Keywords: plasmonic optical biosensors, plasmonic, biosensors, enhancement factor, rotavirus RNA, SERS, Paper-based SERS, Silver clusters, DFT, Experimental analysis, theoretical modelling, Raman, photoscience in biology, experimental techniques, Raman spectroscopy, theoretical approaches, single molecules, synthesis methods, ultrafast photochemistry, photoscience at nanoscale, infrared spectroscopy, surface enhanced raman spectroscopy, press, sciene, big scale research,