Bright Aggregation-Induced-Emission Dots for Targeted Synergetic NIR-II Fluorescence and NIR-I Photoacoustic Imaging of Orthotopic Brain Tumors

Multimodal Contrast Agents for Optoacoustic Brain Imaging in Small Animals

Optoacoustic (photoacoustic) imaging has demonstrated versatile applications in biomedical research, visualizing the disease pathophysiology and monitoring the treatment effect in an animal model, as well as toward applications in the clinical setting. Given the complex disease mechanism, multimodal imaging provides important etiological insights with different molecular, structural, and functional readouts in vivo. Various multimodal optoacoustic molecular imaging approaches have been applied in preclinical brain imaging studies, including optoacoustic/fluorescence imaging, optoacoustic imaging/magnetic resonance imaging (MRI), optoacoustic imaging/MRI/Raman, optoacoustic imaging/positron emission tomography, and optoacoustic/computed tomography. There is a rapid development in molecular imaging contrast agents employing a multimodal imaging strategy for pathological targets involved in brain diseases. Many chemical dyes for optoacoustic imaging have fluorescence properties and have been applied in hybrid optoacoustic/fluorescence imaging. Nanoparticles are widely used as hybrid contrast agents for their capability to incorporate different imaging components, tunable spectrum, and photostability. In this review, we summarize contrast agents including chemical dyes and nanoparticles applied in multimodal optoacoustic brain imaging integrated with other modalities in small animals, and provide outlook for further research.

Dithieno[3,2-b:2',3'-d]silole-based conjugated polymers for bioimaging in the short-wave infrared region

The short-wave infrared window (SWIR, 900–1700 nm) fluorescence imaging has been demonstrated to have excellent imaging performance in signal/noise ratio and tissue penetration compared to the conventional NIR biological window (NIR-I, 700–900 nm). Conventional organic SWIR fluorescent materials still suffer from low fluorescence quantum efficiency. In this work, a donor unit with sp³ hybrid configuration and an acceptor unit with small hindered alkyl side chains are employed to construct donor–acceptor (D–A) type conjugated polymers P1 and P2, which were substituted with one or two fluorine atoms. These structural features can alleviate the aggregation-caused quenching (ACQ) and contribute to charge transfer, resulting in a significantly improved fluorescence quantum efficiency. The SWIR fluorescent quantum efficiencies of P1 and P2 nanoparticles are 3.4% and 4.4%, respectively, which are some of the highest for organic SWIR fluorophores reported so far. Excellent imaging quality has been demonstrated with P2 nanoparticles for SWIR imaging of the vascular system of nude mice. The results indicate that our design strategy of introducing sp³ hybrid configuration and small hindered alkyl side chains to fabricate conjugated polymers is efficient in improving the fluorescent quantum efficiency as SWIR fluorescent imaging agents for potential clinical practice.

A D–A type polymer with a SWIR fluorescence quantum efficiency of 4.4% was obtained after structural optimization.

Photochemical Synthesis of Nonplanar Small Molecules with Ultrafast Nonradiative Decay for Highly Efficient Phototheranostics

There has been much recent progress in the development of photothermal agents (PTAs) for biomedical and energy applications. Synthesis of organic PTAs typically involves noble metal catalysts and high temperatures. On the other hand, photochemical synthesis, as an alternative and green chemical technology, has obvious merits such as low cost, energy efficiency, and high yields. However, photochemical reactions have rarely been employed for the synthesis of PTAs. Herein, a facile and high-yield photochemical reaction is exploited for synthesizing nonplanar small molecules (NSMs) containing strong Michler's base donors and a tricyanoquinodimethane acceptor as high-performance PTAs. The synthesized NSMs show interesting photophysical properties including good absorption for photons of over 1000 nm wavelength, high near-infrared extinction coefficients, and excellent photothermal performance. Upon assembling the NSMs into nanoparticles (NSMN), they exhibit good biocompatibility, high photostability, and excellent photothermal conversion efficiency of 75%. Excited-state dynamic studies reveal that the NSMN has ultrafast nonradiative decay after photoexcitation. With these unique properties, the NSMN achieves efficient in vivo photoacoustic imaging and photothermal tumor ablation. This work demonstrates the superior potential of photochemical reactions for the synthesis of high-performance molecular PTAs.

Add the Finishing Touch: Molecular Engineering of Conjugated Small Molecule for High-Performance AIE Luminogen in Multimodal Phototheranostics

Phototheranostics based on luminogens with aggregation-induced emission (AIE) characteristics is captivating increasing research interest nowadays. However, AIE luminogens are inherently featured by inferior absorption coefficients (ε) resulting from the distorted molecular geometry. Besides, molecular innovation of long-wavelength light-excitable AIE luminogens with highly efficient phototheranostic outputs is an appealing yet significantly challenging task. Herein, on the basis of a fused-ring electron acceptor-donator-acceptor (A-D-A) type molecule (IDT) with aggregation-caused quenching (ACQ) properties, molecular engineering smoothly proceeds and successfully yields a novel AIE luminogen (IDT-TPE) via simply modifying tetraphenylethene (TPE) moieties on the sides of IDT backbone. The AIE tendency endows IDT-TPE nanoparticles with enhanced fluorescence brightness and far superior fluorescence imaging performance to IDT nanoparticles for mice tumors. Moreover, IDT-TPE nanoparticles exhibit near-infrared light-excitable features with a high ε of 8.9 × 10⁴ m^-1 cm^-1 , which is roughly an order of magnitude higher than that of most previously reported AIE luminogens. Combining with their reactive oxygen species generation capability and extremely high photothermal conversion efficiency (59.7%), IDT-TPE nanoparticles actualize unprecedented performance in multimodal phototheranostics. This study thus brings useful insights into the development of versatile phototheranostic materials with great potential for practical cancer theranostics.

