Microwave-induced modulation of intracellular distribution of peptides based on mitochondrial targeting sequences

Microwave (MW) irradiation has recently emerged as a promising physical approach for modulating the intracellular behavior of bioactive molecules. However, its potential effects on intracellular distribution and spatial association remain largely unexplored. In this study, we investigated MW-induced changes in the intracellular distribution of peptides designed based on previously reported mitochondrial targeting sequences under MW irradiation at 2.45 GHz. Peptide-derived fluorescence and its intracellular distribution were analyzed using confocal laser scanning microscopy and flow cytometry. MW irradiation induced sequence-dependent changes in cellular fluorescence intensity, with (Cha-r)₂-R₄ showing a more pronounced increase compared with non-irradiation conditions, whereas maintaining high cell viability. Colocalization analysis indicated an increase in spatial association between peptide-derived fluorescence and mitochondrial staining, although Pearson correlation coefficients remained low. These results suggested MW-induced modulation of peptide delivery to mitochondrial regions, although further quantitative and/or detailed analyses, such as mitochondrial function assays would be required. To the best of our knowledge, this study is the first to demonstrate the potential of MW for delivering peptides conjugated with a signal sequence to the mitochondrial region.