title: An improved method of protein localization in artworks through SERS nanotag-complexed antibodies.
abstract: There are several analytical techniques currently in use in conservation science to identify proteins in artworks. However, as is often the case, the determination of the exact location of a protein in a complex layer structure is challenging due to difficulty in separating layers. Localization of the protein in a cross-section has been demonstrated through attenuated total reflectance-Fourier transform infrared mapping and imaging as well as chemiluminescent and fluorescent-labeled antibodies; however, these techniques either require expensive instrumental setups or produce results that can be challenging to interpret. This paper will present research using surface-enhanced Raman scattering (SERS) nanotags complexed to secondary antibodies in conjunction with primary antibodies for the localization of ovalbumin, collagen, and casein in cross-sections from replicas and artworks containing avian egg, animal glue, or casein binders. The advantages of this technique over the others are (1) the detection method is a Raman microscope, equipment found in several museum laboratories; (2) the distinctive SERS signal from the nanotag increases the detection limit of the protein and decreases the interference from other colorants present in the cross-section layers; and finally, (3) the large (120 nm) SERS-labeled antibodies do not appear to penetrate into the cross-section, eliminating the risk of spurious signal and misidentification. Any agglomerations due to surface texture are clearly visible under normal illumination and can be avoided easily during analysis or removed with a light polish. This technique not only allows protein localization in multilayered samples while preserving the stratigraphic information but also retains the protein specificity of the antibody approach.
authors.affiliation: The Metropolitan Museum of Art, 1000 Fifth Avenue, New York, NY 10028, USA. Julie.Arslanoglu@metmuseum.org
authors.forename: Julie
authors.initials: J
authors.lastname: Arslanoglu
authors.forename: Stephanie
authors.initials: S
authors.lastname: Zaleski
authors.forename: John
authors.initials: J
authors.lastname: Loike
mesh_terms: D000906:Antibodies / Q000032:analysis*; D001154:Art; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D011506:Proteins / Q000032:analysis*; D013059:Spectrum Analysis, Raman / Q000295:instrumentation / Q000379:methods*; D020349:Surface Plasmon Resonance
chemical_list: D000906:Antibodies; D011506:Proteins