Au-Doped Ag2 Te Quantum Dots with Bright NIR-IIb Fluorescence for In Situ Monitoring of Angiogenesis and Arteriogenesis in a Hindlimb Ischemic Model

Fluorescence located in 1500-1700 nm (denoted as the near-infrared IIb window, NIR-IIb) has drawn great interest for bioimaging, owing to its ultrahigh tissue penetration depth and spatiotemporal resolution. Therefore, NIR-IIb fluorescent probes with high photoluminescence quantum yield (PLQY) and stability along with high biocompatibility are urgently pursued. Herein, a novel NIR-IIb fluorescent probe of Au-doped Ag₂ Te (Au:Ag₂ Te) quantum dots (QDs) is developed via a facile cation exchange method. The Au dopant concentration in the Ag₂ Te QDs is tunable from 0% to 10% by controlling the ratio of supplied Au precursor to Ag₂ Te QDs, resulting in a wide range of PL emission in the NIR-IIb window and a much-enhanced PL intensity. After surface modification, the Au:Ag₂ Te QDs possess bright NIR-IIb emission, high colloidal stability and photostability, and decent biocompatibility. Further, in vivo monitoring of the process of angiogenesis and arteriogenesis in an ischemic hindlimb is successfully performed.

NIR-II cell endocytosis-activated fluorescent probes for in vivo high-contrast bioimaging diagnostics

Fluorescence probes have great potential to empower bioimaging, precision clinical diagnostics and surgery. However, current probes are limited to in vivo high-contrast diagnostics, due to the substantial background interference from tissue scattering and nonspecific activation in blood and normal tissues. Here, we developed a kind of cell endocytosis-activated fluorescence (CEAF) probe, which consists of a hydrophilic polymer unit and an acid pH-sensitive small-molecule fluorescent moiety that operates in the "tissue-transparent" second near-infrared (NIR-II) window. The CEAF probe stably presents in the form of quenched nanoaggregates in water and blood, and can be selectively activated and retained in lysosomes through cell endocytosis, driven by a synergetic mechanism of disaggregation and protonation. In vivo imaging of tumor and inflammation with a passive-targeting and affinity-tagged CEAF probe, respectively, yields highly specific signals with target-to-background ratios over 15 and prolonged observation time up to 35 hours, enabling positive implications for surgical, diagnostic and fundamental biomedical studies.

Dynamic nanoassembly-based drug delivery system (DNDDS): Learning from nature

Dynamic nanoassembly-based drug delivery system (DNDDS) has evolved from being a mere curiosity to emerging as a promising strategy for high-performance diagnosis and/or therapy of various diseases. However, dynamic nano-bio interaction between DNDDS and biological systems remains poorly understood, which can be critical for precise spatiotemporal and functional control of DNDDS in vivo. To deepen the understanding for fine control over DNDDS, we aim to explore natural systems as the root of inspiration for researchers from various fields. This review highlights ingenious designs, nano-bio interactions, and controllable functionalities of state-of-the-art DNDDS under endogenous or exogenous stimuli, by learning from nature at the molecular, subcellular, and cellular levels. Furthermore, the assembly strategies and response mechanisms of tailor-made DNDDS based on the characteristics of various diseased microenvironments are intensively discussed. Finally, the current challenges and future perspectives of DNDDS are briefly commented.

A Small-Molecule Diketopyrrolopyrrole-Based Dye for in vivo NIR-IIa Fluorescence Bioimaging

Organic small-molecule fluorophores with near-infrared IIa (NIR-IIa) emission have great potential in pre-clinical detection and inoperative imaging due to the high-spatial resolution and deep penetration. However, developments of the NIR-IIa fluorophores are still facing considerable challenges. In this work, a series of diketopyrrolopyrrole (DPP)-based fluorophores were designed and synthesized. Subsequently, nanomaterial T25@F127 with significant NIR-IIa emission properties was rationally prepared by encapsulating DPP-based fluorophore T25, and was selected for fluorescence angiography and cerebral vascular microscopic imaging with nearly 800 μm penetrating depth and excellent signal-background ratio of 4.07 and 2.26 (at 250 and 400 μm), respectively. Furthermore, the nanomaterial T25@cRGD with tumor targeting ability can image tiny metastatic tumor on intestine with a small size of 0.3 mm×1.0 mm and high-spatial resolution (SBR=3.84). This study demonstrates that the nanomaterials which encapsulated T25 behave as excellent NIR-IIa fluorescence imaging agents and have a great potential for in vivo biological application.

Dramatically Enhanced and Red-shifted Photoluminescence Achieved by Introducing an Electron-withdrawing Group into a Non-traditional Luminescent Small Organic Compound

Small organic compounds without any traditional fluorescent chromophores are generally non-emissive, and only very few are reported to emit weak blue fluorescence. Here we synthesized a non-traditional luminescent small organic compound N-(2,2,2-trifluoroethyl)acrylamide (TFAM) with dramatically enhanced and red-shifted photoluminescence by introducing a strong electron-withdrawing group into acrylamide (AM). Very impressively, TFAM emits cyan (472 nm) and yellow-green (560 nm) fluorescence in solutions and solid state, respectively. TFAM also shows aggregation-induced emission enhancement (AIEE) and excitation-dependent fluorescence (EDF) characteristics, as well as temperature and metal cations-responsive fluorescence. Theoretical calculations show that the introduction of electron-withdrawing group leads to a lower energy gap between the HOMO-LUMO energy levels in TFAM than in AM. And strong cooperative hydrogen bonds are formed in TFAM molecules, resulting in rigidification of molecular conformations. The study provides a strategy for preparing non-traditional luminescent compounds with enhanced and red-shifted photoluminescence.

Antibacterial AIE polycarbonates endowed with selective imaging capabilities by adjusting the electrostaticity of the mixed-charge backbone

Combining rapid microbial discrimination with antibacterial properties, multi-functional biomacromolecules allow the timely diagnosis and effective treatment of infectious diseases. Through a two-step approach involving organocatalytic ring-opening copolymerization and thiol-ene modification, aggregation-induced emission (AIE) polycarbonates decorated with tertiary amines were prepared. After being ionized using acetic acid, the obtained cationic AIE polycarbonate with excellent water solubility showed bacteria imaging capabilities and antibacterial activities toward both Gram-positive S. aureus and Gram-negative E. coli. It was indicated via scanning electron microscope images that the bactericidal mechanism involved membrane lysis, consistent with most cationic polymers. Through further co-grafting carboxyl and tertiary amine groups, mixed-charge AIE polycarbonates were obtained. The isoelectric points of such mixed-charge AIE polycarbonates could be simply tuned based on the grafting ratio of positive and negative moieties. Compared with the cationic AIE polycarbonate, mixed-charge AIE polycarbonates allowed the rapid and selective imaging of S. aureus, but not E. coli. The selectivity probably arose from the lower binding forces between the mixed-charge AIE polycarbonates and the low-negative-charge components of the E. coli surface. Therefore, these biodegradable polycarbonates, which integrated selective bacteria imaging and antibiotic abilities, potentially suggest a precision medicine approach for infectious diseases. The overall synthesis approach and mixed-charge AIE polycarbonates provide new references for the design and application of bio-related AIE polymers.

