Hydrogels: A 'stepping stone' towards new cleaning strategies for biodeteriorated surfaces

In this work, poly(vinyl)alcohol-borax (PVA-borax) hydrogels containing active ingredients with antimicrobial effects were designed and tested over two biodeteriorated stones of different nature and composition. The polymer network was reinforced with a filler of ZnAl layered double hydroxide (LDH) supporting sodium alginate (SA) chains (LDH@SA) and the active role has been assigned to three ingredients: silver nanoparticles (AgNPs), silver nanoparticles-silver chloride (Ag/AgCl) and thyme essential oil (EO), used either separately or mixed together within the same hydrogel. For better comparison, a final test was performed by preparing hydrogels containing a common antimicrobial agent such as methylisothiazolinone (MIT). The effects of the treatments have been investigated through staining techniques (periodic acid staining PAS, triphenyl-tetrazolium chloride TTC) and colony forming unit assays(CFUs) performed on media specific for bacteria, fungi and algae. The data collected consented to identify the most efficient cleaning systems in the hydrogel prepared with AgNPs and in that with thyme EO, leading the way for a new approach in the field of bioremediation. (C) 2020 Elsevier Masson SAS. All rights reserved.

Automated summary

In this study, a novel PVA-borax hydrogel containing antimicrobial active ingredients was designed and tested on biodeteriorated stones. The hydrogels with silver nanoparticles and thyme essential oil were found to be the most efficient cleaning systems, opening up new possibilities for bioremediation. The effects of the treatments were assessed through staining techniques and colony forming unit assays specific to bacteria, fungi, and algae.