Perspectives for antimicrobial nanomaterials in cultural heritage conservation

Microorganisms are highly proficient at inhabiting and decaying cultural heritage objects architectures. Unfortunately, only a limited range of physical chemical methods available for preventing or removing microbiological damage to items where, all too often, the frequently inadequate clean effectively prevent recolonization. Our shared is an invaluable social environmental resource as well key global economic driver. So how can we protect our tangible from biodeterioration preserve it future generations? The use antimicrobial nanomaterials in science field represents challenging new research opportunities chemists materials scientists, where integrated multidisciplinary approach required tackle heterogeneous composition, uniqueness, value each individual piece. artistic architectural serious recurring problem museums, local authorities, private collectors alike, irreparable unique artifacts result immeasurable losses heritage. Here, present overview current trends products used microbial colonization their deterioration. From conservation-restoration standpoint, contrast compare traditional with state art applied conservation field, highlighting promising potential various different nanomaterials, points concern clear red flags some emerging research. Through examination growing body academic literature offer recommendations practical advice on selecting appropriate assays characterization techniques better evaluate vitro situ properties nanomaterials. IntroductionArtistic form books, paintings, clothing, historic monuments, buildings, among many other artifacts, significant aspects community, region, country’s heritage, which generations will embrace, study, share. preservation constitutes societal priority;1Steinbauer M.J. Gohlke A. Mahler C. Schmiedinger Beierkuhnlein Quantification wall surface heterogeneity its influence species diversity medieval castles–implications environmentally friendly heritage.J. Cult. Herit. 2013; 14: 219-228Crossref Scopus (15) Google Scholar yet, problems caused by lack proper often come attention when tragedies occur, such fire, collapse, water damage. However, there silent threats lurking permanently far eyes great majority people. Environmental (humidity, temperature, light, CO2 concentration, atmospheric pressure, pH) geological conditions two important factors affecting objects; however, composition (organic versus inorganic), quality aging process, internal mechanical stress, biological (originating specifically bacteria, fungi, algae, moss, lichen, insects) constitute principle actors leading decay deterioration artifacts.2Mitchell R. Clifford J. Biodeterioration Preservation Art, Archaeology Architecture. Archetype Publications, 2018Google ScholarIn particular, biodeterioration—“any undesirable change material vital activities organisms”3Hueck H.J. part hylobiology.Mater. Organ. 1965; 1: 5-34Google Scholar—poses persistent Contamination spoilage displayed exhibition rooms stored depots not exceptional; but rather frequent, both old newly built museums. cyanobacteria, algae objects. Paper, leather, stone, textile, ceramic, glass blighted this problem, incurs substantial difficulties heritage.2Mitchell ScholarAll types public museums collections risk attack fungi bacteria: textiles leathers clothes weaponry paper books; mention surfaces stone monuments outdoor environments along mural paintings churches, caves, catacombs.4Strzelczyk A.B. Observations aesthetic structural changes induced Polish microorganisms.Int. Biodeterior. Biodegrad. 2004; 53: 151-156Crossref (59) In example, be root cause host problems: discoloration pigments mortars, formation stains biofilms, salt efflorescence, exfoliation, cracking disintegration paint layers, blisters, degradation binders that results detachment layer(s). Fungi genera Penicillium, Cladosporium, Alternaria, Curvularia, Drechslera, Chaetomium, Fusarium, Trichoderma, Gliomastix, Aureobasidium abundant degraded paintings.2Mitchell Scholar,5Sterflinger K. Pinzari F. revenge time: fungal particular reference parchment.Environ. Microbiol. 