Metabolizable Near-Infrared-II Nanoprobes for Dynamic Imaging of Deep-Seated Tumor-Associated Macrophages in Pancreatic Cancer

Tumor-associated macrophages (TAMs) play a crucial part in cancer evolution. Dynamic imaging of TAMs is of great significance for treatment outcome evaluation and precision tumor therapy. Currently, most fluorescence nanoprobes tend to accumulate in the liver and are difficult to metabolize, which leads to strong background signals and inadequate imaging quality of TAMs nearby the liver such as pancreatic cancer. Herein, we aim to develop metabolizable dextran-indocyanine green (DN-ICG) nanoprobes in the second near-infrared window (NIR-II, 1 000-1 700 nm) for dynamic imaging of TAMs in pancreatic cancer. Compared to free ICG, the NIR-II fluorescence intensity of DN-ICG nanoprobes increased by 279% with significantly improved stability. We demonstrated that DN-ICG nanoprobes could specifically target TAMs through the interaction of dextran with specific ICAM-3-grabbing nonintegrin related 1 (SIGN-R1), which were highly expressed in TAMs. Subsequently, DN-ICG nanoprobes gradually metabolized in the liver yet remained in pancreatic tumor stroma in mouse models, achieving a high signal-to-background ratio (SBR = 7) in deep tissue (∼0.5 cm) NIR-II imaging of TAMs. Moreover, DN-ICG nanoprobes could detect dynamic changes of TAMs induced by low-dose radiotherapy and zoledronic acid. Therefore, the highly biocompatible and biodegradable DN-ICG nanoprobes harbor great potential for precision therapy in pancreatic cancer.

Unlocking the power of optical imaging in the second biological window: Structuring near-infrared II materials from organic molecules to nanoparticles

Biomedical imaging techniques play a crucial role in clinical diagnosis, surgical intervention, and prognosis. Fluorescence imaging in the second biological window (second near-infrared [NIR-II]; 1000-1700 nm) has attracted attention recently. NIR-II fluorescence imaging offers unique advantages in terms of reduced photon scattering, deep tissue penetration, high sensitivity, and many others. A host of materials, including small organic molecules, single-walled carbon nanotubes, polymeric and rare-earth-doped nanoparticles, have been explored as NIR-II emitting fluorescent probes. Efficient and viable approaches to design and develop fluorescence probes with tunable photophysical properties without compromising other key features are of paramount importance. Various chemical strategies are explored to increase the quantum yield of these imaging agents without compromising their spatiotemporal resolution, specificity, and tissue penetration capabilities. This review summarizes the strategies implemented to design and synthesize NIR-II emitting nanoparticles and small organic molecule-based fluorescent probes for applications in the biomedical field. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

Starlike polymer brush-based ultrasmall nanoparticles with simultaneously improved NIR-II fluorescence and blood circulation for efficient orthotopic glioblastoma imaging

Fluorescence imaging (FI) in the second near-infrared region (NIR-II, 1000-1700 nm) has attracted great attention for brain tumor imaging due to its deep penetration and high resolution. However, traditional NIR-II organic fluorescent nanoparticles (NPs) are usually hindered by uncontrolled large size (~30-100 nm), marked aggregation-caused quenching (ACQ) effect, and limited blood circulation (~1-3 h), which have great impact on efficient NIR-II FI of deep brain tumors. Herein, starlike polymer brush-based ultrasmall TQFP-10 NPs, with bright NIR-II fluorescence, prolonged blood circulation, and enhanced tumor accumulation, are facilely prepared for efficient orthotopic glioblastoma (GBM) imaging. Compared with traditional method prepared NPs (physically coated TQF@NPs and PEG modified TQF-PEG_5K NPs), the ultrasmall (~8 nm) TQFP-10 NPs display a higher NIR-II fluorescence QY (1.9%), which is 2.1- and 3.8-fold higher than TQF@NPs (0.9%) and TQF-PEG_5K NPs (0.5%), respectively. In addition, TQFP-10 NPs present a 10.6-fold higher blood circulation half-life (t_1/2 = 8.5 h) than that of TQF-PEG_5K NPs. Consequently, TQFP-10 NPs exhibit 4.2- and 33-fold higher maximal tumor to normal tissue ratio in subcutaneous and in situ NIR-II FI of GBM, respectively, than TQF@NPs and TQF-PEG_5K NPs, attractively realizing GBM imaging. This work provides a general strategy for constructing ultrasmall NIR-II fluorescent NPs with simultaneously improved NIR-II fluorescence and blood circulation for efficient brain tumor imaging.

Recent advances in colorimetry/fluorimetry-based dual-modal sensing technologies

Tailored to the increasing demands for sensing technologies, the fabrication of dual-modal sensing technologies through combining two signal transduction channels into one method has been proposed and drawn considerable attention. The integration of two sensing signals not only promotes the analytical efficiency with reduced assumption, but also improves the analytical performances with enlarged detection linear range, enhanced accuracy, and boosted application flexibility. The two top-rated output signals for developing dual-modal sensors are colorimetric and fluorescent signals because of their outstanding merits for point of care applications and real-time sensitive sensing. Given the rapid development of material chemistry and nanotechnology, the recent decade has witnessed great advance in colorimetric/fluorimetric signal based dual-modal sensing technologies. The new sensing strategy leads to a broad avenue for various applications in disease diagnosis, environmental monitoring and food safety because of the complementary and synergistic effects of the two output signals. In this state-of-the-art review, we comprehensively summarize different types of colorimetric/fluorimetric dual-modal sensing methods by highlighting representative research in the last 5 years, digging into their sensing methodologies, particularly the working principles of the signal transduction systems. Then, the challenges and future prospects for boosting further development of this research field are discussed.

