Precise Deciphering of Brain Vasculatures and Microscopic Tumors with Dual NIR‐II Fluorescence and Photoacoustic Imaging

Diagnostics of cerebrovascular structures and microscopic tumors with intact blood–brain barrier (BBB) significantly contributes to timely treatment of patients bearing neurological diseases. Dual NIR‐II fluorescence and photoacoustic imaging (PAI) is expected to offer powerful strength, including good spatiotemporal resolution, deep penetration, and large signal‐to‐background ratio (SBR) for precise brain diagnostics. Herein, biocompatible and photostable conjugated polymer nanoparticles (CP NPs) are reported for dual‐modality brain imaging in the NIR‐II window. Uniform CP NPs with a size of 50 nm are fabricated from microfluidics devices, which show an emission peak at 1156 nm with a large absorptivity of 35.2 L g^?1 cm^?1 at 1000 nm. The NIR‐II fluorescence imaging resolves hemodynamics and cerebral vasculatures with a spatial resolution of 23 µm at a depth of 600 µm. The NIR‐II PAI enables successful noninvasive mapping of deep microscopic brain tumors (<2 mm at a depth of 2.4 mm beneath dense skull and scalp) with an SBR of 7.2 after focused ultrasound‐induced BBB opening. This study demonstrates that CP NPs are promising contrast agents for brain diagnostics.     

NIR‐II‐Excited Intravital Two‐Photon Microscopy Distinguishes Deep Cerebral and Tumor Vasculatures with an Ultrabright NIR‐I AIE Luminogen

Intravital fluorescence imaging of vasculature morphology and dynamics in the brain and in tumors with large penetration depth and high signal‐to‐background ratio (SBR) is highly desirable for the study and theranostics of vascular‐related diseases and cancers. Herein, a highly bright fluorophore (BTPETQ) with long‐wavelength absorption and aggregation‐induced near‐infrared (NIR) emission (maximum at ≈700 nm) is designed for intravital two‐photon fluorescence (2PF) imaging of a mouse brain and tumor vasculatures under NIR‐II light (1200 nm) excitation. BTPETQ dots fabricated via nanoprecipitation show uniform size of around 42 nm and a high quantum yield of 19 ± 1% in aqueous media. The 2PF imaging of the mouse brain vasculatures labeled by BTPETQ dots reveals a 3D blood vessel network with an ultradeep depth of 924 µm. In addition, BTPETQ dots show enhanced 2PF in tumor vasculatures due to their unique leaky structures, which facilitates the differentiation of normal blood vessels from tumor vessels with high SBR in deep tumor tissues. Moreover, the extravasation and accumulation of BTPETQ dots in deep tumor (more than 900 µm) is visualized under NIR‐II excitation. This study highlights the importance of developing NIR‐II light excitable efficient NIR fluorophores for in vivo deep tissue and high contrast tumor imaging.     

Molecular Engineering of an Organic NIR‐II Fluorophore with Aggregation‐Induced Emission Characteristics for In Vivo Imaging

Design and synthesis of new fluorophores with emission in the second near‐infrared window (NIR‐II, 1000–1700 nm) have fueled the advancement of in vivo fluorescence imaging. Organic NIR‐II probes particularly attract tremendous attention due to excellent stability and biocompatibility, which facilitate clinical translation. However, reported organic NIR‐II fluorescent agents often suffer from low quantum yield and complicated design. In this study, the acceptor unit of a known NIR‐I aggregation‐induced emission (AIE) luminogen (AIEgen) is molecularly engineered by varying a single atom from sulfur to selenium, leading to redshifted absorption and emission spectra. After formulation of the newly prepared AIEgen, the resultant AIE nanoparticles (referred as L897 NPs) have an emission tail extending to 1200 nm with a high quantum yield of 5.8%. Based on the L897 NPs, noninvasive vessel imaging and lymphatic imaging are achieved with high signal‐to‐background ratio and deep penetration. Furthermore, the L897 NPs can be used as good contrast agents for tumor imaging and image‐guided surgery due to the high tumor/normal tissue ratio, which peaks at 9.0 ± 0.6. This work suggests a simple strategy for designing and manufacturing NIR‐II AIEgens and demonstrates the potential of NIR‐II AIEgens in vessel, lymphatic, and tumor imaging.     

