Spatio-Temporally Reporting Dose-Dependent Chemotherapy via Uniting Dual-Modal MRI/NIR Imaging

Article abstract of DOI:10.1002/anie.202009380

Unpredictable in vivo therapeutic feedback of hydroxyl radical (^.OH) efficiency is the major bottleneck of chemodynamic therapy. Herein, we describe novel Fenton-based nanotheranostics NQ-Cy?Fe&GOD for spatio-temporally reporting intratumor

Full text of DOI:10.1002/anie.202009380

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Accepted Article
Title: Spatio-Temporally Reporting Dose-Dependent Chemotherapy via
Uniting Dual-Modal MRI/NIR Imaging
Authors: Yiyu Ma, Chenxu Yan, Zhiqian Guo, Guang Tan, Dechao Niu,
Yongsheng Li, and Wei-Hong Zhu
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To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.202009380
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10.1002/anie.202009380
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RESEARCH ARTICLE
Spatio-Temporally Reporting Dose-Dependent Chemotherapy via
Uniting Dual-Modal MRI/NIR Imaging
Yiyu Ma,† Chenxu Yan,† Zhiqian Guo,* Guang Tan, Dechao Niu, Yongsheng Li, and Wei-Hong Zhu
Y. Ma, Dr. C. Yan, G. Tan, Prof. Dr. Z. Guo, and Prof. Dr. W-H. Zhu
Key Laboratory for Advanced Materials and Institute of Fine Chemicals
Joint International Research Laboratory of Precision Chemistry and Molecular Engineering
Feringa Nobel Prize Scientist Joint Research Center
Frontiers Science Center for Materiobiology and Dynamic Chemistry
School of Chemistry and Molecular Engineering
East China University of Science and Technology, Shanghai 200237 (China)
E-mail: guozq@ecust.edu.cn
Dr. D. Niu, and Prof. Dr. Y. Li
Key Laboratory for Ultrafine Materials of Ministry of Education
School of Materials Science and Engineering
East China University of Science & Technology, Shanghai 200237 (China)
†These authors contributed equally to this work.
Supporting information for this article is given via a link at the end of the document.
Abstract: Unpredictable in vivo therapeutic feedback of hydroxyl
radical (•OH) efficiency is the major bottleneck of chemodynamic
therapy. Herein, we describe novel Fenton-based nanotheranostics
NQ-Cy@Fe&GOD for spatio-temporally reporting intratumor •OH-
mediated treatment, which innovatively unites dual-channel near-
infrared (NIR) fluorescence and magnetic resonance imaging (MRI)
signals. Specifically, MRI signal traces the dose distribution of Fenton-
based iron oxide nanoparticles (IONPs) with high-spatial resolution,
meanwhile timely fluorescence signal quantifies •OH-mediated
therapeutic response with high spatio-temporal resolution. NQ-
Cy@Fe&GOD can successfully monitor the intracellular release of
IONPs and •OH-induced NQO1 enzyme in living cells and tumor-
bearing mice, which makes a breakthrough in conquering the inherent
However, this unpredictable dose-dependent •OH generation
causes abusive doses, thus inevitably leading to undesired side
effect on normal tissues.[6] Therefore, it is an urgent demand
towards such nanotheranostics for in vivo monitoring dose-
dependent therapeutic effects, and synegestically in situ real-time
evaluating and initiating the intratumoral catalytic Fenton reaction.
The spatio-temporal quantification of therapeutic feedback has
a critical effect on the outcome. But the intrinsic short lifetime
and high-reactivity of •OH makes it extremely difficult to trace
and monitor therapeutic performance.[7] In general, magnetic
resonance imaging (MRI) modality is suitable for tracing in vivo
distribution with high spatial resolution, but the lack of the
capability to timely assessment of •OH.[8] Despite significant
advances in fluorescence imaging, it still faces tough hurdles to
establish the in vivo temporal behaviors and concurrently
overcome the self-consumption of •OH.[9] Notably, according to
Keap1-Nrf2 pathway regulation, the expression of NQO1 enzyme
has a direct correlation with the •OH level.[10] Given these
considerations, we envisioned that dual-channel fluorescence
imaging would open a new route to scrutinize the •OH level
without blind spot via sensing NQO1.[11] To overcome the barriers
in uniting spatio-temporal resolution of therapeutic feedback, the
dual-modal MRI/near-infrared (NIR) imaging would be an optimal
strategy, wherein MRI offers detailed dose distribution, and NIR
fluorescence imaging performs for in vivo timely behaviors.[12]
Unfortunately, to date the dilemma between spatial and temporal
resolution of bridging dual-modal MRI/NIR imaging has not yet
been well addressed.
