Label-free detection and characterization of cytochrome-c in human microglial cells (HTHμ) during apoptosis via Raman spectroscopy

Cytochrome c, an essential protein integral to the electron transport chain within cellular mitochondria, plays a crucial role in the intricate process of apoptosis, or programmed cell death. An early event in apoptosis involves the release of cytochrome c from the mitochondria's intermembrane space into the cytoplasm. This paper explores the detection of cytochrome c during apoptosis using Raman spectroscopy, with a specific focus on its release from the mitochondria of human microglial cells (HTHμ). Raman spectroscopy, a non-invasive and label-free analytical technique, allows the examination of biomolecular changes based on their chemical properties. Our experimental approach induced apoptosis in HTHμ cells using methamphetamine (METH) and utilized Raman spectroscopy on both control and apoptotic samples. Through the analysis of spectra by singular value decomposition (SVD), which reveals subtle trends and facilitates biological interpretation, distinct spectral features corresponding to cytochrome c were identified. This evidence supports the concept of cytochrome c release from the mitochondria during apoptosis. The label-free nature and high sensitivity of Raman spectroscopy position it as a promising technique for studying apoptosis in biomedical research and contributing to the development of innovative diagnostic approaches for apoptotic-related disorders.