Single and multiplexed immunoassays for the chemiluminescent imaging detection of animal glues in historical paint cross-sections

Biodeterioration effects of three Aspergillus species on stucco supported on a wooden panel modeled from Sultan al-Ashraf Qaytbay Mausoleum, Egypt

This study focuses on the magnificent decoration of a painted and gilded wooden panel with signs of fungal biodeterioration caused by Aspergillus species in the Mausoleum of Sultan al-Ashraf Qaytbay, Cairo, Egypt. Numerous spectroscopic analyses and investigation techniques, including Scanning Electron Microscope Equipped with Energy Dispersive X-ray analysis (SEM-EDX), Fourier Transform Infrared analysis (FTIR), and X-Ray Diffraction (XRD) have been used to study the materials that comprise this painted and gilded wooden panel composition. Aspergillus niger, A. flavus, and A. terreus were recognized as isolated fungi, and their accession numbers are OQ820164, OQ820163, and OQ820160, respectively. The findings showed that the wooden support is of pinewood (Pinus halepensis), the white priming layer on top of the wooden support was identified as gypsum, the blue paint layer has been proposed to be Azurite, Au (gold) was the primary composition of the gilding layer, while Pb (lead) was detected in some spots, suggesting the use an alloy of gold with lead, and finally, animal glue was the bonding medium. Based on these findings, mimic samples with identical substrates and structural components have been designed, and the biodeterioration signs by the growing of the three Aspergillus species-A. niger, A. flavus and A. terreus were evaluated via SEM and color change. However, A. niger was discovered with density growth on surfaces of pinewood, gypsum, and Azurite and with less growth on the gilding layer after 6-month incubation. This contrasts with A. terreus and A. flavus, which had greater density growth on Azurite and stucco than on pinewood and less growth on the gilding layer. The used analytical methods with detailed analyses revealed the novelty and significant future aspects of the conservation of the painted and gilded wooden panel. Particularly given that this location is used for prayer and is crowded with people five times a day, which increases the accumulation of fungi and negatively affects both the historic Mosque and the worshippers' health.

Combining elemental and immunochemical analyses to characterize diagenetic alteration patterns in ancient skeletal remains

Bones and teeth are biological archives, but their structure and composition are subjected to alteration overtime due to biological and chemical degradation postmortem, influenced by burial environment and conditions. Nevertheless, organic fraction preservation is mandatory for several archeometric analyses and applications. The mutual protection between biomineral and organic fractions in bones and teeth may lead to a limited diagenetic alteration, promoting a better conservation of the organic fraction. However, the correlation between elemental variations and the presence of organic materials (e.g., collagen) in the same specimen is still unclear. To fill this gap, chemiluminescent (CL) immunochemical imaging analysis has been applied for the first time for collagen localization. Then, Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) and CL imaging were combined to investigate the correlation between elemental (i.e., REE, U, Sr, Ba) and collagen distribution. Teeth and bones from various archeological contexts, chronological periods, and characterized by different collagen content were analyzed. Immunochemical analysis revealed a heterogeneous distribution of collagen, especially in highly degraded samples. Subsequently, LA-ICP-MS showed a correlation between the presence of uranium and rare earth elements and areas with low amount of collagen. The innovative integration between the two methods permitted to clarify the mutual relation between elemental variation and collagen preservation overtime, thus contributing to unravel the effects of diagenetic alteration in bones and teeth.

Detection and analysis of sources of lime mineral in ancient buildings

Among the eight detected archaeological samples, one was burned from oyster shells, and others were all burned from limestone and dolomite.

Smart Electrochemical Portable Tools for Cultural Heritage Analysis: A Review

Protecting Cultural Heritage (CH) from corrosion and other environmental damages, mainly involving metallic or organic layers contained in artwork, represents a major challenge for conservation scientists. Electrochemical techniques provide useful information about the deterioration effects of metallic coatings and organic layers. Recently, Electrochemical Impedance Spectroscopy (EIS) has been successfully applied in the study of metallic corrosion. However, EIS has not succeeded in becoming a routine technique, due to problems regarding both instrumental apparatus (which is not ideal for in situ analysis, especially with previous cell configurations), and the difficulty with data processing. At the same time, new portable electrochemical sensors, immunosensors, and biosensors have successfully made a scientific impact, mainly with in situ diagnosis of organic components contained in CH objects. For this purpose, this review presents two sections: the first describes the analytical optimization of impedance electrochemical cell geometries that are suitable for in situ metal-coating investigation; the second reports on the assembly of small electrochemical sensors, immunosensors, and biosensors, which useful for in situ organic layer characterization. This overview summarizes the state of the art regarding the application of electrochemical techniques and small electrochemical devices as alternative tools for the understanding of CH.

