Cellulose-Silver and Cellulose-Gold Bioactive Nanocomposites Obtained Using SCOBY Purified Membranes.

Area of Science:

• Materials Science
• Biotechnology
• Green Chemistry

Background:

• The demand for bioactive nanomaterials is increasing across various sectors, including pharmaceuticals and biotechnology.
• Bacterial cellulose (BC), a byproduct of kombucha fermentation, offers a sustainable platform for nanomaterial synthesis.
• Green synthesis methods are preferred for their environmental friendliness and cost-effectiveness.

Purpose of the Study:

• To develop eco-friendly and low-cost methods for synthesizing bacterial cellulose-silver (AgNPs/SBC) and bacterial cellulose-gold (AuNPs/SBC) bionanocomposites.
• To investigate the influence of different synthesis media (water, black tea, kombucha) on nanoparticle formation and properties.
• To evaluate the antioxidant and antimicrobial potential of the synthesized nanocomposites.

Main Methods:

• Purification of bacterial cellulose (SBC) using an alkaline solution.
• Green synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) on the SBC matrix using metal precursors in water, black tea, and kombucha.
• Characterization of nanocomposite morphology and structure using SEM, TEM, and XRD.
• Assessment of antioxidant capacity via DPPH and ABTS assays.
• Evaluation of antimicrobial activity against *Escherichia coli*, *Staphylococcus aureus*, and *Listeria monocytogenes*.

Main Results:

• Silver and gold nanoparticles were successfully synthesized on the bacterial cellulose matrix in all tested media, indicating cellulose's inherent reducing capability.
• SEM and TEM analyses revealed irregular to quasi-spherical nanoparticles ranging from a few to 70 nm, distributed on cellulose fibers.
• XRD confirmed the formation of crystalline AgNPs and AuNPs, with specific allomorphs of cellulose.
• AgNPs/SBC composites synthesized in kombucha and fresh black tea exhibited the highest antioxidant activity.
• The nanocomposites demonstrated enhanced antimicrobial activity compared to raw SBC, particularly those synthesized in kombucha.

Conclusions:

• Bacterial cellulose serves as an effective template for the green synthesis of AgNPs and AuNPs.
• The synthesis medium significantly influences nanoparticle characteristics and the resulting bioactivity.
• Cellulose-silver and cellulose-gold nanocomposites possess promising antioxidant and antimicrobial properties for applications in medicine and food packaging.