unpredictable
obstacles
on
spatio-temporally
reporting
chemodynamic therapy, so as to manipulate dose-dependent
therapeutic process. This unprecedented strategy can elaborately
bridge MRI and fluorescence imaging modality with spatio-temporal
resolution, and paves a new pathway for accurately evaluating in situ
generation of •OH feedback on the intratumoral catalytic Fenton
reaction.
Introduction
In situ triggering intratumoral generation of reactive oxygen
species (ROS) has emerged as a promising and tumor-specific
treatment paradigm with minimized side effects.[1] Hydroxyl
radical (•OH), as the most powerful oxidant among ROS, is central
to initiate cancer cell death and tissue damages in the ROS-
mediated therapeutic modality.[2] In particular, chemodynamic
therapy (CDT) that catalyzes intratumoral Fenton or Fenton-like
chemical reaction for in situ •OH generation is high desirably for
the concurrent efficacy and specificity of therapy.[3] However, the
CDT strategy is substantially hindered by unsatisfactory in vivo
catalytic efficiency, especially in difficult prediction under the
requirement of rigorous conditions for Fenton reaction-generated
•OH species.[4] To combat these intractable obstacles, nowadays
approaches primarily focus on increasing doses of Fenton agents
or/and H2O2 for the sufficient conversion into •OH radicals.[5]
Herein, we have described, for the first time, an appealing
paradigm of spatio-temporal feedback on intratumor
chemodynamic therapy, which innovatively unites MRI/dual-
channel NIR imaging, and consequently guarantees optimal
therapeutic treatment. This nanotheranostics, termed as NQ-
Cy@Fe&GOD, is engineered by encapsulating dual-channel
fluorescent probe NQ-Cy and iron oxide nanoparticles (IONPs)
with glucose oxidase (GOD), co- loading into the hydrophobic
inner cavity of amphiphilic copolymer DSPE-PEG-FA (Figure 1).
In detail, the MRI signal from IONPs could trace the dose
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Figure 1. Tumor-specific nanotheranostics NQ-Cy@Fe&GOD for in situ real-time reporting of Fenton-based dose-dependent ꞏOH generation: i)
Owing to the passive and active targeting ability, NQ-Cy@Fe&GOD are delivered into tumor sites, along with the enhanced MRI signal; ii) Turn-on NIR
fluorescence signal at 830 nm (NIR-1) is observed in synchronous with its intracellular dissociation for evaluating the released dose of Fenton agents.
Concurrently, the released GOD catalyses glucose to produce H2O2; iii) Subsequently, high-level •OH is generated by IONPs-based Fenton reaction with
intratumor H2O2, thereby triggering the activation of Keap1-Nrf2 pathway for high-level overexpression of NQO1 enzyme, which is timely supervised by a new
emission at 650 nm (NIR-2). Overall, this nanocomposite bridges dual-channel NIR imaging and MRI modality, thereby uniting spatial and temporal resolution
on dose-dependent •OH therapeutic feedback.
distribution of NQ-Cy@Fe&GOD. When targeted delivery into
cancer cells, a turn-on NIR fluorescent enhancement at 830 nm
(NIR-1) is observed from its disassembly. Then, the GOD-release
Results and Discussion
initiates the oxidation reaction to in situ produce large amount of
H2O2. Subsequently, the intratumor •OH generation from H2O2 is
catalyzed by IONPs-based Fenton reaction, thereby triggering
with oxidative stress for the remarkable overexpress of NQO1
enzyme, which is timely supervised by another channel emission
of NQ-Cy at 650 nm (NIR-2) (Figure 2A). Importantly, this Fenton-
based nanocomposite can elaborately bridge MRI and dual-
channel NIR fluorescence imaging, and achieve several
characteristics, such as mapping its dose distribution by MRI
signal, monitoring •OH generation via dual-channel fluorescent
signal without blind spot, and obtaining timely feedback from
catalytic intratumoral Fenton reaction. In this regard, we provide
an appealing paradigm to unite spatial and temporal resolution
feedback on chemodynamic therapy, precisely manipulating and
reporting dose-dependent therapeutic process.
