Skip to main content
NCBI home page
ACS Omega logoLink to ACS Omega
. 2026 Feb 2;11(6):9538–9546. doi: 10.1021/acsomega.5c09631

H2O2‑Responsive Organic Small-Molecule MRI Probes for Acute Kidney Injury Imaging and Detection

Rulong Chen †,‡, Shangpo Yang §,⊥, Duyang Gao §, Jiating Chen †,‡, Jinxin Zhang †,‡, Jiahui Chen †, Tingfei Xie †,‡, Yunpeng Xu †, Xiaolu Sui †, Yanzi Zhang †, Xuechuan Hong #, Zonghai Sheng §,∥, Pengfei Zhang ‡,*, Jihong Chen †,*
PMCID: PMC12917809  PMID: 41726681

Abstract

Magnetic resonance imaging (MRI) has high temporal and spatial resolution without exposing patients to radiation, which shows great potential for acute kidney injury (AKI) detection. Typically, MRI uses gadolinium-based contrast agents to increase local signal intensity by distinguishing tissues or organs that are magnetically similar but histologically distinct, which might induce nephrotoxicity risks. In this work, we explored the potential application of easily available nitroxide-based organic radicals as an intravenously injectable MRI contrast agent. Different from the traditional accumulation-based MRI contrast agents, these organic radicals showed redox-responsive turn-off MRI signals to urinary hydrogen peroxide (H2O2) with ultrafast renal-clearable ability, which provides a new approach to design reaction-based small molecular organic MRI contrast agents for redox-related diagnostic applications.

graphic file with name ao5c09631_0007.jpg

graphic file with name ao5c09631_0005.jpg

1. Introduction

H2O2 is a pivotal redox signaling molecule in vivo, essential for regulating diverse physiological processes. As a redox mediator, H2O2 is produced enzymatically by NOX/SOD, and governs fundamental physiological processes such as proliferation and apoptosis, through dynamic regulation of MAPK, NF-κB, and PI3K/Akt signaling. , Dysregulation of H2O2 metabolism has been identified as a central feature in the pathogenesis of major disorders, including acute kidney injury (AKI), neurodegenerative diseases, diabetes, and cancer. The biological functions of H2O2 are inherently concentration-dependent. At physiological levels, it functions as a second messenger, promoting cell survival and adaptive responses. For instance, low concentration of H2O2 has been shown to activate antioxidant pathways via p53 SUMOylation, thereby enhancing cellular defense mechanisms. Conversely, pathological accumulation of H2O2 has been demonstrated to trigger oxidative stress, leading to DNA damage, lipid peroxidation, and mitochondrial dysfunction through Fenton reactions. In AKI, elevated H2O2 activates NF-κB via IκB kinase (IKK), exacerbating inflammation and tubular damage. In the context of cancer, H2O2 has been observed to promote tumor progression by stimulating angiogenesis, and even to induce cytotoxic apoptosis. Consequently, the capacity to swiftly detect H2O2 within the human body is paramount for the advancement of targeted therapeutic interventions for redox-related diseases, such as AKI.

Various technologies have been developed for the sensitive detection of H2O2 in a variety of biological and clinical contexts, including electrochemical sensors capable of quantitative detection at submicromolar sensitivity levels, colorimetric methods suitable for visual analysis of food and environmental samples, chemiluminescence technology that does not require external excitation, and the most common fluorescence detection technology. − Although various fluorescent probes have been developed for real-time imaging and detection of H2O2 in animal models and clinical samples. − Their further application on biomedical imaging for large animal models or human remains challenge due to the collective limitations of insufficient tissue penetration for deep-organ monitoring, invasive sampling requirements that disrupt physiological H2O2 dynamics, and the inability to perform continuous quantification in deep tissues like kidneys.As for AKI imaging, a recent review comprehensively summarized the progress in molecular probes, such as renal-clearable and NIR-II fluorescent agents; however, the development of organic small-molecule probes for noninvasive magnetic resonance imaging (MRI) detection remains less explored.

Due to its superior soft tissue contrast and nonionizing nature, magnetic resonance imaging (MRI) has become a noninvasive modality of paramount importance in clinical diagnosis, with extensive applications across various medical domains. The utilization of contrast agents in magnetic resonance imaging (MRI) is of paramount importance. This method enables the clear differentiation of vascular structures from adjacent tissues, thus improving the accuracy of diagnosis and delineation of vascular pathologies and other anomalies. The potential for MRI to detect important metabolites in biological processes has been demonstrated, with glutathione, nitric oxide, glucose, and calcium ions being notable examples. − In recent years, there has been a notable increase in research interest in the exploration of organic materials for MRI. The utilization of these materials provides distinct advantages over conventional metal-based contrast agents, including reduced toxicity and enhanced biocompatibility. − Despite the wide range of applications of organic magnetic materials in MRI for the diagnosis of conditions such as cancer and inflammation, there is a clear lack of their use in renal diseases.

