Controlled In Situ Self-Assembly of Biotinylated Trans-Cyclooctene Nanoparticles for Orthogonal Dual-Pretargeted Near-Infrared Fluorescence and Magnetic Resonance Imaging.

A pretargeted strategy that decouples targeting vectors from radionuclides has shown promise for nuclear imaging and/or therapy in vivo. However, the current pretargeted approach relies on the use of antibodies or nanoparticles as the targeting vectors, which may be compromised by poor tissue penetration and limited accumulation of targeting vectors in the tumor tissues. Herein, we present an orthogonal dual-pretargeted approach by combining stimuli-triggered in situ self-assembly strategy with fast inverse electron demand Diels-Alder (IEDDA) reaction and strong biotin-streptavidin (SA) interaction for near-infrared fluorescence (NIR FL) and magnetic resonance (MR) imaging of tumors. This approach uses a small-molecule probe (P-Cy-TCO&Bio) containing both biotin and trans-cyclooctene (TCO) as a tumor-targeting vector. P-Cy-TCO&Bio can efficiently penetrate subcutaneous HeLa tumors through biotin-assisted targeted delivery and undergo in situ self-assembly to form biotinylated TCO-bearing nanoparticles (Cy-TCO&Bio NPs) on tumor cell membranes. Cy-TCO&Bio NPs exhibited an "off-on" NIR FL and retained in the tumors, offering a high density of TCO and biotin groups for the concurrent capture of Gd-chelate-labeled tetrazine (Tz-Gd) and IR780-labeled SA (SA-780) via the orthogonal IEDDA reaction and SA-biotin interaction. Moreover, Cy-TCO&Bio NPs offered multiple-valent binding modes toward SA, which additionally regulated the cross-linking of Cy-Gd&Bio NPs into microparticles (Cy-Gd&Bio/SA MPs). This process could significantly (1) increase r1 relaxivity and (2) enhance the accumulation of Tz-Gd and SA-780 in the tumors, resulting in strong NIR FL, bright MR contrast, and an extended time window for the clear and precise imaging of HeLa tumors.

Ratiometric Afterglow Luminescent Imaging of Matrix Metalloproteinase-2 Activity via an Energy Diversion Process.

Ratiometric afterglow luminescent (AGL) probes are attractive for in vivo imaging due to their high sensitivity and signal self-calibration function. However, there are currently few ratiometric AGL probes available for imaging enzymatic activity in living organisms. Here, we present an energy diversion (ED) strategy that enables the design of an enzyme-activated ratiometric AGL probe (RAG-RGD) for in vivo afterglow imaging. The ED process provides RAG-RGD with a radiative transition for an 'always on' 520-nm AGL signal (AGL520) and a cascade three-step energy transfer (ET) process for an 'off-on' 710-nm AGL signal (AGL710) in response to a specific enzyme. Using matrix metalloproteinase-2 (MMP-2) as an example, RAG-RGD shows a significant ~11-fold increase in AGL710/AGL520 toward MMP-2. This can sensitively detect U87MG brain tumors through ratiometric afterglow imaging of MMP-2 activity, with a high signal-to-background ratio and deep imaging depth. Furthermore, by utilizing the self-calibration effect of ratiometric imaging, RAG-RGD demonstrated a strong negative correlation between the AGL710/AGL520 value and the size of orthotopic U87MG tumor, enabling accurate monitoring of orthotopic glioma growth in vivo. This ED process may be applied for the design of other enzyme-activated ratiometric afterglow probes for sensitive afterglow imaging.

Bioorthogonal Cu Single-Atom Nanozyme for Synergistic Nanocatalytic Therapy, Photothermal Therapy, Cuproptosis and Immunotherapy.

