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. 2025 Jan 30:13:1535787.
doi: 10.3389/fchem.2025.1535787. eCollection 2025.

Citronellol-functionalized natural silica: a biogenic approach for antifungal and antibacterial material applications

Guillermo P Lopez  1   2 , Leyanet Barberia Roque  1 , Katerine Igal  1   3 , Erasmo Gámez Espinosa  1   3 , Natalia Bellotti  1   4
Affiliations

Citronellol-functionalized natural silica: a biogenic approach for antifungal and antibacterial material applications

Guillermo P Lopez et al. Front Chem. .

Abstract

Introduction: New bioactive hybrid materials to prevent biofilm-induced biodeterioration are a significant challenge in indoor environments, where contaminants from microbial films compromise structural integrity and contribute to air pollution, posing health risks from prolonged exposure to biological agents.

Methods: For the first time, diatomaceous earth or diatomite (Dt) was functionalized with quaternary ammonium salt (QAS) and a biogenic compound, citronellol, to develop a bioactive hybrid material (Dt*QC). The hybrids obtained were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). The antifungal and antibacterial activity were assessed by agar diffusion assay, and micro/macro-dilution tests.

Results and discussion: Characterization confirmed successful functionalization. TGA revealed organic contents of 50.9% with citronellol incorporation reaching 48.1%. SEM-EDS corroborated the incorporation of organic components. FTIR further verified the integration of functional groups while preserving the structural stability of the siliceous framework. Antimicrobial assays revealed a broader range of activity for Dt*QC. For bacterial strains, Dt*QC achieved a minimum inhibitory concentration (MIC) of 0.15 mg/mL against Staphylococcus aureus and demonstrated over 99.9% bacterial reduction, even at lower concentrations. This study highlights a novel approach to developing antimicrobial materials by functionalizing Dt with QAS and citronellol. Overall, these findings underscore the potential of Dt*QC as an advanced antimicrobial material for applications in coatings and preservation systems, offering a sustainable solution to prevent biodeterioration and microbial contamination.

Keywords: antibacterial; antifungal; bioactive hybrids; biocide; citronellol; diatomaceous earth; functionalization; terpenoid.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
XRD diffractogram.
FIGURE 2
FIGURE 2
(A) SEM micrograph (magnification: 3,000x), Si and O mapping of the raw DE; (B) EDS spectrum.
FIGURE 3
FIGURE 3
Chemical structures of the Citronellol.
FIGURE 4
FIGURE 4
TGA: Dt, Dt*, Dt*Q and Dt*QC.
FIGURE 5
FIGURE 5
SEM micrographs (magnification ×500) and EDS elemental surface analysis: Dt*, Dt*Q, and Dt*QC.
FIGURE 6
FIGURE 6
FTIR spectra: Dt, Dt*, Dt*Q, and Dt*QC.
FIGURE 7
FIGURE 7
Agar well diffusion assay: Dt*, Dt*Q, and Dt*QC against Aspergillus fumigatus, C. globosum, and P. commune.
FIGURE 8
FIGURE 8
Agar well diffusion assay: Dt*, Dt*Q, and Dt*QC against Escherichia coli and S. aureus.
FIGURE 9
FIGURE 9
The bar graph illustrates the logarithms of CFU for Escherichia coli and S. aureus with and without Dt*QC. The control bars correspond with the culture medium without Dt*QC.
See this image and copyright information in PMC

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