In this work, we explored the potential of one of the nitroxide-based stable organic radicals, 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (CTPO), as a small-molecule MRI probe for noninvasive diagnosis of AKI (Figure ). Its specific purpose is to leverage the H2O2 responsive property of the agent to enable in vivo detection of renal oxidative stress through dynamic T 1-weighted MRI, exploiting its bladder accumulation to reveal significantly reduced contrast enhancement in AKI mice compared to healthy or N-acetylcysteine (NAC)-treated counterparts. Besides, in vitro diagnosis via urine relaxometry, capitalizing on elevated urinary H2O2 levels in AKI patients to induce a quantifiable decrease in the agent’s relaxivity. By providing this dual diagnostic modality and demonstrating its nonmetallic nature and favorable safety profile, this work seeks to offer a practical tool for the sensitive and early detection of AKI based on its fundamental redox imbalance pathology.

1.

1

Open in a new tab

Dual-mode AKI detection via an H2O2-responsive organic radical CTPO.

2. Materials and Methods

2.1. Materials

3-Carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (CTPO) and N,N′-diacetyl-l-Cystine (NAC) were purchased from Bide Pharmatech (St. Shanghai, China) and used as received. Cisplatin was obtained from Shanghai Seebio Biotech, Inc. (Shanghai, China). Regenerated cellulose dialysis membranes (molecular weight cutoff 8,000–14,000) were acquired from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). Male BALB/c mice, aged 6 weeks, were obtained from Vital River Laboratory Animal Technology Co., Ltd. (Beijing, China). All animal experimental protocols were approved by the Experimental Animal Ethics Committee of Shenzhen University Medical School (approval number: A20250039). Investigator Rulong Chen was approved by the Ethics Committee of The Second Affiliated Hospital of Shenzhen University (approval number: 20241114055).

2.2. EPR Spectroscopy of Radicals

The EPR spectra of Gd-DOTA and CTPO were acquired using an EPR spectrometer (Bruker EMXplus, Germany) operating at X-band frequency (∼9.85 GHz). For analysis, samples were prepared by dissolving CTPO in phosphate-buffered saline (PBS, pH 7.4) to a final concentration of 0.1 mM. Aliquots (50 μL) were loaded into quartz capillaries (inner diameter 1.0 mm), and measurements were performed at room temperature with the following parameters: microwave power 20 mW, modulation amplitude 1.0 G, modulation frequency 100 kHz, sweep width 100 G, and a scan rate of 5 G/s. Each spectrum was averaged over 5 scans to enhance signal-to-noise ratio. Spectral simulations and g-factor calculations were conducted using Bruker Xenon software (version 1.2) to confirm the presence of unpaired electrons and evaluate the stability of radicals.

2.3. Relaxivity Measurement

For the relaxivity measurements, different concentrations of Gd-DOTA and CTPO (from 0.15 to 20 mM) were prepared. 3T NMR-analyzer (GY-PNMR-10) was used to measure the T 1 relaxivities. The T 1-weighted images were acquired with spin echo acquisition (echo time [TE] = 8.6 ms, repetition time [TR] = 100 ms). Relaxivity values (r1) were determined from the curve fitting of 1/T 1 relaxation time (s–1) versus the concentration of radical.

2.4. Urine Reactivity and MRI Contrast Assessment

Urine samples from clinical samples from AKI patients (n = 6) and healthy volunteers (n = 6), were centrifuged (3,000 × g, 10 min) to remove cellular debris. CTPO (10 mM in PBS, pH 7.4) was incubated with urine at 37 °C for 10–60 min. Control groups included Gd-DOTA (1 mM) and untreated urine. MRI was performed on a 3.0 T scanner using a 3D fast spin–echo sequence (TE/TR = 15/800 ms).

