Biocleaning of starch glues from textiles by means of α-amylase-based treatments.

Glues based on starch are widely used for the consolidation of brittle fibres in historic and archaeological textiles. Ageing fabrics are affected by hydrolysis/oxidation and cross-linking of these glues, a decrease of glues' solubility, the formation of cracks, and discoloration. The hydrolytic action of enzymes on starch-based glues is promising, as molecular recognition offers great selectivity. However, a systematic assessment of the best methods for applying enzymatic formulations has not been explored yet. Here, α-amylase was applied either by pipetting a solution or combining with gellan gel (embedded in the gel or spread on the gel surface). The effectiveness of the different formulations on the removal of potato and wheat starch was evaluated by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and colorimetric measurements. Enzymes dispersed in gel showed weak diffusion at the surface, resulting in poor starch breakdown and removal. On the contrary, amylase applied by pipette and spread on gel resulted in high starch removal selectivity and efficiency, with neither swelling nor damage to the fibres. These results validate protocols for the assessment of the enzymatic activity on glue-consolidated fibres, identify best application methods and confirm the excellent properties of amylase dispersions for the conservation of historic and archaeological textiles.Key points• Application of α-amylase by pipette and combined with gellan gel to remove starch glues from wool.• Systematic assessment of the best application methods following a multi-analytical protocol.• Enzymes dispersed in gel exhibit poor diffusion at the surface, leading to weak starch removal.• Enzymes applied by pipette and spread on gel are efficient in starch cleaning, without damage to the fibres.

Immobilized Enzymes on Gold Nanoparticles: From Enhanced Stability to Cleaning of Heritage Textiles.

Enzyme-based treatments are used in heritage conservation for the effective removal of glues and other damaging organic layers from the surfaces of historic and artistic works. Despite their potential, however, the application of enzymatic treatments is currently limited because of their poor efficiency and low operational and environmental stability. We demonstrate the use of α-amylase immobilized on gold nanoparticles to improve the efficacy of enzymatic treatments enhancing both the reactivity and the stability of the formulations. Gold nanoparticles coated with α-amylase exhibit significant advantages compared to free enzymes. We report up to 5× greater resistance to environmental changes, up to 2× higher efficacy toward removal of starch-based glues from textiles and deeper penetration through the fibers, without causing damage or inducing salt precipitation. These results offer exciting prospects for the development of enzymatic formulations, both for heritage conservation and the wider application of enzymes, such as in medicine, the detergent industry, and green chemistry.