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.

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.

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.

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.

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.

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.

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.

Alkaline Phosphatase Enabled Fluorogenic Reaction and in situ Coassembly of Near-Infrared and Radioactive Nanoparticles for in vivo Imaging.

Smart near-infrared (NIR) fluorescence (FL) and positron emission tomography (PET) bimodal probes have shown promise for preoperative and intraoperative imaging of tumors. In this paper, we report an enzyme-activatable probe (P-CyFF-68Ga) and its cold probe (P-CyFF-Ga) using an enzyme-induced fluorogenic reaction and in situ coassembly strategy and demonstrate the utility for NIR FL/PET bimodality imaging of enzymatic activity. P-CyFF-68Ga and P-CyFF-Ga can be converted into dephosphorylated CyFF-68Ga and CyFF-Ga in response to alkaline phosphatase (ALP) and subsequently coassemble into fluorescent and radioactive nanoparticles (NP-68Ga). The ALP-triggered in situ formed NP-68Ga is prone to anchoring on the ALP-positive HeLa cell membrane, permitting the concurrent enrichment of NIR FL and radioactivity. The enhancements in NIR FL and radioactivity enables high sensitivity and deep-tissue imaging of ALP activity, consequently facilitating the delineation of HeLa tumor foci from the normal tissues in vivo.

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 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.

Design and Development of a Bioorthogonal, Visualizable and Mitochondria-Targeted Hydrogen Sulfide (H2 S) Delivery System.

Hydrogen sulfide (H2 S) is an important endogenous gasotransmitter, but the targeted delivery and real-time feedback of exogenous H2 S are still challenging. With the aid of density functional theory (DFT) calculations, we designed a new 1,3-dithiolium-4-olate (DTO) compound, which can react with a strained alkyne via the 1,3-dipolar cycloaddition and the retro-Diels-Alder reaction to generate carbonyl sulfide (COS) as the precursor of H2 S, and a thiophene derivative with turn-on fluorescence. Moreover, the diphenylamino substituent in DTO greatly increases the mitochondrial targeting of this H2 S delivery system. Such a bioorthogonal click-and-release reaction has integrated three functions in one system for the first time: (1) in situ controllable H2 S release, (2) concomitant fluorescence response, and (3) mitochondria-targeted delivery. In addition, we investigated the mitochondrial membrane potential loss alleviation by using this system in H9c2 cells under oxidative stress.

An Activatable Afterglow/MRI Bimodal Nanoprobe with Fast Response to H2 S for In Vivo Imaging of Acute Hepatitis.

Accurate detection of hepatic hydrogen sulfide (H2 S) to monitor H2 S-related enzymes' activity is critical for acute hepatitis diagnosis, but remains a challenge due to the dynamic and transient nature of H2 S. Here, we report a H2 S-activatable near-infrared afterglow/MRI bimodal probe F1-GdNP, which shows an "always-on" MRI signal and "off-on" afterglow signal toward H2 S. F1-GdNP shows fast response, high sensitivity and specificity toward H2 S, permitting afterglow imaging of H2 S and evaluation of cystathionine γ-lyase (CSE)'s activity in living mice. We further employ the high spatial-resolution MRI signal of F1-GdNP to track its delivery and accumulation in liver. Importantly, F1-GdNP offers a high signal-to-background ratio (SBR=86.2±12.0) to sensitively report on the increased hepatic H2 S level in the acute hepatitis mice via afterglow imaging, which correlated well with the upregulated CSE activity in the liver, showcasing the good potential of F1-GdNP for monitoring of acute hepatitis process in vivo.

Tailoring a Near-Infrared Macrocyclization Scaffold Allows the Control of In Situ Self-Assembly for Photoacoustic/PET Bimodal Imaging.

