Extraction and characterization of polysaccharide mixtures from Chlamydomonas reinhardtii. A case study as a consolidant for paper-based artworks

Lately, microalgae use in cultural heritage conservation and protection has gained interest for their ability to meet the sector's innovation and sustainability demands, benefiting both the environment and practitioners. An eco-friendly material, extracted from Chlamydomonas reinhardtii with hot water treatment and ethanol precipitation, for paper-based artwork conservation is presented. The study represents an advancement over the current state of the art, detailing the polysaccharide extract characterization and its validation in real application on samples. The polysaccharides' chemical composition was analyzed by spectroscopy and chromatography methods, revealing glucose (28 %), mannose (27 %), rhamnose (36 %), and xylose (9 %) mixture. The obtained bio-material was tested as a consolidant on artificially depolymerized paper samples and incoherent paint layers. Some commercial consolidants (Klucel G, Funori, Sturgeon glue, and crystalline nanocellulose) were used to compare and evaluate extract efficacy. The consolidating treatment was analyzed via optical and electron microscopy, mechanical strength quantification, and color alteration. The data obtained showed a breaking load increase (∼35 %) and no color variation, proving a notable consolidating capacity of the mixture on the artificially aged paper and pictorial film samples, compared with commercially available products. These findings show the potential of this polysaccharide extract as a sustainable solution for paper artwork conservation.