Single-atom nanozymes (SAzymes) with atomically dispersed active sites are potential substitutes for natural enzymes. A systematic study of its multiple functions can in-depth understand SAzymes's nature, which remains elusive. Here, we develop a novel ultrafast synthesis of sputtered SAzymes by in situ bombarding-embedding technique. Using this method, sputtered copper (Cu) SAzymes (CuSA) is developed with unreported unique planar Cu-C3 coordinated configuration. To enhance the tumor-specific targeting, we employ a bioorthogonal approach to engineer CuSA, denoted as CuSACO. CuSACO not only exhibits minimal off-target toxicity but also possesses exceptional ultrahigh catalase-, oxidase-, peroxidase-like multienzyme activities, resulting in reactive oxygen species (ROS) storm generation for effective tumor destruction. Surprisingly, CuSACO can release Cu ions in the presence of glutathione (GSH) to induce cuproptosis, enhancing the tumor treatment efficacy. Notably, CuSACO's remarkable photothermal properties enables precise photothermal therapy (PTT) on tumors. This, combined with nanozyme catalytic activities, cuproptosis and immunotherapy, efficiently inhibiting the growth of orthotopic breast tumors and gliomas, and lung metastasis. Our research highlights the potential of CuSACO as an innovative strategy to utilize multiple mechanism to enhance tumor therapeutic efficacy, broadening the exploration and development of enzyme-like behavior and physiological mechanism of action of SAzymes.

Single-Cell Caspase-3 Measurement Using a Biomimetic Nanochannel.

Direct single-cell caspase-3 (Casp-3) analysis has remained challenging. A study of single-cell Casp-3 could contribute to revealing the fundamental pathogenic mechanisms in Casp-3-associated diseases. Here, a biomimetic nanochannel capable of single-cell sampling and ionic detection of intracellular Casp-3 is devised, which is established upon the installment of target-specific organic molecules (luc-DEVD) within the orifice of a glass nanopipette. The specific cleavage of luc-DEVD by Casp-3 could induce changes of inner-surface chemical groups and charge properties, thus altering the ionic response of the biomimetic nanochannel for direct Casp-3 detection. The practical applicability of this biomimetic nanochannel is confirmed by probing intracellular Casp-3 fluctuation upon drug stimulation and quantifying the Casp-3 evolution during induced apoptosis. This work realizes ionic single-cell Casp-3 analysis and provides a different perspective for single-cell protein analysis.

A Near-infrared Fluorescence and Positron Emission Tomography Bimodal Probe for In Vivo Imaging of Amyloid-ß Species.

Noninvasive imaging of amyloid-ß (Aß) species in vivo is important for the early diagnosis of Alzheimer's disease (AD). In this paper, we report a near-infrared (NIR) fluorescence (FL) and positron emission tomography (PET) bimodal probe (NIR-[68Ga]) for in vivo imaging of both soluble and insoluble Aß species. NIR-[68Ga] holds a high binding affinity, high selectivity and high sensitivity toward Aß42 monomers, oligomers, and aggregates in vitro. In vivo imaging results show that NIR-[68Ga] can cross the blood-brain-barrier (BBB), and produce significantly higher PET and NIR FL bimodal signals in the brains of APP/PS1 transgenic AD mice relative to that of age-matched wild-type mice, which are also validated by the ex vivo autoradiography and histological staining images. Our results demonstrate that NIR-[68Ga] is an efficient NIR FL and PET bimodal probe for the sensitive imaging of soluble and insoluble Aß species in AD mice.

Cascade In Situ Self-Assembly and Bioorthogonal Reaction Enable the Enrichment of Photosensitizers and Carbonic Anhydrase Inhibitors for Pretargeted Cancer Theranostics.

We report here a tumor-pretargted theranostic approach for multimodality imaging-guided synergistic cancer PDT by cascade alkaline phosphatase (ALP)-mediated in situ self-assembly and bioorthogonal inverse electron demand Diels-Alder (IEDDA) reaction. Using the enzymatic catalysis of ALP that continuously catalyses the dephosphorylation and self-assembly of trans-cyclooctene (TCO)-bearing P-FFGd-TCO, a high density of fluorescent and magnetic TCO-containing nanoparticles (FMNPs-TCO) can be synthesized and retained on the membrane of tumor cells. They can act as 'artificial antigens' amenable to concurrently capture lately administrated tetrazine (Tz)-decorated PS (775NP-Tz) and carbonic anhydrase (CA) inhibitor (SA-Tz) via the fast IEDDA reaction. This two-step pretargeting process can further induce FMNPs-TCO regrowth into microparticles (FMNPs-775/SA) directly on tumor cell membranes, which is analyzed by bio-SEM and fluorescence imaging. Thus, efficient enrichment of both SA-Tz and 775NP-Tz in tumors can be achieved, allowing to alleviate hypoxia by continuously inhibiting CA activity and improving PDT of tumors. Findings show that subcutaneous HeLa tumors could be completely eradicated and no tumor recurred after irradiation with an 808 nm laser (0.33 W cm-2 , 10 min). This pretargeted approach may be applied to enrich other therapeutic agents in tumors to improve targeted therapy.