Enzyme-triggered macrocyclization and in situ self-assembly of small molecules into nanoparticles has shown promise to design activatable probes for molecular imaging. However, controlling macrocyclization and self-assembly to concurrently augment positron emission tomography (PET) and photoacoustic (PA) signals for bimodality imaging is challenging. Herein, we report the engineering of a triazole-IR780 fluorophore as a versatile macrocyclization scaffold for controlling in situ self-assembly and design a caspase-3-activatable PA/PET bimodal probe ([18 F]-IR780-1) for in vivo imaging of tumor apoptosis. By leveraging the high-sensitivity whole-body imaging signals offered by PET with the high-resolution imaging signals offered by PA, [18 F]-IR780-1 can provide a promising tool for the early evaluation of antitumor efficacy, helpful for optimizing the therapeutic protocol for patients. This scaffold may be adopted to design other activatable bimodal probes for in vivo imaging.

An Activatable Near-Infrared Fluorescence Probe for in Vivo Imaging of Acute Kidney Injury by Targeting Phosphatidylserine and Caspase-3.

Renal-clearable and target-responsive near-infrared (NIR) fluorescent imaging probes have been promising for in vivo diagnosis of acute kidney injury (AKI). However, designing an imaging probe that is renal-clearable and concurrently responsive toward multiple molecular targets to facilitate early detection of AKI with improved sensitivity and specificity is challenging. Herein, by leveraging the receptor-mediated binding and retention effect along with enzyme-triggered fluorescence activation, we design and synthesize an activatable small-molecule NIR fluorescent probe (1-DPA2) using a "one-pot sequential click reaction" approach. 1-DPA2 can target both the externalized phosphatidylserine (PS) and active caspase-3 (Casp-3), two essential biomarkers of apoptosis, producing enhanced 808 nm NIR fluorescence and a high signal-to-background ratio (SBR) amenable to detecting the onset of cisplatin-induced AKI in mice as early as 24 h post-treatment with cisplatin. We not only monitor the gradual activation of Casp-3 in the kidney of mice upon AKI progression but also can report on the progressive recovery of kidney functions in AKI mice following N-acetyl-l-cysteine (NAC) therapy via real-time fluorescence imaging by 1-DPA2. This study demonstrates the ability of 1-DPA2 for longitudinal monitoring of renal cell apoptosis by concurrently targeting PS externalization and Casp-3 activation, which is efficient for early diagnosis of AKI and useful for prediction of potential drug nephrotoxicity as well as in vivo screening of anti-AKI drugs' efficacy.

Ratiometric Imaging of MMP-2 Activity Facilitates Tumor Detection Using Activatable Near-Infrared Fluorescent Semiconducting Polymer Nanoparticles.

Enzyme-activatable ratiometric near-infrared (NIR) fluorescent probes enabling noninvasive imaging of enzyme activity in vivo are promising for biomedical research; however, such probes with ratiometric fluorescence emissions both in NIR window under a single NIR light excitation are largely unexplored. Here, a quenched NIR fluorophore of Cy5.5 is integrated with NIR fluorescent poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT)-based semiconducting polymer nanoparticles (SPNs), and an αv ß3 integrin-targeting and matrix metalloproteinase-2 (MMP-2)-activatable ratiometric fluorescent probe (SPN-MMP-RGD) is developed. Under excitation at 660 nm, SPN-MMP-RGD shows "always-on" fluorescence of PCPDTBT (830 nm) and activatable fluorescence of Cy5.5 (690 nm) toward MMP-2, affording a remarkable ≈176-fold enhancement in fluorescence intensity ratio between 690 and 830 nm (I690 /I830 ) for sensitive detection of MMP-2 activity in vitro and in tumor cells. By virtue of ratiometric fluorescence imaging independently of probe's concentration, SPN-MMP-RGD can not only accurately report on MMP-2 levels regarding different tumor sizes, but also noninvasively delineate MMP-2-positive tiny gastric tumors metastasis in vivo. The authors' study reveals the potential of SPN-MMP-RGD for ratiometric fluorescence imaging of MMP-2 activity via combining two independent NIR fluorophores, which can be amenable for the design of other enzyme-activatable ratiometric NIR fluorescent probes for reliable in vivo imaging.

Sulfoximines Assisted Rh(III)-Catalyzed C-H Activation/Annulation Cascade to Synthesize Highly Fused Indeno-1,2-benzothiazines.

