Surface plasmon resonance (SPR) reflectivity measurements are surface-sensitive, spectroscopic methods that can be used to characterize the thickness and/or index of refraction of ultrathin organic and biopolymer films at noble metal (Au, Ag, Cu) surfaces. Surface plasmon resonance spectroscopy has become widely used in the fields of chemistry and biochemistry to characterize biological surfaces and to monitor binding events. The success of these SPR measurements is primarily due to three factors: (i) with SPR spectroscopy the kinetics of biomolecular interactions can be measured in real time, (ii) the adsorption of unlabeled analyte molecules to the surface can be monitored, and (iii) SPR has a high degree of surface sensitivity that allows weakly bound interactions to be monitored in the presence of excess solution species. SPR spectroscopy has been used to monitor such events as antibody-antigen binding, DNA hybridization, and protein-DNA interactions.

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.

Some of our recent papers in this area:

• 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).



• Bryce P. Nelson, Timothy E. Grimsrud, Mark R. Liles, Robert M. Goodman, and Robert M. Corn,
  "Surface Plasmon Resonance Imaging Measurements of DNA and RNA Hybridization Adsorption onto DNA Microarrays"
  Analytical Chemistry, 73 1-7 (2001).



• Jennifer M. Brockman and Robert M. Corn,
  "SPR Imaging Measurements of Biopolymer Adsorption,"
  Ann. Rev. Phys. Chem., 51 41-63 (2000).
  Abstract



• Jennifer M. Brockman, Anthony G. Frutos and Robert M. Corn,
  "A Multi-Step Chemical Modification Procedure to Create DNA Arrays on Gold Surfaces for the Study of Protein-DNA Interactions with Surface Plasmon Resonance Imaging,"
  J. Am. Chem. Soc., 121 8044-8051 (1999).
  Abstract