Atomic‐Precision Gold Clusters for NIR‐II Imaging

Near‐infrared II (NIR‐II) imaging at 1100–1700 nm shows great promise for medical diagnosis related to blood vessels because it possesses deep penetration and high resolution in biological tissue. Unfortunately, currently available NIR‐II fluorophores exhibit slow excretion and low brightness, which prevents their potential medical applications. An atomic‐precision gold (Au) cluster with 25 gold atoms and 18 peptide ligands is presented. The Au₂₅ clusters show emission at 1100–1350 nm and the fluorescence quantum yield is significantly increased by metal‐atom doping. Bright gold clusters can penetrate deep tissue and can be applied in in vivo brain vessel imaging and tumor metastasis. Time‐resolved brain blood‐flow imaging shows significant differences between healthy and injured mice with different brain diseases in vivo. High‐resolution imaging of cancer metastasis allows for the identification of the primary tumor, blood vessel, and lymphatic metastasis. In addition, gold clusters with NIR‐II fluorescence are used to monitor high‐resolution imaging of kidney at a depth of 0.61 cm, and the quantitative measurement shows 86% of the gold clusters are cleared from body without any acute or long‐term toxicity at a dose of 100 mg kg^?1.     

Hierarchically Nanostructured Hybrid Platform for Tumor Delineation and Image‐Guided Surgery via NIR‐II Fluorescence and PET Bimodal Imaging

Bimodal imaging with fluorescence in the second near infrared window (NIR‐II) and positron emission tomography (PET) has important significance for tumor diagnosis and management because of complementary advantages. It remains challenging to develop NIR‐II/PET bimodal probes with high fluorescent brightness. Herein, bioinspired nanomaterials (melanin dot, mesoporous silica nanoparticle, and supported lipid bilayer), NIR‐II dye CH‐4T, and PET radionuclide ⁶⁴Cu are integrated into a hybrid NIR‐II/PET bimodal nanoprobe. The resultant nanoprobe exhibits attractive properties such as highly uniform tunable size, effective payload encapsulation, high stability, dispersibility, and biocompatibility. Interestingly, the incorporation of CH‐4T into the nanoparticle leads to 4.27‐fold fluorescence enhancement, resulting in brighter NIR‐II imaging for phantoms in vitro and in situ. Benefiting from the fluorescence enhancement, NIR‐II imaging with the nanoprobe is carried out to precisely delineate and resect tumors. Additionally, the nanoprobe is successfully applied in tumor PET imaging, showing the accumulation of the nanoprobe in a tumor with a clear contrast from 2 to 24 h postinjection. Overall, this hierarchically nanostructured platform is able to dramatically enhance fluorescent brightness of NIR‐II dye, detect tumors with NIR‐II/PET imaging, and guide intraoperative resection. The NIR‐II/PET bimodal nanoprobe has high potential for sensitive preoperative tumor diagnosis and precise intraoperative image‐guided surgery.     

High‐Resolution 3D NIR‐II Photoacoustic Imaging of Cerebral and Tumor Vasculatures Using Conjugated Polymer Nanoparticles as Contrast Agent

Exogenous contrast‐agent‐assisted NIR‐II optical‐resolution photoacoustic microscopy imaging (ORPAMI) holds promise to decipher wide‐field 3D biological structures with deep penetration, large signal‐to‐background ratio (SBR), and high maximum imaging depth to depth resolution ratio. Herein, NIR‐II conjugated polymer nanoparticle (CP NP) assisted ORPAMI is reported for pinpointing cerebral and tumor vasculatures. The CP NPs exhibit a large extinction coefficient of 48.1 L g^?1 at the absorption maximum of 1161 nm, with an ultrahigh PA sensitivity up to 2 µg mL^?1. 3D ORPAMI of wide‐field mice ear allows clear visualization of regular vasculatures with a resolution of 19.2 µm and an SBR of 29.3 dB at the maximal imaging depth of 539 µm. The margin of ear tumor composed of torsional dense vessels among surrounding normal regular vessels can be clearly delineated via 3D angiography. In addition, 3D whole‐cortex cerebral vasculatures with large imaging area (48 mm²), good resolution (25.4 µm), and high SBR (22.3 dB) at a depth up to 1001 µm are clearly resolved through the intact skull. These results are superior to the recently reported 3D NIR‐II fluorescence confocal vascular imaging, which opens up new opportunities for NIR‐II CP‐NP‐assisted ORPAMI in various biomedical applications.     