Design of Nanotheranostics with Dose-Dependent MRI
Signal
Owing to higher saturation magnetization and portable synthesis,
IONPs are frequently employed as MRI agents for diagnosis.
Firstly, for achieving high accumulation in tumors, we chose
amphiphilic block copolymer DSPE-PEG-FA with biotin-targeted
unit as nanocarrier (Figure 1).[13] According to the coprecipitation
protocol, the dissolved mixture of IONPs, NQ-Cy, and DSPE-
PEG-FA in tetrahydrofuran (THF) were added dropwise into the
water-soluble GOD enzyme solution. Then, the THF and
unloaded agent were removed via dialysis to obtain NQ-
Cy@Fe&GOD nanoparticles. Besides, as the controls, we also
constructed NQ-Cy@PEG (only NQ-Cy loaded), NQ-Cy@GOD
(NQ-Cy and GOD co-loaded) and NQ-Cy@Fe (NQ-Cy and IONPs
co-loaded) nanoparticles (Figure S1 and Table S1). From the
dynamic light scattering (DLS) test, NQ-Cy@Fe&GOD displayed
uniform size 68 nm (Figure 2B).[14] Notably, NQ-Cy@Fe&GOD
showed only subtle dimensional changes in culture medium
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(DMEM, Dulbecco's modified eagle medium) within 72 h,
suggestive that our designed NQ-Cy@Fe&GOD possessed well-
controlled, uniform and bio-stable nanostructures.
The ratio of signal intensity in T1 and T2-weighted MRI contrast
agent could enhance the sensitivity of detection. Subsequently,
NQ-Cy@Fe&GOD with different IONPs contents were carried out
in aqueous medium, which displayed T2 and T1-weighted MRI
contrast.[16] Then, the longitudinal (T1, rt1 = 2.19 mM-1 s-1) and
transverse (T2, rt2 = 62.8 mM-1 s-1) relaxivities of NQ-Cy
@Fe&GOD was measured, respectively (Figure 2D). The
reciprocal values of relaxation times were plotted as a function of
iron concentration. Impressively, the rt2/rt1 ratio of NQ-Cy
@Fe&GOD was calculated as 28.7, indicating it as an excellent
T2-dominated MRI contrast agent. More importantly, the plot of
1/T2 against concentrations of Fenton agents (ranging from 0.2 to
1.0 mM) displayed an excellent linear relationship (R2 = 0.995).
This linear curve of the 1/T2 (Figure 2D) indicated that NQ-Cy
@Fe&GOD allows for quantitatively mapping its dosage
distribution by using MRI signal intensity.
signal enhancement in
a concentration-dependent manner
(Figure 2C). In fact, the rt2/rt1 ratio is an important factor to predict
whether a given contrast agent is either T1 or T2-dominated MRI
contrast.[15] In detail, high rt2/rt1 ratio (>8) results in T2-dominated
contrast, while low rt2/rt1 ratio (<5) leads to T1-dominated
Figure 2. Magnetic signals, and dual-channel fluorescence response of NQ-Cy@Fe&GOD. (A) Sensing mechanism of NQ-Cy towards NQO1, along with
a remarkable fluorescent shift from 830 to 650 nm. (B) The bio-stablity of NQ-Cy@Fe&GOD in DMEM. (C) T2 and T1-Weighted MRI images of NQ-
Cy@Fe&GOD at various ferrous ion concentrations. (D) T2 (1/T2) and T1 (1/T1) relaxation rates as a function of the IONPs in nanoparticles. (E) Fluorescence
spectra of NQ-Cy@Fe&GOD in aqueous solution with different THF fraction (λex = 740 nm). (F) Hydrodynamic diameters of NQ-Cy@Fe&GOD at THF (green
bars) or pure water (blue bars). Absorption (G) and fluorescence spectra (H, λex = 740 nm; I, λex = 550 nm) of NQ-Cy (2 μM) to various concentrations of NQO1
enzyme (0-20 U) and NADH (500 μM) in PBS buffer (pH = 7.4) with 0.007% bovine serum albumin (BSA) at 37 oC. (J) The normalized emission spectra of
NQ-Cy (2 μM) was recorded over time in the presence of NQO1 enzyme (each point was recorded after exposure to 5U NQO1, NADH, and BSA at 37 oC in
PBS buffer solution).