Rational design of high performance nanotheranostics for NIR-II fluorescence/magnetic resonance imaging guided enhanced phototherapy

Nanotheranostics, which can provide great insight into cancer therapy, has been deemed as a promising technology to settle the unmet medical needs. The rational design of high performance nanotheranostics with multiple complementary imaging features and satisfactory therapeutic efficacy is particularly valuable. Herein, versatile nanotheranostic agents DPPB-Gd-I NPs were fabricated by using gadolinium-diethylenetriaminepentaacetic acid chelates and an iodine-decorated copolymer as encapsulation matrixes to encapsulate a polymer DPPB through one-step nanoprecipitation. We have demonstrated that such nanoagents are able to efficiently damage tumors under single dose injection and NIR laser illumination conditions due to the enhanced photodynamic therapy and enhanced photothermal therapy (the tumor inhibition rate was as high as 94.5%). Moreover, these nanoagents can be utilized as dual-modal NIR-II fluorescence/magnetic resonance imaging probes for tumor diagnosis with high sensitivity, deep tissue penetration, and excellent spatial resolution. Overall, this work offers a powerful tactic to fabricate high performance nanotheranostics for clinical application.

Organic optical agents for image-guided combined cancer therapy

As a promising non-invasive treatment method, phototherapy has attracted extensive attention in the field of combined cancer therapy. Among various optical agents, organic ones have been considered as a promising clinical phototheranostic agent due to its high safety and non-toxic property. In addition, due to the clear structure, facile processability, organic optical agents can be easily endowed with multiple imaging and phototherapeutic functions, significantly simplifying the relatively complex system of imaging-guided combined cancer therapy. This review summarizes the recent research on organic optical agents in imaging-guided combined cancer therapy. The application of organic optical agents in a variety of combined cancer therapeutic modes guided by imaging are introduced respectively, including photodynamic and photothermal combined therapy, phototherapy-combined cancer chemotherapy, and phototherapy-combined cancer immunotherapy. Finally, the concluding remarks and the future prospects are discussed.

One-for-All Phototheranostic Agent Based on Aggregation-Induced Emission Characteristics for Multimodal Imaging-Guided Synergistic Photodynamic/Photothermal Cancer Therapy

Phototheranostics represents a promising direction for modern precision medicine, which has recently received considerable attention for cancer research. The ingenious integration of all phototheranostic modalities in a single molecule with precise spatial colocalization is a tremendously challenging task, which mainly arises from the complexity of molecular design and energy dissipation. Reports on a single molecular one-for-all theranostic agent are still very rare. Herein, we designed two novel aggregation-induced emission (AIE)-active fluorogens (AIEgens, named DPMD and TPMD) with a cross-shaped donor-acceptor structure via a facile synthetic method and constructed versatile nanoparticles (NPs) by encapsulating AIEgen with an amphiphilic polymer. The AIEgen TPMD with a twisted structure, high donor-acceptor (D-A) strength, small singlet-triplet energy gap, and abundant intramolecular rotators and vibrators was selected as an ideal candidate for balancing and utilizing the radiative and nonradiative energy dissipations. Notably, TPMD NPs simultaneously possess adequate near-infrared (NIR) fluorescence emission at 821 nm for fluorescence imaging, effective reactive oxygen species generation for photodynamic therapy (PDT), and outstanding photothermal effect for photoacoustic imaging, photothermal imaging, and photothermal therapy (PTT), which demonstrates the superior potential of AIE NPs in multimodal imaging-guided synergistic PDT/PTT therapy.

Construction of nanomaterials as contrast agents or probes for glioma imaging

Malignant glioma remains incurable largely due to the aggressive and infiltrative nature, as well as the existence of blood-brain-barrier (BBB). Precise diagnosis of glioma, which aims to accurately delineate the tumor boundary for guiding surgical resection and provide reliable feedback of the therapeutic outcomes, is the critical step for successful treatment. Numerous imaging modalities have been developed for the efficient diagnosis of tumors from structural or functional aspects. However, the presence of BBB largely hampers the entrance of contrast agents (Cas) or probes into the brain, rendering the imaging performance highly compromised. The development of nanomaterials provides promising strategies for constructing nano-sized Cas or probes for accurate imaging of glioma owing to the BBB crossing ability and other unique advantages of nanomaterials, such as high loading capacity and stimuli-responsive properties. In this review, the recent progress of nanomaterials applied in single modal imaging modality and multimodal imaging for a comprehensive diagnosis is thoroughly summarized. Finally, the prospects and challenges are offered with the hope for its better development.

Near-infrared Fluorophores for Thrombosis Diagnosis and Therapy

Thrombosis is an adverse physiological event wherein the resulting thrombus and thrombus-induced diseases collectively result in high morbidity and mortality rates. Currently, nano-medicines that incorporate fluorophores emitting in the near-infrared-I (NIR-I, 700-900 nm) spectral region into their systems have been adopted to afford thrombosis theranostics. However, several unsolved problems such as limited penetration depth and image quality severely impede further applications of such nano-medicine systems. Fortunately, the ability to incorporate fluorophores emitting in the NIR-II (1000-1700 nm) window into nano-medicine systems can unambiguously identify biological processes with high signal-to-noise, deep tissue penetration depth, and high image resolution. Considering the inherently favorable properties of NIR-II fluorophores, we believe such have enormous potential to quickly become incorporated into nano-medicine systems for thrombosis theranostics. In this review, we i) discuss the development of NIR fluorescence as an imaging modality and fluorescent agents; ii) comprehensively summarize the recent development of NIR-I fluorophore-based nano-medicine systems for thrombosis theranostics; iii) highlight the state-of-the-art NIR-II fluorophores that have been designed for the specific purpose of affording thrombotic diagnosis; iv) speculate on possible forward avenues for the use of NIR-II fluorophores towards thrombosis diagnosis and therapy; and v) discuss the potential for their clinical translation.

Harnessing Hypoxia-Dependent Cyanine Photocages for In Vivo Precision Drug Release

Photocaging holds promise for the precise manipulation of biological events in space and time. However, current near-infrared (NIR) photocages are oxygen-dependent for their photolysis and lack of timely feedback regulation, which has proven to be the major bottleneck for targeted therapy. Herein, we present a hypoxia-dependent photo-activation mechanism of dialkylamine-substituted cyanine (Cy-NH) accompanied by emissive fragments generation, which was validated with retrosynthesis and spectral analysis. For the first time, we have realized the orthogonal manipulation of this hypoxia-dependent photocaging and dual-modal optical signals in living cells and tumor-bearing mice, making a breakthrough in the direct spatiotemporal control and in vivo feedback regulation. This unique photoactivation mechanism overcomes the limitation of hypoxia, which allows site-specific remote control for targeted therapy, and expands the photo-trigger toolbox for on-demand drug release, especially in a physiological context with dual-mode optical imaging under hypoxia.