A facile access to highly fused tetracyclic indeno-1,2-benzothiazines has been established via a Rh(III)-catalyzed C-H bond activation and intramolecular annulation cascade between sulfoximides and all-carbon diazo indandiones. This strategy is characterized by the fact that the diazo coupling partners do not require preactivation, along with its high efficiency, broad substrate generality, and facile transformation. Particularly, the highly conjugated tetracyclic products demonstrate good optical properties and can easily enter cells to emit bright fluorescence for live cell imaging.

Noninvasive ratiometric fluorescence imaging of γ-glutamyltransferase activity using an activatable probe.

γ-Glutamyltranspeptidase (GGT) is an important aminopeptidase overexpressed in many malignant tumors, and accurate detection of its activity is useful for the diagnosis and treatment of tumors. Herein, we report a GGT-activatable ratiometric fluorescent probe (1) constructed by covalently linking an 'always-on' BODIPY fluorophore with a GGT-activatable near-infrared (NIR) fluorescent substrate. Upon interaction with GGT, the NIR fluorescence at 735 nm in probe 1 is significantly enhanced, while the fluorescence of BODIPY at 517 nm remains unchanged. Using BODIPY fluorescence as an internal standard, significantly enhanced ratiometric fluorescence between 735 nm and 517 nm could be achieved, allowing accurate detection of the activity of GGT in living subjects independent of probe concentration. We demonstrate that probe 1 is feasible for the evaluation of GGT levels in different tumor cells and differentiation of GGT-positive tumor cells from GGT-negative normal tissue cells. Moreover, probe 1 is further applied for the visualization of tumor via noninvasive ratiometric fluorescence imaging of GGT activity, which could facilitate the detection of GGT-positive tumor tissues and study of GGT-related pathological processes.

Enzyme-Mediated In Situ Self-Assembly Promotes In Vivo Bioorthogonal Reaction for Pretargeted Multimodality Imaging.

Pretargeted imaging has emerged as a promising approach to advance nuclear imaging of malignant tumors. Herein, we combine the enzyme-mediated fluorogenic reaction and in situ self-assembly with the inverse electron demand Diels-Alder (IEDDA) reaction to develop an activatable pretargeted strategy for multimodality imaging. The trans-cyclooctene (TCO) bearing small-molecule probe, P-FFGd-TCO, can be activated by alkaline phosphatase and in situ self-assembles into nanoaggregates (FMNPs-TCO) retained on the membranes, permitting to (1) amplify near-infrared (NIR) fluorescence (FL) and magnetic resonance imaging (MRI) signals, and (2) enrich TCOs to promote IEDDA ligation. The Gallium-68 (68 Ga) labeled tetrazine can readily conjugate the tumor-retained FMNPs-TCO to enhance radioactivity uptake in tumors. Strong NIR FL, MRI, and positron emission tomography (PET) signals are concomitantly achieved, allowing for pretargeted multimodality imaging of ALP activity in HeLa tumor-bearing mice.

NIR Scaffold Bearing Three Handles for Biocompatible Sequential Click Installation of Multiple Functional Arms.

Near-infrared (NIR) probes are ideal for fluorescence labeling and imaging of biological targets in living animals. However, the instability of common NIR dyes hampers the construction of NIR probes bearing multiple functional components such as biomolecules for specific targeting and imaging reagents for multimodality imaging. To overcome these limitations, we designed a novel NIR scaffold bearing two terminal alkynes as clickable handles and a chloride on the heptamethine backbone that allows nucleophilic substitution with an azide to generate the third clickable handle. This unique scaffold allows for facile installation of multiple functional arms for the construction of multifunctional NIR probes. Various biomacromolecules or imaging reagents can be introduced to the NIR scaffold by sequential one-pot click reactions under biocompatible conditions. The preclickable handle chloride on the NIR backbone does not interfere with the initial click reactions, and it can be easily transformed into an azide for a following click reaction. On the basis of this unique NIR scaffold, we developed a highly efficient method to construct diverse NIR probes containing multiple functional biomolecules including peptides, antibodies, nucleic acids, and NIR/PET (positron emission tomography) dual-modality imaging probes bearing tumor-targeting groups. NIR imaging or multimodality imaging using these probes was performed on live cells or tumor models on living mice.