2012; 559-566Crossref PubMed (74) fact, particularly threatening because hyphae undergo rapid proliferation penetrate deep into organic inorganic materials. Meanwhile spores, dormant state, ever germination growth become more favorable.5Sterflinger Furthermore, carboxylic acids produced through metabolism (e.g., oxalic, citric, succinic, formic, malic, acetic, fumaric, glyoxylic, gluconic, tartaric acids) produce aggressive second wave corrosive attack.Consequently, immense financial alike. More still represent identity, communities, regions, countries. Although effective climate control, frequent cleaning, phenomenological monitoring help reduce biogenic historical factors, acquired resistance antibacterial agents (inadequate storage conditions, dampness, floods, transportation/relocation, etc.) require wider suitable biocides.6Allsopp D. Seal K.J. Gaylarde C.C. Introduction Biodeterioration. Cambridge University Press, 2004Crossref Moreover, extreme bacterial biofilms closed spaces also inherent (often severe) health risks employees visitors indoor environments.7Gaylarde Morton L.H.G. Deteriogenic buildings control: review.Biofouling. 1999; 59-74Crossref (126) community has risen grand challenge disinfect recent progressive addition, methodologies cleaning long-term biofilm growth; plus, certain coatings, paints, varnishes themselves subject attack.8Paulus W. Directory Microbicides Protection Materials: Handbook. Springer Science & Business Media, 2005Crossref ScholarRecently, been drive greater Recent examples include protecting textiles, murals, glass, paper. Of course, based nano-silver nano-titania studied frequently, variety readily multifunctional have shown serve alternative solutions issues.9Misra Franco Castillo I. Müller D.P. González Eyssautier-Chuine S. Ziegler de la Fuente J.M. Mitchell S.G. Streb Polyoxometalate-Ionic Liquids (POM-ILs) anticorrosion coatings natural stones.Angew. Chem. Int. Ed. Engl. 2018; 57: 14926-14931Crossref (33) Scholar, 10Castillo I.F. De Matteis L. Marquina Guillén E.G. Martínez 18th century using nano-magnesium oxide.Int. 2019; 141: 79-86Crossref (3) 11Franco García E. M Silva Preventing antifungal cellulase inhibiting magnesium oxide nanoparticles.J. Mater. B. 7: 6412-6419Crossref review, provide critical summary nanomaterials-based treatments perspective order considerations conservation-restoration, science, standpoints. We aim comprehensive analysis principal most nanomaterial analytical biochemical accurately properties, laboratory cell cultures under model samples realistic settings. functional perspective, first step properly characterize physicochemical (i.e., size, morphology, stability, so on); stage requires precise evaluation against relevant microorganisms screen candidates, develop structure-property relationships, thus select active agent protective method Crucially, interests attempt standardize demand fundamental assessment confidence data obtain comparable results. Choosing wrong performing non-standard could lead irreproducible non-comparable results, even false-negative -positive Consequently, heart review outline standardized assays/protocols compounds rigorously interested readers antibiofilm methods, depending desired end substrates.In examples, articles cited substrate materials—most possess no true value—are efficacy treatments. cases these might include, same quarries those construction buildings,9Misra Scholar,10Castillo Scholar,12Sierra-Fernandez Rosa-García S.C. Gomez-Villalba L.S. Gómez-Cornelio Rabanal M.E. Fort Quintana P. Synthesis, photocatalytic, MgO, ZnO Zn/Mg nanoparticles protection calcareous heritage.ACS Appl. Interfaces. 2017; 9: 24873-24886Crossref (45) ceramic tiles prepared historically accurate production filter paper, slides freshly made bricks,13Graziani Quagliarini D’Orazio M. role roughness porosity self-cleaning anti-biofouling efficiency TiO2-Cu TiO2-Ag nanocoatings fired bricks.Constr. Build. 