A carbonic anhydrase-targeted NIR-II fluorescent cisplatin theranostic nanoparticle for combined therapy of pancreatic tumors.

Optically active organic nanoparticles capable of emitting strong near-infrared II (NIR-II) fluorescence and eliciting tumor hyperthermia are promising for tumor imaging and photothermal therapy (PTT). However, their applications for the treatment of pancreatic tumors via mere PTT are challenging as both the nanoparticles and light are hard to enter the deeply located pancreatic tumors. Here, we report a NIR-II light excitable, carbonic anhydrase (CA)-targeting cisplatin prodrug-decorated nanoparticle (IRNPs-SBA/PtIV) for NIR-II fluorescence imaging (FLI)-guided combination PTT and chemotherapy of pancreatic tumors. IRNPs-SBA/PtIV is designed to hold a high photothermal conversion efficiency (PCE ≈ 65.17 %) under 1064 nm laser excitation, a strong affinity toward CA (Kd = 14.40 ± 5.49 nM), and a prominent cisplatin release profile in response to glutathione (GSH) and 1064 nm laser irradiation. We show that IRNPs-SBA/PtIV can be actively delivered into pancreatic tumors where the CA is upregulated, and emits NIR-II fluorescence to visualize tumors with a high sensitivity and penetration depth under 980 nm laser excitation. Moreover, the tumor-resided IRNPs-SBA/PtIV can efficiently inhibit the CA activity and consequently, relieve the acidic and hypoxic tumor microenvironment, benefiting to intensify chemotherapy. Guided by the NIR-II FLI, IRNPs-SBA/PtIV is capable of efficiently inhibiting pancreatic tumor growth via combinational PTT and chemotherapy with 1064 nm laser excitation under a low-power density (0.5 W cm-2, 10 min). This study demonstrates promise to fabricate NIR-II excitable nanoparticles for FLI-guided precise theranostics of pancreatic tumors.

Smart Lipid Nanoparticle that Remodels Tumor Microenvironment for Activatable H2S Gas and Photodynamic Immunotherapy.

Hydrogen sulfide (H2S) has shown promise for gas therapy. However, it is still controversial whether H2S can remodel the tumor microenvironment (TME) and induce robust antitumor immunity. Here, a tumor-targeting and TME-responsive "smart" lipid nanoparticle (1-JK-PS-FA) is presented, which is capable of delivering and releasing H2S specifically in tumor tissues for on-demand H2S gas and photodynamic immunotherapy. 1-JK-PS-FA enables a burst release of H2S in the acidic TME, which promptly reduces the embedded organic electrochromic materials and consequently switches on near-infrared fluorescence and photodynamic activity. Furthermore, we found that high levels of H2S can reprogram the TME by reducing tumor interstitial fluid pressure, promoting angiogenesis, increasing vascular permeability, ameliorating hypoxia, and reducing immunosuppressive conditions. This leads to increased tumor uptake of 1-JK-PS-FA, thereby enhancing PDT efficacy and eliciting strong immunogenic cell death during 808 nm laser irradiation. Therefore, 1-JK-PS-FA permits synergistic H2S gas and photodynamic immunotherapy, effectively eradicating orthotopic breast tumors and preventing tumor metastasis and recurrence. This work showcases the capacity of H2S to reprogram the TME to enhance H2S gas and immunotherapy.

A Fast and Reversible Responsive Bionic Transmembrane Nanochannel for Dynamic Single-Cell Quantification of Glutathione.

