Water Soluble Melanin of Streptomyces lusitanus DMZ3 Persuade Synthesis of Enhanced Bio-medically Active Silver Nanoparticles

Enhanced bio-medically active silver nanoparticles were produced from water soluble melanin of Streptomyces lusitanus DMZ3. Synthesis of silver nanoparticles within 80 s was facilitated by microwave radiation. Melanin silver nanoparticles produced in the range of 13–22 nm sizes were confirmed and characterized by UV–Vis spectrum, transmission electron microscopy, dynamic light scattering, X-ray diffraction and Fourier transform infrared spectroscopy analysis. Silver nanoparticles produced from water soluble melanin showed potential biomedical attributes. Promising antioxidant activity of melanin silver nanoparticles with 130 µg/mL IC 50 (50 % inhibition concentration) and 82.5 µg/mL EC 50 (50 % effective concentration) functional potentials were recorded following DPPH (2,2′diphenyl-1-picryldrazyl) method and phosphomolybdate assay respectively. These melanin silver nanoparticles were found to be potential cytotoxic agent with 0.34 µg/mL LC 50 (50 % lethal concentration) employing brine shrimps. Water soluble melanin, explored in the study, naturally would be a strategic biological reducing agent to produce melanin silver nanoparticles with greater biomedical activities.