2.5. In Vivo MRI

The contrast enhancement of Gd-DOTA and CTPO was investigated in BALB/c mice with KB xenografts. All animal procedures were approved by the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, in accordance with the ethical guidelines of the Animal Committee, and were compliant with the principles of animal protection, welfare, and ethics. Male BALB/c mice weighing 21–24 g were used in this study. Each experimental group consisted of six BALB/c mice (n = 6). Animals were randomly assigned to healthy control, AKI model, and NAC treated groups. MRI image analysis was performed independently by two researchers blinded to group allocation. Data are presented as mean ± standard deviation (SD). Statistical comparisons were performed using one way ANOVA followed by Tukey’s post hoc test in GraphPad Prism 9.0, a P value <0.05 was considered statistically significant. AKI models were established by administering an intraperitoneal injection of cisplatin (20 mg/kg body weight) to the BALB/c mice. For the control group, an equivalent volume of normal saline was injected. The AKI mice were divided into three groups, 3 mice per group. The first group was treated with radical (20 mg/kg), the second group was treated with CTPO (20 mg/kg), and the third group was treated with PBS. Afterward, the BALB/c mice were transferred and fixed into an animal handing system coupled with micromouse RF probe (Bruker, Germany), then they were inserted into the gradient system in the 3T microimaging system. During image acquisition, the mice were monitored by a life monitoring facility. In vivo T 1-weighted images (spin echo) were acquired with the following parameters: TR/TE = 500/5.7 ms, RARE factor = 4, number of average = 8, FOV = 2.8 × 2.8 cm², matrix = 128 × 128 with slice thickness of 0.5 mm. The total acquisition time was about 11 min. Scans were completed 5 h after injection of Gd-DOTA and CTPO, as described above. In order to make the contrast of different images comparable, Gd-DOTA and CTPO dose was 20 mg/kg and the sequence parameters TE and TR were kept the same for all animal scans. Meanwhile, water was used as a reference sample in the in vivo MRI experiments, and the intensity of pure water is defined as 1.00, then the intensity of the ROI (region of interest) tumor regions in the T 1-weighted images can be normalized.

2.6. Tissue Staining

Heart, liver, spleen, lung, and kidney tissues from CTPO-treated and control mice (n = 10 per group) were harvested 24 h postinjection, fixed in 10% neutral buffered formalin, and embedded in paraffin. Sections (4 μm thick) were stained with hematoxylin and eosin (H&E) using standard protocols. Additionally, PAS and Masson’s trichrome staining were performed on kidney tissue. Briefly, deparaffinized slides were immersed in hematoxylin (Sigma-Aldrich) for 5 min, differentiated in 1% acid ethanol, counterstained with eosin (0.5% aqueous solution), and mounted with resin. Histopathological evaluation (necrosis, inflammatory infiltration) was performed blindly by two pathologists using an Olympus BX53 microscope (200× magnification). Quantitative analysis of lesion areas was conducted with ImageJ.

2.7. Serum Biochemical Indicator Tests

Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea (UREA), and creatinine (CREA) were measured in control and CTPO (n = 5) using commercial ELISA kits. Blood samples were collected via retro-orbital puncture 24 h postinjection, allowed to clot at 4 °C for 30 min, and centrifuged (3,000 × g, 10 min) to isolate serum. Serum was diluted 1:10 with assay buffer, loaded onto precoated plates, and incubated with detection antibodies (37 °C, 60 min). Absorbance was measured at 450 nm (ALT/AST) and 520 nm (UREA/CREA) using a microplate reader.

2.8. Urinary Hydrogen Peroxide Detective

Urinary hydrogen peroxide (H2O2) levels in clinical samples from AKI patients (n = 6) and healthy volunteers (n = 6) were quantified using a commercial H2O2 assay kit (Abcam, ab234046). Briefly, urine samples were centrifuged (3,000 × g, 10 min) to remove particulates, diluted 1:5 with assay buffer, and incubated with the kit’s reaction mix (30 min, 37 °C). Absorbance was measured at 570 nm on a microplate reader (BioTek Synergy H1), with H2O2 concentrations calculated against a standard curve.

2.9. Statistical Analysis

All data were expressed as mean ± standard deviation (SD) from at least 3 biological replicates and at least 3 independent experiments. Data analysis was performed using GraphPad Prism and Origin software. Data from more than 2 groups were subjected to One-way ANOVA followed by Tukey’s post hoc test. Statistical significance was set at P < 0.05.

3. Results and Discussion

In order to clarify the magnetic resonance imaging capability of the probes, electron paramagnetic resonance of radicals was detected using EPR and the results are shown (Figure A). CTPO exhibited a longitudinal relaxivity (r 1) of 0.173 mM–1 s–1, supporting its utility as a T 1 contrast agent likely due to its radical structure (Figure C). To elucidate the redox-selective responsiveness of CTPO, we systematically screened its interactions with 20 metabolites in blood and urine. As control group, Gd-DOTA also reacted with these metabolites (Figure E). Among these metabolites, hydrogen peroxide was observed to significantly reduce the contrast of CTPO. However, the contrast of Gd-DOTA remained unaffected by any metabolites. The mass spectrometry analysis results confirmed that CTPO reacted with H2O2 (Figure S1). Gd-DOTA is gadolinium chelated with DOTA and is not susceptible to redox reactions. This specificity arises from CTPO’s nitrogen–oxygen radical reacting with H2O2, diminishing MRI contrast. This redox-responsive property enables potential diagnosis of oxidative stress-related diseases. To rigorously evaluate the selectivity of CTPO for H2O2 over other pathologically relevant oxidants, we incubated it with a concentration gradient (31.25–500 μM) of hydrogen peroxide (H2O2), hypochlorite (NaClO), a peroxynitrite donor (SIN-1), and cisplatin. MRI analysis revealed a dose-dependent decrease in longitudinal relaxivity (r 1) only in the presence of H2O2, which reduced the r 1 to 30% of baseline at 500 μM (Figure S2). In contrast, NaClO and SIN-1 induced only a modest reduction, while cisplatin exhibited no effect, unequivocally demonstrating the high specificity of CTPO for H2O2.