Biological channels can rapidly and continuously modulate ion transport behaviors in response to external stimuli, which play essential roles in manipulating physiological and pathological processes in cells. Here, to mimic the biological channels, a bionic nanochannel is developed by synergizing a cationic silicon-substituted rhodamine (SiRh) with a glass nanopipette for transmembrane single-cell quantification. Taking the fast and reversible nucleophilic addition reaction between glutathione (GSH) and SiRh, the bionic nanochannel shows a fast and reversible response to GSH, with its inner-surface charges changing between positive and negative charges, leading to a distinct and reversible switch in ionic current rectification (ICR). With the bionic nanochannel, spatiotemporal-resolved operation is performed to quantify endogenous GSH in a single cell, allowing for monitoring of intracellular GSH fluctuation in tumor cells upon photodynamic therapy and ferroptosis. Our results demonstrate that it is a feasible tool for in situ quantification of the endogenous GSH in single cells, which may be adapted to addressing other endogenous biomolecules in single cells by usage of other stimuli-responsive probes.

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.

Controlled sequential in situ self-assembly and disassembly of a fluorogenic cisplatin prodrug for cancer theranostics.

Temporal control of delivery and release of drugs in tumors are important in improving therapeutic outcomes to patients. Here, we report a sequential stimuli-triggered in situ self-assembly and disassembly strategy to direct delivery and release of theranostic drugs in vivo. Using cisplatin as a model anticancer drug, we design a stimuli-responsive small-molecule cisplatin prodrug (P-CyPt), which undergoes extracellular alkaline phosphatase-triggered in situ self-assembly and succeeding intracellular glutathione-triggered disassembly process, allowing to enhance accumulation and elicit burst release of cisplatin in tumor cells. Compared with cisplatin, P-CyPt greatly improves antitumor efficacy while mitigates off-target toxicity in mice with subcutaneous HeLa tumors and orthotopic HepG2 liver tumors after systemic administration. Moreover, P-CyPt also produces activated near-infrared fluorescence (at 710 nm) and dual photoacoustic imaging signals (at 700 and 750 nm), permitting high sensitivity and spatial-resolution delineation of tumor foci and real-time monitoring of drug delivery and release in vivo. This strategy leverages the advantages offered by in situ self-assembly with those of intracellular disassembly, which may act as a general platform for the design of prodrugs capable of improving drug delivery for cancer theranostics.

Crosslinked albumin-manganese nanoaggregates with sensitized T1 relaxivity and indocyanine green loading for multimodal imaging and cancer phototherapy.

Albumin-manganese-based nanocomposites (AMNs) characterized by simple preparation and good biocompatibility have been widely used for in vivo T1-weighted magnetic resonance imaging (MRI) and cancer theranostics. Herein, an aggregation and crosslinking assembly strategy was proposed to achieve the sensitization to T1 relaxivity of the albumin-manganese nanocomposite. At a relatively low Mn content (0.35%), the aggregation and crosslinking of bovine serum albumin-MnO2 (BM) resulted in a dramatic increase of T1 relaxivity from 5.49 to 67.2 mM-1 s-1. Upon the loading of indocyanine green (ICG) into the crosslinked BM nanoaggregates (C-BM), the T1 relaxivity of the C-BM/ICG nanocomposite (C-BM/I) was further increased to 97.3 mM-1 s-1, which was much higher than those reported previously even at high Mn contents. Moreover, the presence of C-BM greatly enhanced the photoacoustic (PA) and photothermal effects of ICG at 830 and 808 nm, respectively, and the second near infrared fluorescence (NIR-II FL) of ICG also showed better stability. Therefore, the synthesized C-BM/ICG nanocomposite exhibited remarkable performance in in vivo multimodal imaging of tumors, such as T1-weighted MRI, NIR-II FL imaging and PA imaging, and cancer phototherapy with little side effects. This work provided a highly efficient and promising multifunctional nanoprobe for breaking through the limits of cancer theranostics, and opened a new avenue for the development of high-relaxivity AMNs and multimodal imaging methodology.

Smart Nanosensitizers for Activatable Sono-Photodynamic Immunotherapy of Tumors by Redox-Controlled Disassembly.