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Bridging between Release of IONPs and Detection of NQO1
Enzyme via Dual-Channel NIR Fluorescence Signal
of NQ-Cy@Fe&GOD. With the increasing fraction of THF, NQ-Cy
@Fe&GOD became into a dissociated state and displayed a
sharp decrease in size from ca. 68 to 9.6 nm, indicating the total
release of IONPs (100% release, Figure 2F and Figure S4).
Concurrently, as shown in Figure 2E, the emission at 830 nm was
gradually increased. These results clearly indicated that the
distribution of MRI is in synchronism from the release of IONPs,
which could be monitored by fluorescence signals at 830 nm
(NIR-1).
As well known, high-level of •OH could efficiently induce the
expression of NQO1 enzyme so that makes it possible to timely
assess •OH generation with the evaluation of NQO1 levels.
Attaching a trimethyl-locked quinone propionic acid as an
activatable trigger group in Figure 2A, probe NQ-Cy was rationally
designed for the detection of NQO1 enzyme, thus leading to an
obvious wavelength-shift in both absorption and emission spectra.
We investigated the NQO1-driven wavelength shift from 830 nm
(NIR-1) to 650 nm (NIR-2). As shown in Figure 2G, upon the
To overcome the hurdles of uniting spatio-temporal resolution, the
key issue is how to bridge dual-modal NIR fluorescence imaging
with MRI signal from IONPs. It is highly desirable that the detailed
distribution of MRI signal from the release of IONPs is in
synchronism with fluorescence response. Herein, dual-channel
NIR fluorescence response of NQ-Cy@Fe&GOD with NQO1
enzyme makes it possible to bridge MRI signal with fluorescence
response for tracing in vivo behaviors. In Figure 2E, due to the
aggregation of probe NQ-Cy in the hydrophobic inner core, NQ-
Cy@Fe&GOD displayed non-emissive signal at its initial state
(indicating 0% release of IONPs). We obtained the compact
nanoparticles with uniform size and enough stability. Indeed, this
aggregation-caused quenching (ACQ) phenomenon was further
confirmed with the increasing concentration of NQ-Cy (Figure S2
and S3).[17] To assess fluorescent response during the unloading
behavior, we added organic solvent THF into an aqueous solution
Figure 3. Dual-channel fluorescence response for monitoring the release of IONPs and Fenton synergistic treatment. Dual-channel confocal images
of NQ-Cy (incubated for 60 min at 37 °C) in normal cells QSG-7701 (A), cancer cells A549 pre-treated without (B) and with (C) the inhibitor of NQO1 enzyme.
Dual-channel confocal images of A549 cells incubated with NQ-Cy@PEG (D) and NQ-Cy@Fe&GOD (E). Note: NIR-1 channel: the green signal (λex = 740
nm, λem = 830 nm) indicates the fluorescence from free NQ-Cy; NIR-2 channel: the red signal (λex = 550 nm, λem = 650 nm) indicates NQO1-triggered response.
(F) Relative dual-channel fluorescence intensity in cell imaging experiments. (G) Time dependent dual-channel fluorescence intensity in A549 cells incubated
with NQ-Cy@Fe&GOD. (H) Cell viability of A549 cells using a MTT assay, incubated with various concentrations (0-8 µM) of NQ-Cy@PEG, NQ-Cy@GOD,
NQ-Cy@Fe and NQ-Cy@Fe&GOD for 24 h (the concentration is in terms of NQ-Cy). Data were shown as mean ± s.d., n = 3.
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addition of NQO1 enzyme, the initial absorption at 740 nm was
decreased, while a new band centered at 550 nm was found,
along with an obvious color change. Concomitantly, a remarkable
hypochromic shift was observed in the emission spectra. That is,
the NIR fluorescence at 830 nm was completely quenched (Figure
2H), accompanying with a significant enhancement emission at
650 nm (Figure 2I). It took within 90 min to reach the equilibrium
(Figure 2J). The sensing mechanism of dual-channel
fluorescence response of probe NQ-Cy with NQO1 enzyme
further confirmed by high-resolution mass spectrometry (Figure
S5). Taken together, for NQ-Cy@Fe&GOD, the light-up NIR-1
signal derived from its dissociation was in synchronism with the
dose distribution of MRI signal, and the new emission NIR-2
signal induced by NQO1 enzyme was employed for timely and
quantitatively monitoring •OH generation. Notably, it makes a
breakthrough in achieving spatio-temporal resolution of feedback
by elaborately bridging between the MRI signal from the released
IONPs and the •OH-mediated timely fluorescent signal.
nm (NIR-1). Furthermore, after incubated A549 cells with
dicoumarol (the inhibitor of NQO1 enzyme), we only observed
with the NIR-1 signal of NQ-Cy (Figure 3C), the similar response
as in normal QSG-7701 cells, confirming the role of the
endogenous NQO1 enzyme. These dual-channel fluorescence
responses of NQ-Cy (Figure 3F) were consistent with their cellular
NQO1 levels. All these results supported that probe NQ-Cy could
be used to detect endogenous NQO1 level in living cells.