2.

2

Open in a new tab

Paramagnetic characteristics of the CTPO. (A) Electron paramagnetic resonance of the radical. (B) T 1 weighted MRI images of 10 mM radical solution in water acquired at 3T at 37 °C. (C) Longitudinal relaxivity of radicals in water by 3T MRI. (D) Design of MRI experiments following CTPO and Gd-DOTA hybrid metabolite reactions. (E) MRI of blood and urine metabolites mixed with radical and Gd-DOTA.

Radical and Gd-DOTA were evaluated for contrast media suitability in vivo following intravenous injections to BALB/c mice. Following injection, T 1-weighted images were acquired every 2.5 min following a preinjection scan, which was used to establish baseline voxel intensity (Figure S3A, C). Overall, contrast enhancement of CTPO appeared to accumulate significantly over time in the mouse bladder, with contrast reaching 177% at 2.5 min and increasing to 359% at 10 min (Figure S3B). As for Gd-DOTA, the contrast enhancement relative to precontrast scans reached 245% in the heart at 1 min, and it remains 179% at 10 min (Figure S3D). Extended imaging in healthy mice revealed that the bladder signal plateaued between 10–20 min postinjection and returned to near-baseline levels by 50 min, defining its clearance window (Figure S4). The redox-dependent interaction of CTPO with endogenous H2O2 in the bloodstream may underlie its diminished vascular contrast enhancement, as T 1 relaxation mechanism of Gd-DOTA remains unaffected by such redox-active metabolites.

The differential contrast enhancement properties of CTPO were evaluated in both physiological and pathological models. Cisplatin-induced acute kidney injury (AKI) was established in mice via a single intraperitoneal injection (25 mg/kg) followed by 48-h observation. Following intravenous administration of CTPO, dynamic MRI scans at sequential time points (0–10 min postinjection) revealed fundamentally distinct behaviors between groups. In healthy mice, bladder signal intensity exhibited progressive enhancement with a 2 fold increase in contrast-to-noise ratio (CNR) at 10 min compared to baseline (Figure A,B). Conversely, cisplatin-AKI models displayed complete suppression of contrast dynamics, maintaining stable CNR values within ± 5% of baseline throughout the monitoring period (Figure C,D). Following NAC treatment, the signal that had increased over time reappeared in the bladder of mice and reached 1.5 times the baseline at 10 min (Figure E,F).

3.

3

Open in a new tab

Application of CTPO for AKI detection based on urinary bladder imaging. MRI scans of (A, B) Normal, (C, D) AKI and (E, F) NAC treatment mice were acquired both preinjection and every 2.5 min postinjection following the administration of CTPO. (G) PAS, H&E and Mason staining of kidney of normal, AKI and NAC treatment mice. Data are presented as mean ± SD (n = 6, from 3 independent experiments).***, −––, +++ P < 0.001.

PAS, H&E and Mason staining revealed significant tubular injury in AKI mice, characterized by brush border loss, luminal casts, and basement membrane thickening, which was alleviated by NAC treatment. Quantitative analysis confirmed that NAC significantly mitigated the cisplatin-induced increases in tubular injury score and tubulointerstitial fibrosis (Figure G). This histological recovery underscores the role of oxidative stress in AKI and aligns with the restored CTPO MRI signal following NAC administration. This contrast discrepancy is attributable to redox-active interactions between CTPO and disease-altered urinary metabolites. The physiological microenvironment’s low oxidative stress preserves CTPO‘s structural integrity and paramagnetic stability, enabling strong T 1-weighted signaling. Conversely, AKI-induced urinary H2O2 elevation drives CTPO oxidation or aggregation that quenches paramagnetic relaxation enhancement. −

Given the bladder-localized MRI contrast enhancement mediated by CTPO and its potential as an AKI-specific probe, urine samples were collected from both healthy and AKI mice to investigate whether CTPO could generate differential MRI signals in vitro (Figure A, S5). The CTPO (10 mM) was initially administered to the urine of both Ctrl and AKI mice/patients. Subsequent MRI results demonstrated that the contrast of CTPO in the urine of both AKI mice and patients was significantly reduced by approximately 50% (Figure B,C). Following this, the hydrogen peroxide content in the urine of Ctrl and AKI mice/patients was examined, and it was found that the content was elevated by approximately 80 and 100 μmol in the urine of AKI mice and patients, respectively (Figure D). It has been demonstrated that hydrogen peroxide significantly reduces the MRI contrast of CTPO (Figure E). To further validate the diagnostic efficacy of the CTPO-based assay, we performed receiver operating characteristic (ROC) analysis, which demonstrated excellent discrimination between AKI patients and healthy controls with an area under the curve (AUC) of 0.96 (Figure S6A). Furthermore, the CTPO signal intensity in urine exhibited a strong negative correlation with serum creatinine levels (R 2 = 0.9030, p < 0.001; Figure S6B), the gold-standard clinical biomarker for renal function. This robust correlation underscores the clinical relevance and potential of our approach as a noninvasive diagnostic tool for AKI. The functional stability of CTPO was further assessed by monitoring its MRI signal in urine over 48 h (Figure S7). CTPO exhibited excellent stability in control urine over a 48 h period, while AKI urine demonstrated progressive signal quenching, thereby confirming probe stability.

