Methods for Intracellular Delivery of Quantum Dots

Quantum dots (QDs) have attracted considerable attention as fluorescent probes for life sciences. The advantages of using QDs in fluorescence-based studies include high brilliance, a narrow emission band allowing multicolor labeling, a chemically active surface for conjugation, and especially, high photostability. Despite these advantageous features, the size of the QDs prevents their free transport across the plasma membrane, limiting their use for specific labeling of intracellular structures. Over the years, various methods have been evaluated to overcome this issue to explore the full potential of the QDs. Thus, in this review, we focused our attention on physical and biochemical QD delivery methods-electroporation, microinjection, cell-penetrating peptides, molecular coatings, and liposomes-discussing the benefits and drawbacks of each strategy, as well as presenting recent studies in the field. We hope that this review can be a useful reference source for researches that already work or intend to work in this area. Strategies for the intracellular delivery of quantum dots discussed in this review (electroporation, microinjection, cell-penetrating peptides, molecular coatings, and liposomes).

Generation of Intramolecular FRET Probes via Noncanonical Amino Acid Mutagenesis

Förster resonance energy transfer (FRET) probes are powerful tools to monitor protein-protein interactions and enzyme activities in a spatiotemporal manner in live cells. Using a combination of noncanonical amino acid (ncAA) mutagenesis and bioorthogonal labeling, we have developed intramolecular FRET probes consisting of a fluorescent protein and an organic dye within an individual protein. Herein we present a general approach to establish intramolecular FRET probes for imaging of protein activity in live cells.