Noninvasive In Vivo Imaging and Monitoring of 3D-Printed Polycaprolactone Scaffolds Labeled with an NIR Region II Fluorescent Dye

Significant progress has been made in fabricating porous scaffolds with ultrafine fibers for tissue regeneration. However, the lack of noninvasive tracking methods in vivo makes it impossible to track the fate of such scaffolds in situ. The development of near-infrared region II (NIR-II, 1000-1700 nm) dyes provides the possibility of performing noninvasive visualization with deep-tissue penetration and high spatial resolution in vivo. Herein, we developed a polycaprolactone (PCL) ink containing the small organic NIR-II dye SY-1030 and the fluorescently labeled macromolecular dye SY-COO-PCL and fabricated high-resolution NIR-II active scaffolds via electrohydrodynamic jet (EHDJ) printing. All printed scaffolds subcutaneously implanted in mice were clearly imaged one week after the operation. Compared with scaffolds containing SY-1030, the fluorescence intensity emitted from scaffolds containing SY-COO-PCL can be tracked for up to three weeks. Moreover, the image quality can be optimized by adjusting the dye concentration, laser power, and exposure time. The advantage of such NIR-II active scaffolds is evidenced by the lower dye concentration, longer tracking period, and better in vivo stability. We also demonstrated the biocompatibility and biodegradability of the scaffolds containing SY-COO-PCL over a 3-month period. The developed NIR-II active scaffolds have potential applications in biopolymer implant tracking, tissue reconstruction monitoring, and target-position-based drug delivery.

Engineering Oxaliplatin Prodrug Nanoparticles for Second Near-Infrared Fluorescence Imaging-Guided Immunotherapy of Colorectal Cancer

Colorectal cancer (CRC) ranks as the third common and the fourth lethal cancer type worldwide. Immune checkpoint blockade therapy demonstrates great efficacy in a subset of metastatic CRC patients, but precise activation of the antitumor immune response at the tumor site is still challenging. Here a versatile prodrug nanoparticle for second near-infrared (NIR-II) fluorescence imaging-guided combinatory immunotherapy of CRC is reported. The prodrug nanoparticles are constructed with a polymeric oxaliplatin prodrug (PBOXA) and a donor-spacer-acceptor-spacer-donor type small molecular fluorophore TQTCD. The later displays large Stokes shift (>300 nm), fluorescence emission over 1000 nm, and excellent photothermal conversion performance for NIR-II fluorescence imaging-guided photothermal therapy (PTT). The prodrug nanoparticles show seven times higher intratumoral OXA accumulation than free oxaliplatin. TQTCD-based PTT and PBOXA-induced chemotherapy trigger immunogenic cell death of the tumor cells and elicit antitumor immune response in a spatiotemporally controllable manner. Further combination of the prodrug nanoparticle-based PTT/chemotherapy with programmed death ligand 1 blockade significantly promotes intratumoral infiltration of the cytotoxic T lymphocytes and eradicates the CRC tumors. The NIR-II fluorescence imaging-guided immunotherapy may provide a promising approach for CRC treatment.

Biologically Excretable Aggregation-Induced Emission Dots for Visualizing Through the Marmosets Intravitally: Horizons in Future Clinical Nanomedicine

Superb reliability and biocompatibility equip aggregation-induced emission (AIE) dots with tremendous potential for fluorescence bioimaging. However, there is still a chronic lack of design instructions of excretable and bright AIE emitters. Here, a kind of PEGylated AIE (OTPA-BBT) dots with strong absorption and extremely high second near-infrared region (NIR-II) PLQY of 13.6% is designed, and a long-aliphatic-chain design blueprint contributing to their excretion from an animal's body is proposed. Assisted by the OTPA-BBT dots with bright fluorescence beyond 1100 nm and even 1500 nm (NIR-IIb), large-depth cerebral vasculature (beyond 600 µm) as well as real-time blood flow are monitored through a thinned skull, and noninvasive NIR-IIb imaging with rich high-spatial-frequency information gives a precise presentation of gastrointestinal tract in marmosets. Importantly, after intravenous or oral administration, the definite excretion of OTPA-BBT dots from the body is demonstrated, which provides influential evidence of biosafety.

Smart On-Site Immobilizable Near-Infrared II Fluorescent Nanoprobes for Ultra-Long-Term Imaging-Guided Tumor Surgery and Photothermal Therapy

Accurate diagnosis and efficient treatment of tumors are highly significant in battling cancer. Near-infrared II (NIR-II) fluorescence imaging shows big promise for deep tumor visualization in living systems due to high temporal and spatial resolution and deep tissue penetration capability, whereas the development of efficient NIR-II probes for tumor theranostics still faces a huge challenge. Herein, we have designed and constructed intelligent mPEG₅₀₀₀-PCL₃₀₀₀-encapsulated NIR-II nanoprobe ZM1068-NPs that showed great chemical stability and excellent biocompatibility. With the merits of the strong fluorescence in the NIR-II region and prominent optical-thermal conversion efficiency, this probe was successfully used for NIR-II imaging-guided surgery and photothermal therapy of breast carcinoma in living mice. More notably, it was for the first time found that ZM1068 dyes could be covalently on-site-immobilized within tumors through the thiol-chlor nucleophilic substitution reaction, resulting in improved tumor accumulation and retention time. We thus envision that this probe may provide an attractive means for precise cancer diagnosis and treatment.

A Near-Infrared-II Polymer with Tandem Fluorophores Demonstrates Superior Biodegradability for Simultaneous Drug Tracking and Treatment Efficacy Feedback

NIR-II (1000-1700 nm) fluorescence imaging is continually attracting strong research interest. However, current NIR-II imaging materials are limited to small molecules with fast blood clearance and inorganic nanomaterials and organic conjugated polymers of poor biodegradability and low biocompatibility. Here, we report a highly biodegradable polyester carrying tandem NIR-II fluorophores as a promising alternative. The polymer encapsulated a platinum intercalator (56MESS, (5,6-dimethyl-1,10-phenanthroline) (1S,2S-diaminocyclohexane) platinum(II)) and was conjugated with both a cell-targeting RGD peptide and a caspase-3 cleavable peptide probe to form nanoparticles for simultaneous NIR-II and apoptosis imaging. In vitro, the nanoparticles were approximately 4-1000- and 1.5-10-fold more potent than cisplatin and 56MESS, respectively. Moreover, in vivo, they significantly inhibited tumor growth on a multidrug-resistant patient-derived mouse model (PDX^MDR). Finally, through label-free laser desorption-ionization mass spectrometry imaging (MALDI-MSI), in situ 56MESS release in the deeper tumors was observed. This work highlighted the use of biodegradable NIR-II polymers for monitoring drugs in vivo and therapeutic effect feedback in real-time.