4.

4

Open in a new tab

Application of CTPO for AKI detection based on Clinical urine tests. (A) Urine sample collection procedure for humans. (B) Representative T 1-weighted MRI images and corresponding T 1 maps of urine samples from normal and AKI mice/patients with the addition of CTPO. The color bar indicates T 1 relaxation time, with blue/green representing shorter T 1 values and red/yellow representing longer T 1 values. (C) MRI results of urine samples collected from normal/AKI mouse and AKI patients with addition of CTPO. (D) Hydrogen peroxide detection results of urine samples collected from normal/AKI mouse and AKI patients. Data are presented as mean ± SD (n = 6, from 3 independent experiments). ***P < 0.001.

The differential MRI contrast of CTPO in healthy versus AKI urine samples highlights the distinctiveness of its redox-dependent diagnostic mechanism, a feature unattainable with conventional gadolinium-based agents. Oxidative stress has been identified as a significant trigger for AKI, with the generation of substantial amounts of ROS by this process promoting the synthesis and excretion of hydrogen peroxide. H2O2 quenches CTPO‘s nitroxide radicals, reducing their MRI signal. Clinically, CTPO signal loss occurs early in AKI at urinary H2O2 concentrations corresponding to disease onset, prior to serum creatinine elevation. Critically, its ex vivo diagnostic workflow using centrifuged urine avoids the nephrotoxic risks of in vivo contrast agents, a major advantage for renal-impaired patients. In conclusion, the present study establishes redox-responsive organic probes as tools for the purpose of bridging metabolic dysregulation and imaging diagnostics in AKI.

The biological safety of CTPO was subsequently analyzed. The results showed that no significant pathological changes were observed in the heart, liver, spleen, lungs, or kidneys (Figure S8A). Serum biochemical analysis revealed that liver and kidney function markers (ALT, AST, UREA, CREA) indicated no hepatotoxicity or nephrotoxicity for CTPO (Figure S8B). Furthermore, to assess the biosafety of CTPO at the cellular level, we investigated its cytotoxicity against human renal proximal tubular epithelial (HK-2) cells and mouse fibroblast (3T3-L1) cells. The CCK-8 assay revealed no significant decrease in cell viability after 24 h of incubation with CTPO at concentrations up to 200 μM (Figure S8C), collectively demonstrating its favorable biosafety profile.

4. Conclusions

In summary, we performed an MRI diagnostic study of AKI using CTPO. We found that intravenous injection of CTPO allows MRI imaging of the bladder in mice within 1 min. However, in cisplatin-induced acute kidney injury (AKI) models, CTPO failed to generate detectable bladder signals. Biosafety assessments confirmed the biocompatibility of CTPO, with no organ toxicity observed. Furthermore, clinical urine samples have demonstrated that CTPO can react with hydrogen peroxide in the urine of AKI patients for the purpose of vitro AKI diagnosis. These findings advance the use of organic contrast agents in targeted disease imaging and provide a new strategy for rapid noninvasive diagnosis and monitoring of AKI impediments.

The diagnostic utility of CTPO is emphasized by its favorable kinetic profile for H2O2 sensing, which enables rapid signal quenching, which is essential for dynamic MRI. This organic radical probe further distinguishes itself from emerging metal-based or nanoparticle renal probes by offering a nonmetallic, small-molecule alternative with an inherently biocompatible profile and potential for rapid clearance, thus mitigating long-term toxicity concerns associated with cumulative tissue retention. While the present study demonstrates the diagnostic potential of CTPO in a cisplatin-induced AKI model, it is essential for future investigations to validate its responsiveness in other clinically relevant AKI models, such as ischemia-reperfusion injury or sepsis-associated AKI, in order to assess its broader applicability across different oxidative stress environments. Furthermore, exploration of the behavior of CTPO in chronic oxidative stress settings, such as chronic kidney disease or diabetic nephropathy, would be valuable for extending its translational utility. Additionally, the diagnostic readout of CTPO relies on signal attenuation relative to a baseline, which in practice may not always be available from the same individual. It is vital to acknowledge the necessity of establishing population-based reference ranges for CTPO MRI signals in healthy subjects, as well as correlating the degree of signal quenching with established AKI staging criteria, in order to facilitate a diagnosis that is stratified according to severity. Such developments are considered to be of paramount importance with respect to future clinical translation.

