UC San Diego

Cell-pentrating peptides have the ability to translocate across cell membranes and deliver macromolecules into cells without disruption to the membranes, making them highly desirable for either experimental or therapeutic purposes. Our interest is in utilizing the capabilities of peptides to deliver conjugated quantum dots to astrocytes in an efficient and high-throughput manner. To deliver the quantum dot to the cytoplasm of primary astrocytes, quantum dot was self-assembled with poly arginine (poly-R) peptides with a histidine tag at the C-terminal end of the peptides, which has a dissociation constant in the nanomolar range. In order to deliver the quantum dot to intracellular targets, we employed signal peptides including nuclear localization sequence (NLS) and endoplasmic reticulum (ER). The arginine length of R11 peptide compared to R8 peptide resulted in an increase of quantum dot internalization; the R11 peptide was also the most efficient peptide tested. Concentration, incubation time, buffer conditions, and temperature all affect optimal QD internalization. Transmission electron microscopy results confirmed the uptake of QDs inside cells. Overall, the work in this study provides preliminary approaches for future delivery of quantum dot based sensors into live cells utilizing cell-penetrating peptides