The aim of this study was to investigate the I-131 and I-127 labeled linezolid and moxifloxacin effects of minimum inhibitory concentration, and minimum bactericidal concentration on mature biofilm and microorganism within the biofilm. Linezolid and moxifloxacin were labeled with I-131 and I-127 and chromatography studies were carried out with thin layer radiochromatograpy and high-pressure liquid radiochromatography techniques. Specific activities of radiolabeled LZD and MXF was found to be 53.3 +/- 3.1 and 127.3 +/- 1.1 MBq/A mu mol for [I-131]LZD and 7.6 +/- 0.02 and 55.6 +/- 0.8 MBq/A mu mol for [I-131]MXF, respectively. The minimum inhibitory concentration and Time-Kill of Linezolid and moxifloxacin alone and their I-131 and I-127 labeled forms were tested with a standard strain of meticillin-susceptible StaphylocA +/- ccus aureus. MIC values of LNZ and MXF were 2.96 nmol/mL (1 A mu g/ml) and 0.141 nmol/mL (0.062 A mu g/ml). Time Kills of MXF and LZD were found to be 0.06 and 1 mu g, respectively. Antibiotics labeled with beta-emitting radioactive molecule may be a new theranostics strategy for biofilm infections.