What question did this study set out to answer?

Evaluate a SiO2NPs/Paraloid B-72 nanocomposite for its efficacy in restoring fungal-deteriorated sandstone.

April 16, 2026Sustainability0 citationsOpen Access

SiO2NPs/Paraloid B-72 Nanocomposite-Based Formulation for Sustainable Restoration and Mitigation of Fungal Deterioration of Sandstone Cultural Heritage

MAMohamed Hssan Hassan AbdelhafezUniversity of Ha'il MTMabrouk TouahmiaUniversity of Ha'il AAAli Aldersoni

Key Points

Evaluate a SiO2NPs/Paraloid B-72 nanocomposite for its efficacy in restoring fungal-deteriorated sandstone.
Synthesis and characterization of SiO2NPs and Paraloid B-72 nanocomposite using TEM and XRD.
Cultural identification of fungal isolates using PCR and DNA sequencing.
Laboratory antifungal tests to assess the efficacy of the nanocomposite at varying concentrations.
Mechanical testing of sandstone for compressive strength pre- and post-treatment using SEM-EDX and other analytical techniques.
SiO2NPs at 300 ppm inhibited mycelial growth by 91.59% for P. chrysogenum, 90.77% for A. niger, and 85.2% for A. alternata.
Compressive strength of treated sandstone increased from 26.5 MPa to 27.4 MPa.
Effective homogeneous dispersion of the nanocomposite on stone grains was confirmed by SEM images.

Abstract

This study evaluates a SiO2 nanoparticle (SiO2NPs)/Paraloid B-72 nanocomposite as a restorative and antifungal treatment for deteriorated sandstone at the Ptolemaic Temple of Isis, located within a densely populated residential area. The temple stones exhibit structural damage, soiling, and severe microbiological deterioration. Fungal isolates from the sandstone were cultured on PDA medium and identified by ITS region DNA sequencing as Alternaria alternata, Penicillium chrysogenum, and Aspergillus niger. The SiO2NPs and their Paraloid B-72 nanocomposites were synthesized and characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Stone samples, examined before and after treatment via SEM-EDX, TEM, and XRD, were used to assess both conservation performance and compatibility. Laboratory antifungal tests showed that SiO2NPs at 300 ppm exhibited the greatest inhibition of mycelial growth, reaching 91.59% for P. chrysogenum, 90.77% for A. niger, and 85.2% for A. alternata. Mechanical testing demonstrated that treatment with the SiO2NPs/Paraloid B-72 nanocomposite enhanced stone strength, increasing compressive strength from 26.5 MPa to 27.4 MPa. SEM images confirmed excellent, homogeneous dispersion of the nanocomposite on stone grains, forming a coherent coating without pore occlusion. Overall, the SiO2NPs/Paraloid B-72 formulation improved sandstone surface properties while substantially improving short-term mechanical performance and antifungal efficacy, indicating promise for enhancing restoration procedures when combined with established conservation protocols for sandstone architectural heritage.

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