2016; 129: 116-124Crossref (31) plaster, others. These initial proof-of-concept studies one stages evaluation, since any unforeseen undesired effects character original item preclude direct mitigating biodeterioration. numerous evaluated antique architectures sites around world, highlights scope effort being understand address (Figure 1). reports colorimetric measurements,14Fonseca A.J. Pina Macedo M.F. Leal N. Romanowska-Deskins Laiz Gómez-Bolea Saiz-Jimenez Anatase application mortars: comparison biocides.Int. 2010; 64: 388-396Crossref (80) recolonization,15Pinna Galeotti Perito Daly G. Salvadori recolonization lichens after innovative conservative archaeological stones Fiesole (Italy).Int. 132: 49-58Crossref (8) Scholar,16Carrillo-González Martínez-Gómez M.A. González-Chávez M.D.C.A. Mendoza Hernández J.C. Inhibition involved site silver green synthesis method.Sci. Total Environ. 565: 872-881Crossref (17) biocidal treatments.17Coutinho M.L. Miller A.Z. Martin-Sanchez P.M. Mirão Gomez-Bolea Machado-Moreira Cerqueira-Alves Jurado V. Lima et al.A multiproxy biodeteriorated majolica glazed tiles.Environ. 18: 4794-4816Crossref (13) Scholar,18Pietrzak Otlewska Danielewicz Dybka Pangallo Kraková Puškárová Bu?ková Scholtz ?urovi? al.Disinfection archival documents thyme essential oil, misting low temperature plasma.J. 24: 69-77Crossref (12) A complete description type test performed items, location, dating, image references provided Table S1.Current biodeteriorationBiodeterioration ongoing materials, consequently, number preventive indirect (such control) corrective (mechanical, biological, physical, chemical) currently threat. section, focus commonly commercial biocides whose function inhibit eliminate microorganisms. Many effect, toxic, corrosive. This due fact designed mind instead transferred agricultural sector. unwanted negative treated works, characteristics.28Palla Barresi Biotechnology Conservation Cultural Heritage. Springer, 2017Crossref ScholarBiocides inorganic, latter longer-lasting action than (which deteriorate rapidly, especially environments). It clarify typically overall quite ineffective elimination microorganisms, if they exposed environments. therefore necessary reapply regular intervals consider adapt poorly chosen biocides.29Kakakhel Wu Gu J.D. Feng H. Shah Wang Controlling biocides: review.Int. 143: 104721Crossref ScholarWhen applying product, chemically inert, stable, colorless avoid interference possible interaction intervention consolidants). cyto- ecotoxicity must considered. Also, meet requirements, external alteration agents, reversible without causing case maintaining adequate permeability obstructing porosity.30Sameño Puerto El biodeterioro en edificios del patrimonio cultural: metodología evaluación tratamientos biocidas. Tesis Doctoral Inédita. Universidad Sevilla, Sevilla2018Google ScholarThe effectiveness biodeterioration, obtained application, depend concentration stability duration solvent, pH solution, presence cracks content water, existence wind rain during treatment, ambient light intensity, entity.31Caneva Nugari M.P. O. II Controllo Degrado Biologico–I Biocidi nel Restauro dei Materiali Lapidei. Nardini Editore, 1996Google ScholarIt keep modify activity may affect longevity over time, biocide applied. responsible success failure products, interventions carried out worldwide. though routinely conservation, said enough assess efficacy, materials.28Palla commercially prevention heterotrophic autotrophic yeast, molds, bacteria), plants (like moss bryophyte), summarized 1.Table 1Commercial biodeteriorationChemical classificationActive ingredient nameSubstrate targeted microorganismEfficacyExamples/notesRefs.Alcoholsethanolstone materials,papercontradictory results: Trebouxia sp., Gloeocapsa sp. Chroococcus brushing 96% ethanolic (30%, 70%, 100%) revealed short long term papergranite (laboratory test)filter test)Sequeira al.32Sequeira S.O. Phillips A.J.L. Cabrita E.J. Ethanol treatment paper: short-term effects.Stud. Conserv. 