Novel l‑Arginine‑Dextran70 based-silver nanoparticles (SNPs) (SNPs), functionalized with Riboflavin (RF) and Human Serum Albumin (HSA) were characterized by UV-Vis absorption, Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), fluorescence and circular dichroism spectroscopy, chemiluminescence and Neutral red assays. TEM analysis showed the formed faceted particles, large clumps/fused aggregates, nano-featured with the mean particle size of 41.60 nm. Chemiluminescence and Neutral red assays for in vitro antioxidant and cytotoxic activities of the SNPs/RF/HSA systems have been studied. It was pointed out that SNPs functionalized with RF and HSA resulted in a bio-nanosystem which leads to a high activity against oxygen free radicals, altered viability, morphology, apoptotic bodies and decreased cell density of L929 fibroblast cells. Results are relevant for understanding the redox properties of RF in the case of biological applications and especially for RF containing drugs.