To profile the release of IOPNs for catalyzing the intracelluar
•OH-generation and thus leading to the overexpression of NQO1
enzyme, the time-dependent changes of NQ-Cy@PEG and NQ-
Cy@Fe&GOD were investigated by incubation with A549 cancer
cells (Figure 3D and 3E). Clearly, the enhancement of NQ-
Cy@Fe&GOD at 830 nm was observed during cell uptake within
30 min, while it became sharply decrease from 30 to 60 min
(Figure 3G). It could be interpreted that the initial enhancement
was owing to the dissociation of tumor-targeting nanoparticles
with the release of NQ-Cy in concomitant with IONPs, while the
subsequent decrease was attributed to the •OH-dependent level
of NQO1 enzyme, thereby the consumption of NQ-Cy (Figure 3G,
Figure S6 and S7). In contrast, the continuous enhancement of
NQ-Cy@Fe&GOD at 650 nm provided the reliable evidences for
overexpressed NQO1 generation by intracellular Fenton reaction
(Figure 3E and 3G). Clearly, the intensity of NQ-Cy@Fe&GOD at
650 nm was much higher than that of in NQ-Cy@PEG (Figure 3D
and 3E). It was also confirmed that the role of IOPNs is catalyzing
the Fenton reaction for sufficient •OH generation, and thus
triggering the intracellular overexpressed NQO1 enzyme. All
these results demonstrated that orchestrate nanotheranostics
NQ-Cy@Fe &GOD could track the release and assess
intracellular •OH-mediated production of NQO1 enzyme.
Importantly, the distinct dual-channel NIR fluorescence response
Mapping Intracellular Release of IONPs and •OH-Mediated
Chemodynamic Therapy in Living Cells
To prove the feasibility of NQ-Cy@Fe&GOD for monitoring •OH-
mediated therapy, we firstly investigated the fluorescence
response of probe NQ-Cy with endogenous NQO1 enzyme.
Herein, human lung cancer cells A549 with overexpressed NQO1
enzyme and normal liver cell QSG-7701 were chosen as model
cell lines.[18] As expected, the strong NIR-2 signal of NQ-Cy was
only observed in normal QSG-7701 cells (Figure 3A), while dual-
channel fluorescence signal of NIR-1 and NIR-2 were both found
from probe NQ-Cy incubation with A549 cells (Figure 3B). Indeed,
a high level of cellular NQO1 enzyme triggered the cleavage of
NQ-Cy (Figure 2A) to allow an obvious emission enhancement at
650 nm (NIR-2), but concomitantly weak the initial emission at 830
Figure 4. Mapping of the bio-distribution with MRI signal by intravenous injection. T1-Weighted (A and B) and T2-Weighted (C and D) MR images of
A549 xenograft tumor-bearing mice with exposure to a magnetic field at different time points after the intravenous administration of NQ-Cy@Fe&GOD at NQ-
Cy-equivalent dose of 0.2 mg kg-1. Red circles indicate the tumor sites (0 h means pre-injection). Normalized T2 signals (E) and 1/T2 (F) values at tumor site of
above in vivo MRI imaging experiments. (G) T2-weighted MR images of NQ-Cy@Fe&GOD at various ferrous ion concentrations (Intratumor injection). (H)
Standard curve of the normalized 1/T2 against concentration as a function of NQ-Cy@Fe&GOD concentration via intratumor injection. Data with error bars are
expressed as mean ± s.d., n= 3.