Tumor-targeted and stimuli-activatable nanosensitizers are highly desirable for cancer theranostics. However, designing smart nanosensitizers with multiple imaging signals and synergistic therapeutic activities switched on is challenging. Herein, we report tumor-targeted and redox-activatable nanosensitizers (1-NPs) for sono-photodynamic immunotherapy of tumors by molecular co-assembly and redox-controlled disassembly. 1-NPs show a high longitudinal relaxivity (r1 =18.7±0.3 mM-1 s-1 ), but "off" dual fluorescence (FL) emission (at 547 and 672 nm), "off" sono-photodynamic therapy and indoleamine 2,3-dioxygenase 1 (IDO1) inhibition activities. Upon reduction by glutathione (GSH), 1-NPs rapidly disassemble and remotely release small molecules 2-Gd, Zn-PPA-SH and NLG919, concurrently switching on (1) dual FL emission, (2) sono-photodynamic therapy and (3) IDO1 inhibition activities. After systemic injection, 1-NPs are effective for bimodal FL and magnetic resonance (MR) imaging-guided sono-photodynamic immunotherapy of orthotropic breast and brain tumors in mice under combined ultrasound (US) and 671-nm laser irradiation.

Controlling Disassembly of Paramagnetic Prodrug and Photosensitizer Nanoassemblies for On-Demand Orthotopic Glioma Theranostics.

Controlling delivery and release of therapeutic agents to accomplish on-demand synergistic therapy of orthotopic gliomas is desired but challenging. Here, we report a glioma targeting and redox activatable theranostic nanoprobe (Co-NP-RGD1/1) for magnetic resonance (MR) and fluorescence (FL) bimodal imaging-guided on-demand synergistic chemotherapy/photodynamic therapy (Chemo-PDT) of orthotopic gliomas. Co-NP-RGD1/1 is formed via molecular coassembly of two paramagnetic and fluorogenic small-molecule probes CPT-RGD and PPa-RGD at an optimized molar ratio of 1/1, which shows a high longitudinal relaxivity (r1 = 17.0 ± 0.6 mM-1 s-1, 0.5 T) but weak FL emissions and low Chemo-PDT activity. Upon reduction by endogenous glutathione (GSH), Co-NP-RGD1/1 disassemble and release small molecules 2-RGD, chemodrug camptothecin (CPT), and near-infrared (NIR) photosensitizer (PS) PPa-SH that further binds to endogenous albumin to form PPa-SH-albumin complex, allowing to turn on FL, chemotherapeutic efficacy, and PDT activity for synergistic Chemo-PDT of orthotopic U87MG or U251 gliomas in living mice. Moreover, Co-NP-RGD1/1 can also allow noninvasive detection and monitoring of orthotopic brain tumor growth via FL and MR imaging. Findings suggest the potential of cascade coassembly and stimuli-controlled intracellular disassembly strategy for constructing targeted and activatable nanoagents for improving combinational cancer theranostics.

Organic Molecular Probe Enabled Ionic Current Rectification toward Subcellular Detection of Glutathione with High Selectivity, Sensitivity, and Recyclability.

Single-cell interrogation with the solid-state nanoprobes enables understanding of the linkage between cellular behavior and heterogeneity. Herein, inspired by the charge property of the organic molecular probe (OMP), a generic ionic current rectification (ICR) single-cell methodology is established, exemplified by subcellular detection of glutathione (GSH) with high selectivity, sensitivity, and recyclability. The as-developed nanosensor can transduce the subcellular OMP-GSH interaction via a sensitive ionic response, which stems from the superior specificity of OMP and its essential charge property. In addition, the nanosensor exhibits good reversibility, since the subsequent tandem reaction after the recognition can well recover the sensing surface. Given the diverse structures and tailorable charge properties of OMP, this work underpins a new and general method of OMP-based ICR single-cell analysis.

Near-Infrared Electrochromic Behavior of Dibenzothiepin Derivatives Attached with Two Michler's Hydrol Blue Units.