Supplementary Material

ao5c09631_si_001.pdf (834.2KB, pdf)

Acknowledgments

We are grateful for the National Key Research and Development Program of China (2023YFC3605502), the High-level Medical Team Project in Baoan, Shenzhen (no. 202401), the National Natural Science Foundation of China (82470719, 22574170), the Guangdong Basic and Applied Basic Research Fund Enterprise Joint Fund (2023A1515220119), the Shenzhen Science and Technology Program (KQTD20210811090115019), and the Research Project on High-Quality Innovative Development of Medical-Education Collaboration (YJXT20250401). All animal procedures were performed in accordance with the Guidelines for the Care and Use of Laboratory Animals of “Peking” University and approved by the Animal Ethics Committee of “SHENZHEN PKU-HKUST MEDICAL CENTER” (approval number: 2024-549). All human-related experiments were performed in accordance with the Guidelines “1964 Helsinki Declaration” and its later amendments or comparable ethical standards’ and approved by the ethics committee at “The Second Affiliated Hospital of Shenzhen University” (approval number: BYL20240471). Informed consents were obtained from human participants of this study.

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.5c09631.

  • Mass spectrometry data confirming the reaction between CTPO and H2O2 (Figure S1); MRI-based assessment of CTPO’s specificity toward H2O2 compared to other pathologically relevant oxidants: hypochlorite; peroxynitrite donor; cisplatin (Figure S2); original signal curves for the in vivo dynamic contrast enhancement of CTPO and Gd-DOTA in mice (Figure S3); schematic diagram of the mouse urine sample collection procedure (Figure S4); receiver operating characteristic (ROC) curve for AKI diagnosis based on the CTPO signal and its correlation analysis with serum creatinine levels (Figure S5); stability test results of CTPO in urine over 48 h (Figure S6); biosafety assessments of CTPO: histopathological sections of major organs; serum biochemical parameters; cytotoxicity assays (Figure S7) (PDF)

The authors declare no competing financial interest.

