10 research outputs found
ATP-Activatable Photosensitizer Enables Dual Fluorescence Imaging and Targeted Photodynamic Therapy of Tumor
Targeted delivery
of intracellular stimuli-activatable photosensitizers
(PSs) into tumor cells to achieve selective imaging and on-demand
photodynamic therapy (PDT) of tumors has provided a vital opportunity
for precise cancer diagnosis and therapy. In this paper, we report
a tumor targeting and adenosine triphosphate (ATP)-activatable nanophotosensitizer
Apt-HyNP/BHQ<sub>2</sub> by modifying hybrid micellar nanoparticles
with both nucleolin-targeting aptamer AS1411 and quencher BHQ<sub>2</sub>-labeled ATP-binding aptamer BHQ<sub>2</sub>-ATP-apt. We demonstrated
that both of the fluorescence emissions at 555 and 627 nm were quenched
by BHQ<sub>2</sub> in Apt-HyNP/BHQ<sub>2</sub>, resulting in low PDT
capacity. After selective entry into tumor cells through nucleolin-mediated
endocytosis, the high concentration of intracellular ATP could bind
to BHQ<sub>2</sub>-ATP-apt and trigger Apt-HyNP/BHQ<sub>2</sub> dissociation,
leading to turning āonā both fluorescence and PDT. The
āoffāonā fluorescence emissions at both 555 and
627 nm were successfully applied for dual color fluorescence imaging
of endogenous ATP levels and real-time monitoring of intracellular
activation of Apt-HyNP/BHQ<sub>2</sub> in tumor cells. Moreover, imaging-guided
precise PDT of tumors in living mice was also demonstrated, allowing
for selective ablation of tumors without obvious side effects. This
study highlights the potential of using a combination of tumor-targeting
and ATP-binding aptamers to design ATP-activatable PSs for both fluorescence
imaging and imaging-guided PDT of tumors in vivo
Aggregation-Induced Electrochemiluminescence from a Cyclometalated Iridium(III) Complex
Aggregation-induced
emission has been extensively found in organic compounds and metal
complexes. In contrast, aggregation-induced electrochemiluminescence
(AI-ECL) is rarely observed. Here, we employ two tridentate ligands
[2,2ā²:6ā²,2ā³-terpyridine (tpy) and 1,3-bisĀ(1<i>H</i>-benzimidazol-2-yl)Ābenzene (bbbiH<sub>3</sub>)] to construct
a cyclometalated iridiumĀ(III) complex, [IrĀ(tpy)Ā(bbbi)] (<b>1</b>), showing strong AI-ECL. Its crystal structure indicates that neighboring
[IrĀ(tpy)Ā(bbbi)] molecules are connected through both ĻāĻ-stacking
interactions and hydrogen bonds. These supramolecular interactions
can facilitate the self-assembly of complex <b>1</b> into nanoparticles
in an aqueous solution. The efficient restriction of molecular vibration
in these nanoparticles leads to strong AI-ECL emission of complex <b>1</b>. In a dimethyl sulfoxideāwater (H<sub>2</sub>O) mixture
with a gradual increase in the H<sub>2</sub>O fraction from 20% to
98%, complex <b>1</b> showed a ā¼39-fold increase in the
electrochemiluminescence (ECL) intensity, which was ā¼4.04 times
as high as that of [RuĀ(bpy)<sub>3</sub>]<sup>2+</sup> under the same
experimental conditions. Moreover, the binding of bovine serum albumin
to the nanoparticles of complex <b>1</b> can improve the ECL
emission of this complex, facilitating the understanding of the mechanism
of AI-ECL for future applications
Targeted Delivery of a Ī³āGlutamyl Transpeptidase Activatable Near-Infrared-Fluorescent Probe for Selective Cancer Imaging
The
noninvasive and specific detection of cancer cells in living
subjects has been essential for the success of cancer diagnoses and
treatments. Herein, we report a strategy of combining an Ī±<sub>v</sub>Ī²<sub>3</sub>-integrin-receptor-targetable ligand, c-RGD,
with the Ī³-glutamyl transpeptidase (GGT)-recognizable substrate,
Ī³-glutamate (Ī³-Glu), to develop a tumor-targeting and
GGT-activatable near-infrared (NIR)-fluorescent probe for the noninvasive
imaging of tumors in living mice. We demonstrated that the probeās
fluorescence was off initially, but when the Ī³-Glu in the probe
was specifically cleaved by GGT, the fluorescent product was released
and could be selectively taken up by U87MG-tumor cells via Ī±<sub>v</sub>Ī²<sub>3</sub>-receptor-mediated endocytosis. Remarkably,
enhanced intracellular NIR fluorescence distributed mainly in the
lysosomes was observed in the tumor cells only, showing that the probe
was capable of differentiating the tumor cells from the GGT-positive,
Ī±<sub>v</sub>Ī²<sub>3</sub>-deficient normal cells. Moreover,
the probe also showed a high selectivity for the real-time and noninvasive
detection of GGT activity in xenograft U87MG tumors following iv administration.
