Supramolecular Dipeptide-Based Near-Infrared Fluorescent Nanotubes for Cellular Mitochondria Targeted Imaging and Early Apoptosis

Abstract

Herein, we have designed and synthesized unsymmetrical visible Cy–3 and near-infrared (NIR) Cy–5 chromophores anchoring mitochondria targeting functional group conjugated with a Phe-Phe dipeptide by a microwave-assisted Fmoc solid phase peptide synthesis method on Wang resin. These dipeptide-based Cy–3-TPP/FF as well as Cy–5-TPP/FF molecules self-assemble to form fluorescent nanotubes in solution, and it has been confirmed by TEM, SEM, and AFM. The Cy–3-TPP/FF and Cy–5-TPP/FF molecules in solution exhibit narrow excitation as well as emission bands in the visible and NIR region, respectively. These lipophilic cationic fluorescent peptide molecules spontaneously and selectively accumulate inside the mitochondria of human carcinoma cells that have been experimentally validated by live cell confocal laser scanning microscopy and display a high Pearson’s correlation coefficient in a colocalization assay. Live cell multicolor confocal imaging using the NIR Cy–5-TPP/FF in combination with other organelle specific dye is also accomplished. Moreover, these lipophilic dipeptide-based cationic molecules reach the critical aggregation concentration inside the mitochondria because of the extremely negative inner mitochondrial membrane potential [(ΔΨm)cancer ≈ −220 mV] and form supramolecular nanotubes which are accountable for malignant mitochondria targeted early apoptosis. The early apoptosis is arrested using Cy–5-TPP/FF and confirmed by annexin V-FITC/PI apoptosis detection assay.

Biological roles of sulfur dioxide and sulfite in the regulation of mitochondrial viscosity

“…Mitochondrial membrane potential is an indicator for the early apoptosis of living cells. [21][22][23] The SO 3 2À and SO 2 donor (T-R, 10 mM) was used for real-time tracing of MMP using rhodamine 123. As shown in Fig.…”

Recent advances in nanotechnology mediated mitochondria-targeted imaging

“…There have been a wide variety of TPP-based compounds that have proved to be useful for mitochondria-targeted imaging, such as NIR Cy-5-TPP/FF, 41 WSSe/MnO 2 -INH-TPP@CM, 42 C-dots-TPP 43 and Gold-TPP. 44 In addition to TPP, which can be used as a small molecular group targeting the mitochondrial outer membrane, PQC is also a group that can target mitochondria.…”

“…There have been a wide variety of TPP-based compounds that have proved to be useful for mitochondria-targeted imaging, such as NIR Cy-5-TPP/FF, 41 WSSe/MnO 2 -INH-TPP@CM, 42 C-dots-TPP 43 and Gold-TPP. 44…”

Co-assembled Coiled-Coil Peptide Nanotubes with Enhanced Stability and Metal-Dependent Cargo Loading

“…While less common than simpler nanofibrils, these three-dimensional materials contain an inner cavity and outer shell to allow for multifunctionality. Peptide-based nanotubes specifically are an attractive choice owing to their tunability and biocompatibility. − As such, peptide nanotubes have been derived from a diverse collection of structures including dipeptides, − cyclic peptides, − peptoids, − triple helices, , β-sheets, − and coiled-coils. − …”