Through Scalp and Skull NIR‐II Photothermal Therapy of Deep Orthotopic Brain Tumors with Precise Photoacoustic Imaging Guidance

Brain tumor is one of the most lethal cancers owing to the existence of blood–brain barrier and blood–brain tumor barrier as well as the lack of highly effective brain tumor treatment paradigms. Herein, cyclo(Arg‐Gly‐Asp‐D‐Phe‐Lys(mpa)) decorated biocompatible and photostable conjugated polymer nanoparticles with strong absorption in the second near‐infrared (NIR‐II) window are developed for precise photoacoustic imaging and spatiotemporal photothermal therapy of brain tumor through scalp and skull. Evidenced by the higher efficiency to penetrate scalp and skull for 1064 nm laser as compared to common 808 nm laser, NIR‐II brain‐tumor photothermal therapy is highly effective. In addition, via a real‐time photoacoustic imaging system, the nanoparticles assist clear pinpointing of glioma at a depth of almost 3 mm through scalp and skull with an ultrahigh signal‐to‐background ratio of 90. After spatiotemporal photothermal treatment, the tumor progression is effectively inhibited and the survival spans of mice are significantly extended. This study demonstrates that NIR‐II conjugated polymer nanoparticles are promising for precise imaging and treatment of brain tumors.     

Molecular Cancer Imaging in the Second Near‐Infrared Window Using a Renal‐Excreted NIR‐II Fluorophore‐Peptide Probe

In vivo molecular imaging of tumors targeting a specific cancer cell marker is a promising strategy for cancer diagnosis and imaging guided surgery and therapy. While targeted imaging often relies on antibody‐modified probes, peptides can afford targeting probes with small sizes, high penetrating ability, and rapid excretion. Recently, in vivo fluorescence imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) shows promise in reaching sub‐centimeter depth with microscale resolution. Here, a novel peptide (named CP) conjugated NIR‐II fluorescent probe is reported for molecular tumor imaging targeting a tumor stem cell biomarker CD133. The click chemistry derived peptide‐dye (CP‐IRT dye) probe afforded efficient in vivo tumor targeting in mice with a high tumor‐to‐normal tissue signal ratio (T/NT > 8). Importantly, the CP‐IRT probes are rapidly renal excreted (≈87% excretion within 6 h), in stark contrast to accumulation in the liver for typical antibody‐dye probes. Further, with NIR‐II emitting CP‐IRT probes, urethra of mice can be imaged fluorescently for the first time noninvasively through intact tissue. The NIR‐II fluorescent, CD133 targeting imaging probes are potentially useful for human use in the clinic for cancer diagnosis and therapy.     

3D NIR‐II Molecular Imaging Distinguishes Targeted Organs with High‐Performance NIR‐II Bioconjugates

Greatly reduced scattering in the second near‐infrared (NIR‐II) region (1000–1700 nm) opens up many new exciting avenues of bioimaging research, yet NIR‐II fluorescence imaging is mostly implemented by using nontargeted fluorophores or wide‐field imaging setups, limiting the signal‐to‐background ratio and imaging penetration depth due to poor specific binding and out‐of‐focus signals. A newly developed high‐performance NIR‐II bioconjugate enables targeted imaging of a specific organ in the living body with high quality. Combined with a home‐built NIR‐II confocal set‐up, the enhanced imaging technique allows 900 µm‐deep 3D organ imaging without tissue clearing techniques. Bioconjugation of two hormones to nonoverlapping NIR‐II fluorophores facilitates two‐color imaging of different receptors, demonstrating unprecedented multicolor live molecular imaging across the NIR‐II window. This deep tissue imaging of specific receptors in live animals allows development of noninvasive molecular imaging of multifarious models of normal and neoplastic organs in vivo, beyond the traditional visible to NIR‐I range. The developed NIR‐II fluorescence microscopy will become a powerful imaging technique for deep tissue imaging without any physical sectioning or clearing treatment of the tissue.     

