Red Microalgal Sulfated Polysaccharide-Cu₂O Complexes: Characterization and Bioactivity

Area of Science:

• Marine biotechnology
• Biomaterials science
• Microbiology

Background:

• Algal polysaccharides possess anion-exchange properties useful for metal complexation.
• Developing novel bioactive materials from natural resources is a key area in biotechnology.
• Copper oxide nanoparticles exhibit antimicrobial properties.

Purpose of the Study:

• To synthesize and characterize a novel copper oxide (Cu₂O)-polysaccharide complex.
• To evaluate the antimicrobial and antibiofilm activities of the synthesized complex.
• To investigate the structural features responsible for the observed bioactivities.

Main Methods:

• Complexation of Cu₂O with sulfated polysaccharide from *Porphyridium* sp.
• Chemical, rheological, and atomic force microscopy characterization.
• Antimicrobial assays against bacteria (*A. baumannii*, *P. aeruginosa*, *E. coli*, *S. aureus*, *B. subtilis*) and fungi (*C. albicans*).
• Antibiofilm assays against *P. aeruginosa* and *C. albicans*.

Main Results:

• The Cu₂O-polysaccharide complex demonstrated covalent copper binding and enhanced viscosity and conductivity.
• The complex exhibited significant antimicrobial activity, particularly against *Candida albicans* (92% growth inhibition).
• Antibiofilm activity was observed against *Pseudomonas aeruginosa* and *Candida albicans*.
• Atomic force microscopy revealed unique needle-like surface structures (spikes) on the complex.

Conclusions:

• The Cu₂O-polysaccharide complex is a novel bioactive material with potent antimicrobial and antibiofilm properties.
• The observed bioactivities are likely mediated by the unique spike-like surface structures on the complex.
• This material holds promise for diverse biotechnological applications, warranting further investigation.