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Figure 5. Dual-channel NIR fluorescence imaging of NQ-Cy@Fe&GOD in vivo tracking via intravenous injection. In vivo fluorescence imaging of A549
xenograft tumor-bearing mice at various times (0, 2, 4, 8, 12 and 24 h) after the intravenous injection of NQ-Cy (A and B) and NQ-Cy@Fe&GOD (C and D)
administered at a NQ-Cy-equivalent dose of 0.2 mg kg-1. The tumor site is circled in red. Ex vivo NIR-fluorescence imaging of the excised organs (heart, liver,
spleen, lung, kidney and tumor) at 24 h after the intravenous injection of NQ-Cy (E and F) and NQ-Cy@Fe&GOD (G and H).
of NQ-Cy@Fe&GOD bridged between the release of IOPNs and
sensing NQO1 enzyme in living cells.
To simulate the early stage of tumor, mice with small-sized A549
xenograft tumor (size: 3.0 ± 0.4 mm) was chosen. As mentioned,
NQ-Cy@Fe&GOD showed an excellent T2-dominated MRI signal
in solution (Figure 2C), displaying a good linear relationship of
1/T2 against concentration. Accordingly, in contrast with T1
imaging (Figure 4A and 4B), NQ-Cy@Fe&GOD displayed much
more legible in vivo signals of T2 imaging (Figure 4C and 4D),
which was consistent with the in vitro experiments. Specifically,
its tumor site bestowed continuous enhancement of negative
contrast signal (1/T2) in 8 h, whereas no obvious signal was
observed in the kidney (Figure 4C). Notably, this excellent tumor-
targeting ability could be attributed to passive targeting from EPR
effect and active targeting mediated by folic acid unit.[19] The MRI
signal (1/T2) reached a maximum level after 12 h post-injection
(Figure 4E and 4F), then decayed slowly from 12 to 24 h (Figure
S6). Obviously, NQ-Cy@Fe&GOD has great potential as T2-
weighted MRI contrast for in vivo tracking tumor-specific
distribution.
Next, in order to quantify the negative contrast signal (1/T2)
from MRI agents, NQ-Cy@Fe&GOD were investigated via direct
intratumoral injection (Figure 4G).[20] Clearly, there was observed
from a linear correlation between the normalized 1/T2 signal and
the concentration of NQ-Cy@Fe&GOD (R2 = 0.996, Figure 4H).
Thus, this obtained calibration curve enabled to quantify in vivo
MRI signals of Fenton agents from NQ-Cy@Fe&GOD. In other
words, the concentration of intratumor Fenton agents could be
determined at each set point-of-time (Table S2). For example, by
extrapolating the calibration curve, we could calculate the
concentration of Fenton agents (102 μM) from NQ-Cy@Fe&GOD
at tumor site after 12 h post-injection. We thus demonstrated that
Impressively, nanotheranostics NQ-Cy@Fe&GOD exhibited
significant cytotoxicity than other three formulations (Figure 3H).
In contrast, NQ-Cy@PEG (without IONPs and GOD) and NQ-
Cy@Fe (with IONPs loaded) exhibited almost no cytotoxic effects
on cells with good biocompatibility (Figure 3H). Moreover, NQ-Cy
@GOD (with GOD loaded) displayed high cytotoxicity in cancer
cells, suggestive of the starvation therapy from the released GOD
enzyme. The remarkable cytotoxicity of NQ-Cy@Fe&GOD is
ascribed to two aspects: GOD catalyzes the aerobic glycolysis
and produces large amount of H2O2; the catalytic Fenton reaction
from the release of IONPs makes H2O2 to generate highly toxic
•OH. All these results indicated that intracellular •OH-mediated
therapeutic responses are completely consistent with the cell in
vivo imaging. Thus, we demonstrated that the Fenton-synergistic
treatment of NQ-Cy@Fe&GOD is real-timely profiled by •OH-
mediated therapeutic response in living cells, that is, directly
tracing the IONPs release via a light-up emission channel at 830
nm, and assessing the in situ generation of •OH via another
emission channel at 650 nm.
Uniting Spatio-temporal Resolution of Dual-Modal MRI and
NIR Imaging for Dose-dependent Therapeutic Response
Encouraged by the intracellular release of IONPs synchronous
with fluorescence response, we further investigated that dual-
modal MRI and fluorescence imaging was united for in situ
evaluating therapeutic response in mice. First of all, to evaluate
whether the high-spatial bio-distribution could be traced via MRI
signal, NQ-Cy@Fe&GOD were administered intravenously into
nude mice bearing lung cancer cell A549 subcutaneous xenograft. the in vivo MRI signals of NQ-Cy@Fe&GOD can be used to
6
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10.1002/anie.202009380
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quantitatively trace its dose distribution with high-spatial
resolution in living mice.