Repurposing Cyanine NIR‐I Dyes Accelerates Clinical Translation of Near‐Infrared‐II (NIR‐II) Bioimaging

The significantly reduced tissue autofluorescence and scattering in the NIR‐II region (1000–1700 nm) opens many exciting avenues for detailed investigation of biological processes in vivo. However, the existing NIR‐II fluorescent agents, including many molecular dyes and inorganic nanomaterials, are primarily focused on complicated synthesis routes and unknown immunogenic responses with limited potential for clinical translation. Herein, the >1000 nm tail emission of conventional biocompatible NIR cyanine dyes with emission peaks at 700–900 nm is systematically investigated, and a type of bright dye for NIR‐II imaging with high potential for accelerating clinical translation is identified. The asymmetry of the π domain in the S₁ state of NIR cyanine dyes is proven to result in a twisted intramolecular charge‐transfer process and NIR‐II emission, establishing a general rule to guide future NIR‐I/II fluorophore synthesis. The screened NIR dyes are identified to possess a bright emission tail in the NIR‐II region along with high quantum yield, high molar‐extinction coefficient, rapid fecal excretion, and functional groups amenable for bioconjugation. As a result, NIR cyanine dyes can be used for NIR‐II imaging to afford superior contrast and real‐time imaging of several biological models, facilitating the translation of NIR‐II bioimaging to clinical theranostic applications.     

Miniature Hollow Gold Nanorods with Enhanced Effect for In Vivo Photoacoustic Imaging in the NIR‐II Window

The miniaturization of gold nanorods exhibits a bright prospect for intravital photoacoustic imaging (PAI) and the hollow structure possesses a better plasmonic property. Herein, miniature hollow gold nanorods (M‐AuHNRs) (≈46 nm in length) possessing strong plasmonic absorbance in the second near‐infrared (NIR‐II) window (1000–1350 nm) are developed, which are considered as the most suitable range for the intravital PAI. The as‐prepared M‐AuHNRs exhibit 3.5 times stronger photoacoustic signal intensity than the large hollow Au nanorods (≈105 nm in length) at 0.2 optical density under 1064 nm laser irradiation. The in vivo biodistribution measurement shows that the accumulation in tumor of miniature nanorods is twofold as high as that of the large counterpart. After modifying with a tumor‐targeting molecule and fluorochrome, in living tumor‐bearing mice, the M‐AuHNRs group gives a high fluorescence intensity in tumors, which is 3.6‐fold that of the large ones with the same functionalization. Moreover, in the intravital PAI of living tumor‐bearing mice, the M‐AuHNRs generate longer‐lasting and stronger photoacoustic signal than the large counterpart in the NIR‐II window. Overall, this study presents the fabrication of M‐AuHNRs as a promising contrast agent for intravital PAI.     

NIR‐Responsive Polycationic Gatekeeper‐Cloaked Hetero‐Nanoparticles for Multimodal Imaging‐Guided Triple‐Combination Therapy of Cancer

Responsive multifunctional organic/inorganic nanohybrids are promising for effective and precise imaging‐guided therapy of cancer. In this work, a near‐infrared (NIR)‐triggered multifunctional nanoplatform comprising Au nanorods (Au NRs), mesoporous silica, quantum dots (QDs), and two‐armed ethanolamine‐modified poly(glycidyl methacrylate) with cyclodextrin cores (denoted as CD‐PGEA) has been successfully fabricated for multimodal imaging‐guided triple‐combination treatment of cancer. A hierarchical hetero‐structure is first constructed via integration of Au NRs with QDs through a mesoporous silica intermediate layer. The X‐ray opacity and photoacoustic (PA) property of Au NRs are utilized for tomography (CT) and PA imaging, and the imaging sensitivity is further enhanced by the fluorescent QDs. The mesoporous feature of silica allows the loading of a typical antitumor drug, doxorubicin (DOX), which are sealed by the polycationic gatekeepers, low toxic hydroxyl‐rich CD‐PGEA/pDNA complexes, realizing the co‐delivery of drug and gene. The photothermal effect of Au NRs is utilized for photothermal therapy (PTT). More interestingly, such photothermal effect also induces a cascade of NIR‐triggered release of DOX through the facilitated detachment of CD‐PGEA gatekeepers for controlled chemotherapy. The resultant chemotherapy and gene therapy for glioma tumors are complementary for the efficiency of PTT. This work presents a novel responsive multifunctional imaging‐guided therapy platform, which combines fluorescent/PA/CT imaging and gene/chemo/photothermal therapy into one nanostructure.     

