Assessment of green cleaning effectiveness on polychrome surfaces by MALDI‐TOF mass spectrometry and microscopic imaging

This article proposes an innovative methodology which employs nondestructive techniques to assess the effectiveness of new formulations based on ionic liquids, as alternative solvents for enzymes (proteases), for the removal of proteinaceous materials from painted surfaces during restoration treatments. Ionic liquids (ILs), also known as “designer” solvents, because of their peculiar properties which can be adjusted by selecting different cation‐anion combinations, are potentially green solvents due totheir low vapour pressure. In this study, two ionic liquids were selected: IL1 (1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM][BF₄])) and IL2 (1‐ethyl‐3‐methylimidazolium ethylsulphate ([EMIM][EtSO₄])). New formulations were prepared with these ILs and two different proteases (E): one acid (E1—pepsin) and one alkaline (E2—obtained from Aspergillus sojae). These formulations were tested on tempera and oil mock‐up samples, prepared in accordance with historically documented recipes, and covered with two different types of protein‐based varnishes (egg white and isinglass—fish glue). A noninvasive multiscale imaging methodology was applied before and after the treatment to evaluate the cleaning's effectiveness. Different microscopic techniques—optical microscopy (OM) with visible and fluorescent light, scanning electron microscopy (SEM) and atomic force microscopy (AFM)—together with Matrix‐Assisted Laser Desorption/Ionization—Time of Flight Mass Spectrometry (MALDI‐TOF MS) were applied on areas cleaned with the new formulations (IL + E) and reference areas cleaned only with the commercial enzyme formulations (gels). MALDI‐TOF proved particularly very useful for comparing the diversity and abundance of peptides released by using different enzymatic systems. Microsc. Res. Tech. 77:574–585, 2014. © 2014 Wiley Periodicals, Inc.     

Preparation and characterization of thin transducer layers sensitive to free chlorine in water

The paper deals with preparation and characterization of layers of optical absorption transducers sensitive to free chlorine in water and based on commercially available chemicals. The electrochemical deposition and chemical approach based on the sol–gel method were employed for the immobilization of the transducers onto ITO-coated planar optical substrates. The transducers, namely methylene blue, o-phenylenediamine, Lu (III) acetate pthalocyanine tetrasulfonate tetrasodium salt (Lu-III-complex), murexid, quercetin, 1,2,3-benzenetriazole, benzopurpurine, thionine, bilirubin and its metal complexes, and 3-methyl-4 nitro-1(4-nitrophenyl) 2-pyriazoline-5-one (picrolonic acid), were tested. Transmission spectra, redox potentials, layer thickness and optical responses of the transducer layers to chlorine were investigated. By using sensitive layers based on o-phenylenediamine and methylene blue it was possible to detect chlorine in a minimum concentration of 0.25 ppm. The best results were obtained with the o-phenylenediamine layers prepared electrochemically. Both these transducer layers are useable for detection of chlorine up to concentration  8 ppm.     

An innovative,interdisciplinary, and multi‐technique study of gilding and painting techniques in the decoration of the main altarpiece of Miranda do Douro Cathedral (XVII‐XVIIIth centuries,Portugal)

The research results presented in this paper are part of a larger study on the materials and techniques used in polychrome altarpieces of gilded woodcarving decoration (“talha dourada”) in Portugal. The paper focuses on a narrative Portuguese Altarpiece from Miranda do Douro, considered one of the masterpieces of “talha dourada” among all the retables of the Iberian Peninsula in XVII^th and XVIII^th centuries. Although on the Portuguese territory, the altarpiece was made by artists from the Royal Spanish school of Valladolid, under a mannerist style. Thus the study opens a window on the artists' circulation between Spain and Portugal and influences of the Spanish schools in Baroque epoch on the Portuguese “talha”. During its history this altarpiece underwent several transformations and extensive conservation treatments in 1989. On this occasion more than 50 samples were collected and analyzed using an interdisciplinary multi‐technique methodology. 27 of these samples are chosen for this study in order to investigate the chromatic palette, the materials and techniques used in the polychromy of the retable. A novel protocol of investigation using different conventional and unconventional analytical techniques (OM + fluorescent staining tests on cross‐sections, Raman microscopy, XRD, XRF, X‐ray micro‐CT, SEM‐EDX, MALDI‐TOF‐MS and LC‐MS/MS) was established within an innovative research project ( http://sites.fct.unl.pt/gilt‐teller/ ) and applied on these samples. This protocol is necessary to confirm the results obtained in the 1989 campaign and to have further insight into the gilding and polychrome decoration materials and techniques and the additional information reported in the historical documents. The material and technical history of this important altarpiece will be thus re‐documented from a scientific perspective, meant to confirm and bring new information on the decorative technique used in the creation of this complex Portuguese monument. Microsc. Res. Tech. 76:733–743, 2013. © 2013 Wiley Periodicals, Inc.     

Individual DNA Methylation Pattern Shifts in Nanoparticles-Exposed Workers Analyzed in Four Consecutive Years

A DNA methylation pattern represents an original plan of the function settings of individual cells and tissues. The basic strategies of its development and changes during the human lifetime are known, but the details related to its modification over the years on an individual basis have not yet been studied. Moreover, current evidence shows that environmental exposure could generate changes in DNA methylation settings and, subsequently, the function of genes. In this study, we analyzed the effect of chronic exposure to nanoparticles (NP) in occupationally exposed workers repeatedly sampled in four consecutive years (2016–2019). A detailed methylation pattern analysis of 14 persons (10 exposed and 4 controls) was performed on an individual basis. A microarray-based approach using chips, allowing the assessment of more than 850 K CpG loci, was used. Individual DNA methylation patterns were compared by principal component analysis (PCA). The results show the shift in DNA methylation patterns in individual years in all the exposed and control subjects. The overall range of differences varied between the years in individual persons. The differences between the first and last year of examination (a three-year time period) seem to be consistently greater in the NP-exposed subjects in comparison with the controls. The selected 14 most differently methylated cg loci were relatively stable in the chronically exposed subjects. In summary, the specific type of long-term exposure can contribute to the fixing of relevant epigenetic changes related to a specific environment as, e.g., NP inhalation.