10,11-Bis[bis(4-dimethylaminophenyl)methylene]dibenzo[bf]thiepin (1) and -oxepin (2) were prepared as stable yellow crystalline compounds, which are the cyclic analogues of electron-donating hexaarylbutadienes. Upon two-electron oxidation, they are reversibly transformed into the title dications (12+ and 22+ ) exhibiting near-infrared (NIR) absorptions, which were also isolated as stable salts. These redox pairs can serve as new entries into less well-explored organic NIR-electrochromic systems, and the separation of redox peaks (electrochemical bistability) was attained for 1/12+ and 2/22+ , thanks to drastic geometrical changes between neutral and dicationic states, as revealed by a series of X-ray analyses. Thiepin-S,S-dioxide analogue (3/32+ ) exhibits quite similar dynamic redox behavior due to nonaromatic nature of the dibenzothiepin and -oxepin unit in 12+ and 22+ , whereas the thiepin-S-oxide derivative (4/42+ ) does not exhibit bistability due to the smaller change in geometry upon electron transfer, showing that a subtle change of a bridging atom in the central seven-membered ring can modify the redox properties.

Activatable Multimodal Probes for In Vivo Imaging and Theranostics.

Multimodal imaging, which harnesses two or more imaging modalities to produce complementary anatomical and molecular information of a living subject, has become as a powerful tool in both basic biomedical research and clinical diagnosis. The progresses in multimodal imaging are paralleled by the advances in multimodal probes, particularly activatable multimodal imaging probes that can generate concurrent switches in different imaging modality signals upon interaction with a molecular target. These probes are extremely promising for in vivo imaging. In this Minireview, we summarize the recent progress in activatable multimodal probes for in vivo imaging and cancer theranostics, focusing on their design principle, signal activation mechanism and biomedical applications. The current challenges and perspectives for future developments of activatable multimodal probes are also briefly discussed. We hope that this Minireview will provide inspiration for the design of other activatable multimodal probes for improving in vivo imaging and theranostics.

A caspase-3-activatable bimodal probe for photoacoustic and magnetic resonance imaging of tumor apoptosis in vivo.

Multimodal imaging probes have shown promise in both biomedical research and clinical diagnosis. However, the development of molecular probes capable of being switched on multimodality imaging signals in response to a biomarker of interest remains challenging. In this paper, we report a caspase-3-activatable small-molecule bimodal probe (Gd-IR780) for photoacoustic imaging (PAI) and magnetic resonance imaging (MRI) of tumor apoptosis via caspase-3-triggered intramolecular macrocyclization and in situ self-assembly process. Upon interaction with caspase-3, Gd-IR780 can be efficiently converted into a macrocyclic product, Gd-IR780-MC, which subsequently self-assembles into near-infrared absorptive and paramagnetic nanoparticles (Gd-IR780-NPs), allowing to concurrently switch on PAI (∼4.3-fold at 855 nm) and MRI (r1 relaxivity increases from 7.98 ± 0.03 mM-1 s-1 to 19.66 ± 0.7 mM-1 s-1 at 0.5 T) bimodal signals in caspase buffer. Noninvasive in vivo imaging results show that Gd-IR780 can enter apoptotic U87MG tumor tissues after systemic administration, and produce markedly enhanced PAI and MRI signals for high sensitivity and spatial-resolution visualization of caspase-3 activity in the doxorubicin-treated apoptotic U87MG tumor tissues. Gd-IR780 holds a good potential to report tumor apoptosis via combined PAI and MRI, which is beneficial for the early evaluation of antitumor efficacy in vivo.

A Ratiometric Photoacoustic Probe with a Reversible Response to Hydrogen Sulfide and Hydroxyl Radicals for Dynamic Imaging of Liver Inflammation.

Reversible imaging probes that allow for the dynamic visualization of the redox cycle between hydroxyl radical (⋅OH) and hydrogen sulfide (H2 S) are vital to probe the redox imbalance-involved pathological process in vivo. Herein, we report a reversible ratiometric photoacoustic (PA) imaging nanoprobe (1-PAIN) for the real-time imaging of ⋅OH/H2 S redox cycle in vivo. 1-PAIN displays a low PA ratio between 690 and 825 nm (PA690 /PA825 ), which significantly increases by ≈5-fold upon oxidation by ⋅OH, and is switched back to the initially low PA690 /PA825 value upon reduction by H2 S. 1-PAIN could dynamically report on the hepatic ⋅OH production in mice during the lipopolysaccharide (LPS)-induced liver inflammation process, and visualize hepatic H2 S generation during the N-acetyl cysteine (NAC)-induced anti-inflammation process. 1-PAIN can act as a useful tool to probe the redox state in living biology, beneficial for the study of redox imbalance-related diseases.