Antibodies
are powerful tools that may potentially find wide applications
in live-cell bioimaging, disease diagnostics, and therapeutics. Their
practical applications have however remained limited thus far, owing
to their inability to cross the cell membrane. Existing approaches
for cytosolic delivery of functional antibodies are available, but
they are constantly plagued by the need for chemical/genetic modifications,
low delivery efficiency, and severe endolysosomal trapping. Consequently,
it is of paramount importance to develop new strategies capable of
highly efficient cytosolic delivery of native antibodies with immediate
bioavailability. Herein, we report a modification-free, convenient
“mix-and-go” strategy for the cytosolic delivery of
native antibodies to different live mammalian cells efficiently, with
minimal endolysosomal trapping and immediate bioavailability. By simply
mixing a cell-permeant bioadaptor (derived from protein A or TRIM21)
with a commercially available off-the-shelf antibody, the resulting
noncovalent complex could be immediately used for intracellular delivery
of native antibodies needed in subsequent cytosolic target engagement.
The versatility of this approach was successfully illustrated in a
number of applications, including antibody-based, live-cell imaging
of the endogenous protein glutathionylation to detect oxidative cell
stress, antibody-based activation of endogenous caspase-3, and inhibition
of endogenous PTP1B activity, and finally TRIM21-mediated endogenous
protein degradation for potential targeted therapy. Our results thus
indicate this newly developed, “mix-and-go” antibody
delivery method should have broad applications in chemical biology
and future drug discovery.
As a powerful tool to advance drug discovery, molecular imaging may provide new insights into the process of drug effect and therapy at cellular and molecular levels. When compared with other detection methods, fluorescence-based strategies are highly attractive and can be used to illuminate pathways of drugs’ transport, with multi-color capacity, high specificity and good sensitivity. The conjugates of fluorescent molecules and therapeutic agents create exciting avenues for real-time monitoring of drug delivery and distribution, both in vitro and in vivo. In this short review, we discuss recent developments of small molecule-based fluorophore-drug conjugates, including non-cleavable and cleavable ones, that are capable of visualizing drug delivery.
Nitroreductase (NTR), one of the flavin-dependent enzymes and an upregulated enzyme under tumor hypoxia, has been studied for decades. Many fluorescent probes were developed to detect NTR activity; however, these probes tend to diffuse away from their reaction site (NTR) inevitably, leading to inappropriate sample fixation, lower accuracy of NTR localization, and weaker signal-to-noise ratio. Herein, we present the design, synthesis, in vitro evaluation, and biological applications of an NTRactivatable fluorogenic and labeling probe FY. By integrating with quinone methide (QM) proximity-based protein labeling, the additional fluoromethyl group on FY serves as a potential origin of QM. Compared with conventional fluorescent probes, this new NTR probe not only offers mitochondrial localizable and fluorogenic response but also achieves permanent retention on the site of activation with an enhanced spatial resolution to improve the detection sensitivity even after cell fixation. We believe our work could offer an expandable synthetic approach to develop these permanent labeling and imaging fluorescence probes for deciphering complex biological events.
Monitoring gene delivery has significant benefits in gene therapy. Herein, we reported a nanoquencher system by doping a FRET pair during nucleic acid-assisted cell penetrating poly(disulfide)s (CPDs) formation. Our results...
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