Cleaning of paper artworks: development of an efficient gel-based material able to remove starch paste

The removal of old glue from paper artworks is of paramount importance for the preservation of its integrity during the restoration process. Wet cleaning is one of the traditional methods, although it may cause damages on artworks. In this work, an advantageous alternative method, based on the use of a rigid hydrogel, for a simple and localized removal of starch paste from paper supports is presented. The use of an appropriate hydrogel allows to overcome many of the problems faced by restorers minimizing damages, through a controlled release of water to the artwork, and a simple and not invasive application and removal. At the same time, the specific and targeted enzyme activity leads to a significant reduction in the application time of the cleaning procedure. In this context, experiments were carried out applying Gellan hydrogel carrying α-amylase enzyme on several paper samples soiled with starch paste. To assess the cleaning efficacy of the proposed hydrogel, we have used a multidisciplinary approach, by means of spectroscopic techniques, scanning electron microscopy, chromatographic analysis, and pH investigations

A selective paper artwork cleaning process using modified Gellan hydrogel

Paper manuscripts are among the most valuable historical artifacts, but they are also very fragile. Furthermore, they were often strengthened by gluing external materials (like wooden or cardboard lining paper) to the original piece and the used glue underwent to structural transformations that accelerates the degradation processes of the artwork itself. Wet cleaning is one of the most important and critical steps in a paper artwork restoration process, and in the last years innovative cleaning methodologies have been proposed based on application of suitable hydrogels. Unfortunately often, to remove contaminants from paper artworks like glues or hydrophobic material components, additional specific procedures are required. In this work we present innovative multi-component materials able to remove in a single, simple and not invasive treatment, specific contaminants from paper artworks. The materials are based on rigid Gellan hydrogel; after investigating the cleaning ability of the Gellan gel “per se”, indeed, we also evaluated the possibility of using Gellan gel as a carrier of tuned cleaning agent. More in detail, Gellan hydrogel carrying alpha-amylase or proteinase K enzymes has been applied on several paper samples to remove starch paste or animal glues respectively. In this system, the enzyme works as selective cleaning agent, hydrolyzing not easily removable glues into smaller fragments soluble into the gel, which, in turn, plays the role of support and removal matrix for the enzymatic products. Finally, Gellan gel could be a not suitable agent to remove hydrophobic contaminants, due to its hydrophilic nature; to this end, we performed preliminary experiments by preparing a “mixed Gellan gel” carrying opportune polimeric surfactants.To assess the effectiveness and safety of the proposed cleaning method on the several samples under examination, we have employed a multitechnique approach, using high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and pH measurements

Analytical evaluation of gelatin removal from ancient papers induced by wet cleaning: a comparison between immersion treatment and application of rigid Gellan gum

In paper conservation, wet cleaning treatments are usually performed to remove harmful degradation substances. Although cleaning treatments are fundamental in this field, the use of free water, besides causing an excessive swelling of cellulose fibres and sometimes also strong alterations of graphic media, could induce the extraction of the original sizing agents, resulting in a weakening of the paper structure. Rigid polysaccharide hydrogels (i.e. Gellan gum) can be effectively used to minimize the impact of water on paper. The present study evaluates the rate of gelatine removal from paper artworks comparing two different wet cleaning treatments: washing by immersion in free deionised water and by means of Gellan gum application. After a preliminary characterization of the paper samples through Hertzberg stain test and Fourier Transform Infrared Spectroscopy (FT-IR), the study is carried out using Gas Chromatography - Mass Spectrometry analysis (GC-MS). The results showed that Gellan gum was less invasive than immersion treatment since it caused the extraction of lower amounts of gelatine from paper. The gelatine removal was also tested by statistical analysis, in particular Principal Component Analysis (PCA) of amino acids

Hydrolates and Gellan: An Eco-innovative Synergy for Safe Cleaning of Paper Artworks

The gellan hydrogel is used as a cleaning agent for paper artworks. The purposes of this work were to give the gellan hydrogel both a microbial resistance and a cytocidal action against the biodeteriogens using hydrolates. Broth microdilution assays were performed to identify the fungicidal action of 16 hydrolates vs 3 fungal strains. The study concerned the Minimal Fungicidal Concentration and pH, colour, and ultra-structural variations on all paper samples, by placing them in contact with GELYD (GELlan + hYDrolat). The in vitro tests showed that eight out of 16 hydrolates strongly inhibited fungal growth, but only two of them (Monarda fistulosa, Citrus aurantium subsp amara) showed in situ fungicidal action. Data indicate a new and interesting eco-innovative use of hydrolates, since GELYD is able not only to clean paper artworks, but also to kill the fungal cells present on paper that are potentially harmful for paper and operators

Cleaning of Paper Artworks: Development of an Efficient Gel-Based Material Able to Remove Starch Paste

The removal of old glue from paper artworks is of paramount importance for the preservation of its integrity during the restoration process. Wet cleaning is one of the traditional methods, although it may cause damages on artworks. In this work, an advantageous alternative method, based on the use of a rigid hydrogel, for a simple and localized removal of starch paste from paper supports is presented. The use of an appropriate hydrogel allows to overcome many of the problems faced by restorers minimizing damages, through a controlled release of water to the artwork, and a simple and not invasive application and removal. At the same time, the specific and targeted enzyme activity leads to a significant reduction in the application time of the cleaning procedure. In this context, experiments were carried out applying Gellan hydrogel carrying α-amylase enzyme on several paper samples soiled with starch paste. To assess the cleaning efficacy of the proposed hydrogel, we have used a multidisciplinary approach, by means of spectroscopic techniques, scanning electron microscopy, chromatographic analysis, and pH investigations

IDROLATI: NUOVA FRONTIERA NELLA DISINFEZIONE E CONSERVAZIONE DELLA CARTA

Gli oli essenziali, cos\uec come gli idrolati, sono considerati composti bioattivi di origine vegetale e quindi \u201cnaturali\u201d. Questo spiega il sempre maggiore interesse verso le potenzialit\ue0 di utilizzo da parte dell\u2019industria farmaceutica, di quella veterinaria, alimentare, cosmetica, cos\uec come in ambito agricolo al fine di una maggiore salvaguardia dell\u2019ambiente riducendo l\u2019apporto di sostanze chimiche inquinanti; non da ultimo, l\u2019impiego in ambito culturale, con lo scopo di preservare beni artistici costituiti da materiali di vario genere (lapidei, cartacei, ecc.). Gi\ue0 da alcuni anni l\u2019ICRCPAL, in collaborazione con altri atenei italiani, quali l\u2019Universit\ue0 di Bologna e quella di Tor Vergata (Roma), \ue8 impegnata in ricerche finalizzate alla difesa e conservazione di testi cartacei, come risulta da alcune recenti pubblicazioni (Di Vito M, 2018). Di seguito, si riporta una sintetica rassegna di quanto esposto nelle relazioni presentate nell\u2019ambito della giornata divulgativa \u201cOli essenziali \u2013 nuova frontiera nella disinfezione e conservazione della carta\u201d (Roma, 4 maggio 2018)

Effects of pre‐operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study

We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05-1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4-7 days or >= 8 days of 1.25 (1.04-1.48), p = 0.015 and 1.31 (1.11-1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care