Real‐Time and High‐Resolution Bioimaging with Bright Aggregation‐Induced Emission Dots in Short‐Wave Infrared Region

Fluorescence imaging in the spectral region beyond the conventional near‐infrared biological window (700–900 nm) can theoretically afford high resolution and deep tissue penetration. Although some efforts have been devoted to developing a short‐wave infrared (SWIR; 900–1700 nm) imaging modality in the past decade, long‐wavelength biomedical imaging is still suboptimal owing to the unsatisfactory materials properties of SWIR fluorophores. Taking advantage of organic dots based on an aggregation‐induced emission luminogen (AIEgen), herein microscopic vasculature imaging of brain and tumor is reported in living mice in the SWIR spectral region. The long‐wavelength emission of AIE dots with certain brightness facilitates resolving brain capillaries with high spatial resolution (≈3 µm) and deep penetration (800 µm). Owning to the deep penetration depth and real‐time imaging capability, in vivo SWIR microscopic angiography exhibits superior resolution in monitoring blood–brain barrier damage in mouse brain, and visualizing enhanced permeability and retention effect in tumor sites. Furthermore, the AIE dots show good biocompatibility, and no noticeable abnormalities, inflammations or lesions are observed in the main organs of the mice. This work will inspire new insights on development of advanced SWIR techniques for biomedical imaging.     

In Vivo Dynamic Monitoring of Bacterial Infection by NIR‐II Fluorescence Imaging

Time window of antibiotic administration is a critical but long‐neglected point in the treatment of bacterial infection, as unnecessary prolonged antibiotics are increasingly causing catastrophic drug‐resistance. Here, a second near‐infrared (NIR‐II) fluorescence imaging strategy based on lead sulfide quantum dots (PbS QDs) is presented to dynamically monitor bacterial infection in vivo in a real‐time manner. The prepared PbS QDs not only provide a low detection limit (10⁴ CFU mL^?1) of four typical bacteria strains in vitro but also show a particularly high labeling efficiency with Escherichia coli (E. coli). The NIR‐II in vivo imaging results reveal that the number of invading bacteria first decreases after post‐injection, then increases from 1 d to 1 week and drop again over time in infected mouse models. Meanwhile, there is a simultaneous variation of dendritic cells, neutrophils, macrophages, and CD8+ T lymphocytes against bacterial infection at the same time points. Notably, the infected mouse self‐heals eventually without antibiotic treatment, as a robust immune system can successfully prevent further health deterioration. The NIR‐II imaging approach enables real‐time monitoring of bacterial infection in vivo, thus facilitating spatiotemporal deciphering of time window for antibiotic treatment.     

Emitting/Sensitizing Ions Spatially Separated Lanthanide Nanocrystals for Visualizing Tumors Simultaneously through Up‐ and Down‐Conversion Near‐Infrared II Luminescence In Vivo