References

  1. Sies H.. Hydrogen peroxide as a central redox signaling molecule in physiological oxidative stress: Oxidative eustress. Redox Biol. 2017;11:613–619. doi: 10.1016/j.redox.2016.12.035. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Brown D.I., Griendling K.K.. Nox proteins in signal transduction. Free Radic Biol. Med. 2009;47(9):1239–1253. doi: 10.1016/j.freeradbiomed.2009.07.023. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Veal E. A., Day A. M., Morgan B. A.. Hydrogen peroxide sensing and signaling. Mol. Cell. 2007;26(1):1–14. doi: 10.1016/j.molcel.2007.03.016. [DOI] [PubMed] [Google Scholar]
  4. Yan J., Jiang J., He L.. et al. Mitochondrial superoxide/hydrogen peroxide: An emerging therapeutic target for metabolic diseases. Free Radic Biol. Med. 2020;152:33–42. doi: 10.1016/j.freeradbiomed.2020.02.029. [DOI] [PubMed] [Google Scholar]
  5. Li T., Santockyte R., Shen R. F., Tekle E., Wang G., Yang D. C. H., Chock P. B.. Expression of SUMO-2/3 induced senescence through p53- and pRB-mediated pathways. J. Biol. Chem. 2006;281(47):36221–36227. doi: 10.1074/jbc.M608236200. [DOI] [PubMed] [Google Scholar]
  6. Yao Y., Hu X., Feng X.. et al. Dexmedetomidine alleviates lipopolysaccharide-induced acute kidney injury by inhibiting the NLRP3 inflammasome activation via regulating the TLR4/NOX4/NF-κB pathway. J. Cell Biochem. 2019;120(10):18509–18523. doi: 10.1002/jcb.29173. [DOI] [PubMed] [Google Scholar]
  7. Lennicke C., Rahn J., Lichtenfels R., Wessjohann L. A., Seliger B.. et al. Hydrogen peroxide – production, fate and role in redox signaling of tumor cells. Cell Commun. Signal. 2015;13:39. doi: 10.1186/s12964-015-0118-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Singh J., Singh R., Singh S., Mitra K., Mondal S., Vishwakarma S., Ray B.. Colorimetric detection of hydrogen peroxide and cholesterol using Fe3O4-brominated graphene nanocomposite. Anal Bioanal Chem. 2022;414(6):2131–2145. doi: 10.1007/s00216-021-03848-w. [DOI] [PubMed] [Google Scholar]
  9. Zhao T. T., Jiang Z. W., Zhen S. J., Huang C. Z., Li Y. F.. A copper­(II)/cobalt­(II) organic gel with enhanced peroxidase-like activity for fluorometric determination of hydrogen peroxide and glucose. Mikrochim. Acta. 2019;186(3):168. doi: 10.1007/s00604-019-3290-3. [DOI] [PubMed] [Google Scholar]
  10. Hao Y., Li Z., Ding N.. et al. A new near-infrared fluorescence probe synthesized from IR-783 for detection and bioimaging of hydrogen peroxide in vitro and in vivo. Spectrochim Acta A Mol. Biomol Spectrosc. 2022;268:120642. doi: 10.1016/j.saa.2021.120642. [DOI] [PubMed] [Google Scholar]
  11. Patel V., Kruse P., Selvaganapathy P. R.. Solid State Sensors for Hydrogen Peroxide Detection. Biosensors. 2021;11(1):9. doi: 10.3390/bios11010009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Jiang G., Li C., Liu X., Chen Q., Li X., Gu X., Zhang P., Lai Q., Wang J.. Wang, Lipid droplet-targetable fluorescence guided photodynamic therapy of cancer cells with an activatable AIE-active fluorescent probe for hydrogen peroxide. Adv. Optical Mater. 2020;8:2001119. doi: 10.1002/adom.202001119. [DOI] [Google Scholar]
  13. Chen X., Ren X., Zhang L.. et al. Mitochondria-targeted fluorescent and photoacoustic imaging of hydrogen peroxide in inflammation. Anal. Chem. 2020;92(20):14244–14250. doi: 10.1021/acs.analchem.0c03506. [DOI] [PubMed] [Google Scholar]
  14. Wang M., Zhang F., Wang C. Q., Yin N., Wang Y., Qin G., Xu Q., Gong J., Liu H., Duan X.. et al. Target-binding accelerated response for sensitive detection of basal H2O2 in tumor cells and tissues via a dual-functional fluorescence probe. Anal. Chem. 2022;94(15):5962–5969. doi: 10.1021/acs.analchem.2c00400. [DOI] [PubMed] [Google Scholar]
  15. Gu T., Mo S., Mu Y.. et al. Detection of endogenous hydrogen peroxide in living cells with para-nitrophenyl oxoacetyl rhodamine as turn-on mitochondria-targeted fluorescent probe. Sens. Actuator B Chem. 2020;309:127731. doi: 10.1016/j.snb.2020.127731. [DOI] [Google Scholar]
  16. Guo H., Chen G., Gao M.. et al. Imaging of endogenous hydrogen peroxide during the process of cell mitosis and mouse brain development with a near-infrared ratiometric fluorescent probe. Anal. Chem. 2019;91(1):1203–1210. doi: 10.1021/acs.analchem.8b05326. [DOI] [PubMed] [Google Scholar]
  17. Luo X., Cheng S., Zhang W.. et al. Near-Infrared fluorescence probe for indication of the pathological stages of wound healing process and its clinical application. ACS Sens. 2024;9(2):810–819. doi: 10.1021/acssensors.3c02147. [DOI] [PubMed] [Google Scholar]
  18. Sitara M., Zhang W., Gao H.. et al. Recent Progress in Molecular Probes for Imaging of Acute Kidney Injury. Chem. Biomed Imaging. 2024;2(8):526–541. doi: 10.1021/cbmi.4c00024. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Laothamatas I., Al Mubarak H., Reddy A., Wax R., Badani K., Taouli B., Bane O., Lewis S.. Multiparametric MRI of solid renal masses: Principles and applications of advanced quantitative and functional methods for tumor diagnosis and characterization. J. Magn Reson Imaging. 2023;58(2):342–359. doi: 10.1002/jmri.28718. [DOI] [PubMed] [Google Scholar]