Miniaturized Biosensors to Preserve and Monitor Cultural Heritage: from Medical to Conservation Diagnosis

The point-of-care testing concept has been exploited to design and develop portable and cheap bioanalytical systems that can be used on-site by conservators. These systems employ lateral flow immunoassays to simultaneously detect two proteins (ovalbumin and collagen) in artworks. For an in-depth study on the application of these portable biosensors, both chemiluminescent and colorimetric detections were developed and compared in terms of sensitivity and feasibility. The chemiluminescent system displayed the best analytical performance (that is, two orders of magnitude lower limits of detection than the colorimetric system). To simplify its use, a disposable cartridge was designed ad hoc for this specific application. These results highlight the enormous potential of these inexpensive, easy-to-use, and minimally invasive diagnostic tools for conservators in the cultural heritage field.

A follow-up on the analytical study of discolouration of the marble statues of Orsanmichele in Florence

The research complements the complex study carried out to understand the source of brown discolourations of ten marble statues in the Church of Orsanmichele in Florence, Italy. Originally located in exterior niches, the statues were restored to reverse the extensive alterations they had undergone throughout the centuries. One of the major alterations was the application of a dark brown patina that dated just after 1789. After the statues were placed indoors, brownish discolourations started to appear on their surfaces. Cross sections were examined using FTIR mapping and immunological methods. In parallel, the pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) data already obtained from the statues' scrapings were compared with data from aged casein films applied to microscope glass slides and aged milk-treated marble. All the statues had been treated with milk-based substances before the time the bronze patina was applied. The values of temperature and illumination of the room were important factors in the ageing of organic substances and in the formation of calcium oxalates. It is likely that products of thermo-oxidation and photo-oxidation of the oils together with the oxalates caused the darkening. The marble samples corresponded to a Lunense provenance.

Immunochemical Methods Applied to Art-Historical Materials: Identification and Localization of Proteins by ELISA and IFM

Despite the large diffusion of natural organic substances in art-historical materials, their characterization presents many challenges due to the chemical complexity and instability with respect to degradation processes. Among natural products, proteins have been largely used in the past as binders but also as adhesives or additives in coating layers. Nevertheless, biological identification of proteins in art-historical objects is one of the most recent achievements obtained in heritage science thanks to the development of specifically tailored bio-analytical strategies. In the context of this active emerging discipline, immunological methods stand out for sensitivity, specificity and versatility for both protein recognition and localization in micro-samples. Furthermore, the growing use of immunological techniques for advanced diagnostics and clinical applications ensures continuous improvement in their analytical performance. Considering such, this review provides an overview of the most recent applications of enzyme linked immunosorbent assay and immunofluorescence microscopy techniques in the field of heritage materials. Specifically, the main strengths and potentials of the two techniques as well as their limits and drawbacks are presented and discussed herein.

Immunochemical Micro Imaging Analyses for the Detection of Proteins in Artworks

The present review is aimed at reporting on the most advanced and recent applications of immunochemical imaging techniques for the localization of proteins within complex and multilayered paint stratigraphies. Indeed, a paint sample is usually constituted by the superimposition of different layers whose characterization is fundamental in the evaluation of the state of conservation and for addressing proper restoration interventions. Immunochemical methods, which are based on the high selectivity of antigen-antibody reactions, were proposed some years ago in the field of cultural heritage. In addition to enzyme-linked immunosorbent assays for protein identification, immunochemical imaging methods have also been explored in the last decades, thanks to the possibility to localize the target analytes, thus increasing the amount of information obtained and thereby reducing the number of samples and/or analyses needed for a comprehensive characterization of the sample. In this review, chemiluminescent, spectroscopic and electrochemical imaging detection methods are discussed to illustrate potentialities and limits of advanced immunochemical imaging systems for the analysis of paint cross-sections.

Identification of Proteinaceous Binders in Ancient Tripitaka by the Use of an Enzyme-linked Immunosorbent Assay

Proteinaceous materials, such as ovabumin and collagen, were commonly used as binding media, and as adhesives and protective coatings. However, the identification of ancient proteinaceous binders is a great challenge for archaeologists, due to their limited sample size, complex combinations of various ingredients and reduced availability of the binder during the process of protein degradation. In this paper, an enzyme-linked immunosorbent assay (ELISA) provides to be a particularly promising method for the detection of proteinaceous binding materials in ancient relics. The present work focused on the specific identification of proteins in archaeological binders, which was brushed on the Tripitaka. Two samples, the adhesion area (S1) and the ink area (S2), were tested by ELISA. The results showed that both S1 and S2 reacted positively when treated with an anti-collagen-I antibody. It proved the existence of proteinaceous binders in Ancient Tripitaka, and the percentage of collagen in S1 and S2 was 61.44 and 15.4%, respectively. Compared with other conventional techniques, ELISA has advantages of high specificity, sensitivity, rapidity and low cost, making it especially suitable for the protein detection in the archaeological field.

Circularly polarized luminescence reveals interaction between commercial stains and protein matrices used in paintings

Here we show that circularly polarized luminescence (CPL) can give unique insight into interactions between fluorescent commercial stains and protein-based materials used in painting. CPL can complement information from ECD and fluorescence.

Carboxy-terminated immuno-SERS tags overcome non-specific aggregation for the robust detection and localization of organic media in artworks

Surface-enhanced Raman scattering (SERS) nano-tags with a carboxy-terminated PEG surface coating overcome non-specific aggregation when applied for the immunological detection and localization of proteinaceous binding media in art samples.