Can traditional artist's pigments hinder paint binder characterization using immunofluorescence microscopy? : application of widefield fluorescent and confocal laser scanning microscopies for advanced imaging and surface topography scans

Kosel, Janez (author), Tavzes, Črtomir (author), Retko, Klara (author), Ropret, Polonca (author)

The aim of the study was to address the problematics of proteinous binder characterization, within a cross section of painted model samples, using immunofluorescence microscopy. Problems arise from certain pigments which can alter the epitope sites of target binders (lead white and verdigris) or can exhibit a strong natural autofluorescence (lake pigments). Therefore, dual layered model samples were prepared containing a lower egg tempera paint and an upper oil paint, and both paints were made of the same pigment. As an extra challenge for fluorescence microscopy, half of samples were additionally covered with pure linseed oil (as a third layer), which is known to physically reflect fluorescence. Cross-sections were hybridized with anti-ovalbumin antibodies and with FITC labelled secondary antibodies. To reduce unspecific fluorescence, apart from widefield fluorescence, laser-scanning confocal immunofluorescence microscopy was performed. Finally, 3D surface topography models were constructed which were used to check off any unspecific fluorescence originating from cracks or holes. Results show that immunofluorescence microscopy in the widefield observation mode was successful in its specificity and clarity of highlighting the egg paint layer in the presence of 8 out of 10 pigments, including the problematic lead white and verdigris pigments. Several of these pigments (lead white, malachite, yellow ochre, madder lake and carbon black) exhibited autofluorescence; however it was not bright enough to interfere with the successful immunofluorescence microscopy result. In the widefield mode, immunofluorescence microscopy was unsuccessful in the presence of 2 pigments; carmine lake (pigment adsorbs antibodies) and Dragon’s blood (pigment dissolved during resin curing at 50 °C). The confocal observation mode in comparison to the widefield mode achieved a much more specific and clear immunofluorescence microscopy picture (especially in the presence of Prussian blue, Vermilion and carbon black) and removed nearly all of the unspecific fluorescence originating from resin’s surface reflection, from pure oil binder, from small indentations and from illumination glair that would have otherwise spread across different layers. Lastly, 3D topography models showed that in general samples with smooth surfaces gave a much clearer immunofluorescence microscopy picture.

• Language: English
• Keywords: cultural heritage, heritage science, artists’ pigments, immunofluorescent microscopy, confocal fluorescent microscopy, antibodies, 3D topography scans
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: Str. 76-90
• Numbering: Vol. 61
• PID: 20.500.12556/RUL-155113
• UDC: 719:543
• ISSN on article: 1296-2074
• DOI: 10.1016/j.culher.2023.03.006
• COBISS.SI-ID: 147930627
• Publication date in RUL: 20.03.2024

Record is a part of a journal

• Title: Journal of cultural heritage
• Shortened title: J. cult. herit.
• Publisher: Elsevier, Consiglio Nazionale delle Ricerche
• ISSN: 1296-2074
• COBISS.SI-ID: 1228053

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: dediščinska znanost, mikroskopija, naravoslovne preiskave, pigmenti, kulturna dediščina, analizna kemija