DNA arrays on surfaces have caused a revolution in nucleic acid analysis, and a similar revolution is required for proteins if high-throughput screening of their functions is to be realized. [1,2] In addition, proteins can also form the basis of self-assembling nanostructures. [3,4] One important obstacle is the assembly of functional protein monolayers on useful surfaces. Unlike DNA, proteins must retain an intricate threedimensional structure to function, and measurement of these conformations under changing solution conditions is difficult in monomolecular films. However, our increasing awareness of natively unfolded proteins, which adopt defined conformations only upon interaction with ligands or receptors, means that structural change is also an important readout for protein-protein and protein-DNA interactions. [5] Finally, measurement of changes in protein secondary structure that lead to insoluble protein aggregates is crucial to the study and identification of conditions such as Alzheimers disease and Creutzfeldt-Jacob disease (CJD). [6] Fourier-transform infrared spectroscopy in either attenuated total internal reflection or grazing incidence modes is very useful for measuring protein structure in monolayers, [3,7] but its use is limited by its sensitivity to bulk water. Fluorescence spectroscopy is a sensitive but not a generic assay for protein folding, as it relies upon the presence of aromatic amino acids in suitable positions. Circular dichroism (CD) spectroscopy in the ultraviolet range (l = 180-250 nm) measures the conformation of the core peptide backbone and is insensitive to the presence of bulk water. [8] The characteristic spectra for helix, sheet, or random structures, which arise from the p-p* and n-p transitions, make this the spectroscopic method of choice for protein scientists who wish to monitor folding, stability, and conformational change. [9] Small sample size, accessible concentrations, and relatively inexpensive instrumentation mean that CD spectroscopy is the