Importantly, our strategy unprecedently unites MRI and NIR
fluorescence imaging, making a breakthrough in conquering
unpredictable obstacles of intratumoral catalytic Fenton reaction.
It is believed that this appealing paradigm paves a new pathway
for spatiotemporally reporting dose-dependent chemodynamic
therapy.
The above promising results inspired us to further validate the
feasibility of uniting MRI and dual-channel NIR fluorescence
imaging in chemodynamic therapy. After the intravenous injection
of NQ-Cy@Fe&GOD with tumor-bearing nude mice, the in vivo
behavior of NQ-Cy@Fe&GOD was profiled by dual-channel
fluorescence signals (NIR-1, yellow-red represented at 830 nm;
NIR-2, rainbow represented at 650 nm). As shown in Figure 5A
and 5B, after 4 h post-injection of probe NQ-Cy (as a control),
almost no accumulation signal at 830 nm was observed at the
tumor site, but strong fluorescence of NIR-1 signal was found from
the liver. In contrast, the tumor bestowed significant accumulation
of NIR-1 signal after 8 h post-injection of NQ-Cy@Fe&GOD
(Figure 5C), suggestive of a well-targeting ability. Meanwhile,
strong fluorescence of NQ-Cy@Fe&GOD at 650 nm (NIR-2) was
observed (Figure 5D), resulting from the release of NQ-Cy
towards •OH-induced of overexpressed NQO1 enzyme at the
tumor site. Concurrently, there was weak fluorescence in the
other organs in Figure 5G and 5H. Accordingly, in conjunction with
the in vitro results, with the two distinct fluorescence channels,
tumor-targeting accumulation and therapy could be timely
visualized without blind spot, thus acquiring the in vivo behaviors
with high-temporal resolution (Figure 1).
Acknowledgements
This work was supported by NSFC/China (21788102, 21636002,
21622602, 21878087, and 21908060), National Key Research
and Development Program (2016YFA0200300), the Innovation
Program of Shanghai Municipal Education Commission,
Shuguang Program (18SG27), China Postdoctoral Science
Foundation (2019M651417), and Fundamental Research Funds
for the Central Universities. This study was performed in strict
accordance with the NIH guidelines for the care and use of
laboratory animals (NIH Publication No. 85-23 Rev. 1985) and
was approved by the Institutional Animal Care and Use
Committee of National Tissue Engineering Center (Shanghai,
China).
Keywords: fluorescent probe • near-infrared dual-channel •
assembly nanotheranostics • chemodynamic therapy• magnetic
resonance imaging
Most importantly, the dynamic change in fluorescence imaging
signal was synchronously bridged with the MRI signal of NQ-Cy
@Fe&GOD. Specifically, the NIR-1 signal at 830 nm indicated
that its accumulation was found at 12 h after intravenous post-
injection (Figure 5C), then slowly decayed from 12 to 24 h.
Consistently, the MRI signal (1/T2 intensity) confirmed that the
peak of tumor accumulation also occurred at 12 h (Figure 4F).
Importantly, these synchronous responses bridged between
fluorescence imaging and MRI signal, indicating when Fenton
agents were accumulated (from MRI signal) and released (NIR-1
signal from 830 nm), subsequently catalyzing in situ •OH
generation, thereby leading to high level of NQO1 enzyme (NIR-
2 signal from 650 nm) at the tumor site. Taken together, our
strategy has successfully achieved the spatio-temporal feedback
on therapeutic responses by uniting MRI and dual-channel NIR
imaging, that is, tracing the dose distribution of Fenton-based
IONPs by MRI signal, meanwhile timely quantifying •OH-
mediated dose-dependent response by NIR signal.
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RESEARCH ARTICLE
Entry for the Table of Contents
Spatio-Temporally Reporting Dose-Dependent Chemotherapy via Uniting Dual-Modal MRI/NIR
Imaging
Yiyu Ma,† Chenxu Yan,† Zhiqian Guo,* Guang Tan, Dechao Niu, Yongsheng Li, and Wei-Hong Zhu
We described a spatio-temporal feedback on the intratumoral catalytic Fenton reaction, innovatively bridging dual-modal MRI/NIR
imaging, thereby making a breakthrough in conquering inherent unpredictable barriers in chemodynamic therapy. This appealing
paradigm paves a new pathway for accurately evaluating •OH dose-dependent feedback.
9
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