62: 33-42Crossref (10) Scholarbacteria, algaecan act conidia activatorIsothiazolones2-methyl-4-isothiazolone- 3-oneProClin 950-Sigma Aldrichstone materialslow efficacy: killed 20%–40% cellslaboratory testBartolini al. 33Bartolini Pietrini A.M. Ricci Valutazione dell’efficacia di alcuni nuovi biocidi per il trattamento microflora fotosintetica e briotite su materiali lapidei.Bollettino ICR. 2007; 101-111Google ScholarKumar Kumar 34Kumar A.V. Stone Tropical Environments: An Overview. Getty 1999Google ScholarBlazquez al.35Blazquez Lorenzo Flores Gomez-Alarcon Evaluation effect organisms isolated monuments.Aerobiologia. 2000; 16: 423-428Crossref (16) ScholarFonseca al.14Fonseca ScholarCoutinho 17Coutinho Scholaralgae2-octyl-2H-isothiazolon- 3-one + didecyl dimethyl ammonium chloride propanol formic acidRocima 103- Dow ChemicalMasonry paintingsefficient brushing, 2% waterarchaeological Ostia Antica, Rome, Italyfungi, algaemust diluted use5-chloro-2-methyl isothiazolinone,2-methyl isothiazolone, methyl-benzimidazol-2-ylcarbamate +2-n-octylisothiazolinoneMergal S97-Troy corporationstone materialseffectivelaboratory testfungi, yeastcrystallization pores make penetration solution difficultgood distribution surfacen-octyl-isothiazolonestone materialseffective, 5% ethanolagar diffusion tests, test)fungi, actinobacteriadi-n-decyl-dimethyl chloride, 2,N-ottil-2H-isotiazol-3-one isopropanol acidbiotin T-CTSstone materialsceramic materialswall paintingscontradictory v/vefficient, occurred 6 monthsPalacio Nacional da Pena, Sintra, Portugalfishing house Marquis Pombal Palace, Oeiras, Portugalfungi, bacteriathe anionic surfactants hard waters should avoidedMixesimidazole isothiazolinoneParmetol DF 12-Schülke Mayrstone materialsplastic materialstextilemetalshigh efficiency. Effective 4 yearsAngkor Wat, (Cambodia)Kumar Kuma34Kumar ScholarRiederer 36Riederer weathering building tropical countries.Stud. 1986; 31: 151-154Crossref (1) Scholarfungi, algaeethanol (70%) was destabilize. Avoid alkaline solutionsiodopropynylbutyl carbamate n-octyl-isothiazolone dissolved 2(2?-oxydiethanol)biotin R-CTSstone results:effective until saturationnot 4% v/v ethanol applicationSegovia cathedral cloister, (Spain)Limestone, Classic Karst plateau (Italy)fungi, bryophyte, bacteriabarely miscible watersodium dimethyldithiocarbamate sodium 2-mercaptobenzothiazoleVancide 51-Vanderbiltstone materialscottonwoodpapermetalsplaster worksgood bacteria three times 1% isopropanolgood 1–2 yearsmarbles, lichentributyltin quaternary saltThaltox Q-Wykamolstone materialswoods lacking interestwall paintingseffective spraying, 3 years almost completely washed-out rainCopan (Honduras)algae, lichenreapplication every 8 yearsOxidizing agentscalcium hypochloritestone materialsgood hot waterPalace Saints George Michael, Corfù, (Greece)Washington Legislative Building (USA)Pantazidou Theoulakis 37Pantazidou, A., Theoulakis, (1997). Cyanophytes associated flora neoclassical palace St Michael Corfù (Greece). Aspects procedures, Proceedings 4th International Symposium Monuments Mediterranean Basin pp. 355–368.Google ScholarPantazidou Scholaralgae, lichenits maintained (recolonization 1 year)hydrogen peroxidestone materialscontradictory 10% watereffective sprayed 15% (v/v) carbonate/ bicarbonate buffer solutionhistoric cemetery Drapano, Kefalonia, (Greece)Slovenian cavesalgae, lichencan bleach materialssodium materialswater saturated woodgood 3.5% (Greece)algae, licheninterferes (excessive bleaching secondary yellowing action)may react wood ligninits longphenolic compoundsdiuron 3-[3,4-dichlorophenyl]-1,1-dimethylureapreventol A6-Lansessplasterseffectivelaboratory testBlazquez ScholarSavvides al.38Savvides A.L. Nikolakopoulou T.L. Kyratsous Katsifas E.A. Kanini Karagouni A.D. Bacterial marble monuments: study project acropolis monuments.Geomicrobiol. 2014; 726-736Crossref (4) Scholaralgaeit darkening limestone less detectable granite surfacesn-butyl-1,2 benzoisotiazolin-3-onealgophase-phasestone 3% waterAcropolis, Athens, Greecebacteria, fungia recommended devitalize microfl