A computational and experimental investigation of donor-acceptor BODIPY based near-infrared fluorophore for in vivo imaging

TD-DFT quantum calculation was performed to predict and/or illustrate the electronic transition, the related absorption and emission maxima of some pyrrole-difluoroboron derivatives with different electron donor-acceptor unit or π-conjugated degree. Upon the calculated results, a new near infrared (NIR) fluorophore (abbreviated as TPBD-BP) was designed and fabricated through linking triphenylamine and pyrrole-difluoroboron units to benzothiadiazole (BTD) backbone. The fluorescence of TPBD-BP in solid state centered at 932 nm, which was 985 nm for TPBD-BP nanoparticles (TPBD-BP dots) encapsulated in PEG-6000. The fluorescence of TPBD-BP in both solid state and dots exhibited off-peak tail emission to NIR-II region (extended to 1300 nm). The TPBD-BP dots showed excellent water solubility, biocompatibility and aggregation induced emission (AIE), which was suitable to be applied in vivo imaging. NIR-II emission signal of TPBD-BP dots can be observed in the reproductive organ of normal nude mice after tail vein injection. This attractive combination of computational and experimental investigation would help to develop new-typed small-molecular NIR fluorophores.

Long-wavelength visible to near infrared photoluminescence from carbon-bridged styrylstilbene and thiadiazole conjugates in organic and aqueous media

Donor–acceptor–donor conjugates composed of electron-donating carbon-bridged styrylstilbene (COPV2) and electron-accepting thiadiazole derivatives equipped with carbazolyl (Cz) terminators, Cz-COPV2-A-COPV2-Cz (A = benzothiadiazole (BTz), naphthobis(thiadiazole) (NTz), or benzobis(thiadiazole) (BBTz)), were newly synthesized and found to serve as efficient and stable long-wavelength photoluminescent dyes in organic and aqueous media. In particular, Cz-COPV2-BBTz-COPV2-Cz showed photoluminescence in the near infrared region (895–927 nm) with a photoluminescence quantum yield (PLQY) of up to 0.19 in cyclohexane and of 0.02–0.03 in THF/water mixtures. Its analogues with weaker acceptors, Cz-COPV2-BTz-COPV2-Cz and Cz-COPV2-NTz-COPV2-Cz, showed yellow to deep-red emission in organic solvents, with PLQYs of up to 0.71 in organic solvents and 0.45 in THF/water mixtures.

Efficient long-wavelength visible to NIR-emitting materials have been synthesized by use of rigid planar styrylstilbene as a donor component.

Near-infrared small molecule coupled with rigidness and flexibility for high-performance multimodal imaging-guided photodynamic and photothermal synergistic therapy

Photodynamic therapy (PDT) synergized photothermal therapy (PTT) shows superior clinical application prospects than single PDT or PTT. On the other hand, multimodal imaging can delineate comprehensive information about the lesion site and thus help to improve therapy accuracy. However, integrating all these functions into one single molecule is challenging, let alone balancing and maximizing the efficacy of each function. Herein, a near-infrared (NIR) small molecule (ETTC) with an "acceptor-donor-acceptor" structure was designed and synthesized by coupling rigity and flexibility to simultaneously achieve NIR-II fluorescence imaging (NIR-II FLI), photoacoustic imaging, PTT and PDT. The efficacy of each functionality was well balanced and optimized (NIR-II quantum yield: 3.0%; reactive oxygen species generation: 3.2-fold higher than ICG; photothermal conversion efficiency: 52.8%), which may be attributed to the coupling of the rigid and flexible structures in ETTC to tactically manipulate the energy dissipation paths (non-radiative against radiative decay). As a proof-of-concept, under the effective guidance of local-tumor imaging by PA and whole-body imaging by NIR-II FL, complete tumor eradication was achieved via PDT and PTT combinational therapy. This work provides a novel perspective into conceiving and developing single molecule for efficient versatile biomedical applications.

Ultrabright NIR-II Emissive Polymer Dots for Metastatic Ovarian Cancer Detection

Intraoperative diagnosis of metastatic tumors is of significant importance to the treatment of ovarian cancer. NIR-II fluorescence imaging holds great promise for facile detection of tumor in situ with high sensitivity and resolution. Herein, a kind of NIR-II fluorescent polymer dots (NIR-II Pdots) with high brightness is developed for real-time detection of metastatic ovarian cancer via NIR-II fluorescence imaging. The NIR-II Pdots are constructed via the self-assembly of NIR-II emissive aggregation induced emission luminogens (NIR-II AIEgens) and poly (styrene)-graft-poly(ethylene glycol) in water. Such NIR-II Pdots show very high fluorophore contents of nearly 30% and high quantum yield of 5.4% at emission maximum near 1020 nm. Further modification of the NIR-II Pdots with targeting peptides yields NIR-II Pdots-GnRH, which can afford enhanced affinity of NIR-II Pdots to ovarian cancer. Upon intravenous injection of the NIR-II Pdots, whole-body organs and vessels, peritoneal and lymphatic metastases of ovarian cancer are clearly visualized by NIR-II fluorescence imaging. Under the guidance of NIR-II fluorescence imaging, the metastatic foci with the diameter down to ≈2 mm can be facilely eliminated. The results indicate preclinical potential value of the NIR-II Pdots for metastatic ovarian cancer detection.

Tiny 2D silicon quantum sheets: a brain photonic nanoagent for orthotopic glioma theranostics

We report that atomically thin two-dimensional silicon quantum sheets (2D Si QSs), prepared by a scalable approach coupling chemical delithiation and cryo-assisted exfoliation, can serve as a high-performance brain photonic nanoagent for orthotopic glioma theranostics. With the lateral size of approximately 14.0 nm and thickness of about 1.6 nm, tiny Si QSs possess high mass extinction coefficient of 27.5 L g^-1 cm^-1 and photothermal conversion efficiency of 47.2% at 808 nm, respectively, concurrently contributing to the best photothermal performance among the reported 2D mono-elemental materials (Xenes). More importantly, Si QSs with low toxicity maintain the trade-off between stability and degradability, paving the way for practical clinical translation in consideration of both storage and action of nanoagents. In vitro Transwell filter experiment reveals that Si QSs could effectively go across the bEnd.3 cells monolayer. Upon the intravenous injection of Si QSs, orthotopic brain tumors are effectively inhibited under the precise guidance of photoacoustic imaging, and the survival lifetime of brain tumor-bearing mice is increased by two fold. Atomically thin Si QSs with strong light-harvesting capability are expected to provide an effective and robust 2D photonic nanoplatform for the management of brain diseases.

