Porphyran-capped silver nanoparticles as a promising antibacterial agent and electrode modifier for 5-fluorouracil electroanalysis.

In the present work, the green synthesis of silver nanoparticles (AgNPs) using the sulfated polysaccharide porphyran (PFR) as capping agent and d-glucose as reducing agent is described. PFR was extracted from red seaweed and characterized by employing C NMR and determination of total sugar, protein, and sulfate contents. The obtained AgNPs-PFR were characterized by using UV-VIS spectroscopy, zeta potential determination, FESEM, and TEM, which demonstrated that PFR was effective at capping the AgNPs, yielding stable suspensions. The AgNPs-PFR presented good antimicrobial properties against Gram-positive and Gram-negative bacterial strains (Staphylococcus aureus and Escherichia coli, respectively). The AgNPs-PFR were also employed as the modifier of carbon paste electrodes, which were efficiently applied as electrochemical sensors for the determination of 5-fluorouracil (5-FU), an important anticancer drug, through square wave voltammetry (SWV). The AgNPs-PFR improved the electrochemical properties of the electrodes, and enhanced their electroanalytical performance. The developed sensing device presented detection and quantification limits equal to 10.7 and 35.8 μmol L-1, respectively, towards 5-FU determination. The proposed electrochemical sensor successfully quantified 5-FU in a real pharmaceutical formulation, confirming its potential as a new promising analytical detection tool for 5-FU quality control purposes.