Combining a hydrogel and an electrochemical biosensor to determine the extent of degradation of paper artworks

Abstract

Paper-based artworks are among the most valuable assets for transmission of knowledge. Historical paper is composed of different polysaccharides (e.g. cellulose), binders, and glues. During aging all of these components undergo several degradation processes, as a result of external and intrinsic causes, and these can compromise the state of conservation of the document. In this work, application of a new biotechnological strategy for paper artefact preservation is reported. By making use of innovative and non-invasive materials, for example appropriate hydrogels, in combination with selective electrochemical biosensors, it is possible to simultaneously verify the degradation condition of the paper artwork and then to efficiently clean it, while monitoring the process of removal of both pollution and degradation products. In this paper, we focus on specific examples in which such techniques have been applied to paper artworks and that illustrate the advantages and potential of this biotechnology compared with the traditional paper-cleaning methods currently in use.

Gellan hydrogel as a powerful tool in paper cleaning process: A detailed study

“…Due to their high retention power and their viscosity, the penetration of these liquids into the paper sheets can be significantly reduced, therefore minimizing paper fibers swelling [4][5][6][7]. However, a complete removal of these gels often requires an abrasive mechanical action (i.e., removal with a brush or by wet cotton swabs), which is often unsafe for the artwork.…”

“…At the same time, gel residues can induce dangerous microbial growth [8,9]. To overcome this drawbacks, highly rigid and film forming hydrogels may represent a useful alternative [3,5,7,10], as they can be completely and easily removed in one operation after their application, thus minimizing the side effects already presented. In this contest, a new wet cleaning technique based on the use of a rigid hydrogel of Gellan gum has been recently developed [3,6,11].…”

New Strategy for the Cleaning of Paper Artworks: A Smart Combination of Gels and Biosensors

“…In this way, it is possible to know when the cleanup process will be completed, avoiding lengthy and sometimes unnecessary cleaning material applications. For example, in the case of the degradation compounds and pollution of paper, the combination of glucose biosensor and gel would allow the restorers to determine when the process of removing this degradation product of cellulose is finished and to evaluate the cleaning efficiency [8].…”

“…Finally, due to its viscoelastic properties, its application and removal are fairly simple while allowing a localized cleaning operation (Figure 1). Since it is stiff and nonsticky, it can be peeled from a surface in one piece, minimizing residues [8]. These features make this gel particularly suitable to perform safer wet cleaning treatments on paper artworks, ensuring the maintenance of the structural and aesthetic properties of paper.…”

Rheoreversible hydrogels in paper restoration processes: a versatile tool

“…Due to the high retention power and viscosity of gels, the penetration of the liquids into the paper sheets is significantly reduced, therefore minimizing damages [2-5]. However, to impair dangerous microbial growth [6,7], a complete removal of the gel is required and such a procedure often requires abrasive mechanical action (i.e., removal with scraper) or solvents, often unsafe for the artwork.…”