This study reveals the advantage of using a combination of receptor-mediated
cell uptake and molecular-target-triggered activation to design molecular
probes for improved cancer imaging, which could facilitate effective
cancer diagnoses
Lysosome-Targeting Fluorogenic Probe for Cathepsin B Imaging in Living Cells
Cathepsin B (CTB) is a lysosomal
protease which has been recognized
as a promising biomarker for many malignant tumors, and accurate detection
of its activity is important in early diagnosis of cancers and predicting
metastasis. Herein, we reported a lysosome-targeting fluorogenic small-molecule
probe for fluorescence imaging of lysosomal CTB in living cancer cells
by incorporating a CTB-recognitive peptide substrate Cbz-Lys-Lys-<i>p</i>-aminobenzyl alcohol (Cbz-Lys-Lys-PABA) and a lysosome
locating group morpholine. We demonstrated that the probe could be
efficiently activated by CTB to generate ā¼73-fold enhancement
in fluorescence under acidic lysosomal environment (pH 4.5ā6.0),
allowing for high sensitivity and specificity to detect CTB. Fluorescence
imaging results showed selective accumulation and fluorescence turn-on
in the lysosomes of cancer cells, which were capable of reporting
on lysosomal CTB activity in cancer cells and normal tissue cells.
This study highlights the potential of using a lysosome-targeting
group to design a sensitive and specific fluorogenic probe for fluorescence
imaging of lysosomal CTB in living cells
Surface-Roughened SERS-Active Single Silver Nanowire for Simultaneous Detection of Intracellular and Extracellular pHs
The simultaneous and accurate detection of intracellular
pH (pHi) and extracellular pH (pHe) is essential
for studying
the complex physiological activities of cancer cells and exploring
pH-related therapeutic mechanisms. Here, we developed a super-long
silver nanowire-based surface-enhanced Raman scattering (SERS) detection
strategy for simultaneous sensing of pHi and pHe. A surface-roughened silver nanowire (AgNW) with a high aspect ratio
is prepared at a nanoelectrode tip using a Cu-mediated oxidation process,
which is then modified by pH-sensitive 4-mercaptobenzoic acid (4-MBA)
to form 4-MBA@AgNW as a pH sensing probe. With the assistance of a
4D microcontroller, 4-MBA@AgNW is efficient in simultaneously detecting
pHi and pHe in both 2D and 3D culture cancer
cells by SERS, with minimal invasiveness, high sensitivity, and spatial
resolution. Further investigation proves that the surface-roughened
single AgNW can also be used in monitoring the dynamic variation of
pHi and pHe of cancer cells upon stimulation
with anticancer drugs or under a hypoxic environment
Activatable QD-Based Near-Infrared Fluorescence Probe for Sensitive Detection and Imaging of DNA
Accurate
detection of DNA is essential for the precise diagnosis of diseases.
