, 4086-4087 (2004).



• Greta J. Wegner, Hye Jin Lee, and Robert M.Corn,
  "Surface Plasmon Resonance Imaging Measurements of DNA, RNA, and Protein Interactions to Biomolecular Arrays,"
  Protein Microarray Technology, Wiley, ISBN: 3-527-30597-1, pp 107-129 (2004).



• Greta J. Wegner, Hye Jin Lee, Gerard Marriott, and Robert M.Corn,
  "Fabrication of Histidine-Tagged Fusion Protein Arrays for Surface Plasmon Resonance Imaging Studies of Protein-Protein and Protein-DNA Interactions,"
  Analytical Chem., 75 4740-4746 (2003).



• Emily A. Smith and Robert M.Corn,
  "Surface Plasmon Resonance Imaging as a Tool to Monitor Biomolecular Interactions in an Array Based Format,"
  Applied Spectroscopy, 57 320A-332A (2003).



• Emily A. Smith, William D. Thomas, Laura L. Kiessling, and Robert M. Corn,
  "Surface Plasmon Resonance Imaging Studies of Protein-Carbohydrate Interactions,"
  J. Am. Chem. Soc., 125 6140-6148 (2003).