Abstract <p>Microbial biodeterioration represents a major challenge in the conservation of photographic heritage, particularly silver gelatin prints. In this study, the antifungal efficacy of clove essential oil (<i>Syzygium aromaticum</i>) and selenium nanoparticles (SeNPs) was evaluated separately against <i>Aspergillus flavus</i>. Both treatments significantly inhibited fungal growth and sporulation, with SeNPs showing superior activity at lower concentrations, while clove oil exhibited strong inhibition at higher doses. Computational analyses revealed distinct mechanisms: clove oil phytochemicals targeted ergosterol biosynthesis, cell wall organization, and lipid metabolism, whereas SeNPs induced oxidative stress and disrupted antioxidant defenses. This work provides the first integrated experimental and computational framework applying these eco-friendly agents directly to photographic materials, establishing a mechanistic basis for sustainable antifungal strategies in heritage preservation.</p> Key points <p>• <i>Clove oil and selenium nanoparticles effectively prevent fungal damage to photographs.</i></p> <p>• <i>Different antifungal mechanisms were observed through computational analyses.</i></p> <p>• <i>Provides a sustainable, eco-friendly strategy for cultural heritage preservation.</i></p>