Near‐infrared lights have received increasing attention regarding imaging applications owing to their large tissue penetration depth, high spatial resolution, and outstanding signal‐to‐noise ratio, particularly those falling in the second near‐infrared window (NIR II) of biological tissues. Rare earth nanoparticles containing Er³⁺ ions are promising candidates to show up‐conversion luminescence in the first near‐infrared window (NIR I) and down‐conversion luminescence in NIR II as well. However, synthesizing particles with small size and high NIR II luminescence quantum yield (QY) remains challenging. Er³⁺ ions are herein innovatively combined with Yb³⁺ ions in a NaErF₄@NaYbF₄ core/shell manner instead of being codoped into NaLnF₄ matrices, to maximize the concentration of Er³⁺ in the emitting core. After further surface coating, NaErF₄@NaYbF₄@NaYF₄ core/shell/shell particles are obtained. Spectroscopy studies are carried out to show the synergistic impacts of the intermediate NaYbF₄ layer and the outer NaYF₄ shell. Finally, NaErF₄@NaYbF₄@NaYF₄ nanoparticles of 30 nm with NIR II luminescence QY up to 18.7% at room temperature are obtained. After covalently attaching folic acid on the particle surface, tumor‐specific nanoprobes are obtained for simultaneously visualizing both subcutaneous and intraperitoneal tumor xenografts in vivo. The ultrahigh QY of down‐conversion emission also allows for visualization of the biodistribution of folate receptors.     

The Nanoassembly of an Intrinsically Cytotoxic Near‐Infrared Dye for Multifunctionally Synergistic Theranostics

The combination of diagnostic and therapeutic functions in a single theranostic nanoagent generally requires the integration of multi‐ingredients. Herein, a cytotoxic near‐infrared (NIR) dye (IR‐797) and its nanoassembly are reported for multifunctional cancer theranostics. The hydrophobic IR‐797 molecules are self‐assembled into nanoparticles, which are further modified with an amphiphilic polymer (C18PMH‐PEG5000) on the surface. The prepared PEG‐IR‐797 nanoparticles (PEG‐IR‐797 NPs) possess inherent cytotoxicity from the IR‐797 dye and work as a chemotherapeutic drug which induces apoptosis of cancer cells. The IR‐797 NPs are found to have an ultrahigh mass extinction coefficient (444.3 L g^?1 cm^?1 at 797 nm and 385.9 L g^?1 cm^?1 at 808 nm) beyond all reported organic nanomaterials (<40 L g^?1 cm^?1) for superior photothermal therapy (PTT). In addition, IR‐797 shows some aggregation‐induced‐emission (AIE) properties. Combining the merits of good NIR absorption, high photothermal energy conversion efficiency, and AIE, makes the PEG‐IR‐797 NPs useful for multimodal NIR AIE fluorescence, photoacoustic, and thermal imaging‐guided therapy. The research exhibits the possibility of using a single ingredient and entity to perform multimodal NIR fluorescence, photoacoustic, and thermal imaging‐guided chemo‐/photothermal combination therapy, which may trigger wide interest from the fields of nanomedicine and medicinal chemistry to explore multifunctional theranostic organic molecules.     

Preoperative Detection and Intraoperative Visualization of Brain Tumors for More Precise Surgery: A New Dual‐Modality MRI and NIR Nanoprobe

In clinical practice, it is difficult to identify tumor margins during brain surgery due to its inherent infiltrative character. Herein, a unique dual‐modality nanoprobe (Gd‐DOTA‐Ag₂S QDs, referred as Gd‐Ag₂S nanoprobe) is reported, which integrates advantages of the deep tissue penetration of enhanced magnetic resonance (MR) imaging of Gd and the high signal‐to‐noise ratio and high spatiotemporal resolution of fluorescence imaging in the second near‐infrared window (NIR‐II) of Ag₂S quantum dots (QDs). Due to the abundant tumor angiogenesis and the enhanced permeability and retention effect in the tumor, a brain tumor (U87MG) in a mouse model is clearly delineated in situ with the help of the Gd assisted T1 MR imaging and the intraoperative resection of the tumor is precisely accomplished under the guidance of NIR‐II fluorescence imaging of Ag₂S QDs after intravenous injection of Gd‐Ag₂S nanoprobe. Additionally, no histologic changes are observed in the main organs of the mouse after administration of Gd‐Ag₂S nanoprobe for 1 month, indicating the high biocompatibility of the nanoprobe. We expect that such a novel “Detection and Operation” strategy based on Gd‐Ag₂S nanoprobe is promising in future clinical applications.     

