Comparison of Inhibitory Effect of Colloidal Silver and Silver Nanoparticle against Propionibacterium acnes bacteria

The paper describes a comparison between Colloidal Silver (CS) and Silver Nanoparticles (SNP) in terms of production technique, absorption peak wavelength, particle size, clear zone diameter, and the duration before the emergence of resistance in Propionibacterium acnes. CS was produced using an electrolysis technique employing a pair of slab electrodes made from 99.95% silver with some additional bromide (AgBr). Observations of silver concentration as a function of time were conducted over 2 hours at a voltage difference of 24 Volts. The SNP was produced using a synthesis technique that involved mixing silver nitrate (AgNO3) and trisodium citrate (Na3C6H5O7). Both CS and SNP samples were prepared at concentrations of 10 ppm and 30 ppm.

Absorption wavelength observations were performed using a UV-visible spectrophotometer and found that the absorption peak wavelengths of CS and SNP were 437 nm and 425 nm, respectively. The differences in these absorption peak wavelengths were discussed in the paper. Particle size measurements were conducted using dynamic light scattering, revealing that the particle diameter of CS is significantly larger than that of SNP. These size measurement differences were also properly discussed.

The assessment of antibacterial inhibition was carried out using the Kirby-Bauer disk diffusion method. The clear zone diameters of CS and SNP were compared to each other and to chloramphenicol as a positive control. The comparison also included the duration before the emergence of bacterial resistance for CS, SNP, and chloramphenicol.