  20. Minhas A.S., Oliver R.. Magnetic resonance imaging basics. Adv. Exp. Med. Biol. 2022;1380:47–82. doi: 10.1007/978-3-031-03873-0_3. [DOI] [PubMed] [Google Scholar]
  21. Yuan D., Ding L., Sun Z., Li X.. MRI/Fluorescence bimodal amplification system for cellular GSH detection and tumor cell imaging based on manganese dioxide nanosheet. Sci. Rep. 2018;8(1):1747. doi: 10.1038/s41598-018-20110-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Lu C., Liao S., Chen B.. et al. Responsive probes for in vivo magnetic resonance imaging of nitric oxide. Nat. Mater. 2025;24(1):133–142. doi: 10.1038/s41563-024-02054-0. [DOI] [PubMed] [Google Scholar]
  23. Barandov A., Bartelle B. B., Williamson C. G., Loucks E. S., Lippard S. J., Jasanoff A.. Brain glucose activated MRI contrast agent for early diagnosis of alzheimer’s disease. Anal. Chem. 2022;94(46):16213–16221. doi: 10.1021/acs.analchem.2c03765. [DOI] [PubMed] [Google Scholar]
  24. A A., Bartelle B., Williamson C. G., Loucks E. S., Lippard S. J., Jasanoff A.. et al. Sensing intracellular calcium ions using a manganese-based MRI contrast agent. Nat. Commun. 2019;10(1):897. doi: 10.1038/s41467-019-08558-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Rajca A., Wang Y., Boska M., Paletta J.T., Olankitwanit A., Swanson M. A., Mitchell D. G., Eaton S. S., Eaton G. R.. et al. Organic radical contrast agents for magnetic resonance imaging. J. Am. Chem. Soc. 2012;134(38):15724–15727. doi: 10.1021/ja3079829. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Nguyen H.V.T., Detappe A., Harvey P., Gallagher N., Mathieu C., Agius M.P., Zavidij O., Wang W., Jiang Y., Rajca A.. et al. Pro-organic radical contrast agents (“pro-ORCAs”) for real-time MRI of pro-drug activation in biological systems. Polym. Chem. 2020;11(29):4768–4779. doi: 10.1039/D0PY00558D. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Sowers M. A., McCombs J. R., Wang Y.. et al. Redox-responsive branched-bottlebrush polymers for in vivo MRI and fluorescence imaging. Nat. Commun. 2014;5:5460. doi: 10.1038/ncomms6460. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Lumata J. L., Hagge L. M., Gaspar M. A., Trashi I., Ehrman R. N., Koirala S., Chiev A. C., Wijesundara Y. H., Darwin C. B., Pena S.. et al. TEMPO-conjugated tobacco mosaic virus as a magnetic resonance imaging contrast agent for detection of superoxide production in the inflamed liver. J. Mater. Chem. B. 2024;12(13):3273–3281. doi: 10.1039/D3TB02765A. [DOI] [PubMed] [Google Scholar]
  29. Yuan X., Yu H., Wang L., Uddin M. A., Ouyang C.. et al. Nitroxide radical contrast agents for safe magnetic resonance imaging: Progress, challenges, and perspectives. Mater. Horiz. 2025;12:1726–1756. doi: 10.1039/D4MH00995A. [DOI] [PubMed] [Google Scholar]
  30. Bousquet J.C., Saini S., Stark D. D., Hahn P.F., Nigam M., Wittenberg J., Ferrucci J.T. Jr. Gd-DOTA: Characterization of a new paramagnetic complex. Radiology. 1988;166(3):693–698. doi: 10.1148/radiology.166.3.334076. [DOI] [PubMed] [Google Scholar]
  31. Pabla N., Dong Z.. Cisplatin nephrotoxicity: Mechanisms and renoprotective strategies. Kidney Int. 2008;73(9):994–1007. doi: 10.1038/sj.ki.5002786. [DOI] [PubMed] [Google Scholar]
  32. Banerjee D., Madhusoodanan U. K., Nayak S., Jacob J.. Urinary hydrogen peroxide: A probable marker of oxidative stress in malignancy. Clin. Chim. Acta. 2003;334(1–2):205–209. doi: 10.1016/S0009-8981(03)00236-5. [DOI] [PubMed] [Google Scholar]
  33. Liu D., Huang P., Li X.. et al. Using inflammatory and oxidative biomarkers in urine to predict early acute kidney injury in patients undergoing liver transplantation. Biomarkers. 2014;19(5):424–429. doi: 10.3109/1354750X.2014.924997. [DOI] [PubMed] [Google Scholar]
  34. Duan J. L., Yin J., Ren W. K.. et al. Pyrrolidine dithiocarbamate restores gastric damages and suppressive autophagy induced by hydrogen peroxide. Free Radic Res. 2015;49(2):210–218. doi: 10.3109/10715762.2014.993627. [DOI] [PubMed] [Google Scholar]
  35. Aranda-Rivera A., Cruz-Gregorio A., Aparicio-Trejo O. E., Pedraza-Chaverri J.. et al. Mitochondrial redox signaling and oxidative stress in kidney diseases. Biomolecules. 2021;11(8):1144. doi: 10.3390/biom11081144. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Sadowska-Bartosz I., Bartosz G.. The cellular and organismal effects of nitroxides and nitroxide-containing nanoparticles. Int. J. Mol. Sci. 2024;25(3):1446. doi: 10.3390/ijms25031446. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Lunyera J., Mohottige D., Alexopoulos A. S., Campbell H., Cameron C. B., Sagalla N., Amrhein T. J., Crowley M. J., Dietch J. R., Gordon A. M.. et al. Risk for Nephrogenic Systemic Fibrosis After Exposure to Newer Gadolinium Agents: A Systematic Review. Ann. Int. Med. 2020;173(2):110–119. doi: 10.7326/M20-0299. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

ao5c09631_si_001.pdf (834.2KB, pdf)

Articles from ACS Omega are provided here courtesy of American Chemical Society

RESOURCES