Small Molecular NIR-II Fluorophores for Cancer Phototheranostics

Phototheranostics integrates deep-tissue imaging with phototherapy (containing photothermal therapy and photodynamic therapy), holding great promise in early diagnosis and precision treatment of cancers. Recently, second near-infrared (NIR-II) fluorescence imaging exhibits the merits of high accuracy and specificity, as well as real-time detection. Among the NIR-II fluorophores, organic small molecular fluorophores have shown superior properties in the biocompatibility, variable structure, and tunable emission wavelength than the inorganic NIR-II materials. What's more, some small molecular fluorophores also display excellent cytotoxicity when illuminated with the NIR laser. This review summarizes the progress of small molecular NIR-II fluorophores with different central cores for cancer phototheranostics in the past few years, focusing on the molecular structures and phototheranostic performances. Furthermore, challenges and prospects of future development toward clinical translation are discussed.

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Phototheranostics combines diagnostic imaging with phototherapy, showing broad applications in the early diagnosis and precise treatment of tumors

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Small molecular NIR-II fluorophores with good biocompatibility, tunable structure, high imaging quality, and excellent phototoxicity, have shown great potential for cancer phototheranostics

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Small molecular NIR-II fluorophores with different central cores for cancer phototheranostics are summarized, highlighting the design strategies and phototheranostic performances

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Challenges and prospects of future development toward clinical translation are discussed

Small Molecular NIR-II Fluorophores for Cancer Phototheranostics

Phototheranostics integrates deep-tissue imaging with phototherapy (containing photothermal therapy and photodynamic therapy), holding great promise in early diagnosis and precision treatment of cancers. Recently, second near-infrared (NIR-II) fluorescence imaging exhibits the merits of high accuracy and specificity, as well as real-time detection. Among the NIR-II fluorophores, organic small molecular fluorophores have shown superior properties in the biocompatibility, variable structure, and tunable emission wavelength than the inorganic NIR-II materials. What's more, some small molecular fluorophores also display excellent cytotoxicity when illuminated with the NIR laser. This review summarizes the progress of small molecular NIR-II fluorophores with different central cores for cancer phototheranostics in the past few years, focusing on the molecular structures and phototheranostic performances. Furthermore, challenges and prospects of future development toward clinical translation are discussed.

Revealing the Distribution of Aggregation-Induced Emission Nanoparticles via Dual-Modality Imaging with Fluorescence and Mass Spectrometry

Aggregation-induced emission nanoparticles (AIE NPs) are widely used in the biomedical field. However, understanding the biological process of AIE NPs via fluorescence imaging is challenging because of the strong background and poor penetration depth. Herein, we present a novel dual-modality imaging strategy that combines fluorescence imaging and label-free laser desorption/ionization mass spectrometry imaging (LDI MSI) to map and quantify the biodistribution of AIE NPs (TPAFN-F127 NPs) by monitoring the intrinsic photoluminescence and mass spectrometry signal of the AIE molecule. We discovered that TPAFN-F127 NPs were predominantly distributed in the liver and spleen, and most gradually excreted from the body after 5 days. The accumulation and retention of TPAFN-F127 NPs in tumor sites were also confirmed in a tumor-bearing mouse model. As a proof of concept, the suborgan distribution of TPAFN-F127 NPs in the spleen was visualized by LDI MSI, and the results revealed that TPAFN-F127 NPs were mainly distributed in the red pulp of the spleen with extremely high concentrations within the marginal zone. The in vivo toxicity test demonstrated that TPAFN-F127 NPs are nontoxic for a long-term exposure. This dual-modality imaging strategy provides some insights into the fine distribution of AIE NPs and might also be extended to other polymeric NPs to evaluate their distribution and drug release behaviors in vivo.

AIE-active polyelectrolyte based photosensitizers: the effects of structure on antibiotic-resistant bacterial sensing and killing and pollutant decomposition

A facile and effective multifunctional platform with high bacterial detection sensitivity, good antibacterial activity, and excellent dye decomposition efficiency holds great promise for wastewater treatment. To explore the design rationality and mechanism of material platforms with various integrated components into a single molecule for wastewater treatment applications, herein, four kinds of polyelectrolyte photosensitizers with aggregation-induced emission (AIE) fluorescent units are synthesized and systematically studied to investigate the structure-property relationship that influences the level of conjugation and the hydrophobicity-hydrophilicity balance. By improving the strength of the conjugation, the new AIE photosensitizers DBPVEs (including DBPVE-4 and DBPVE-6) generate a reactive oxygen species (ROS), and a decomposition efficiency of around 55% is obtained for dyes when they are exposed to DBPVEs under white light irradiation, which is higher than those of DBPEs (including DBPE-4 and DBPE-6). More importantly, owing to the longer and more flexible aliphatic chains of DBPVE-6 that facilitate efficient intercalation into cell membranes, the staining ability of DBPVE-6 for methicillin-resistant S. epidermidis (MRSE) is greatly enhanced as compared to that of DBPVE-4. It should be noted that the antibacterial experiment indicates that DBPVE-6 displays potent toxicity to MRSE with 99.9% killing efficiency under white light irradiation. This work provides essential theoretical and experimental guidance on the designing of new photosensitizers for wastewater treatment.

Millimeter-Deep Detection of Single Shortwave-Infrared-Emitting Polymer Dots through Turbid Media

Fluorescence imaging at longer wavelengths, especially in the shortwave-infrared (SWIR: 1000-1700 nm) region, leads to a substantial decrease in light attenuation, scattering, and background autofluorescence, thereby enabling enhanced penetration into biological tissues. The limited selection of fluorescent probes is a major bottleneck in SWIR fluorescence imaging. Here, we develop SWIR-emitting nanoparticles composed of donor-acceptor-type conjugated polymers. The bright SWIR fluorescence of the polymer dots (primarily attributable to their large absorption cross-section and high fluorescence saturation intensity (as high as 113 kW·cm^-2)) enables the unprecedented detection of single particles as small as 14 nm through millimeter-thick turbid media. Unlike most SWIR-emitting nanomaterials, which have an excited-state lifetime in the range of microseconds to milliseconds, our polymer dots exhibit a subnanosecond excited-state lifetime. These characteristics enable us to demonstrate new time-gated single-particle imaging with a high signal-to-background ratio. These findings expand the range of potential applications of single-particle deep-tissue imaging.

