Antimicrobial Activity of Nano-GeO2/CTAB Complex Against Fungi and Bacteria Isolated from Paper

Microbial attack, particularly fungal degradation of cellulose, is a leading cause of paper damage. To address fungal spores and the rising concern of microbial drug resistance, a nano-Germanium dioxide (GeO₂)/cetyltrimethylammonium bromide (CTAB) complex (nano-GeO₂/CTAB complex) with potent antibacterial properties was synthesized. Its inhibitory effects were evaluated against bacteria, including Gram-positive <i>Staphylococcus aureus</i> and Gram-negative <i>Escherichia coli</i>, as well as fungi isolated from paper (<i>Fusarium</i> spp., <i>Aspergillus</i> spp., and <i>Penicillium citrinum</i>). The nano-GeO₂/CTAB complex exhibited significant (<i>p</i> < 0.05) inhibitory effects against <i>S. aureus</i> and <i>E. coli</i>. Moreover, a 60 min treatment with 1 mg/mL of the complex significantly inhibited the growth of all tested fungi and reduced their biomass after five days of culture, while 4 mg/mL completely deactivated spores. Filter paper pre-treated with the nano-GeO₂/CTAB complex showed complete resistance to microbial attack, exhibiting no fungal growth and a clear inhibition zone devoid of bacterial growth. In contrast, untreated controls displayed fungal coverage exceeding 95% within five days. These findings highlight the nano-GeO₂/CTAB complex as a promising antimicrobial agent for protecting paper materials from microbial degradation.