Here we report an activatable near-infrared (NIR) fluorescence nanoprobe
(QD-Al-GFLX) composed of NIR quantum dots (QDs) and AlĀ(III)-gatifloxacin
(Al-GFLX) complexes for the sensitive detection of double-stranded
DNA (dsDNA) both in aqueous solution and in living cells. We demonstrated
that the initial strong NIR fluorescence of QDs in QD-Al-GFLX was
quenched by the Al-GFLX complex via a photoinduced electron transfer
(PET) mechanism. Upon interaction with dsDNA, the high binding affinity
between dsDNA and Al-GFLX complex could trigger QD-Al-GFLX dissociation,
which could eliminate the PET process, resulting in significant enhancement
of NIR fluorescence. QD-Al-GFLX was sensitive and specific to detect
dsDNA in aqueous solution, with a detection limit of 6.83 ng/mL. The
subsequent fluorescence imaging revealed that QD-Al-GFLX holds a high
ability to enter into live cells, generating strong NIR fluorescence
capable of reporting on dsDNA levels. This study highlighted the potential
of using QD-Al-GFLX nanoprobe for the real-time detection and imaging
of dsDNA in living cells
Surface-Roughened SERS-Active Single Silver Nanowire for Simultaneous Detection of Intracellular and Extracellular pHs
The simultaneous and accurate detection of intracellular
pH (pHi) and extracellular pH (pHe) is essential
for studying
the complex physiological activities of cancer cells and exploring
pH-related therapeutic mechanisms. Here, we developed a super-long
silver nanowire-based surface-enhanced Raman scattering (SERS) detection
strategy for simultaneous sensing of pHi and pHe. A surface-roughened silver nanowire (AgNW) with a high aspect ratio
is prepared at a nanoelectrode tip using a Cu-mediated oxidation process,
which is then modified by pH-sensitive 4-mercaptobenzoic acid (4-MBA)
to form 4-MBA@AgNW as a pH sensing probe. With the assistance of a
4D microcontroller, 4-MBA@AgNW is efficient in simultaneously detecting
pHi and pHe in both 2D and 3D culture cancer
cells by SERS, with minimal invasiveness, high sensitivity, and spatial
resolution. Further investigation proves that the surface-roughened
single AgNW can also be used in monitoring the dynamic variation of
pHi and pHe of cancer cells upon stimulation
with anticancer drugs or under a hypoxic environment
Surface-Roughened SERS-Active Single Silver Nanowire for Simultaneous Detection of Intracellular and Extracellular pHs
The simultaneous and accurate detection of intracellular
pH (pHi) and extracellular pH (pHe) is essential
for studying
the complex physiological activities of cancer cells and exploring
pH-related therapeutic mechanisms. Here, we developed a super-long
silver nanowire-based surface-enhanced Raman scattering (SERS) detection
strategy for simultaneous sensing of pHi and pHe. A surface-roughened silver nanowire (AgNW) with a high aspect ratio
is prepared at a nanoelectrode tip using a Cu-mediated oxidation process,
which is then modified by pH-sensitive 4-mercaptobenzoic acid (4-MBA)
to form 4-MBA@AgNW as a pH sensing probe. With the assistance of a
4D microcontroller, 4-MBA@AgNW is efficient in simultaneously detecting
pHi and pHe in both 2D and 3D culture cancer
cells by SERS, with minimal invasiveness, high sensitivity, and spatial
resolution. Further investigation proves that the surface-roughened
single AgNW can also be used in monitoring the dynamic variation of
pHi and pHe of cancer cells upon stimulation
with anticancer drugs or under a hypoxic environment
Magnetic Resonance Imaging of Stem Cell Apoptosis in Arthritic Joints with a Caspase Activatable Contrast Agent
About 43 million individuals in the U.S. encounter cartilage injuries due to trauma or osteoarthritis, leading to joint pain and functional disability. Matrix-associated stem cell implants (MASI) represent a promising approach for repair of cartilage defects. However, limited survival of MASI creates a significant bottleneck for successful cartilage regeneration outcomes and functional reconstitution. We report an approach for noninvasive detection of stem cell apoptosis with magnetic resonance imaging (MRI), based on a caspase-3-sensitive nanoaggregation MRI probe (C-SNAM). C-SNAM self-assembles into nanoparticles after hydrolysis by caspase-3, leading to 90% amplification of <sup>1</sup>H MR signal and prolonged <i>in vivo</i> retention. Following intra-articular injection, C-SNAM causes significant MR signal enhancement in apoptotic MASI compared to viable MASI. Our results indicate that C-SNAM functions as an imaging probe for stem cell apoptosis in MASI. This concept could be applied to a broad range of cell transplants and target sites
Redox-Mediated Disassembly to Build Activatable Trimodal Probe for Molecular Imaging of Biothiols
Activatable
multimodal probes that show enhancement of multiplex
imaging signals upon interaction with their specific molecular target
have become powerful tools for rapid and precise imaging of biological
processes. Herein, we report a stimuli-responsive disassembly approach
to construct a redox-activatable fluorescence/<sup>19</sup>F-MRS/<sup>1</sup>H-MRI triple-functional probe <b>1</b>. The small molecule
probe <b>1</b> itself has a high propensity to self-assemble
into nanoparticles with quenched fluorescence, attenuated <sup>19</sup>F-MRS signal, and high <sup>1</sup>H-MRI contrast. Biothiols that
are abundant in reducing biological environment were able to cleave
the disulfide bond in probe <b>1</b> to induce disassembly of
the nanoparticles and lead to fluorescence activation (ā¼70-fold), <sup>19</sup>F-MRS signal amplification (ā¼30-fold) and significant <i>r</i><sub>1</sub> relaxivity reduction (ā¼68% at 0.5 T).
Molecular imaging of reducing environment in live cells and <i>in vivo</i> was realized using probe <b>1</b>. This approach
could facilitate the development of other stimuli-responsive trimodal
probes for molecular imaging