Comprehensive Analysis of Polychrome Grotto Relics: A Case Study of the Paint Layers from Anyue, Sichuan, China

Application of ELISA in Cultural Heritage: Recent Advances and Challenges

Organic residue analyses have long been the primary focus and challenge in the fields of scientific archaeology and cultural heritage. Enzyme-linked immunosorbent assay (ELISA) has emerged as a valuable method for detecting organic residues owing to its high sensitivity and specificity. Organic components have been observed within four categories of archaeological artifacts: mortars, adhesives, animal and plant remains, and daily use artifacts. Therefore, in this article, we critically analyzed the advantages and limitations of ELISA in detecting organic residues by tracking its recent application in the abovementioned categories. The current focus of ELISA applications is on the preparation of customized antibodies, development of multicomponent detection methods, and meeting on-site identification demands. Additionally, understanding organic residue degradation mechanisms and the proper handling of archaeological samples are also key factors in these applications. Integration of ELISA with biomolecular science and electrochemistry has allowed the development of comprehensive detection and analyses. In the future, ELISA will be capable of handling more complex and diverse analyses, revealing highly intricate information from archaeological samples.

Characterization of Animal Protein-Based Binders in Ancient Chinese Wall Paintings Using Atomic Force Microscopy and Fourier Transform Infrared Spectroscopy

In this study, the topographical characteristics of protein-based binders in ancient Chinese wall paintings and the properties of their sources were investigated and identified. Fifteen samples of protein-based binders (skin glue, bone glue, egg glue, and milk glue) before and after aging and mixing azurite were prepared. Next, the topographical characteristics, adhesive properties, and infrared spectra for each chemical group in the binders were analyzed using atomic force microscopy and attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), and the sources of various binders were identified using ATR FT-IR and principal component analysis (PCA). Results showed that protein binders such as fish bladder, cow bone, and egg white glue had lower roughness values and good consolidation properties. The most distinctive feature of skin and bone glues before and after aging or mixed with azurite was the stretching vibration peak of CH₂ deformation vibration at around 1335 cm^-1, while the significant characteristics of egg and milk glue was the C=O stretching vibration in Serine at 1306 cm^-1 and C=O stretching vibrations in aspartic acid and glutamic acid at 1416 cm^-1. In addition, the significant differences of absorbance peaks were observed in the infrared spectra of various bone, skin, egg, and milk glue samples before and after aging while the spectral differences become insignificant after mixing with azurite. The results of PCA confirmed that egg yolk and ewe's and cow's milk were well differentiated from animal skin and bone glue regardless of whether fresh, aged, or mixed with azurite. In addition, the differences between skin and bone glues were significant, and the various types of bone glue could be also differentiated before and after aging.