Near‐Infrared‐II Molecular Dyes for Cancer Imaging and Surgery

Fluorescence bioimaging affords a vital tool for both researchers and surgeons to molecularly target a variety of biological tissues and processes. This review focuses on summarizing organic dyes emitting at a biological transparency window termed the near‐infrared‐II (NIR‐II) window, where minimal light interaction with the surrounding tissues allows photons to travel nearly unperturbed throughout the body. NIR‐II fluorescence imaging overcomes the penetration/contrast bottleneck of imaging in the visible region, making it a remarkable modality for early diagnosis of cancer and highly sensitive tumor surgery. Due to their convenient bioconjugation with peptides/antibodies, NIR‐II molecular dyes are desirable candidates for targeted cancer imaging, significantly overcoming the autofluorescence/scattering issues for deep tissue molecular imaging. To promote the clinical translation of NIR‐II bioimaging, advancements in the high‐performance small molecule–derived probes are critically important. Here, molecules with clinical potential for NIR‐II imaging are discussed, summarizing the synthesis and chemical structures of NIR‐II dyes, chemical and optical properties of NIR‐II dyes, bioconjugation and biological behavior of NIR‐II dyes, whole body imaging with NIR‐II dyes for cancer detection and surgery, as well as NIR‐II fluorescence microscopy imaging. A key perspective on the direction of NIR‐II molecular dyes for cancer imaging and surgery is also discussed.     

Corannulene‐Incorporated AIE Nanodots with Highly Suppressed Nonradiative Decay for Boosted Cancer Phototheranostics In Vivo

Fluorescent nanoparticles (NPs) based on luminogens with aggregation‐induced emission characteristic (AIEgens), namely AIE dots, have received wide attention because of their antiquenching attitude in emission and reactive oxygen species (ROS) generation when aggregated. However, few reports are available on how to control and optimize their fluorescence and ROS generation ability. Herein, it is reported that enhancing the intraparticle confined microenvironment is an effective approach to advanced AIE dots, permitting boosted cancer phototheranostics in vivo. Formulation of a “rotor‐rich” and inherently charged near‐infrared (NIR) AIEgen with 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐[methoxy(polyethylene glycol)‐2000] and corannulene‐decorated PEG affords DSPE‐AIE dots and Cor‐AIE dots, respectively. Compared to DSPE‐AIE dots, Cor‐AIE dots show 4.0‐fold amplified fluorescence quantum yield and 5.4‐fold enhanced ROS production, because corannulene provides intraparticle rigidity and strong interactions with the AIEgen to restrict the intramolecular rotation of AIEgen to strongly suppress the nonradiative decay and significantly facilitate the fluorescence pathway and intersystem crossing. Thus, it tremendously promotes phototheranostic efficacies in terms of NIR image‐guided cancer surgery and photodynamic therapy using a peritoneal carcinomatosis‐bearing mouse model. Collectively, it not only provides a novel strategy to advanced AIE dots for cancer phototheranostics, but also brings new insights into the design of superior fluorescent NPs for biomedical applications.     

Visible to Near‐Infrared Fluorescence Enhanced Cellular Imaging on Plasmonic Gold Chips

Rapid and sensitive detections of a variety of surface and intracellular proteins, nucleic acids, and other cellular biomarkers are important to elucidating biological signaling pathways and to devising disease diagnostics and therapeutics. Here, sensitive imaging and detection of cellular proteins on fluorescence‐enhancing, nanostructured plasmonic gold (pGold) chips is presented. Imaging of fluorescently labeled cellular biomarkers on pGold is enhanced by 2–30‐fold in the visible to near infrared (NIR) range of ≈500–900 nm. The high fluorescence enhancement of >700 nm significantly improves the dynamic range and signal/background ratios of NIR imaging, allowing high‐performance multicolor imaging in the visible–NIR range using high quantum yield (QY) visible dyes and lower QY NIR fluorophores. Further, multiple cellular proteins of single cells of various cell types can be detected through microarraying of cells, useful for potentially hundreds and thousands different types of cells assayed on a single chip down to small cell numbers. This work suggests a simple, high throughput, high sensitivity, and multiplexed single‐cell analysis method on fluorescence enhancing plasmonic substrates in the entire visible to NIR window.