Upconversion NIR-II fluorophores for mitochondria-targeted cancer imaging and photothermal therapy

NIR-II fluorophores have shown great promise for biomedical applications with superior in vivo optical properties. To date, few small-molecule NIR-II fluorophores have been discovered with donor-acceptor-donor (D-A-D) or symmetrical structures, and upconversion-mitochondria-targeted NIR-II dyes have not been reported. Herein, we report development of D-A type thiopyrylium-based NIR-II fluorophores with frequency upconversion luminescence (FUCL) at ~580 nm upon excitation at ~850 nm. H4-PEG-PT can not only quickly and effectively image mitochondria in live or fixed osteosarcoma cells with subcellular resolution at 1 nM, but also efficiently convert optical energy into heat, achieving mitochondria-targeted photothermal cancer therapy without ROS effects. H4-PEG-PT has been further evaluated in vivo and exhibited strong tumor uptake, specific NIR-II signals with high spatial and temporal resolution, and remarkable NIR-II image-guided photothermal therapy. This report presents the first D-A type thiopyrylium NIR-II theranostics for synchronous upconversion-mitochondria-targeted cell imaging, in vivo NIR-II osteosarcoma imaging and excellent photothermal efficiency.

Dual-Mode Fluorescence and Magnetic Resonance Imaging by Perylene Diimide-Based Gd-Containing Magnetic Ionic Liquids

Bioimaging plays a key role in the diagnosis/treatment of diseases and in scientific research studies. Compared with single imaging techniques, dual-mode and multimode imaging techniques facilitate high accuracy. In this work, a perylene diimide (PDI)-based Gd-containing magnetic ionic liquid, Per-6-Diimi[Gd(NO₃)₄], is reported for dual-modal imaging, in which a Gd(III) complex was used for magnetic resonance imaging (MRI), while PDI was used for fluorescence imaging. Because of the difference in the biological microenvironment, there is a switch between dispersed and aggregated states of Per-6-Diimi[Gd(NO₃)₄] molecules in hydrophobic and hydrophilic media. When it was in the aqueous solution, the intensive π-π interaction of PDI cores made Per-6-Diimi[Gd(NO₃)₄] aggregates to form particles. The paramagnetic nanoparticles ensure prolonging the rotational correlation time, which results in a strong enhancement of MRI with a longitude relaxation coefficient of 14.94 mM^-1 s^-1. In an in vivo MRI experiment, the tumor site is imaged by MRI through the enhanced permeability and retention effect. However, when the molecule is present on the hydrophobic membrane of the cells, the dispersed Per-6-Diimi[Gd(NO₃)₄] showed good fluorescence imaging capabilities due to the high fluorescence quantum yield of PDI. Thus, the fluorescence imaging of cells can be carried out. Moreover, ex vivo fluorescence imaging of organs is performed after MRI. Per-6-Diimi[Gd(NO₃)₄] is enriched in the liver, kidneys, and tumors.

Self-Assembled Hybrid Nanocomposites for Multimodal Imaging-Guided Photothermal Therapy of Lymph Node Metastasis

Multimodal imaging-guided therapy holds great potential for precise theranostics of cancer metastasis. However, imaging agents enabling the convergence of complementary modalities with therapeutic functions to achieve perfect theranostics have been less exploited. This study reports the construction of a multifunctional nanoagent (FIP-^99mTc) that comprises Fe₃O₄ for magnetic resonance imaging, radioactive ^99mTc for single-photon-emission computed tomography, and IR-1061 to serve for the second near-infrared fluorescence imaging, photoacoustic imaging, and photothermal therapy treatment of cancer metastasis. The nanoagent possessed superior multimodal imaging capability with high sensitivity and resolution attributing to the complement of all the imaging modalities. Moreover, the nanoagent showed ideal photothermal conversion ability to effectively kill tumor cells at low concentration and power laser irradiation. In the in vivo study, FIP-^99mTc confirmed the fast accumulation and clear delineation of metastatic lymph nodes within 1 h after administration. Attributing to the efficient uptake and photothermal conversion, FIP-^99mTc could raise the temperature of metastatic lymph nodes to 54 °C within 10 min laser irradiation, so as to facilitate tumor cell ablation. More importantly, FIP-^99mTc not only played an active role in suppressing cancer growth in metastatic lymph nodes with high efficiency but also could effectively prevent further lung metastasis after resection of the primary tumor. This study proposes a simple but effective theranostic approach toward lymph node metastasis.

In Vivo Real-Time Pharmaceutical Evaluations of Near-Infrared II Fluorescent Nanomedicine Bound Polyethylene Glycol Ligands for Tumor Photothermal Ablation

Pharmaceutical evaluations of nanomedicines are of great significance for their further launch into industry and clinic. Near-infrared (NIR) fluorescence imaging plays essential roles in preclinical drug development by providing important insights into the biodistributions of drugs in vivo with deep tissue penetration and high spatiotemporal resolution. However, NIR-II fluorescence imaging has rarely been exploited for in vivo real-time pharmaceutical evaluations of nanomedicine. Herein, we developed a highly emissive NIR-II luminophore to establish a versatile nanoplatform to noninvasively monitor the in vivo metabolism of nanomedicines bound various polyethylene glycol (PEG) ligands in a real-time manner. An alternative D-A-D conjugated oligomer (DTTB) was synthesized to achieve NIR-II emission peaked at ∼1050 nm with high fluorescence QYs of 13.4% and a large absorption coefficient. By anchoring with the DTTB molecule, intrinsically fluorescent micelles were fabricated and bound with PEG ligands at various chain lengths. In vivo NIR-II fluorescence and photoacoustic imaging results revealed that an appropriate PEG chain length could effectively contribute to the longer blood circulation and better tumor targeting. In vivo therapeutic experiments also confirmed the optimized nanomedicines have efficient photothermal elimination of tumors and good biosafety. This work offered an alternative highly fluorescent NIR-II material and demonstrated a promising approach for real-time pharmaceutical evaluation of nanomedicine in vivo.